RAPID DETECTION AND EVALUATION OF CLINICAL CHARACTERISTICS OF EMERGING MULTIPLE-DRUG-RESISTANT GRAM-NEGATIVE RODS CARRYING THE METALLO-BETA-LACTAMASE GENE BLA(IMP)

Gram-negative rods (GNR) carrying the transferable carbapenem resistan ce gene bla,,,, including Pseudomonas aeruginosa and Serratia marcesce ns, have been isolated from more than 20 hospitals in Japan, Although the emergence of such multiple-drug-resistant bacteria is of utmost cl inical concern, little information in regard to the distribution of bl a(IMP)-positive GNR in hospitals and the clinical characteristics of i nfected patients is available. To address this, a system for the rapid detection of the bla(IMP) gene with a simple DNA preparation and by e nzymatic detection of PCR products was developed. A total of 933 cefta zidime-resistant strains of GNR isolated between 1991 and 1996 at Naga saki University Hospital, Nagasaki, Japan, were screened for the bla(I MP) gene; 80 isolates were positive, including 53 P. aeruginosa isolat es, 13 other glucose-nonfermenting bacteria, 13 S. marcescens isolates , and 1 Citrobacter freundii isolate. Most of the patients from whom b la(IMP)-positive organisms were isolated had malignant diseases (53,8% ), The organisms caused urinary tract infections, pneumonia, or other infections in 46.3% of the patients, while they were just colonizing t he other patients evaluated. It was possible that bla(IMP)-positive P. aeruginosa strains contributed to the death of four patients, while t he other infections caused by GNR carrying bla,, were not lethal. DNA fingerprinting analysis by pulsed-field gel electrophoresis suggested the cross transmission of strains within the hospital, The isolates we re ceftazidime resistant and were frequently resistant to other antibi otics. Although no particular means of pathogenesis of bla(IMP)-positi ve GNR is evident at present, the rapid detection of such strains is n ecessary to help with infection control practices for the prevention o f their dissemination and the transmission of the resistance gene to o ther pathogenic bacteria.