Pseudomonas aeruginosa (ATCC 31480)
Pseudomonas aeruginosa (ATCC 700370)
Pseudomonas aeruginosa (ATCC 700371)
Table of Contents
- 1. Hazard Assessment
- 2. Exposure Assessment
- 3. Risk Characterisation
- 4. Conclusion
- 5. References
- Appendix 1A: Characteristics of DSL-listed P. aeruginosa strains – Growth Rate in Trypticase Soy Broth 36
- Appendix 1B: Characteristics of DSL-listed P. aeruginosa strains - Growth on Different Media at 28°C and 37°C
- Appendix 1C: Characteristics of DSL-listed P. aeruginosa strains – Fatty Acid Methyl Ester (FAME) Analysis
- Appendix 2: List of some Pseudomonas aeruginosa mobile elements and associated traits
- Appendix 3: List of toxins produced by P. aeruginosa
- Appendix 4: LD50 values for P. aeruginosa and its toxins
- Appendix 5A: Pathogenicity/toxicity to plants, invertebrates and vertebrates (controlled studies)
- Appendix 5B: Pathogenicity/toxicity to vertebrates in natural settings
- Appendix 6: Selected outbreaks caused by P. aeruginosa reported in the literature
- Appendix 7: Considerations for Levels of Hazard Severity, Exposure and Risk as per Health Canada and Environment Canada’s “Framework for Science-Based Risk Assessment of Micro-organisms regulated under the Canadian Environmental Protection Act, 1999”
Pursuant to paragraph 74(b) of the Canadian Environmental Protection Act, 1999 (CEPA 1999), the Ministers of Environment and of Health have conducted a screening assessment on three strains of Pseudomonas aeruginosa(ATCCstrains 31480, 700370 and 700371). These strains are listed on the Domestic Substances List (DSL) thus indicating that they were added to the DSL under Section 105 of CEPA 1999 because they were manufactured or imported into Canada between January 1, 1984 and December 31, 1986 and they entered or were released to the environment without being subject to conditions under CEPA 1999 or any other federal or provincial legislation.
The species Pseudomonas aeruginosa is generally considered a ubiquitous bacterium, occurring naturally in many environmental media; P. aeruginosa is probably one of the most widespread of all bacterial species. It has the ability to adapt to and thrive in many ecological niches especially those that are moist. The species possesses characteristics that allow for multiple potential uses in various industrial and commercial sectors. These include waste degradation (particularly in oil refineries), textile, pulp and paper, mining and explosives industries, as well as in commercial and household drain cleaners and degreasers, septic tank additives and general cleaning products and odour control products.
P. aeruginosa is recognized as a Risk Group 2 pathogen by the Canadian Food Inspection Agency (Animal Pathogen Import Program), and requires a permit in order to be imported to Canada. Generally, Risk Group 2 pathogens are any pathogens that can cause disease but, under normal circumstances, are unlikely to be a serious risk to healthy organisms in the environment. If needed, effective treatment and preventive measures are available, and the risk of spread is limited.
Information from the scientific literature indicates that this micro-organism has pathogenic potential in both otherwise healthy and immunocompromised humans. P. aeruginosa is recognized by the Public Health Agency of Canada as a Risk Group 2 human pathogen. It has the ability to spread and acquire antibiotic resistance genes which may compromise the effectiveness of antibiotics that are currently used for the treatment of P. aeruginosa infections. P. aeruginosa produces a wide variety of extracellular enzymes and toxins that are important factors for its pathogenicity in susceptible humans.
To establish whether living organisms on the DSL continue to be manufactured in or imported into Canada, a notice was issued pursuant to paragraph 71(1)(a) of the CEPA 1999. There were no reports of industrial activity (import or manufacture) with respect to these substances in Canada for the specified reporting year of 2008. These results indicate that in 2008, the three DSL-listed strains of P. aeruginosa (31480, 700370 and 700371) were not imported or manufactured and therefore the likelihood of exposure to these substances in Canada resulting from commercial activity is low.
Based on available information, and until new information is received indicating that these substances are entering, or may enter, the environment from commercial activity or from other anthropogenic sources, it is proposed that the above substances are currently not entering or likely to enter the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity or constitute a danger to the environment on which life depends or that constitute a danger in Canada to human life or health. Therefore, it is proposed that these substances do not meet any of the criteria as set out in section 64 of CEPA 1999.
However, should exposure increase through new activities, there is a potential risk to human health and the environment based on the pathogenicity and toxicity of P. aeruginosa to susceptible humans and non-human species. Therefore, there is concern that new activities for the above substances which have not been identified or assessed under CEPA 1999 could lead to the substances meeting the criteria as set out in section 64 of the Act. Therefore, it is recommended that the above substances be subject to the Significant New Activity provisions specified under subsection 106(3) of the Act, to ensure that any new manufacture, import or use of these substances will undergo ecological and human health assessments as specified in section 108 of the Act, prior to the substances being considered for introduction into Canada.
Pursuant to paragraph 74(b) of the Canadian Environmental Protection Act, 1999 (CEPA 1999), the Ministers of Environment and of Health are required to conduct screening assessments of those living organisms listed on the Domestic Substances List (DSL) to determine whether they present or may present a risk to the environment or human health (according to criteria as set out in section 64 of CEPA 1999). These living organisms were nominated and added under the DSL under Section 105 of CEPA 1999 because they were manufactured or imported into Canada between January 1, 1984 and December 31, 1986 and they entered or were released into the environment without being subject to conditions under CEPA 1999 or any other federal or provincial legislation.
Screening assessments examine scientific information and develop conclusions by incorporating a weight-of-evidence approach and precaution. This screening assessment considered hazard information obtained from the public domain as well as from unpublished research data and from internal and external experts. Exposure information was also obtained from the public domain as well as information from a mandatory CEPA 1999 s. 71 Notice published in the Canada Gazette Part 1 on October 3, 2009. Further details on the risk assessment methodology used are available in the Risk Assessment Framework document titled “Framework on the Science-Based Risk Assessment of Micro-organisms under the Canadian Environmental Protection Act, 1999”.
Data that are specific to the three DSL-listed P. aeruginosa strains (ATCC 31480, ATCC700370, ATCC 700371) are identified as such. Where data concerning the three particular strains were not available, surrogate information from literature searches of both P. aeruginosa and the genus Pseudomonas was used. Surrogate organisms are identified in each case to the taxonomic level provided by the source. Information identified as of June 2010 was considered for inclusion in this report.
A hazard assessment characterizes the micro-organism (Section 1.1) and identifies the potential adverse effects on the environment and/or human health and the extent and duration of these effects (Section 1.2). The hazards may be posed by the micro-organism itself, its genetic material or its toxins, metabolites or structural components.
The accurate taxonomic identification of a micro-organism is essential in distinguishing pathogenic from non-pathogenic species and strains. A polyphasic approach combining classical microbiological methods relying on a mixture of traditional tools (such as culture-based methods) and molecular tools (such as genotyping and fatty acids analysis) is often required.
Pseudomonas aeruginosa is a Gram-negative, motile, rod-shaped bacterium. Information regarding colony morphology of the DSL-listed P. aeruginosa strains and ATCC 31479, the parental strain of ATCC 31480, is outlined in Table 1.
Table 1: Selected colony morphology of ATCC strains 31479, 31480, 700370 and 700371
|ATCC #||Shape||Size (mm) Diameter||Margin||Elevation||Colour||Opacity||Pigment|
|31479[*]||slightly irregular||3-6||wrinkled-undulate||flat||white||slightly opaque||fluorescent yellow|
|31480[†]||circular||10||undulate||raised||off-white/ colourless||opaque||diffusible green-blue|
|700370[†]||circular||8||entire-undulate||raised - slightly umbonate||tan–gold||opaque with translucent rings||diffusing green|
|700371[†]||irregular||6||entire-undulate||raised||off-white/light beige||semi-translucent||colourless translucent material that extends beyond the described colony|
[†] Data generated by Health Canada’s Healthy Environments and Consumer Safety Branch. Refer to Appendix 1B for a summary of the three DSL-listed strains’ growth kinetics on different media at 28°C and 37°C.
