Exotoxin A from various Pseudomonas aeruginosa cultures: in vitro activity measured by enzyme-linked immunosorbent assay (ELISA).

An enzyme-linked immunosorbent assay (ELISA) for the detection of Pseudomonas aeruginosa exotoxin A (toxin A) was developed. The level of toxin A produced by fresh P. aeruginosa isolates was compared to the level of toxin A produced by twelve-months-old subcultures derived from the same strains. Results obtained with the ELISA showed that toxin A was produced in similar amounts both by the fresh isolates and the subcultures. The production of toxin A seems to represent a stable property of the assayed P. aeruginosa strains. This is in contrast to other exoproducts from the same strains, such as extracellular proteinases. Some proteinases were produced at very different levels when freshly isolated P. aeruginosa cultures were compared with their twelve-months-old counterparts, confirming earlier reports in this respect.