Detection of methicillin-resistant Staphylococcus aureus within raw milk and cheese samples

In consequence of previous study of bacterial propagation in milk and yogurt samples, present investigation endeavored to determine the existence of drug resistant Staphylococcus aureus especially the methicillin resistant S. aureus (MRSA) in raw milk and cheese samples collected from different areas in Dhaka City, Bangladesh. Total 80 samples (40 raw milk and 40 cheese samples) were microbiologically analyzed through cultural and the confirmative biochemical identification. Out of 80 samples studied, 17 (9 raw milk and 8 cheese) were found to harbor S. aureus. The drug resistance pattern of the staphylococcal isolates was determined against six antibiotics i.g. novobiocin (30μg), ciprofloxacin (5 μg), nalidixic acid (5 μg), methicillin (5 μg), oxacillin (1 μg) and erythromycin (15 μg) by the agar well diffusion method on MullerHinton agar. Three isolates from cheese samples and 8 isolates from raw milk samples were found to be resistant against at least two commonly used antibiotics. The highest resistance was found against methicillin (5μg, 58.82%) and oxacillin (1μg, 100%). The presence of methicillin resistant staphylococcal species as found from this study may pose a great public health threat, especially to the children.