Changing trends in frequency and antimicrobial resistance of urinary pathogens in outpatient clinics and a hospital in Southern Israel, 1991–1995

Abstract

In order to monitor changes in the frequency and antimicrobial resistance of urinary pathogens over several years, urinary cultures received from outpatient clinics and from a hospital during a period of one month each in 1991 and 1995 were analyzed at a clinical microbiology laboratory. In 1991 and 1995, 1366 and 1534 significant monomicrobic cultures respectively were reviewed. The frequency ofEscherichia coli dropped significantly in the outpatient clinics from 70.5% to 61.2% (p<0.0001). The frequency ofProteus mirabilis, Morganella morganii, Pseudomonas aeruginosa and other gram-negative bacteria also decreased, but the frequency ofKlebsiella spp. andEnterobacter spp. increased from 2.6% to 5.8% (p<0.0001). In the hospital, the frequency ofEnterobacter spp. (p<0.04),Escherichia coli andMorganella morganii declined from 1991 to 1995, whereas the frequency ofPseudomonas aeruginosa (p=0.001),Acinetobacter spp. (p<0.05),Klebsiella spp.,Proteus mirabilis and other gram-negative rods increased considerably. The frequency of gram-positive aerobic bacteria rose markedly in outpatient specimens from 6.1% to 13.5% (p<0.0001), while a decline from 14.4% to 9.3% was noted in hospital specimens (p<0.02). A significant rise in the resistance ofEscherichia coli to gentamicin and ciprofloxacin (p<0.0001) was detected in outpatient isoates. In the hospital, gram-negative urinary pathogens demonstrated increased resistance to ampicillin (p=0.042), cefuroxime (p=0.005), gentamicin (p=0.002) and ciprofloxacin (p<0.0001) during the study period. The changing etiology of urinary tract infections and the increasing resistance of organisms indicate that periodic monitoring and possibly also modification of empirical therapy are required.