Study of Prevalence and Characteristics of Staphylococcus aureus and CA-MRSA Nasal Colonization in 2-5 Years Old Children in Isfahan

Background and Aim: We carried out a descriptive study to determine the extent of nasal colonization and characteristics of Staphylococcus aureus and CA-MRSA isolates in 2-5 year old children of day care centers in Isfahan. Materials and Methods: The characteristics of isolates were determined using standard phenotypic profiles including colony morphology, Gram staining, catalase, hyaluronidase, coagulase and Dnase tests as well as mannitol fermentation. The MRSA detection was carried out according to CLSI guidelines with oxacillin agar screen test. Methicillin resistance was further confirmed by detection of a 310 bp fragment of mecA gene of MRSA by PCR. Drug susceptibility testing to antibiotics other than methicillin was conducted by disk diffusion. The Beta-lactamase production and inducible clindamycin resistance were also determined by performing the double-disc diffusion and D-test.Results: Out of 323 children, 115 (35.6%) carried S. aureus and 11 (9.5%) carried MRSA. All MRSA strains were found to contain mecA gene. The susceptibility of strains to vancomycin, rifampicin and Linezolid were 100%. The susceptibility of strains to gentamicin, clindamycin, erythromycin, co-trimoxazole, amoxiclav, ciprofloxacin, tetracycline and penicillin were 99%, 97%, 94%, 94%, 93%, 88%, 44.4% and 1.8% respectively. Beta-lactamase production was seen in 19 (16.5%) of staphylococcal strains. Inducible clindamycin resistance was seen in 4 (3.5%) of the isolates. Conclusions: Our data indicates that the spread of CA-MRSA within Iranian population is worthy of consideration and merits further molecular investigation to determine the source and mode of transmission.

Keywords:

Beta-lactamase , inducible clindamycin resistance , methicillin resistant Staphylococcus aureus , mecA gene