PRODUCTION OF EXTRACELLULAR VIRULENCE FACTORS BY PSEUDOMONAS-AERUGINOSA ISOLATES OBTAINED FROM TRACHEAL, URINARY-TRACT, AND WOUND INFECTIONS

This study was conducted to determine the effect of the local environm ent within the host on the ability of P. aeruginosa to produce differe nt extracellular virulence factors (elastase, phospholipase C, toxin A , and exoenzyme S). A total of 105 P. aeruginosa isolates was obtained from patients with tracheal, urinary tract, and wound infections. Qua ntitative analysis of the virulence factors was done by growing the is olates in vitro in different defined media. Single colonies of each is olate were inoculated from the primary isolation plates into the defin ed medium. All four virulence factors were produced by most isolates. However, depending on the location of their isolation, the isolates va ried in the level of virulence factors they produced. High levels of e lastase and phospholipase C were produced by most isolates obtained fr om trachea, urinary tract, and wounds. A significantly higher level of toxin A was produced by wound isolates, while a significantly higher level of exoenzyme S was produced by wound and urinary tract isolates. Some P. aeruginosa strains were frequently isolated from the same sit e of infection (persistent infection isolates). Comparative analysis o f virulence factors produced by these isolates showed that, regardless of the isolation site, subsequent isolates produced higher levels of exoenzyme S. These results suggest that: (1) elastase, phospholipase C , toxin A, and exoenzyme S are produced by P. aeruginosa isolates from different sites of infection; (2) the production of higher levels of elastase and phospholipase C is important in all types of infections, while the production of toxin A and exoenzyme S is important in wound infection; (3) persistent infection with P. aeruginosa may enhance exo enzyme S production. (C) 1996 Academic Press, Inc.