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Virulence Attributes and Host Response Assays for Determining Pathogenic Potential of Pseudomonas Strains Used in Biotechnology.

Tayabali AF, Coleman G, Nguyen KC - PLoS ONE (2015)

Bottom Line: However, Pf and Pp strains were the most antibiotic resistant, with ciprofloxacin and colistin being the most effective of those tested.Serum amyloid A was elevated at ≥ 48 h post-exposure by only some Pa strains.No relationship was observed between strains and levels of peripheral leukocytes.

View Article: PubMed Central - PubMed

Affiliation: Biotechnology Laboratory, Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Environmental Health Centre, Health Canada, Ottawa, Ontario, Canada.

ABSTRACT
Pseudomonas species are opportunistically pathogenic to humans, yet closely related species are used in biotechnology applications. In order to screen for the pathogenic potential of strains considered for biotechnology applications, several Pseudomonas strains (P.aeruginosa (Pa), P.fluorescens (Pf), P.putida (Pp), P.stutzeri (Ps)) were compared using functional virulence and toxicity assays. Most Pa strains and Ps grew at temperatures between 28°C and 42°C. However, Pf and Pp strains were the most antibiotic resistant, with ciprofloxacin and colistin being the most effective of those tested. No strain was haemolytic on sheep blood agar. Almost all Pa, but not other test strains, produced a pyocyanin-like chromophore, and caused cytotoxicity towards cultured human HT29 cells. Murine endotracheal exposures indicated that the laboratory reference strain, PAO1, was most persistent in the lungs. Only Pa strains induced pro-inflammatory and inflammatory responses, as measured by elevated cytokines and pulmonary Gr-1 -positive cells. Serum amyloid A was elevated at ≥ 48 h post-exposure by only some Pa strains. No relationship was observed between strains and levels of peripheral leukocytes. The species designation or isolation source may not accurately reflect pathogenic potential, since the clinical strain Pa10752 was relatively nonvirulent, but the industrial strain Pa31480 showed comparable virulence to PAO1. Functional assays involving microbial growth, cytotoxicity and murine immunological responses may be most useful for identifying problematic Pseudomonas strains being considered for biotechnology applications.

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Related in: MedlinePlus

Pulmonary Clearance of Pseudomonas Strains.At various times following endotracheal exposure of 106 cfu per mouse of each Pseudomonas strain, the lungs of mice were harvested, homogenized and serially diluted in physiological saline. Dilutions were spread-plated onto nutrient broth and bacteria were enumerated 18 h later. The red markers represent the mean colony count; blue markers represent counts from each mouse. Black arrows point to noteworthy features described in the Results section.
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pone.0143604.g002: Pulmonary Clearance of Pseudomonas Strains.At various times following endotracheal exposure of 106 cfu per mouse of each Pseudomonas strain, the lungs of mice were harvested, homogenized and serially diluted in physiological saline. Dilutions were spread-plated onto nutrient broth and bacteria were enumerated 18 h later. The red markers represent the mean colony count; blue markers represent counts from each mouse. Black arrows point to noteworthy features described in the Results section.

Mentions: Following endotracheal exposure, the number of bacteria in lungs was enumerated at intervals to determine the rate of bacterial clearance. No bacteria were recovered from mice treated with saline alone. Fig 2 shows pulmonary bacteria levels from two to 168 h post-exposure. Most rapid clearance was observed between zero and 24 h post-exposure. At two hours post-exposure, Ps17587 showed marginally greater levels than the other bacteria, but numbers dropped rapidly thereafter. Almost all bacteria were completely eliminated at the 168 h time-point, with the exception of Pa700370. At 168 h post-exposure, this strain resulted in one of three mice with residual bacteria (not observed at 24, 48, or 96 h), albeit at low levels. Notably, mice exposed to PAO1 showed bacteria persisting between four and 48 h; this was not observed with any of the other strains.


