Methicillin-Resistant Staphylococcus aureus Isolated from Nasal Swab: Profiling of Some Virulence Genes

Background: Healthcare workers (HCWs) carrying Staphylococcus aureus may act as a source of infection. This study was carried out to investigate the prevalence of MRSA and the genetic make-up of S. aureus nasal colonizers among HCWs. Methodology: Nasal swabs were obtained from 202 HCWs and 205 NHCWs and molecular characterization of identified methicillin resistant S. aureus isolates was achieved using polymerase chain reaction technique for leukocidin toxin, pyrogenic toxins and toxic shock syndrome toxin. Results: seventy-four HCWs (36.6%) were colonized with S. aureus (MSSA = 51; MRSA = 23). The overall MRSA colonization rate was 11.3 % (n/N=23/202) and 31.1% (n/N=23/74) of those colonized with S. aureus harbored MRSA. There was statistically significant difference in S. aureus colonization rate between HCWs and NHCWs (P = 0.003). Most of the 74 isolates contained at least one of the 13 enterotoxin genes. The most prevalent enterotoxin was seg (63.5%), followed by sei (55.4%), sea (45.9%), seb (36.4%), see (9.4%) and sej (5.4%). Considerable genetic diversity was detected. The present study demonstrated a relatively high rate of tst (48.6%), eta (44.5%) and luk (31%) as well as the wide occurence of enterotoxin genes among colonizing S. aureus. The highest combination between positive mecA isolates and other virulence genes was found in mecA-seg (41.8%), mecA-sei (40.5%), and mecA-sea-seb-seg-sei (24.3%). Conclusions: These findings provide insight into the virulence genes of S. aureus nasal carriage among the HCWs and NHCWs in Gaza Strip.