Table 2 outlines various aspects of taxonomic identification and strain history for DSL-listed P. aeruginosa strains ATCC 31480, ATCC700370 and ATCC 700371. Strain HCP (ATCC 31479) is the parent strain that was chemically mutated to generate strain ATCC31480. BIOLOG and API were used to identify the strains as P. aeruginosa. These approaches provided consistent results for the biochemical identification of various P. aeruginosaisolates based on the results generated from Health Canada’s Double Blind International Cooperative Study for the Identification of Pseudomonas Species (Micah Krichevsky, personal communication, 2010).
Additional data generated by Health Canada on growth kinetics at different temperatures (Appendix 1A), growth on different media at 28ºC and 37ºC (Appendix 1B) and fatty acid methyl-ester (FAME) analysis (Appendix 1C), provided further confirmation of the identification. It should be noted that these techniques can not be used to differentiate the DSL-listed strains from other P. aeruginosa strains.
Table 2: Taxonomic identification and strain history
|Identification Method||ND||BIOLOG, FAME[x]and AFLP marker[†]||BIOLOG, FAME[x]and API||BIOLOG, and FAME[x]|
|Original Source||soil from Salem, Virginia, USA||mutant of parent strain ATCC 31479||environment||environment|
|Isolated for:||N/A||its synergistic activity with other bacteria in degradation of oleaginous materials in wastewater||biodegradation properties||oxidation properties|
|Modifications||N/A||mutated from the parent strain ATCC 31479 using 0.2% 8-azaguanine in a bench-top biotower; selective pressure from pentachlorophenol||none||none|
N/A not applicable
[*] Obtained from Spraker, 1981 and DSL Nomination Form B (confidential business information)
[x] FAME data was generated by Health Canada’s Healthy Environments and Consumer Safety Branch (see Appendix 1C)
[†] Generated by Environment Canada (Xiang et al., 2010)
Genotypic methods, such as full genomic sequencing (Stover et al., 2000)(Ivanova et al. 2003), multi-locus sequence typing (MLST) (Khan et al., 2008; Curran et al., 2004), and terminal restriction fragment length polymorphism (T-RFLP) profiling of the 16S–23S rRNA internal transcribed spacer (ITS1) gene region (Spasenovski et al., 2009) have been extensively used to demonstrate the phylogenetic relationships and the genomic variations among clinical and environmental isolates of P. aeruginosa. 16S rDNA sequence analyses of the three DSL P. aeruginosastrains, conducted by Health Canada, have shown greater than 99% homology (less than 10 base pairs difference) compared to other P. aeruginosaisolates on the proprietary MicroSeq ® ID library (ATCC 10145, ATCC27853, ATCC 25619). This data set shows that the 16S rDNA from test DSL strains in this study have been matched at the level of genus and species. DSL P. aeruginosa 16S rDNA sequences also show high similarity when compared to published P. aeruginosa sequences in NCBI-Blast (National Center for Biotechnology Information- Basic Local Alignment Search Tool).
Studies have suggested that some P. aeruginosa clinical isolates are phenotypically, genotypically, chemotaxonomically and functionally indistinguishable from environmental isolates, such as the three DSL-listed strains. Römling et al. (1994) reported that a clone frequently isolated from cystic fibrosis patients was also detected at a high frequency in aquatic environments, and Alonso et al. (1999) reported that both oil-contaminated soil isolates and clinical isolates of P. aeruginosa show pathogenic and biodegradative properties. Wolfgang et al. (2003) reported that the genomes of P. aeruginosa strains, representing distinct clinical or environmental sources, are highly conserved. The genome size of P. aeruginosa is approximately 6.3 Mb (Stover et al., 2000); the isolates from cystic fibrosis patients and the environmental strains share more than 80% of this genome sequence (Spencer et al., 2004). The remarkable conservation of genes encoding proteins associated with virulence suggests that most P. aeruginosa strains, regardless of source, possess the same basic pathogenic mechanisms necessary to cause a wide variety of infections.
Horizontal gene transfer has been recognized as one of the major mechanisms driving the evolution of micro-organisms and plays a key role in their ability to adapt to various environments through acquisition of new traits. Studies of several strains of P. aeruginosa, using various hybridization methods or comparison of sequenced genomes, pointed towards the acquisition and exchange of genetic material as an important factor in the genomic diversity and evolution of the species (Kulasekara and Lory, 2004).
The mosaic structure of the P. aeruginosa genome is believed to be the result of multiple acquisitions from different donors during its evolution (Kulasekara and Lory, 2004). Other evidence of horizontal gene transfer includes the presence of genes or remnants of genes associated with mobile elements (i.e., insertion sequences, bacteriophages or plasmids) and the presence of numerous genomic islands (Kulasekara and Lory, 2004), which are horizontally acquired clusters of genes. P. aeruginosagenomic islands have been found to possess genes encoding factors that are involved in genetic mobility and in various virulence traits such as iron uptake functions, antibiotic resistance, biofilm synthesis, type III secretion systems, toxins and adhesins that augment the ability of pathogens to survive in diverse hosts and cause disease (Qui et al., 2009; Kulasekara and Lory, 2004).
The genomes of all P. aeruginosa strains sequenced to date contain a significant fraction of these genomic islands. Different genes carried by a single island often have diverse origins, and blocks are built gradually through insertion and deletion events (He et al., 2004). For example, the well characterized P. aeruginosa genomic island PAPI-1 contains genes that have a high level of similarity with plant pathogens such as Xylella fastidiosa, Agrobacterium tumefaciens, P. syringae and Xanthomonas campestris (Ramos, 2004).
Genetic exchange by conjugation has been observed in clinical and environmental strains of P. aeruginosa (Kidambi et al., 1994; Klockgether et al., 2004; Malloff et al., 2001; Poirel et al., 2004; Yu & Head, 2002), and in freshwater (O’Morchoe et al., 1988). PAPI-1, which encodes a number of virulence factors involved in attachment, biofilm synthesis and antibiotic resistance, was reported to have been transferred by conjugation into recipient P. aeruginosa strains (Qui et al., 2006).
Transduction is another important mechanism of gene transfer for P. aeruginosa. P. aeruginosa bacteriophages were shown to be formidable transducers of naturally occurring microbial communities. For instance, Ripp et al. (1994) reported that phage UT1 is capable of mediating transfer of both chromosomal and plasmid DNA between strains of P. aeruginosa and between P. aeruginosa and indigenous populations of micro-organisms in natural lake water environments.
The impact of gene transfer among P. aeruginosa strains has been demonstrated by their ability to adapt in different niches, their ability to infect a broad range of host organisms, and, most dramatically, by the rapid emergence and dissemination of multiple-antibiotic resistance genes (Blahova et al.,1998; Harrison et al., 2010; He et al., 2004).
The ability of P. aeruginosa to produce infections (pathogenicity) in both human and non-human species is attributed to a wide array of mechanisms, including adherence, invasion, evasion of host defences and damage to host cells (Salyers and Whitt, 2002).
The first step in the pathogenic sequence of P. aeruginosa animal infections is colonization of an epithelial surface using specific adhesins, in order to initiate contact with biological surfaces. Adherence of non-mucoid P. aeruginosato mammalian epithelial cells is mainly mediated by type IV pili which account for 90% of the adherence capacity. In cystic fibrosis patients, P. aeruginosa also binds with mucin which is the main component of the mucus that forms a viscous gel and traps inhaled particles on the airway epithelium (Ramos, 2004).
