The Relationship Between Antibiotic Resistance and Agr Type in Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated From Burn Wound of Hospitalized Patient in Tehran

Staphylococcus aureus is the major cause of hospital and community-acquired infections. This bacterium possesses an accessory gene regulator (agr) that plays role in colonization, expression of virulence factors and antibiotic resistance. It’s four major polypeptide with variable sequences lead to at least four agr type in S. aureus.The aim of this study was to determine the relationship between the antibiogram patterns with agr type of clinical S. aureus. Detection of methicillin-resistant Staphylococcus aureus (MRSA) from burn wounds was performed by phenotypic and genotypic profiles. The antibiotics resistance pattern was determined by disk agar diffusion (Tigecycline (TGC), Ciprofloxacin(CIP), Erythromycin(E), Cloxacillin(CX), Clindamycin(CD), Imipenem(IMI), Co-trimoxazole(SXT), Kanamycin(K), Teicoplanin(TEC), Gentamicin(GM), Mupirocin(MUP), Ceftriaxone (CTR)). The agr typing by PCR-RFLP method using the Restriction endonuclease ScaI was performed and spss19 was used for data analysis. The total of 76 MRSA isolates was studied. The agr type distribution was 75.6% Type I, 8.2% Type II, 5.4% Type III, 10.8% type IV. The most antibiotics resistant agr type belongs to the type I. There was no significance relationship between every agr type and antibiotics but only a statistically significant association exist between CX, E, CTR, SXT, GM, CIP antibiotics and all agr types (P<0.05). There was no significance relationship between every agr type and antibiotics but significant relationship observed between resistance to some antibiotics with all agr types could be related to the number and source of isolated bacteria or extra use of these antibiotics. By considering that agr locus belongs to upstream genes so it may use the Quorum Sensing (QS) system to induce the most drug resistance.