Multidrug-resistant Pseudomonas aeruginosa isolated from the urine of patients with urinary tract infection.

We report the clinical courses of 3 patients with urinary obstruction who developed acute pyelonephritis caused by multidrug-resistant (MDR) Pseudomonas aeruginosa. Genome fingerprinting was performed to clarify the route of cross-infection, and an imipenem-resistance gene was detected by the polymerase chain reaction (PCR) method. The study included 17 patients at our institute who had urinary tract infections caused by P. aeruginosa between January and December 1997. MDR was defined as that when all the minimum inhibitory concentrations (MICs) were determined to show resistance according to the breakpoints recommended by the National Committee for Clinical Laboratory Standards (NCCLS) for P. aeruginosa. Pulse-field gel electrophoresis (PFGE) was carried out for genome fingerprinting. PCR was used to detect the metallo-beta-lactamase gene ( bla(IMP)). Three strains were revealed for MDR. The strains were isolated from the 3 patients with urinary tract obstruction who developed acute pyelonephritis. The treatment consisted of urinary drainage for the obstructed urinary tract and parenterally administered antimicrobials. Although none of the strains was susceptible to any antimicrobials, all patients had favorable outcomes. PFGE revealed that two strains had an identical genotype, implying cross-infection between the patients. The bla(IMP) gene was not detected in any of the three strains. In febrile patients with urinary tract infection caused by MDR P. aeruginosa, treatment for urinary obstruction is strongly recommended. Initial empirical chemotherapy with antimicrobials to which the organism is not susceptible is often inevitable. Because there was epidemiological evidence of cross-infection with MDR P. aeruginosa, countermeasures against nosocominal infection are warranted.