Elaboration and evaluation of a new screening medium for detection and presumptive identification of extended-spectrum beta-lactamase-producing organisms (ESBL)

Abstract

The new ß-lactamases have arisen largely as a consequence of heavy use of new expanded spectrum ß-lactam antibiotics. Health professionals need to be aware of the resistance problems caused by the new enzymes, and know the correct procedures to detect, prevent and control such problems. In this study, a new screening medium called Ceftazidime-Inositol-Vancomycin-Amphotericin B Agar (CIVA) was elaborated and the microbiological performance was evaluated for the detection and presumptive identification of ESBLproducing members of Enterobacteriaceae. It was performed in 126 stool samples from hospitalized patients at Santa Monica Hospital (Vila Velha, ES, Brazil), who had been heavily exposed to broad-spectrum antibiotic combinations. The bacteria were detected by the medium based on their colony colours (due to inositol fermentation). Additional tests were required for correct identification of these strains. No false positive rates were detected.

Antibiotics promote intestinal growth of carbapenem-resistantEnterobacteriaceaeby enriching nutrients and depleting microbial metabolites

“…For each donor, fresh faeces were inoculated into the distal gut growth medium at a 2% (w/v) concentration. Faecal cultures were supplemented with water (antibiotic-naïve control) or one of the following antibiotics (at concentrations measured in faeces): 2 µg/ml MEM, 2 µg/ml IPM, 37 µg/ml ETP, 139 µg/ml TZP, 152 µg/ml CRO, 22 µg/ml CAZ, 2 µg/ml CTX, 139 µg/ml CIP 18,[26][27][28][57][58][59][60] . These antibiotics are known to promote the intestinal colonisation with CRE and are used frequently in routine clinical practice 5 .…”