ISOLATION, MOLECULAR DETECTION AND ANTIMICROBIAL SUSCEPTIBILITY OF SALMONELLA FROM COW MILK AND BEEF IN SELECTED DISTRICTS OF SIDAMA REGIONAL STATE, ETHIOPIA

Abstract

Salmonella is one of the most common causes of foodborne diseases and frequently reported for exacerbating increase of multi-drug resistance worldwide. Unhygienic practices throughout food chain and cultural habits of raw animal products contributed for the expansion of the infection and increment in antimicrobial resistance especially in developing world like Ethiopia. A cross- sectional type of study was conducted from December, 2022 to June, 2023. The study was aimed with isolation, molecular detection and determination of antimicrobial susceptibility of Salmonella from cow milk and beef in Hawassa, Yirgalem and Wondo Genet districts of Sidama Regional State. A total of 216 samples of which 152 milk and 64 beef samples were collected with purposive and simple random sampling methods for isolation and biochemical identification of Salmonella. Positive isolates obtained from bacteriological and biochemical tests were further confirmed by polymerase chain reaction (PCR). Then, the isolate’s antimicrobial susceptibility profile was tested by using disk diffusion method for twelve selected antimicrobials. SPSS windows version 25.0 was used for statistical analysis. Fisher’s exact test was the measure of association of isolates with different attributes. Bacteriological and biochemical detection tests revealed that 6.5% (N=14/216) Salmonella was isolated from the total sample. However, in molecular detection, only 9 of the 14 isolates were confirmed to be Salmonella using PCR test, which was 4.17% of the total. The proportion was 5.38%, 3.23%, and 2.38% in Hawassa, Yirgalem and Wondo Genet districts, respectively. There was no significant variation in prevalence among the districts and between sample types milk (3.9%) and beef (4.7%) (p > 0.05). Similarly, no significant (p > 0.05) variation was observed in the Salmonella isolation rate among retailers (4.84%), households (5.56%) and farms (1.85%) as well as between yoghurt (6.45%) and raw (3.31%) milk. The result of the antimicrobial susceptibility test showed that Salmonella isolates were 100% resistant to ampicillin, nalidixic acid, clindamycin and cephalothin while they were above 50% sensitive to ceftriaxone, chloramphenicol and gentamycin. Multi-drug resistance (MDR) was demonstrated in all isolates. Overall, this study showed that Salmonella was prevalent in cow milk and beef produced and consumed; and developed MDR which may pose public health concern in the study area. Thus, subsequent regular investigations on serotypes, AMR genes and risk factors as well as rational use of antimicrobials is necessary.