Differentiation of methiclin resistant staphylococcus aureus MRSA from the coagulase negative staphylococcus aureus MRCoNS using the PCR methods in teaching hospitals of shiraz.

Background and Aim : Staphylococcal related infections is one of the major causes of nosocomial infections which leads to wide range of health problems, including skin lesions, invasive infections, such as osteomyelitis and also bacteremia. Hence, the aim of this study was to evaluate the frequency of methicillin resistant staphylococcus aureus (MRSA) isolates and methicillin resistant coagulase negative staphylococcus aureus (MRCoNS) isolates due to the fact that their resistance frequency to methicillin and other antibiotics is increasing. Additionally, it is important to determine pvl genes which are associated with respiratory tract and skin infections.Methods : We have performed a cross-sectional study on a total of ۲۲۱ staphylococci isolated from clinical specimens in two hospitals in Shiraz-Iran during a one year period. (۲۰۱۶-۲۰۱۷). Moreover, antibiotic susceptibility profiles of isolates were evaluated by the disk diffusion methods according to CLSI protocols. Also, DNA extraction was performed by boiling method and we used polymerase- chain-reaction (PCR) for the detection of mecA, femA, pvl gene.Results : Among ۲۲۱ isolates, about ۱۶۸ isolates (۷۶%) were determined as staphylococci, ۵۳ isolate (۲۴%) were coagulase negative staphylococci (CoNS), also ۷۰ isolates were confirmed as MRSA and ۵۳ CoNS and about (۴۹.۵%) ۲۶ isolate were MRCoNS. Molecular investigations showed that among all isolates, ۹۶ isolates (۴۳.۴%) was carrying mecA gene, ۱۶۸ (۷۶%) femA gene and interestingly,۶ isolates was carrying pvl gene. Antibiotic resistance pattern of MRCoNS isolates showed ۷۰% resistance to erythromycin, ۶۹.۲% to gentamicin, and ۶۵% to chloramphenicol, while MRSA isolates showed (۸۲.۸%) resistance to chloramphenicol , (۶۸.۵%) to gentamicin, and also (۶۴.۲%) to tobramycin.Conclusion : We can concluded that the frequency of CoNS isolates and especially MRCoNS isolates in southwest of IRAN (Shiraz) is remarkably increasing. Hence, prevention and control of MRSA isolates in order to prevent the gene transfer and antibiotic resistance are important factors to decrease the mortality rates and also infections.

کلیدواژه ها:

Nosocomial infections ، MRSA ، MRCoNS ، antibiotic ، IRAN.