De. Woods et al., CORRELATION OF PSEUDOMONAS-AERUGINOSA VIRULENCE FACTORS FROM CLINICALAND ENVIRONMENTAL ISOLATES WITH PATHOGENICITY IN THE NEUTROPENIC MOUSE, Canadian journal of microbiology, 43(6), 1997, pp. 541-551
The potential pathogenicity of a microorganism is a major concern for
Health Canada evaluators, who will be processing new biotechnology pro
ducts under the Canadian Environmental Protection Act. Potential patho
genicity is generally predicted by the results of animal pathogenicity
studies. In an attempt to define surrogate data for an animal model,
this study was initiated. Pseudomonas aeruginosa isolates from clinica
l and environmental sources were screened for their pilus type, seroty
pe, lipopolysaccharide type, ability to evade host responses, and prod
uction of toxin A, exoenzyme S, elastase, phospholipase C, and total p
rotease. The 50% lethal dose (LD50) of the same isolates was determine
d in the neutropenic mouse model of infection. An attempted correlatio
n was drawn between each (or combinations) of the virulence determinan
ts and the LD50. Stepwise linear regression showed that the presence o
f high levels of exoenzyme S in association with elastase or phospholi
pase C, or to a minor extent toxin A, was correlated with low numbers
of bacteria required to elicit an LD50. No correlation between any of
the other factors examined and virulence was detected. The data sugges
t that an in vitro high level of exoenzyme S production could be used
as surrogate information for neutropenic mouse modelling; however, the
levels of all of the extracellular enzymes should be considered when
making such an assessment.