After the initial step of mammalian colonization, P. aeruginosa produces several extracellular products that can damage tissue and permit dissemination through the bloodstream (toxigenicity). Refer to Appendix 3 for more comprehensive information on these toxins.
Many pathogens, including P. aeruginosa, couple the production of virulence factors with bacterial cell population density to overcome host defences with a consolidated attack. This strategy depends on the ability of an individual bacterial cell to sense other bacterial cells and in response, differentially express specific sets of genes. Such cell-cell communication is called quorum sensing (QS). Production of several of the P. aeruginosa extracellular toxins described in Appendix 3 is coordinated by QS. QS systems in most Gram-negative bacteria function similarly, with an inducer (I) responsible for the biosynthesis of a specific acylated homoserine lactone (HSL) signaling molecule known as the autoinducer. The autoinducer concentration increases with increasing cell density. A receptor (R) binds its cognate autoinducer, forming a complex that activates target gene transcription, thus enabling coordinated expression of genes as a function of cell density. P. aeruginosa employs two dominant QS systems, LasI/LasR and RhlI/RhlR, which function in tandem to control the expression of a number of virulence genes. The LasI/LasR regulates the production of a number of secreted virulence factors responsible for host tissue destruction during the initiation of the infectious process. These include alkaline protease, LasA, LasB and exotoxin A. The LasR/autoinducer complex also activates LasI expression (creating a positive feedback loop) and it activates the second QS system, RhlI/RhlR. The RhlI/RhlR system, in addition to Las A and B, also regulates the production of rhamnolipid and is necessary for optimal production of pyocyanin, cyanide, lipase and alkaline protease (Lazdunski et al., 2004).
Quorum sensing is also important for proper biofilm development. P. aeruginosa readily forms biofilms on biological and abiotic surfaces. Biofilm cells differ from their planktonic counterparts in the genes and proteins that they express, resulting in distinct phenotypes including altered resistance to disinfectants, antibiotics and the human immune system. These cells have been shown to contribute to the persistence of infections and to be up to 1,000 times more resistant to the effects of antimicrobial agents than their planktonic counterparts (Costerton et al., 1999; Mah et al., 2001). Biofilms develop preferentially on inert surfaces, commonly on medical devices and fragments of dead tissue, but they can also form on living tissues (Costerton et al., 1999).
Due to its huge arsenal of metabolic capabilities and ability to exploit many possible nutrients in the environment, P. aeruginosa is often utilized for biodegradation. However, some of the metabolic pathways which allow P. aeruginosa to acquire nutrients, produce compounds, and thrive in the environment have also been linked to its pathogenicity. The ability of P. aeruginosa to obtain nutrients for replication and maintenance is the quintessential factor leading to quorum-sensing-induced virulence expression. Son et al. (2007) identified metabolic pathways which allow P. aeruginosa to degrade amino acids and metabolize lung surfactant lipids as nutrient sources in the lungs of cystic fibrosis patients.
Also involved in P. aeruginosa virulence are signal transduction systems. These are complex signalling systems responsible for eliciting adaptive responses by readily detecting fluctuations in many chemical and physical conditions, which in turn trigger changes in gene expression. P. aeruginosa has an extraordinary number of putative two-component signal transduction systems. It was predicted from the genome sequence analysis that 8.4% of P. aeruginosa genes are involved in regulation. Known two-component regulatory systems in P. aeruginosa have been involved in alginate production, chemotaxis, catabolism of natural substrates, membrane permeability, motility, antibiotic resistance, adhesion, and toxin production (Wang et al., 2003; Richtings et al., 1995; Whitchurch et al., 2004; Yu et al., 1997; Goodman et al., 2004).
Bacteria which cause infection in mammals survive and proliferate most effectively between 20°C and 40°C. The ability of P. aeruginosa to grow optimally at normal body temperature (37°C) also contributes to the extensive incidence of P. aeruginosa infection reported in humans.
P. aeruginosa is a facultative anaerobe that preferentially obtains its energy via aerobic respiration, but it is well adapted to conditions of limited O2 supply (Palleroni, 1984; Davies et al., 1989).The micro-organism grows optimally at 37ºC and thrives under moist conditions in soil (particularly in association with plants) and in sewage sediments and the aquatic environments (OECD, 1997). It can survive temperatures ranging from 10ºC to 45ºC in both saline and distilled water (Boyle et al., 1991; Garrity 2005; Oberhofer, 1981) and on media pH ranging between 6.0 to 9.0 (Rahman et al., 2005).
P. aeruginosa can use a wide range of organic compounds as a food source, and therefore can adapt to and thrive in many ecological niches including soil, water [river water (Pellett et al., 1983), sea water (Kimata et al., 2004), waste water (Ziegert and Stelzer, 1986)], sediments (Burton et al., 1987), sewage (Havelaar et al., 1985), and oil fields (MacElwee et al., 1990). It has been found to survive in soil and water for periods ranging from 2 to 18 weeks or as long as 4 years if the cells are encapsulated (Ahn et al., 2001; Cassidy et al., 1995; Cassidy et al., 1997; Cornax et al., 1990; Flemming et al., 1994). P. aeruginosa has also been shown to survive in the wheat rhizosphere in the presence of different levels of microbial competition (Morales et al., 1996). It is among the most commonly isolated micro-organisms naturally occurring in petroleum-contaminated soils and groundwater (Ridgway et al., 1990). It is also oligocarbotolerant and can multiply in nutrient-poor environments such as bottled water (Jayasekara et al., 1998; Hunter, 1993). In addition, P. aeruginosa can be found as part of the normal bacterial flora of the intestines, mouth or skin of animals such as cattle, dogs, horses and pigs (OECD, 1997).
Encapsulation and biofilm formation further enhance the ability of the organism to survive in natural and engineered environments (grease traps, water pipes and sewage drain surfaces). The ability of Pseudomonas biofilms to withstand moderate chlorine residuals has lead to the survival of the micro-organism in some water treatment systems (Grobe et al., 2001; Ratnam et al., 1986). According to Teitzel and Parsek (2003), biofilms were observed to be more resistant to heavy metals than planktonic cells in stationary phase or logarithmic growth. The formation of biofilms impedes efforts to control biofouling in a wide variety of industrial settings (Costerton, 2002; Cochran et al., 2000).
P. aeruginosa has been described as an opportunistic pathogen of plants (Bradbury, 1986) and is recognized as a Risk Group 2 pathogen by the Canadian Food Inspection Agency (Animal Pathogen Import Program). Generally, a Risk Group 2 pathogen is any pathogen that can cause disease but, under normal circumstances, is unlikely to be a serious hazard to healthy organisms in the environment. If needed, effective treatment and preventive measures are available, and the risk of spread is limited. A number of pathogenicity/toxicity studies used P. aeruginosa (or its isolated toxins) in a variety of hosts, including plants, invertebrates and vertebrates (Appendix 4, 5A and 5B). A literature search revealed two cases where P. aeruginosa was identified as the causative agent in a naturally-occurring infection in an agricultural setting (Appendix 5B). P. aeruginosa was isolated from infections in four other veterinary cases, but was not definitively shown to be the causative agent. In susceptible plants, P. aeruginosacauses a soft rot that can kill the host; in infected mammals, symptoms can range widely including sepsis, inflammation and pneumonia depending on the site of infection. If the site is a critical body organ such as the lungs or kidneys, the results can be fatal. Many studies have verified that P. aeruginosacan behave as an opportunistic pathogen in a range of plants, invertebrates and vertebrates, for example, when the host has been stressed or weakened by another factor. However, in the absence of such stressors or factors, infection will not occur. In addition, there was no evidence in the scientific literature to suggest any adverse ecological effects at the population level.
