Detection of icaA/icaD Genes and Biofilm Formation among Clinical Isolates of Staphylococcus aureus from Shiraz, Iran

Biofilm producing Staphylococcus aureus is known as one of the major causative agents of infections, failure of implanted devices and persistent infection among hospitalized patients. The aim of the present study was to determine the frequency of biofilm producing S. aureus isolates amongst the clinical specimens. This cross-sectional study was conducted during 2012 to 2013 in two teaching hospitals in Shiraz, southwest of Iran. Totally, 345 S. aureus isolates from various clinical specimens were included. Biofilm producing isolates were phenotypically detected using Congo Red Agar (CRA) and genotypically by PCR assay for the icaA and icaD genes. Of the 345 S. aureus isolates, 42.3% were methicillin-resistant S. aureus (MRSA) and subsequently 57.7% were methicillin susceptible isolates. The results of CRA plates showed that 77 (52.7%) and 74 (37.2%) of MRSA and MSSA were biofilm producing isolates. The frequency of icaA/D genes among MRSA and MSSA isolates was 127 (87%) and 167 (83.9%), respectively. Such a high rate of icaA/D harboring S. aureus among clinical isolates suggest the risk for establishing persistent infections in the hospital settings.