Investigation and Identification of the nuc, fem B mecA and aac(6′)/aph(2′′)-Ia Genes in the Staphylococcus Aureus Isolated from Northwest Iran by Multiplex PCR Method

Backgrounds and Objectives: Staphylococcus aureus is one of the most common pyogenic bacteria possessing highest potentiality to develop resistance to antibiotics. Emergence of resistance towards the most common antibiotics such as aminoglycoside and vancomycin has added burden to the existing MRSA situation. Aminoglycosides are important bactericidal agents. The aminoglycoside resistance is due to drug inactivation by plasmid- or transposon-mediated aminoglycoside modifying enzymes. The aim of this study was to develop a Multiplex-PCR assay for rapid and accurate detection of S. aureus and its resistance genes to aminoglycoside and methicillin. Materials and Methods: Isolates of S. aureus were obtained from various clinical specimens based on standard bacteriological procedures. The antimicrobial susceptibility of the strains was determined using the disk diffusion method. Extraction of genomic DNA was carried out by SDS-Proteinase K method modified with CTAB. The Multiplex-PCR assay was carried out for detection of mecA, nuc, femB and aac(6′)/aph(2//)-Ia genes. Results: Totally 1,389 specimens examined 90 strains of S. aureus were isolated. Antibiotic susceptibility testing using disc diffusion revealed high resistance to penicillin (97.8%). Among the isolates nuc, femB and mecA genes were detected in 90(100%), 86 (95/6%) and 58 (64/4%) strains, respectively. Additionally, 44 (48/9%) strains were found to harbor aac(6′)/aph(2//)-Ia gene. Conclusion: This study highlights that the multiplex PCR method described herein is not only a convenient method for rapid and accurate detection of S. aureus species but also it detects the presence of common antibiotic - resistant genes.

Staphylococcus aureus, Aminoglycosides, Multiplex PCR