Coagulase-negative Staphylococci from Bovine Milk: Virulent gene detection, and Antibiogram Profiles

AbstractBackground Coagulase-negativeStaphylococcusspecies are an emerging cause of intramammary infection, posing a significant economic and public health threat. The cross-sectional study was conducted to isolate and assess virulence factors and antibiogram profiles of coagulase-negativeStaphylococcusspecies in 290 milk samples collected from February to August 2022. Species isolation and identification were performed by plate culturing and biochemical tests and single-plex PCR was used for the detection of virulent genes. The antimicrobial susceptibility profile of each coagulase-negativeStaphylococcusspecies isolate was determined by the Kirby-Bauer disc diffusion test. Results Coagulase-negativeStaphylococcusspecies were isolated in 28.6%, (83/290) of the samples. Of these, theS. epidermidis,S. sciuri,S. warneri,S. haemolyticus,S. simulans,S. chromogens,S. cohnii, andS. captisspecies were isolated at the rates of 11, 5.2, 3.4, 3.1, 3.1, 1, 1, and 0.7% respectively. Coagulase-negative Staphylococcusspecies carried 26.5, 22.1, 21.7, 9.6, 9.6 and 8.4% of theica D,Pvl,Mec A,hlb,Sec, andhlavirulent genes respectively. All the isolates showed a high percentage (100%) of resistance to Amoxicillin, Ampicillin, and Cefotetan and 37.5% of resistance to Oxacillin. The majority (54.2%) of coagulase-negative isolates also showed multidrug resistance. Conclusion The present study revealed that coagulase-negativeStaphylococcusspecies isolates were found carriage of one or more virulent and enterotoxin genes responsible for intramammary and food poisoning infections. The majority of the isolates (54.2%) were also found multidrug resistant. Thus, urgent disease control and prevention measures are warranted to reduce the deleterious impact of coagulase-negative species. This study is the first to document the detection of virulent and food poisoning genes in coagulase-negativeStaphylococcusspecies from milk in Ethiopia.