MOLECULAR EPIDEMIOLOGY OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS (MRSA) IN UNIVERSITY OF JOS COMMUNITY

MOLECULAR EPIDEMIOLOGY OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS (MRSA) IN UNIVERSITY OF JOS COMMUNITY

Abstract:

Staphylococcus aureus is a virulent pathogen that is currently not only the most common cause of infections in hospitalized patients worldwide but increasingly also as a community associated pathogen. This study was aimed at determining the prevalence of methicillin resistant S. aureus among apparently healthy student population of the University of Jos, Jos Nigeria. Two hundred and seventeen (217) urine samples were screened for Staphylococcus aureus. Isolates were characterized by conventional cultural and biochemical methods including rapid test kits (MicrogenID test kit). Their susceptibility profiles were determined against a panel of eleven antibiotics including cefoxitin and oxacillin. The MRSA status were confirmed by the phenotypic test using disc diffusion test method and molecular analysis employing multiplex PCR for the detection of the mecA, nuc genes and spa typing. Of the 217 samples collected 171 (78.8%) were positive for Staphylococcal species while 73(54.1%) of 135 screened with the MicrogenD test kit were identified as S. aureus. The susceptibility test showed that the highest level of resistance was demonstrated against penicillin (91.8%) followed by cefotaxime (80.7%), ofloxacin (79.2%), tetracycline (64.9%) and oxacillin (60.8%) in that order. None of the 33 isolates subjected to E-test was Vancomycin resistant. Phenotypic detection of methicillin resistance with the use of cefoxitin and oxacillin discs gave a prevalence of 79.5% (136/171) of the Staphylococcal isolates and 47.9% of S. aureus. These isolates were resistant to the betalactam antibiotics and were multidrug resistant. They were, however largely susceptible to ciprofloxacin, vancomycin, erythromycin, gentamicin and cotrimoxazole. 88.30% had MAR index greater than 0.3. Sixteen of the S. aureus isolates had the mecA and nuc genes. The nucleotide sequence of 16S rRNA gene of the 16 isolates showed that 12 of them had 77-92% identity with S. aureus strain N315. Three isolates (5, 9 and 16) could not be typed as there was no similarity with GenBank data base. Four of the isolates have common lineage with 8 BWI (2), S1123 and 363LF (1) and CLRSA1 (1) strains. The study shows that mecA gene is present in the study population. mecB gene was also detected in the 16 isolates. This is the first time this gene is being reported in S. aureus and this may increase the level and magnitude of resistance by MRSA. The identification of mecA and mecB genes in community isolates implies that any outbreak of infections caused by these strains may pose a threat to public health as these strains are resistant to all antibiotics tested except ciprofloxacin, vancomycin and co-trimoxazole.

MOLECULAR EPIDEMIOLOGY OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS (MRSA) IN UNIVERSITY OF JOS COMMUNITY