As shown in Appendix 5A, results of pathogenicity and chronic toxicity testing with these strains towards the following terrestrial invertebrates: Folsomia candida (P. aeruginosa 31480, 700370, and 700371), Folsomia fimetara (P. aeruginosa 31480, 700370, and 700371) and Eisenia andrei (P. aeruginosa 31480), demonstrated no adverse effect on adult mortality or juvenile reproduction of these springtails and earthworm species (Princz, 2010). Definitive plant testing using barley (Hordeum vulgare with P. aeruginosa 700370), red fescue (Festuca rubra with P. aeruginosa 31480), red clover (Trifolium pratense with P. aeruginosa31480 and 700371) and northern wheatgrass (Elymus lanceolatus with P. aeruginosa 700371) demonstrated no adverse effect on seedling emergence, shoot and root length and dry mass (Princz, 2010) when tested according to the “Guidance Document for Testing the Pathogenicity and Toxicity of New Microbial Substances to Aquatic and Terrestrial Organisms (EPS 1/RM/44, March 2004)”, developed by Environment Canada.
There is little evidence to demonstrate that environmental P. aeruginosa isolates differ in pathogenicity from clinical isolates, and as indicated in Section 1.1.1, there are studies which show that some P. aeruginosa environmental isolates are indistinguishable from clinical strains, and that many clinical strains are also isolated from the environment. Therefore, in the absence of strain-specific evidence, surrogate information used to characterize the potential human health hazard from the DSL-listed P. aeruginosa strains will include environmental isolates.
Extensive literature searches show that P. aeruginosais essentially an opportunistic pathogen. As such, to initiate infection, P. aeruginosa usually requires a substantial break in first-line defences. Such a break can result from breach or bypass of cutaneous or mucosal barriers (e.g., trauma, surgery, serious burns, indwelling devices, mucosal clearance defects from cystic fibrosis), disruption of the protective balance of normal mucosal flora by broadspectrum antibiotics, or alteration of the immunologic defence mechanisms (e.g., in chemotherapy-induced neutropenia or AIDS), and co-morbidity (diabetes mellitus, heart disease, etc.). P. aeruginosa is associated with numerous chronic and progressive respiratory diseases. It is responsible for life-threatening nosocomial infections and infections in immunocompromised individuals. It has also been implicated in localized and systemic infections in otherwise healthy individuals. Numerous P. aeruginosa outbreaks have been reported worldwide (Appendix 6).
Respiratory infections caused by P. aeruginosa occur almost exclusively in individuals with a compromised respiratory tract. It has been reported as the causative pathogen in mechanically ventilated patients (Brewer et al., 1996; Dunn & Wunderink, 1995, Nag et al., 2005), and acute and chronic sinusitis (Bert & Lambert-Zechovcky, 1996; Danielides et al., 2002; Farr & Ramadan, 1993; Koltai et al., 1985; O’Donnell et al., 1993; Suzuki et al., 1996; Guss et al., 2009). P. aeruginosa is the leading cause of morbidity and mortality in children and adults with Cystic Fibrosis (CF) (Govan & Deretic, 1996; Moss, 1995; Pier, 2000; Speert, 2002; Yu & Head, 2002). CF is a disease caused by an inherited genetic defect. According to the Canadian Cystic Fibrosis Foundation, approximately 3,500 children, adolescents, and adults with cystic fibrosis attend specialized CF clinics. CF leads to changes in the bronchial mucosa that normally prevents microbial infection (Pier, 2000). These changes limit physio-chemical mechanisms that remove excess mucus and debris (e.g., cellular debris, microbes, etc.) from the airways (Govan and Deretic, 1996), permitting repeated microbial colonization of the major airways and pulmonary infections. Most CF patients are ultimately infected with P. aeruginosa. In 2002 it was reported that by the time CF patients reach adulthood, approximately 80% are chronically infected with P. aeruginosa (Speert, 2002), which takes advantage of the highly compartmentalized and anatomically deteriorating lung environment and resists the challenges of the immune defence and antibiotic therapy (Oliver et al., 2000). Recent studies have shown that early aggressive eradication therapy with colistin and ciprofloxacin for intermittent P. aeruginosa airway colonization in cystic fibrosis patients postpones the next occurrence of P. aeruginosa compared to no treatment, and protects up to 80% of patients from development of chronic infection for up to 15 years (Hansel et al., 2008).
Chronic airway infections with P. aeruginosa are regularly seen in patients with advanced stages of chronic obstructive pulmonary disease (COPD). About 15% of the population in North America and Europe are affected by COPD. Intermittent colonization with P. aeruginosa is observed in about 30% of patients with COPD. Chronic airway infections with P. aeruginosa with substantial morbidity and mortality emerge in 5% of COPD patients (Murphy, 2009).
P. aeruginosa also has the ability to cause life-threatening community-acquired or nosocomial infections. The micro-organism is the third leading cause of hospital-acquired urinary tract infections, accounting for about 12 percent of all infections of this type (Pollack, 1995; Shigemura et al., 2009). These infections are commonly related to urinary tract catheterization, instrumentation or surgery. Endocarditis due to P. aeruginosa has been seen in patients with prosthetic heart valves (Wieland, 1986; Kato et al., 2009). In rare cases, it has been associated with meningitis or brain abscess (Pollack, 1992; Huang et al., 2007). P. aeruginosa accounts for 8% of wound infections, including burns (Kluytmans, 1997). According to Kluytmans (1997), in burn patients P. aeruginosa bacteremia has declined as a result of better wound treatment and removal of raw vegetables, which can be contaminated with P. aeruginosa, from the diet. However, P. aeruginosa outbreaks in burn units are associated with high (60%) death rates (Richard et al., 1994). P. aeruginosa is a frequent isolate from wounds, particularly those contaminated with soil, plant material or water. Puncture wounds, particularly those penetrating the bone, may result in osteomyelitis or osteochondritis. The former is common in intravenous drug abusers (Arstenstein & Cross, 1993) and the latter in puncture wounds to the feet in children and diabetics (Jarvis & Skipper, 1994; Lavery et al., 1994; Pollack, 1992; Hartemann-Heurtier & Senneville, 2008).
In individuals with severe immunodeficiencies, such as AIDS, cancer, and bone marrow transplant patients, P. aeruginosaappears to be the major cause of bacteremia (Mendelsen et al., 1994; Manfredi et al., 2000; Saghir et al., 2009). Patients being treated for cancer and people living with AIDSare also at greater risk of acquiring P. aeruginosapneumonia (Krcmery et al., 2006).
P. aeruginosa has also been associated with a variety of localized skin, ear and eye infections in otherwise healthy individuals (Hatchette et al., 2000; Hendersen et al., 1992, Huang et al., 2002; Parkin et al., 1997; Viola et al., 2006). Moisture is a common factor in these infections and consequently infection occurs primarily in moist areas such as the ear, the toe webs, the perineal region, under the diapers of infants, and the skin of whirlpool and hot tub users. Otorhinolaryngologic infections due to P. aeruginosa range from superficial and self-limiting to life-threatening. The most serious ear infection due to this organism is malignant otitis externa, usually resulting from a failure of topical therapy, and resulting in an invasive disease destroying tissue which may progress to osteomyelitis at the base of the skull and possible cranial nerve abnormalities (Arstenstein & Cross, 1993). Other ear infections associated with P. aeruginosa include external otitis, otitis media, chronic suppurative otitis media, and mastoiditis (Arstenstein & Cross, 1993; Kenna, 1994; Legent et al., 1994; Pollack, 1992). P. aeruginosa has also been implicated in folliculitis and unmanageable forms of acne vulgaris. Eye infections attributed to P. aeruginosa are frequently associated with contact lens use. Contaminated contact lens solution and the use of tap water during lens care have been implicated as a source of P. aeruginosa infection (Holland et al., 1993).
