The changing patterns of antimicrobial susceptibility of urinary pathogens in Trinidad.
OBJECTIVE
The prevalence of antimicrobial resistance in urinary pathogens is increasing worldwide. Accurate bacteriologic records of culture results may provide guidance on empirical therapy before sensitivity patterns are available. We report the changing antibiograms of pathogens associated with urinary tract infections (UTI) over a 4-year period at a newly commissioned hospital complex diagnostic laboratory in Trinidad.


METHODS
From January 1992 to December 1995, kept records of antibiograms of all urinary pathogens isolated were examined. Samples were derived from hospital sources (wards and out-patient clinics) and general practice sources (health centers and general practitioners). Quantitative bacteriologic cultures were performed according to standard laboratory procedures, and identification of isolates were based on Gram reaction, morphology and biochemical characteristics. Significant bacteriuria was defined as the presence of greater than 100,000 organisms per mL of a midstream urine specimen or more than 3000 bacteria per mL in a catheter specimen of a single specie. Antimicrobial sensitivities were done using the following antibiotics: norfloxacin, ampicillin, tetracycline, nitrofurantoin, gentamicin, co-trimoxazole (sulfamethoxazole-trimethoprim), trimethoprim, nalidixic acid, cephalexin and augmentin (amoxicillin-clavulanic acid). Control organism was E coli NCTC 10,418 strain.


RESULTS
The total number of specimens for the 4-year period in hospital was 14,181 with an isolation rate of 17%, and a general practice isolation rate of 67% from a total of 5,088 specimens. E coli was the most frequent isolate in both hospital (40%) and general practice (30%). There was an increase isolation of P aeruginosa from community practice reflecting an increase in home care catheterised male patients. Resistance to tetracycline was most significant in hospital (99%) and general practice (81%). Similar trend was observed for trimethoprim in hospital, and co-trimoxazole in both practices. Resistance to ampicillin, augmentin and cephalexin was relatively stable over the 4-year period.


CONCLUSIONS
We conclude that laboratories should encourage accurate bacteriologic record keeping of urinary isolates and their antibiograms to serve as guidance in empirical treatment in UTI. Also, urine microscopy may reduce the number of specimens sent for culture which are not cost-effective.
Orrett
F A
FA
Department of Microbiology/Pathology, Faculty of Medical Sciences, University of West Indies, St Augustine, Trinidad, West Indies.
Shurland
S M
SM
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000453:epidemiology; D006801:Humans; D008297:Male; D015995:Prevalence; D012189:Retrospective Studies; D014300:Trinidad and Tobago / Q000453:epidemiology; D014546:Urinary Catheterization; D014552:Urinary Tract Infections / Q000188:drug therapy* / Q000382:microbiology
D000900:Anti-Bacterial Agents