Molecular Study of Methicillin Resistant Staphylococcus aureus Isolated from Different Hospitals in Najaf-Iraq

Abstract

1 Professor of microbiology, College of Medicine, Kufa University 2 Lecturer in Molecular Biology, College of medicine, Kufa University 3 MSc, Student, Department of Microbiology, College of Medicine, Kufa University Email: hkrooz7@yahoo.com Abstract Aim of Study: The aim is to do molecular characterization of Staphylococcus aureus isolated from hospital staff and environment, in order to determine the gene(s) that is (are) responsible for antibiotics resistance especially mecA and SCCmec. Methodology: This study that aimed to detect methicillin resistant Staphylococcus aureus in isolates from AlSader Teaching Hospital and al-Hakeem General Hospital in Annajaf during the period from November 2015 to April 2016. From a total of 250 clinical samples that were collected to isolate Staphylococcus aureus from the hospital staff (nurses, doctors, workers, medical student ---etc.), and also from different parts of hospital environments. A total of 50 Staphylococcus aureus isolate were detected and confirmed by different morphological and biochemical confirmatory test. Results: These 50 isolates then studied by VITEC2 and also by cefoxitin disc susceptibility test .It was able to detect only 41 isolates that had cefoxitin resistance which represented 82% of the total Staphylococcus isolates which are regarded as Methicillin Resistant Staphylococcus aureus phenotypically. Polymerase chain reaction test was done to find out the genes that are responsible for methicillin resistance in these isolates, using three types of primers one was for Sa442 gene which was designed to confirm that the isolates were Staphylococcus aureus and two other genes to confirm that the isolates were methicillin resistant which were mecA and SCCmec with the different subtypes of the last gene, and it was found that from the 41 isolates which were phenotypically confirimed to be methicillin resistant only 32 were found to harbor these genes which represented only 78% of the phenotypically confirmed MRSA; It was found also that the subtype SCCmec type IV was the most dominant gene among SCCmec types in these isolates as it was detected in 23 out of 32 isolates (71.9%), followed by SCCmec type III Which was found in 5(15.6%) of the isolates. Conclusions: Polymerase chain reaction is the golden slandered for identification of methicillin resistant Staphylococcus aureus MRSA. The SCC mec type IV was the most dominant among SCCmec genotypes of MRSA strains that were isolated from hospitals in the present study. Recommandation: Vancomycin resistant staphylococcus aureas (VRSA) should be taken in consideration when we are working with hospital cross infection. Further studies on large scale should be performed in order to study MRSA in the whole country. Antibiotic prescribing policy should be put under observation and guidenece inside and outside hospitals.