All micro-organisms are considered to be potential sensitizers, though to date, no P. aeruginosa isolates have been described as allergens. As do all Gram negative bacteria, Pseudomonads possess endotoxin (i.e., lipopolysaccharides), which may cause an innate febrile immune response on exposure (Schroeder et al., 2002).
Treatment of human infection with P. aeruginosa is hampered by its ability to readily acquire resistance to antimicrobial drugs. Extensive use of antibiotics to treat P. aeruginosa, particularly in CF patients, has exerted the selective pressure to encourage resistance development. P. aeruginosa displays highlevel multiple intrinsic resistance to a variety of structurally unrelated and clinically important antimicrobial agents, which greatly complicates the clinical management of infected patients. These include ampicillin, amoxicillin-clavulanic acid, ampicillin-sulbactam, tetracyclines, macrolides, rifampin, chloramphenicol, trimethoprim/sulfamethoxazole, narrow- and extended-spectrum cephalosporins, and oral-broad spectrum cephalosporins (cefixime and cefpodoxime) (Kiska & Gilligan, 1999). Table 3 represents an antibiogram generated by Health Canada for the characterization of DSL-listed P. aeruginosa strains.
Table 3: Minimal Inhibitory Concentration (MIC) for the DSL-listed P. aeruginosastrains
|Antibiotic||ATCC 31480||ATCC 700370||ATCC 700371|
|Aztreonam||16 ± 6.9||6 ± 0||0.9 ±0.6|
|Doxcycline||16 ±6.9||6 ± 0||0.37 ± 0|
|Gentamicin||1 ± 0.4||1 ± 0.4||0.6 ±0.2|
|Nalidixic acid||>24||>24||3.5 ±2.3|
MICtests performed by Milne and Gould (2009) on 315 multidrug resistant P. aeruginosa cystic fibrosis isolates and their clinical interpretation are shown in Table 4. Overall, 32.1% of the isolate/drug combinations were susceptible and 49.5% were resistant.
Table 4: P. aeruginosa MIC results on clinically relevant antibiotics
|Antibiotic||Etest range||MIC (mg/L)||Susceptible||Intermediate||Resistant|
|low (mg/L)||high (mg/L)||Number tested||range||MIC50||MIC90||number||%||number||%||number||%|
|Collistin||0.016||1024||315||0.094 to >1024||0.75||6||266||84||28||9||21||7|
|Amikacin||0.016||256||315||1.5 to >256||48||>256||99||32||73||23||143||45|
|Ciprofloxacin||0.002||32||315||0.064 to >32||2||8||95||30||143||45||77||25|
|Meropenem||0.002||32||315||0.023 to >32||24||>32||88||28||40||13||187||59|
|Piperacillin||0.016||256||134||0.75 to >256||>256||>256||36||27||0||0||98||73|
|Piperacillin/ Tazobactam||0.016||256||313||0.38 to >256||>256||>256||84||27||4||1||225||72|
|Netilmicin||0.016||256||273||0.38 to >256||16||128||68||25||99||36||106||39|
|Aztreonam||0.016||256||315||0.04 to >256||>256||>256||76||24||25||8||214||68|
|Ceftazidime||0.016||256||313||0.125 to >256||>256||>256||69||22||23||7||221||71|
|Levofloxacin||0.002||32||315||0.19 to >32||6||>32||67||21||112||36||136||43|
|Gentamicin||0.064||1024||314||0.5 to >256||12||48||65||21||122||39||127||40|
|0.016||256||306||0.19 to >256||>256||>256||63||21||6||2||237||77|
|Imipenem||0.002||32||315||0.19 to >32||>32||>32||45||14||11||4||259||82|
To assess the effectiveness of these antibiotics compared to previous years, Milne and Gould (2009) plotted the annual geometric mean MIC values for the individual antimicrobials (Figure 1). The only two antibiotics to demonstrate a downward trend were levofloxacin and colistin. The trend for ciprofloxacin was level. There was an upward trend in the aminoglycoside MICs, which was least in gentamicin and greatest in tobramycin. Tobramycin susceptibility showed a steady drop from 86% to 54.8% between 2001 and 2006 (data not shown), with an increase in intermediate susceptibility from 6% in 2001 to 33.3% in 2006. With the exception of piperacillin, all other antimicrobials show minor annual fluctuations in susceptibility patterns.
Figure 1: Annual geometric means of the aminoglycoside MICs. AMK, amikacin; GEN, gentamicin; NET, netilmicin; TOB, tobramycin
Also, a total of 1663 combination tests were performed on 44 different antimicrobial pairs. As can be seen in Table 5, synergy was most frequently found with β-lactam and quinolone combinations (10%), followed by β-lactam and aminoglycoside combinations (5%) and carbapenem and quinolone combinations (4%). Antagonism was only found with a β-lactam and quinolone combination (1%).
Table 5: Summary of extended susceptibility testing on 315 strains of P. aeruginosa
|First antimicrobial group||Second antimicrobial group|
|Aminoglycoside||n = 1217|
(37% S, 32% R)
|n = 443||n = 260||n = 58||n = 117|
|β-lactam||SYN = 5%|
ANT = 0%
|n = 1381|
(24% S, 72% R)
|n = 443||n = 149||n = 209|
|Carbapenem||SYN = 1%|
ANT = 0%
|Not applicable||n = 630|
(21% S, 71% R)
|n = 144||n = 140|
|Colistin||SYN = 0%|
ANT = 0%
|SYN = 3%|
ANT = 0%
|SYN = 1%|
ANT = 0%
|n = 315|
(84% S, 7% R)
|n = 143|
|Quinolone||SYN = 1%|
ANT = 0%
|SYN = 10%|
ANT = 1%
|SYN = 4%|
ANT = 0%
|SYN = 2%|
ANT = 0%
|n = 630|
(26% S, 34% R)
S, susceptible; R, resistant; SYN, synergy; ANT, antagonism.
Cells highlighted grey, number of MICs (% susceptible, % resistant); data to right of highlighted cells, number of times combination tested; data to left of highlighted cells, combination results.
In Canada, the most active agents against P. aeruginosaisolates from intensive care units between 2005 to 2006 were amikacin, cefepime, meropenem, and piperacillin/ tazobactam with MIC90(μg/mL) of 16, 32, 16, and 64, respectively (Zhanel et al., 2008). Aggressive antibiotic treatment at early onset of P. aeruginosa infection in CF patients has been shown to be promising (Hansen et al., 2008), while the use of combination antibiotic treatments to enhance antibacterial efficacy are continuously being investigated (Louie et al., 2010).
The ability of the P. aeruginosa DSL strains to grow optimally at 37°C, as shown in Appendix 1A, is a concern from a human health standpoint. In vivo tests were conducted at Health Canada to evaluate the potential of the 3 DSL-listed P. aeruginosa strains to cause adverse immune effects. Results, as shown in Appendix 5A, indicate that P. aeruginosastrains ATCC 31480, ATCC 700370 and ATCC 700371 induced some transient immune-related effects in BALB/c mice 2 and 4 hours after inhalation.
The environmental hazard severity for P. aeruginosa ATCC 31480, 700370 and 700371 is estimated to be medium. Information from the scientific literature indicates that P. aeruginosa is an opportunistic pathogen. Such pathogens, under certain conditions that pre-dispose the host to infection cause a range of symptoms that will debilitate the host and could kill it. However, in the absence of such conditions, infection will not occur. This is consistent with the observation that there is no evidence in the scientific literature to suggest any adverse ecological effects at the population level.
As mentioned previously, specific research results using the DSL-listed strains demonstrated no adverse effect on adult mortality or juvenile reproduction of springtails (Folsomia spp.) and earthworm (Eisenia andrei) species nor any adverse effect on barley (Hordeum vulgare), red fescue (Festuca rubra), red clover (Trifoliumpratense) and northern wheatgrass (Elymus lanceolatus).
