Prevalence and distribution of methicillin resistant Staphylococcus aureus (MRSA) among laboratory science students and laboratory staff from a single hospital in North Saudi Arabia

Staphylococcus aureus causes morbidity and mortality in both community and hospital settings. Methicillin resistant S. aureus (MRSA) is being increasingly reported globally. This study aimed at finding out the prevalence and the distribution of the community-associated MRSA (CA-MRSA) or healthcare-associated MRSA (HA-MRSA) among 150 subjects. Of the 150 subjects, 125 were students of laboratory science and 25 were laboratory staff. Nasal swabs were collected aseptically and cultured using standard microbiological protocols. Antibiotic susceptibility was done according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Methicillin resistance was detected by resistance to oxacillin and cefoxitin and confirmed by detecting mecA gene. Strain typing of MRSA strains was done by pulse field gel electrophoresis (PFGE). The distribution of CA-MRSA from all MRSA isolates were, 100% (2/2) from the first year laboratory science students, 100% (2/2) from the second year laboratory science students, 100% (2/2) from the third year laboratory science students, 67% (2/3) from the fourth year laboratory science students, 43% (3/7) from fifth year students and 40% (4/10) from the hospital staff, respectively. The PFGE results showed that out of total 26 MRSA isolates, there were two major groups; 15 were found to be of one group, consisting of all CA-MRSA with SCCmec type IV; and 11 isolates were of second group, HA-MRSA with SSCmec type III and IIIA on the other group. Additionally, 100% (15/15) and 20% (3/15) CA-MRSA isolates were found positive for Panton-Valentine leukocidin (PVL) and toxic shock syndrome toxin-1 (TSST-1), respectively. Furthermore, the CA-MRSA isolates showed a higher susceptibility pattern to non-β-lactam antibiotics as compared to HA-MRSA. Our study reports a high percentage of CA-MRSA isolates among the healthcare workers who have lesser or no exposure to the hospital environment as compared to those with high exposure. Also, the genetic relatedness, presence of Panton-Valentine leukocidin (PVL) and identical antibiogram of CA-MRSA makes this study interesting, as carriage of these isolates in the laboratory students of hospital setup may play a key role in the epidemiology and pathogenesis of infection in the hospitals in future.