Virulence Attributes and Host Response Assays for Determining Pathogenic Potential of Pseudomonas Strains Used in Biotechnology.

Tayabali AF, Coleman G, Nguyen KC - PLoS ONE (2015)

Pulmonary Clearance of Pseudomonas Strains.At various times following endotracheal exposure of 106 cfu per mouse of each Pseudomonas strain, the lungs of mice were harvested, homogenized and serially diluted in physiological saline. Dilutions were spread-plated onto nutrient broth and bacteria were enumerated 18 h later. The red markers represent the mean colony count; blue markers represent counts from each mouse. Black arrows point to noteworthy features described in the Results section.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664251&req=5

pone.0143604.g002: Pulmonary Clearance of Pseudomonas Strains.At various times following endotracheal exposure of 106 cfu per mouse of each Pseudomonas strain, the lungs of mice were harvested, homogenized and serially diluted in physiological saline. Dilutions were spread-plated onto nutrient broth and bacteria were enumerated 18 h later. The red markers represent the mean colony count; blue markers represent counts from each mouse. Black arrows point to noteworthy features described in the Results section.
Mentions: Following endotracheal exposure, the number of bacteria in lungs was enumerated at intervals to determine the rate of bacterial clearance. No bacteria were recovered from mice treated with saline alone. Fig 2 shows pulmonary bacteria levels from two to 168 h post-exposure. Most rapid clearance was observed between zero and 24 h post-exposure. At two hours post-exposure, Ps17587 showed marginally greater levels than the other bacteria, but numbers dropped rapidly thereafter. Almost all bacteria were completely eliminated at the 168 h time-point, with the exception of Pa700370. At 168 h post-exposure, this strain resulted in one of three mice with residual bacteria (not observed at 24, 48, or 96 h), albeit at low levels. Notably, mice exposed to PAO1 showed bacteria persisting between four and 48 h; this was not observed with any of the other strains.

Bottom Line: However, Pf and Pp strains were the most antibiotic resistant, with ciprofloxacin and colistin being the most effective of those tested.Serum amyloid A was elevated at ≥ 48 h post-exposure by only some Pa strains.No relationship was observed between strains and levels of peripheral leukocytes.

View Article: PubMed Central - PubMed

Affiliation: Biotechnology Laboratory, Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Environmental Health Centre, Health Canada, Ottawa, Ontario, Canada.

ABSTRACT
Pseudomonas species are opportunistically pathogenic to humans, yet closely related species are used in biotechnology applications. In order to screen for the pathogenic potential of strains considered for biotechnology applications, several Pseudomonas strains (P.aeruginosa (Pa), P.fluorescens (Pf), P.putida (Pp), P.stutzeri (Ps)) were compared using functional virulence and toxicity assays. Most Pa strains and Ps grew at temperatures between 28°C and 42°C. However, Pf and Pp strains were the most antibiotic resistant, with ciprofloxacin and colistin being the most effective of those tested. No strain was haemolytic on sheep blood agar. Almost all Pa, but not other test strains, produced a pyocyanin-like chromophore, and caused cytotoxicity towards cultured human HT29 cells. Murine endotracheal exposures indicated that the laboratory reference strain, PAO1, was most persistent in the lungs. Only Pa strains induced pro-inflammatory and inflammatory responses, as measured by elevated cytokines and pulmonary Gr-1 -positive cells. Serum amyloid A was elevated at ≥ 48 h post-exposure by only some Pa strains. No relationship was observed between strains and levels of peripheral leukocytes. The species designation or isolation source may not accurately reflect pathogenic potential, since the clinical strain Pa10752 was relatively nonvirulent, but the industrial strain Pa31480 showed comparable virulence to PAO1. Functional assays involving microbial growth, cytotoxicity and murine immunological responses may be most useful for identifying problematic Pseudomonas strains being considered for biotechnology applications.

Show MeSH
Related in: MedlinePlus