The human hazard severity for P. aeruginosa ATCC 31480, 700370 and 700371 is estimated to be medium (see appendix 7). Information from the scientific literature indicates that this micro-organism has pathogenic potential in both otherwise healthy and immunocompromised humans. P. aeruginosa is recognized by the Public Health Agency of Canada as a Risk Group 2 human pathogen and has the ability to spread and acquire clinically relevant antibiotic resistance genes. P. aeruginosaproduces a wide variety of extracellular enzymes and toxins that are important factors for its pathogenicity in susceptible humans.
An exposure assessment identifies the mechanisms by which a micro-organism is introduced into a receiving environment (Section 2.1) and qualitatively and/or quantitatively estimates the magnitude, likelihood, frequency, duration, and/or extent of human and environmental exposure (Section 2.2). The exposure to the micro-organism itself, its genetic material or its toxins, metabolites or structural components is assessed.
Pseudomonas aeruginosa, as a species, is generally considered a ubiquitous bacterium, occurring naturally in many moist environmental media; it has the ability to adapt to and thrive in many ecological niches. However, this ‘background’ level presence of P. aeruginosa has not been well characterized, and, while acknowledged as a potential source of natural exposure, is not the focus of this screening assessment. With respect to the specific strains that are the focus of this assessment, to date, no quantitative studies were found on their background levels in the Canadian environment. P. aeruginosa as a species has properties that make it of commercial interest in a variety of industries. A search of the public domain (internet, patent databases) suggests multiple potential uses, including waste degradation, particularly in oil refineries, and in textile, pulp and paper, mining and explosives industries, as well as in commercial and household drain cleaners and degreasers, septic tank additives and general cleaning and odour-control products.
The three strains of P. aeruginosa listed on the DSL were imported into Canada between 1984 and 1986 to be used in a variety of waste, water and wastewater treatments, bioremediation, and biodegradation products. The government has attempted to verify continued commercial or consumer activity with these strains. No uses were identified in 2007 based on the outcome of a voluntary questionnaire sent to a subset of key biotechnology companies and on information obtained from other federal government regulatory and non-regulatory programs.
In 2009-2010, the government conducted a mandatory information-gathering Notice (survey) under section 71 of CEPA as published in the Canada Gazette on October 3rd, 2009. The Notice applied to any persons who, during the 2008 calendar year, manufactured or imported a DSL substance, whether alone, in a mixture, or in a product. Anyone meeting these reporting requirements was legally obligated to respond. Respondents were required to submit information on the industrial sector, uses and any trade names associated with products containing these strains, as well as the quantity and concentration of the strain imported or manufactured in the 2008 calendar year. No commercial or consumer activities using P. aeruginosa ATCC 31480, ATCC 700370 or ATCC 700371 were reported in response to the section 71 Notice. For the purposes of this exposure assessment, it is assumed that these strains are no longer imported or manufactured in Canada for commercial or consumer uses, based on the absence of responses to this survey.
Persistence data was obtained by Environment Canada on ATCC 31480, 700370 and 700371; it shows that strain-specific DNA could be amplified from agricultural soil 62, 122 and 126 days, respectively, after live cells were introduced (Xiang et al., 2010). However, there was no attempt to recover live cells from the soil, so specific strain survivability of the three P. aeruginosa strains in the soil was not demonstrated (see Appendix 5A). ATCC 31480 showed no growth in 10 days at 14°C on nutrient broth and nutrient agar (Spraker, 1982). However, given the ubiquity of the species, one could assume that these strains are also able to survive for considerable lengths of time in soil and other media even if there is no evidence of proliferation.
The most likely routes of introduction of the three DSL-listed P. aeruginosa strains into the environment due to household, industrial or manufacturing activities would be into water and soil. The magnitude of exposure (including geographic distribution, timing, duration and frequency of exposure) is presumed to be proportional with the amount of bacteria released into the environment according to the use.
While large inputs of DSL strains into the environment could likely result in concentrations greater than background levels, high numbers are unlikely to be maintained in water and in soil due to natural competition (Leung et al., 1995) and microbiostasis (van Veen et al.,1997), which is an inhibitory effect of soil that results in the rapid decline of populations of introduced bacteria. This is consistent with the research results noted above.
No relevant reports concerning persistence in the environment of toxins produced by P. aeruginosa have been found.
The environmental exposure for P. aeruginosa ATCC 31480, 700371, and 700370 is estimated to be low from consumer and industrial activities or from other anthropogenic sources. This estimation is supported by evidence that these strains were no longer imported, manufactured or used in Canada in 2008, as found through responses to the mandatory section 71 Notice and by results from the voluntary survey conducted in 2007.
P. aeruginosa is considered a Risk Group 2 pathogen requiring a Level 2 containment under the Public Health Agency of Canada’s Laboratory Biosafety Guidelines (3rd Ed. 2004). P. aeruginosa can be transmitted through direct contact with contaminated water or aerosols (Reuter et al., 2002; Moore et al., 2004; Saiman and Siege, 2003). Other modes of transmission include contact of susceptible individuals with discharge from conjunctivae (Lyzak et al., 2000) or the upper respiratory tract (Moore et al., 2004; Saiman and Siege, 2003) of infected persons and through contact with contaminated surfaces, such as sinks, tap water outlets, cleaning equipment, flower vases and humidifiers (Ayliffe et al., 1974; Reuter et al., 2002; Grieble et al., 1970; Taplin and Mertz, 1973; Engelhart et al., 2002), improperly sterilized medical equipment (De Vos et al., 1997; Elhag et al., 1977; Muyldermans et al., 1998), and contaminated distilled water, IV fluids, and antiseptics (Favero et al., 1971; Parrott et al., 1982).
As previously mentioned, P. aeruginosa is commonly found in the environment. The purpose of this section is to characterize the human exposure to the 3 DSL-listed P. aeruginosa strains from their deliberate addition to consumer or industrial products used in Canada.
Humans are likely to be exposed to P. aeruginosathrough inhalation or dermal contact as the micro-organisms are dispersed in the atmosphere attached to dust particles or aerosolized during manufacturing and product application. P. aeruginosa is strongly associated with respiratory infections. Therefore, the most problematic route of exposure to products containing P. aeruginosa is considered to be from inhaling aerosols, whether the product is in liquid or powder formulation. Dermal exposure may also affect humans. Since skin is a natural barrier to microbial invasion of the human body, infection would be more likely to occur if the skin was damaged through abrasions and burns.
The human exposure estimation for P. aeruginosa ATCC 31480, 700370 and 700371 is low, notwithstanding (i) the organism’s ability to cause persistent infections from which it could be shed, (ii) the organism’s ability to persist and establish itself in diverse environments, including manmade environments such as drains, (iii) the organism’s inherent resistance to disinfectants and antibiotics; and based on evidence that these strains are no longer imported, manufactured or used in Canada, as found through the mandatory section 71 Notice for the 2008 calendar year.
Based on the medium level of hazard of the three strains of P. aeruginosa listed on the DSL to human health and, uniquely, also to other biota in the Canadian environment and the likely low potential for exposure as assessed by the absence of reported uses through the section 71 survey for the 2008 calendar year, the risk is estimated to be low with respect to the environment and medium with respect to human health.
Based on available information, it is proposed that P. aeruginosa strains ATCC 31480, ATCC 700370 and ATCC 700371 are not entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity or that constitute or may constitute a danger to the environment on which life depends. Therefore, it is proposed that these strains do not meet the definition of toxic as set out in section 64 of the CEPA1999.
