Prevalence of -lactamase-producing and non-producing methicillin resistant Staphylococcus aureus in clinical samples in Bangladesh

Staphylococcus aureus has been reported to be a major cause of community and hospital acquired infections. Indiscriminate use of antibiotics resulted in the development of multi-drug resistant S. aureus throughout the world. Development of multi-drug resistant strains ofS. aureus is increasingly alarming in Bangladesh. We attempted to study the current prevalence of β-lactamase-producing and non-producing methicillin-resistant S. aureus(MRSA) in clinical samples and to find out the correlation of antimicrobial resistance pattern with their plasmid profiles. Twenty three clinical isolates of S. aureus were evaluated during the study period (2009). The isolates were identified by conventional methods. Antibiotic susceptibility of the isolates was performed by disk diffusion method. Plasmid profiles were observed by agarose gel electrophoresis. In the present investigation, 43·48% isolates were ensured methicillin resistant while the remaining 56·52% isolates were found to be methicillin sensitive by disk diffusion method. β-lactamase test which was performed by acid formation method showed that 50% of the MRSA isolates produced β-lactamase. Our studies of resistance pattern to commonly prescribed antimicrobials showed that MRSA isolates were highly sensitive to vancomycin (100%), fusidic acid (90%), chloramphenicol (80%), neomycin (80%), rifampin (80%), gentamycin (70%), ceftriaxone (60%), cephalexin (60%), ciprofloxacin (60%), and cloxacillin (60%). Plasmid profiling of the selected resistant isolates ofStaphylococcus revealed clear and distinct bands of plasmid DNA. These isolates showed severe resistance to amoxicillin (70%), co-trimoxazole (90%) and erythromycin (80%). Key words: Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), resistance, β-lactamase, Bangladesh.