Passive hemagglutination reaction using formalinized sheep erythrocytes treated with tannic acid and coated with exotoxin of Pseudomonas aeruginosa.

Passive hemagglutination (PHA) tests using fixed sheep erythrocytes coated with exotoxin of Pseudomonas aeruginosa were devised for estimating antibodies of the exotoxin. No serological cross-reactivity among exotoxin OEP, protease and elastase of P. aeruginosa was foud by the PHA tests. The exotoxin PHA reaction was more sensitive than the neutralizing reaction of skin necrotizing activity of exotoxin by guinea pigs. Thirteen out of 40 sera of patients with P. aeruginosa infections showed PHA titers from 40 to 1,280, while those of 20 healthy human sera were under 40.