CEFOXITIN THERAPY OF COMPLICATED URINARY TRACT INFECTIONS WITH SPECIAL REFERENCE TO ITS STABILIITY TO DEGRADATION BY β-LACTAMASE

Abstract

Cefoxitin therapy of complicated urinary tract infections in geriatric patients incurable by treatment with other β-lactam antibiotics was successful in improvement of clinical signs, and in eradication of the causal organisms from the urine. Of 9 cases employed, 4 cases recovered completely, and 4 cases fell into the bacterial substitution with other Gram-negative bacilli and fungi. In the last one case, though the urinary counts of bacteria were reduced significantly, the treatment failed in complete elimination of the causal organisms from the urine.
The susceptibilities of the isolates to cefoxitin more or less decreased during the first treatment with other antibiotics, and most of them were estimated as resistant ones in regard of MIC values. Nevertheless, the antibiotic was stable to hydrolysis by β-lactamase in sonicates of these isolates, but its bioactive concentration was more or less reduced by contact with corresponding whole cells. Thus the effect of cefoxitin on elimination of urinary counts of bacteria was discussed both in connection with its stability to hydrolysis by the crude β-lactamase preparations and reduction of its bioactive concentration with whole cells of the isolates. In some populations of causal organisms, other mechanisms than hydrolysis by β-lactamase may participate in resistance to the antibiotic. Because the cells with such resistance mechanisms should survive the therapy, and subsequently multiply after the treatment, a few cases failed in complete elimination of the organisms from the urine even by treatment with cefoxitin.