Abstract
Summary
An in vitro system was devised to measure the virulence of Pseudomonas aeruginosa based on the organism's ability to form virus-like plaques and toxin Z in cell culture monolayers.
Plaquing efficiency varied among clinical strains and also between the original isolates and their substrains after 10 and 20 subcultures. These variations were significant at the 99.9% confidence level.
The data on the potency of toxin Z produced by these strains as measured by cytopathogenic effect in cell culture and by mouse lethality generally agreed with the data on their plaquing efficiency. Conversely no differences between the tested strains were detected in LD50 determinations in mice. This latter result is in agreement with the findings of other investigators and reemphasizes the need for a more reliable indicator system to assess the virulence of P. aeruginosa. Plaquing efficiency and toxin Z formation in cell culture appear to hold considerable promise as indicators that may satisfy this need.
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