Given the hazardous properties and the current low likelihood of exposure to these strains in Canada, new activities (i.e., importation into, manufacture or use within Canada) for these strains which have not been identified or assessed under CEPA 1999 could increase the potential for exposure and may lead to these strains meeting the criteria set out in section 64 of the Act. Therefore, it is recommended that these substances be subject to the Significant New Activity (SNAc) provisions specified under subsection 106(3) of the Act, to ensure that any new import, manufacture or use of the substance is notified under the New Substances Notification Regulations (Organisms) and will undergo appropriate environmental and human health risk assessments as specified in section 108 of the Act prior to the substance being re-introduced into Canada.
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Appendix 1A: Characteristics of DSL-listed P. aeruginosa strains – Growth Rate in Trypticase Soy Broth[*]
The graphs show changes in optical density (OD) of DSL P. aeruginosa strains grown at various temperatures in Trypticase Soy Broth (TSB). At time 0, bacteria were at 106cfu/well. Kinetic measurements were taken every 15 min with a multi-well spectrophometer at a wavelength of 500 nm.
Appendix 1B: Characteristics of DSL-listed P. aeruginosa strains - Growth on Different Media at 28°C and 37°C (48 hours)[*]
|Strains||TSB (1)||5% Sheep|
|Lysin Iron (4)||Triple Sugar Iron - with pheol red|
Red - neutral to alkaline
Yellow -acidic (5)
|Urea (6)||MYP supple-ments (7)||Man-nitol (8)||Citrate|
Green-neutral to acidic
|Catalase Activity in TSB (10)|
|Bacteria||28 C||37C||28C||37C||growth 37 C||Hydrolysis 37 C||28 C||37 C||28 C||37 C||28 C||37 C||28 C||37 C||28 C||37 C||28 C||37 C||28 C||37 C||28 C||37 C|
|P. aeruginosa 31480||+||+ Green diffusing pigment||■||◙||☼||◙||-||+ Green colony pigment||+||+||+||+||☼||☼||-||-||-||-||-||-||-||+|
|P.aeruginosa 700370||☼||+||■ / ◙||◙||☼||◙||-||☼||+||+||||||☼||☼||-||-||-||-||+||+/-||+||+|
|P. aeruginosa 700371||+||+||■ / ◙||◙||+||◙||-||+||+||+||||||+||+||-||-||-||-||-||-||+||weak|
☼ fluorescent colonies when illuminated with UV365nm
■ no clearing or discolouration observed
◙ discolouration or clearing localized to site of colony
(1) all purpose medium
(2) differential medium that tests the ability of an organism to produce extracellular enzymes that hydrolyse starch
(3) detection of coliform organisms in milk and water; tests for ability of organism to ferment lactose
(4) simultaneous detection of lysine decarboxylase and formation of hydrogen sulfide in the identification of Enterobacteriaceae, in particular Salmonella and Arizona according to Edwards and Fife.
(5) gram-negative enteric bacilli based on glucose, lactose, and sucrose fermentation and hydrogen sulfide production
(6) screening of enteric pathogens from stool specimens - Urea metabolism
(7) B.cereus selective agar
(8) isolation and differentiation of Staphylococci
(9) Citrate utilization test, ability to use citrate as the sole carbon source.
(10) Catalase enzyme assay measures anti-oxidant activity (hydrogen peroxide to water and oxygen).
Appendix 1C: Characteristics of DSL-listed P. aeruginosa strains – Fatty Acid Methyl Ester (FAME) Analysis[*]
Data presented shows the best match between the sample and different MIDI@ databases (clinical and environmental), along with the number of matches (fraction of total number of tests) and the fatty acid profile similarity index (in parentheses; average of all matches).
|Test Strain||Environmental Database||Clinical Database||Bioterrorism Database|
|P. aeruginosa ATCC 31480||8/9 P. aeruginosa (0.898)|
1/9 E. cloacae (0.876)
|8/8 P. aeruginosa (0.725)||No match|
|P. aeruginosa ATCC 700370||11/11 P. aeruginosa (0.880)||5/6 P. aeruginosa (0.766) 1/6 No match||No match|
|P. aeruginosa ATCC 700371||7/7 P. aeruginosa (0.722)||8/8 P. aeruginosa (0.886)||No match|
|Plasmid||pMG1||Resistance to borate, gentamycin, mercury, streptomycin, sulphonamide, tellurite, ultraviolet light||Jacoby, 1974|
|R151||Resistance to carbenicillin, gentamycin, kanamycin, streptomycin, sulphonamide, tobramycin||Bryan et al., 1974|
|Rms 149||Resistance to carbenicillin, gentamycin, streptomycin, sulphonamide||Hedges & Jacoby, 1980|
|Integron||In4||Resistance to gentamycin, streptomycin, carbenicillin||Partridge et al., 2001|
|In28||Resistance to carbenicillin, streptomycin, spectinomycin, and chloramphenicol||Partridge et al., 2001|
|Transposon||Tn501||Resistance to mercury||Stanisich et al., 1989|
|Tn1696||Resistance to mercury, sulphonamide|
|Partridge et al., 2001|
|Tn1403||Integron In28||Partridge et al., 2002|
|Exotoxin A||Collier, 1975; Salyers & Whitt, 2002; Vidal et al., 1993|
|Exoenzyme S (ExoS)||Nicas & Iglewski, 1985; Salyers & Whitt, 2002|
|Exoenzyme T (ExoT)||Sun & Barbieri, 2003|
|Exoenzyme U (ExoU)||Sato et al., 2003|
|Exoenzyme Y (ExoY)||Feltman et al., 2001|
|Haemolytic Phospolipase C (PlcH)||Barker et al., 2004; Chin & Watts, 1988; Hogan & Kolter, 2002; Hollsing et al., 1987; Jander et al., 2000; Ostroff et al., 1989; Rahme et al., 1995; Vasil et al., 2009|
|Rhamnolipid||Read et al., 1992; Van Gennip et al., 2009; Alhede et al., 2009|
|LasB elastase, LasA elastase||Parmely, 2000; Salyers & Whitt, 2002|
|Pyocyanin||Denning et al., 1998a; Denning et al., 1998b; Caldwell et al., 2009; Kong et al., 2006; Lau et al., 2004|
|Phenazine-1-carboxylic acid||Denning et al., 2003|
|1-hydroxyphenazine||Dowling & Wilson, 1998; Munro et al., 1989|
|Hydrogen cyanide||Castric, 1983; Pessi & Haas, 2000; Ryall et al., 2008|
|Pyoverdine and pyochelin||Meyer et al., 1996; Takase et al., 2000|
|Alkaline protease||Matsumoto, 2004; Van Delden, 2004|
|Endoprotease (PrpL)||Wilderman et al., 2001|
golden apple snail (Pomacea canaliculata)
greater wax moth larvae (Galleria mellonella)
2.7x107 cfu (intranasal injection)
3.09x104 - 1.35x106 cfu/ml (72 h LC50 – 5 strains)
7x104 cells (pho23), injected through cuticle
Strain 359 (Serotype 1)
Strain 2915 (Seroptype 7)
21.2.1, B1.1, P1, P2
George et al., 1991
Tamura et al., 1992
Long et al., 1980
Chobchuenchom and Bhumiratana, 2003
Jander et al., 2000
|haemolytic phospolipase C (PlcH)|
5 µg/mouse (intraperitoneal)
PAO1 derivative ADD1976
Berk et al., 1987
Vasil et al., 2009
375 µg (IV injection)
Strain designation not provided
Strain designation not provided
Nicas & Iglewski, 1986
Hirakata et al., 1999
300 µg (IV injection)
Strain designation not provided
Strain designation not provided
Nicas & Iglewski, 1986
Hirakata et al., 1999
silkworm larvae (Bombyx mori)
0.2 µg (IP injection)
0.06 µg (IV injection)
PAO1 (ATCC 15692)
Hossain et al., 2006
|phenazine||nematode (C. elegans)|
>2000 mg/kg dw (24 and 48 h)
54.7 mg/L (24 h); 10.8 mg/L (48h)
|Chemically synthesized||Sochová et al., 2007|
|pyocyanin||silkworm (Bombyx mori)||9.52 μg/larva||PAO1||Chieda et al., 2007|
|rhamnolipid||mouse||5 mg/kg (IP injection)||Strain designation not provided||Nicas & Iglewski, 1986|
6-week old plants
|Rahme et al., 1995|
25-day old plants
|Walker et al., 2004|
|Arabidopsis thaliana||Rahme et al., 2000|
