Enterococcal urinary tract infections: eight years experience at a regional hospital in Trinidad, West Indies

ABSTRACT

OBJECTIVE: To investigate the prevalence of significant enterococcal isolates from urine and determine what factors are associated with the increased prevalence, with particular reference to antibiotic susceptibilities. METHODS: Retrospective analysis over an 8-year period of hospital laboratory records of urinary isolates of enterococci was done. Species were identified via colony morphology, growth in 6.5% sodium chloride and their ability to hydrolyze esculin in the presence of 40% bile salts. Susceptibility testing via the disc diffusion technique with 9 commonly used antibiotics was also done as defined by the National Committee for Clinical Laboratory Standards. RESULTS: From 39,881 urine specimens, 9116 (22.9%) were culture positive. Of this 9116, 1001 (11.0%) were enterococci, the 4th most common urinary isolate. E. coli was the most common (36.2%). Most enterococci were from pediatric patients (28.4%) and the urology unit (24.5%). All enterococci were fully sensitive to ampicillin and augmentin (amoxicillin-clavulanic acid). Sensitivity to gentamicin decreased significantly from 79% in 1990 to 58% in 1997 (P < 0.005). Sensitivity to the cephalosporins and nitrofuratoin were relatively stable, but sensitivity to nalidixic acid varied. No resistance to vancomycin was detected during the study, and no cases of bacteremia complicated bacteriuria were seen. CONCLUSION: Isolation of enterococci was relatively stable during the 8-year period, and all isolates were fully sensitive to the older beta-lactams, ampicillin, cefaclor and augmentin, but displayed varying degrees of multi-resistance to other commonly used urinary agents such as nalidixic acid and co-trimoxazole (trimethoprim-sulfamethoxazole). Because of the emergence of multi-resistant enterococci in many countries, and the high cost of drugs in our society, it is imperative that vigilance be maintained in monitoring enterococcal infections in hospitals.