laboratory records for the period January 1, 1996, through December 31, 1999, were reviewed at the Eric Williams Medical Sciences Complex. Urine specimens were derived from patients on the wards or attending outpatient clinics, general practitioners offices and health centers. Urine samples from patients attending outpatient clinics, general practitioners offices and health centers in the community were all classified as “community practice” isolates, while inpatients isolates were labeled as “hospital practice” isolates.

The method used in this laboratory had not changed since the commissioning of the hospital in the summer of 1991. Since January 1992, manual record-keeping of antimicrobial profiles of all urinary isolates have been kept. All specimens were examined by microscopy for the presence of leukocytes, erythrocytes, casts and bacteria. Quantitative bacteriologic cultures were performed according to standard laboratory procedures. A standard calibrated loop delivering 0.001 mL of urine was used to inoculate sheep blood agar and cysteine lactose electrolyte deficient agar. These plates were incubated aerobical-ly at 37° С for 18 to 24 hours, and colony counts were expressed in colony-forming units (CFU) per mL of urine. A midstream (“clean catch”) urine specimen containing > 105 CFU per mL or >3000 CFU per mL in catheter specimen of a single species were considered as having significant bacteriuria. Organisms’ identities were based on Gram reaction, colonial morphology and biochemical characterization. Repeated recovery of the same organism from the same patient was considered as a single isolate.

Isolates were tested for susceptibilities by the Bauer-Kirby disk diffusion technique, on Mueller-Hinton agar using the following discs and concentrations (in brackets):  (10|ig),  (clavulanic acid) (30|ag), ceftazidime (30|ng), gentamicin (10|^g), acid (30|iig),  (10|ig), (30|iig), co-trimoxazole (trimethoprim-sulfamethoxazole) (25|ng),  (300|ug) and (30 jig). The control organism was the Escherichia coli ATCC 25922 strain supplied by the Caribbean Epidemiology Center, a branch of the Pan American Health Organization/World Health Organization. The statistical significance of changes was cal culated using the chi-square test and Fisher exact probability test, where appropriate.