Molecular expression of mecA gene in Staphylococcus aureus isolated from diabetic foot ulcers

Abstract

Background: The mecA gene is a mobile genetic element contains various structures that encoded resistance to non-β-lactam antibiotics.

Aims: Finding the molecular characterization of mecA gene in clinical isolates of S. aureus obtained from the ulcers of diabetic foot patients with estimating their susceptibility to various antibiotics.

Materials and methods: Swabs of totally 58 diabetic foot ulcers were collected and inoculated in Mannitol salt agar, and then, the isolates of S. aureus were confirmed biochemically. Antibiotic susceptibility was performed using the disk diffusion test among an overall 12 types of antibiotics. Molecular PCR assaying was carried out targeting the mecA gene.  

Results: The findings of traditional isolation and biochemical confirmation revealed the presence of 39.66% positive S. aureus isolates. The antibiotic susceptibility testing using the Kirby-Bauer disk diffusion shown that the positive S. aureus isolates were significantly sensitive to Nitrofurantoin (86.96%), Oxacillin (82.61%), Ofloxacin (69.57%), and Rifampin (56.52%); but highly resistant to Ampcillin (82.61%), Meropenem (82.61%), Amoxcillin (73.91%), Cephalexin (69.57%), Cefotaxim (60.87%), Ciprofloxacin (60.87%), and Methicillin (60.87%). Targeting the mecA gene, molecular testing of 23 positive S. aureus isolates by PCR assay detected that 34.78% were positives.

Conclusion: The presence of resistance and virulence genes can affect significantly on the pattern of sensitivity to antibiotics, especially with increasing of antibiotic resistance. Hence, the using of molecular assay in diagnosis of various resistance and virulence genes can support the cure rate.