Investigation of Extended-Spectrum Beta-Lactamase Producing Escherichia Coli in Milk on Dairy Cattle Farm

The present study was conducted to investigate the presence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) in cattle farm milk mixtures. Thirty two farm milks from 32 farms in Gölhisar district of Burdur city (Türkiye) were concurrently cultured on MacConkey agar plates supplemented with either 2 μg/mL cefotaxime or 2 μg/mL ceftazidime. After incubation at 37°C for 24 h under aerobic conditions, biochemical/physiological tests were applied to the lactose positive colonies for identification of E. coli in the cultures. Subsequently, determination of ESBL production in E. coli isolate was done by the combined disk method. In order to determine the ESBL class, the isolates were screened for CTX-M, SHV and TEM genes by polymerase chain reaction (PCR). After the selective culture of the milk samples, one (1/32, 3.12%) E. coli was isolated. The isolate confirmed as an ESBL procedure by the combined disc method harbored the CTX-M group 1 ESBL gene, but tested negative for TEM and SHV genes. This study showed that ESBL-producing E. coli could be found at low level in farm milks of the cattle farms in the region. Although the source of the ESBL-producing E. coli isolated from the farm milk mixture was not identified in this study, it is important that this bacterium was detected in the milk to be consumed.