Characterization of Staphylococcus aureus isolated from human dental infection

Staphylococcus aureus is an opportunistic pathogen causing dental infection and systemic infections in human body. This organism decreases susceptibility to several types of antibiotics every day and becomes more resistant which is a growing sense of concern in this era. Considering this fact, the study was attempted to characterize the S. aureus from human dental infection and to determine the antibiogram profile of isolates. Sixty four (64) samples were collected from the patients with dental infection who visited different dental clinics and hospitals in Mymensingh, Bangladesh for treatment. Isolation and identification of S. aureus were conducted by using cultural, morphological, and biochemical characteristics. Polymerase chain reaction was performed for final confirmation of S. aureus followed by detection of methicillin resistant S. aureus (MRSA) targeting mecA and mecC genes. Antibiotic susceptibility test of isolated bacteria was tested against seven antibiotics by disk diffusion methods. Forty isolates among 64 samples were found positive for S. aureus based on cultural characteristics. Among them 30 isolates were found positive in coagulase test. Depending on the result of coagulase test, all the 30 isolates were subjected to antibiotic sensitivity test and among them 25 were 100% resistant to penicillin, ampicillin and amoxicillin. All the 25 isolates were subjected to polymerase chain reaction (PCR) to identify methicillin resistant gene mecA and mecC. Eight isolates were positive for mecA gene while no isolates were positive for mecC. The present findings conclude that S. aureus is prevalent in dental infections and contain methicillin resistant genes.   Key words: Dental infection, Staphylococcus aureus, antibiotic resistance, methicillin resistant S. aureus (MRSA).