[Detection of beta-lactamase-producing bacteria from female patients with acute uncomplicated cystitis]

A total of 122 bacterial strains isolated from urine specimens of 113 female patients with acute uncomplicated cystitis were used for the study of beta-lactamase production and their susceptibility to various antimicrobial agents was determined. Beta-Lactamase activity was qualitatively determined by a paper strip acidimetric method with benzylpenicillin as substrate and by chromogenic cephalosporin methods using pyridine-2-azo-p-dimethylaniline cephalosporin or nitrocefin as substrate. Susceptibility to antimicrobial agents, including ampicillin, carbenicillin, cephalexin, cephalothin, gentamicin, minocycline, fosfomycin, pipemidic acid and sulfamethoxazole-trimethoprim was examined by a disc method. The beta-lactamase-producing strains detected by at least one of the three tests were found in 18 of 105 Escherichia coli isolates and in the single strain of Enterobacter cloacae dermidis, 3 Enterococcus faecalis and 1 Staphylococcus aureus produced beta-lactamase. The isolation rate of strains resistant to ampicillin, carbenicillin and cephalothin in the beta-lactamase-producing strains was significantly higher than that in the non-beta-lactamase-producing strains (p less than 0.01). These results suggest that beta-lactamase plays an important role in developing resistance to beta-lactam antibiotics in patients with uncomplicated urinary tract infection as well as complicated infection.