|Alfalfa (variety 57Q77)||Silo-Suh et al., 2002|
|Lettuce (Lactuca sativa var. capitata L.)||Vives-Flórez & Garnica, 2006|
|red clover and red fescue.||ATCC 31480||No adverse effect on seedling emergence, shoot and root length and dry mass of red clover and red fescue.||Princz, 2010|
|barley||ATCC 700370||No adverse effect on seedling emergence, shoot and root length and dry mass of barley.||Princz, 2010|
|red clover and northern wheatgrass.||ATCC 700371||No adverse effect on seedling emergence, shoot and root length and dry mass of red clover and northern wheatgrass.||Princz, 2010|
|soil nematode (Caenorhabditis elegans)|
Tan et al.,
|wax moth larvae (Galleria mellonella)||Jander et al., 1995|
southern pine beetle
fruit fly (Drosophila melanogaster)
2 - 4 day old adult female flies
|D’Argenio et al., 2001|
tobacco hornworm larvae (Manduca sexta)
second day fifth instar larvae
|Horohov & Dunn, 1984|
silkworm larvae (Bombyx mori)
fourth instar larvae
|Iiyama et al., 2007|
|springtails and earthworms.||Princz, 2010|
broiler chicks (white leghorn)
1-day old chicks
|Walker et al., 2002|
|white leghorn chickens (male)||Lin et al., 1993|
|mice||Rahme et al., 1995|
60-day old male
|George et al., 1989|
30-day old male
· 1.61x103 cfu resulted in no mortality or observed morbidity for 14 day study period
· 1.61 x 107 cfu resulted in slight morbidity within 3 to 4 days after dose
· 2.17x109 cfu resulted in 100% mortality within 24 to 36 h post-injection
|George et al., 1991|
|dog||Wyman et al., 1983|
|frogs (Rana pipiens)||Brodkin et al., 1992|
|mink (Sapphire)||Shimizu et al., 1974|
|mice||Preliminary EC HC results|
|mice||Preliminary EC HC research results|
|mice||Preliminary EC HC research results|
|zebrafish (Danio rerio)||Clatworthy et al., 2009|
Cases where P. aeruginosa was isolated from animals showing disease symptoms in a natural setting.
|Klopfeisch et al., 2005|
|turkeys||Gomis et al., 2002|
- species not found in Canada but anatum peregrine falcon (Falco peregrinus anatum) is a threatened species in Canada
|cow||Daly et al., 1999|
|cow||Kivaria & Noordhuizen, 2007|
|dorset horn rams||cited by Hungerford, 1990|
|Year||Place||Type of Infection|
|Not given||University of Iowa Hospitals and Clinics||Outbreak of P. aeruginosa blood stream infections in 7 patients with hematological malignancies caused by a contaminated drain in a whirlpool bathtub. Mortality rate was 71.4% (Berrouane et al., 2000).|
|1975 to 1985||US and Canada||A total of 36 outbreaks of P. aeruginosafolliculitis associated with the use of whirlpools and hot tubs, and to a lesser extent with the use of swimming pools have been reported with increasing frequency during the winter months (Ratnam et al., 1986).|
|1988||Bergamo, Italy||Outbreak of P. aeruginosa infections in neutropenic patients admitted to the Haematological Wards of "Ospedali Riuniti”. Out of 11 cases of P. aeruginosainfections, 8 were bacteraemia. Of these, 7 died within a few days of onset (mortality rate of 87.5%) (Grigis et al., 1993).|
|1996||Royal Women's Hospital, Australia||Over a 10-month period, 24 newborns were infected by P. aeruginosa (resistant to ticarcillin, timentin). There were extensive morbidity and mortality (38%) associated with the infections, which presented as septicemia, pneumonia, meningitis conjunctivitis, otitis externa and conjunctivitis plus otitis externa. In addition, there were 2 pseudo-septicemia and 6 colonized infants, 3 of whom were treated for the presence of P. aeruginosa in endotracheal aspirates (Garland et al. 1996).|
|1998||Edmonton, Canada||40 cases of Pseudomonas hot-foot syndrome occurred after children had used a wading pool. In all patients, the first symptom was intense pain in the soles, followed within hours by marked swelling, redness, a sensation of heat, and exquisite pain that made it impossible to bear weight on the affected areas (PHAC, 2001).|
|1997 to 2000||Colorado and Maine, USA||103 reported cases of P. aeruginosadermatitis and otitis externa outbreaks associated with swimming pool and hot tub use. Symptoms were not limited to rash; they included diarrhea, vomiting, nausea, fever, fatigue, muscle aches, joint pain, swollen lymph nodes, and subcutaneous nodules on hands and feet (MMWR, 2000).|
|2001 to 2002||Johns Hopkins Hospital Baltimore, USA||2 outbreaks of P. aeruginosa infections involving 48 infections of the upper and lower respiratory tracts and bloodstream among 39 of 414 patients who underwent bronchoscopy (9.4%). In 66.7% of these infections, P. aeruginosa was recovered on culture (Srinivasan et al., 2003).|
Appendix 7: Considerations for Levels of Hazard Severity, Exposure and Risk as per Health Canada and Environment Canada’s “Framework for Science-Based Risk Assessment of Micro-organisms regulated under the Canadian Environmental Protection Act, 1999”
Considerations for hazard severity (environment)
Considerations that may result in a finding of high hazard include a micro-organism that:
Considerations that may result in a finding of medium hazard include a micro-organism that:
Considerations that may result in a finding of low hazard include a micro-organism that:
Considerations for hazard severity (human health)
Considerations that may result in a finding of high hazard include a micro-organism for which:
Considerations that may result in a finding of medium hazard include:
Considerations that may result in a finding of low hazard include:
Considerations / examples for level of exposure (environment and human health)
Considerations that may result in a finding of high exposure include a micro-organism for which:
Considerations that may result in a finding of medium exposure include a micro-organism for which:
Considerations that may result in a finding of low exposure include a micro-organism for which:
Considerations for level of risk characterization
|High||A determination of high risk implies that severe, enduring or widespread adverse effects are probable for exposure scenarios predicted from known, foreseeable or intended uses. A conclusion of CEPA-toxic would result and control measures or risk management would be recommended.|
|Medium||A determination of medium risk implies that adverse effects predicted for probable exposure scenarios may be moderate and self-resolving. The conclusion (CEPA toxic or not) is chosen based on the particulars of the case. If the conclusion is not CEPA-toxic, for intended (proposed) use(s) or exposure scenario(s) but, under another significant new activity, may become toxic, application of the SNAcprovision may be recommended to allow for the assessment of new uses/activities.|
|Low||A determination of low risk implies that any adverse effects predicted for probable exposure scenarios are rare, or mild and self-resolving. The conclusion would be not CEPA toxic, and SNAc provisions may or may not be applied.|
 Refer to Appendix 7 for the definitions of exposure levels.
 Refer to Appendix 7 for the definitions for levels of risk.
 Refer to Appendix 4 for LD50 values for some of the toxins.
[*] Data generated by Health Canada’s Healthy Environments and Consumer Safety Branch.
- Date Modified: