Hygiene survey from farm to milk supply stage using E. coli isolation and antimicrobial resistance test
Dairy industry involved various milking operation stages. Coliform and E. coli are marker and indicator of hygiene for fecal contamination of food at any point. Following 17 lactating dairy cow milking operations, five segments of stages consisting of 21 cut-off points were identified. Three hundred four (304) samples from various sources were collected and examined for E. coli to determine point(s) of milk contamination. Randomly selected isolates from all stages were exposed to chloramphenicol (C-30μg), neomycin (N-30μg), oxytetracycline (OT-30μg), polymyxin-B (PB-300IU) and trimethoprimsulfamethoxazole (SXT-1.25/23.75/μg) susceptibility using disc diffusion techniques. E. coli was not isolated from currency used as control. An overall 43.2% E. coli with similar distribution at cow barn (35.3%), milking facility cleaning (38.8%), milking operations (34.8%) and product station (29.4%) but higher (87.2%) on milk marketing Ethiopian currency notes were observed. All of the 21 individual sampling points were almost equally E. coli positive and identified as equally important points. Out of 50 randomly selected and tested isolate for drug resistance, 2.0%, 4.0%, 8.0%, 46.0% and 74.0% were found resistant to polymyxin-B, chloramphenicol, trimethoprim sulfamethoxazole, oxytetracycline and neomycin, respectively in ascending order. Single drug resistant were frequent (55.8%) followed by two drug resistant (36.6%) and MDR (9.7%).
Keywords: Dairy; Milking stage; E. coli, Resistance, Haramaya University; Hygiene