[Microbiology of urinary tract infections in ambulatory patients. Therapeutic options in times of high antibiotic resistance]

Abstract

Objective: To determine the antibiotic resistance of urinary pathogens in ambulatory patients from Mexico City, in order to infer therapeutic options in environments of high resistance.

Methods: Cross sectional survey performed between July 2006, and January 2007, in patients > or =3 year-old from a private institution. Cultured organisms were identified with a commercial biochemical system. For common antibiotics, susceptibility was performed by broth microdilution with a commercial system; for fosfomycin tromethamine, the disk diffusion test was performed.

Results: From 1685 urine specimens, 257 (15.3%) yielded a positive culture; 215 (83.7%) from women and 42 (16.3%) from men. Global resistance was the following: ampicillin, 68.4%; co-amoxiclav, 19.5%; ciprofloxacin, 36.3%; cephalothin, 64.7%; ceftriaxone, 12.2%; cefuroxime, 18.7%; nitrofurantoin, 19%; trimethoprim-sulphamethoxazol, 53.4%; gentamicin, 18.9%; and fosfomycin tromethamine, 0.8%. Escherichia coli was the main pathogen, with 203 (79%) isolations; its specific resistance was similar to the global one, and its production of extended-spectrum beta-lactamases (ESBLs) was 9.4%.

Conclusions: The high resistance rate found is alarming; we have few options for the initial treatment of urinary tract infections in ambulatory patients. To control the problem, health authorities must regulate the indiscriminate use of antibiotics.