Prevalence of SEA and SEB enterotoxin producing methicillin-resistant staphylococcus aureus strains among primary school children in Sari, Iran

Background: Staphylococcus aureus is a frequent hospital and community-acquired infection. It has different types of virulence factors and provides host invasion requirements through the release of various toxins, the super-antigenic enterotoxins, SEA and SEB being the most likely to cause pathogenicity.

Objectives:  To assess the prevalence of SEA and SEB enterotoxin producing MRSA strains among primary school children in Sari, northern Iran.

Method: In this descriptive cross-sectional study, 140 nasal isolates of primary school children were collected for 4 months in 2017 in Sari city. First, isolates were identified utilising biochemical and laboratory methods. Minimum inhibitory concentration of isolates to oxacillin was next determined using phenotypic and molecular methods. The presence of SEA and SEB genes were then detected using polymerase chain reaction sequence specific primers (PCR-SSP).

Results: We identified 70 Staphylococcus aureus isolates through standard microbiological procedures. In the phenotypic antibiotic susceptibility assay of 70 isolates of Staphylococcus aureus, 42 isolates were identified as oxacillin- susceptibility assay of 70 isolates of Staphylococcus aureus, 42 isolates were identified as oxacillin-resistant isolates according to the CLSI guidelines, and were reported as methicillin-resistant staphylococcus aureus (MRSA) nasal carriers. Also, 23 cases of oxacillin-resistant isolates lacked the mecA gene (false positive). Nineteen isolates were definite MRSA using PCR, of which 8 isolates (21.42%) had SEA gene and 3 isolates (7.14%) had SEB gene. Also, three isolates (7.14%) carried both the SEA and SEBgenes.

Conclusions: In primary school children in Sari, northern Iran, of the 19 definite MRSA isolates using PCR, 21.4% had the SEA gene, 7.1% had the SEB gene and 7.1% carried both the SEA and SEB genes.

Sri Lanka Journal of Child Health, 2021; 50: 17-21