Prevalence and antibiotic susceptibility of Staphylococcus aureus isolated from raw and grilled beef in Nyankpala community in the Northern Region of Ghana

Staphylococcus aureus is among the important pathogens contributing to foodborne illnesses. They easily cross contaminate foods from hands that comes in contact with the nose and mouth. They cause endocarditis, boils, impetigo, cellulitis and scalded skin. This study was carried out to determine the prevalence and antibiotic susceptibility of Staphylococcus aureus isolated from raw and grilled beef sold in Nyankpala, Northern Region of Ghana. Isolation of Staphylococcus aureus was done according to the USA-FDA Bacteriological Analytical Manual. Antibiotic susceptibility test was performed using the disc diffusion method and the results interpreted using the CLSI guidelines. A total of 54 beef samples made up of 18 raw beef samples(T1), 18 grilled beef samples tested immediately after grilling (T2) and 18 grilled beef samples tested 1 h 30 min after grilling (T3) were examined. Overall, 16.67% (9) were positive for Staphylococcus aureus. Staphylococcus aureus were isolated from grilled beef immediately (T2) after grilling (33.33%) and 1 h 30 min (T3) after grilling (16.67%). They were not isolated from raw beef samples (T1). Aerobic plate count was highest in T1 (3.59 log cfu/g), followed by T2 (2.94 log cfu/g) and T3 (2.83 log cfu/g). Out of 18 positive samples, 85.19% were susceptible, 14.81% were intermediate resistant and none was resistant. Staphylococcus aureus were all (100%) susceptible to amoxicillin, chloramphenicol, ciprofloxacin, ceftriaxone, gentamicin, and sulfamethoxazole/trimethoprim. This study revealed that Staphylococcus aureus are present in grilled beef rather than the fresh samples examined. In conclusion, Staphylococcus aureus contamination mostly occurred after processing and were susceptible to most antibiotics.