Phenotypic and Genotypic Evaluation of Methicillin-resistant Staphylococcus aureus Strains Isolated from Children in Tehran Children\'s Medical Center, 2016

Background and purpose: The aims of this study were to evaluate the antibiotic resistance of Healthcare-associated Methicillin-resistant Staphylococcus aureus (HA-MRSA) and Community associated MRSA (CA-MRSA)-resistant strains of Staphylococcus aureus strains and to investigate the frequency of different types of spa typing, SCCmec I, II, III, IV, V, and type IV, among the strains of MRSA isolated from clinical specimens of children in Tehran Children's Medical Center Hospital. Materials and methods: In this cross-sectional study, antibiotic susceptibility test was performed using Kirby-Baer method according to the CLSI guidelines. Presence of mecA, PVL, spa genes, as well as different types of SCCmec I, II, III, IV, V, and major subtypes of SCCmec IV were investigated using Multiplex PCR. Results: Among 133 clinical isolates of S. aureus, 70 (53%) were methicillin-susceptible (MSSA) and 63 (47%) were MRSA. The mecA and PVL genes frequency distributions among MRSA strains were 100% and 3.1%, respectively. In the present study, there were 5 SCCmec (I-V) types, indicating wide variations in the hospital investigated. In addition, high prevalence of SCCmec III (30.1%) and III + Iva (23.8%) was observed. Of 63 strains of MRSA, 46 were classified into 11 spa types. The most common type was spa t037 that was found in 53.9% (n= 34) of the strains. Conclusion: High prevalence of SCCmec III + Iva and emergence of CA-MRSA strains in hospitals can be a serious warning to practitioners and infection control committees.