Reduced virulence of Pseudomonas aeruginosa grown in the presence of benzalkonium chloride

Abstract

Resistant cells of Pseudomonas aeruginosa ATCC 9027 which were grown in the presence of 1 mg of benzalkonium chloride (BC) per ml caused only a mild conjunctivitis when they were dropped onto the scratched corneas of rabbits. In contrast, cells of the BC sensitivity parent strain induced a severe keratoconjunctivitis. In addition, the BC grown cells also had a reduced capacity to produce kidney infections in mice as compared to the parent strain. BC grown cells acted as weak complex antigens which conferred slight protection against lethal doses of BC grown cells. No cross protection to cells of the parent strain occurred. The data indicate that growth in the presence of BC results in cells with reduced virulence. (Journal received: 20 April 1976)