Incidence of exotoxin production by Pseudomonas species

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Abstract
P. aeruginosa exotoxin A has been shown to catalyze the transfer of the ADP-ribose [R] moiety of NAD onto elongation factor 2, resulting in the inhibition of mammalian protein synthesis. This enzymatic activity (ADP-ribosyl [ADPR]-transferase) is thought to account for the toxicity of exotoxin A. The distribution of the expression of exotoxin A within Pseudomonas spp. was examined. Laboratory strains as well as clinical isolates of P. aeruginosa were tested. The production of exotoxin A was determined by assaying for ADPR-transferase activity in dialyzed frozen (-20.degree. C) and thawed cell-free supernatants from 22-h cultures or in 10-fold-concentrated supernatants. In addition, toxin production was detected immunologically using a modified Elek test. Exotoxin A production was detected in approximately 90% of the 111 isolates of P. aeruginosa. In contrast, none of the other species of Pseudomonas examined produced exotoxin A detectable by either ADPR-transferase activity or immunological reactivity.