Methicillin-resistant Staphylococcus aureus tracking spread among health-care workers and hospitalized patients in critical wards at a university hospital, Tehran, Iran

Abstract

Health-care workers may serve as a reservoir for dissemination of methicillin-resistant Staphylococcus aureus (MRSA) to patients in hospital settings. The present study aimed to screen MRSA in nasal swabs of health-care workers and clinical specimens from patients and investigate the possible relationship between these isolates at a university hospital in Tehran, Iran. Additionally, we aimed to identify potential risk factors for MRSA colonization in health-care workers. Staphylococcus aureus strains were isolated from health-care workers and inpatients who completed a questionnaire on risk factors. Cefoxitin disc diffusion test was also used for detection of MRSA. Moreover, all of the MRSA isolates were subjected to pulsed-field gel electrophoresis (PFGE). Colonization rate of MRSA among health-care workers was 22.5%. Furthermore, out of 24 S. aureus isolates obtained from patients, nine (37.5%) were MRSA. Regarding risk factors, the prevalence of nasal MRSA carriage among hospital personnel who used masks was significantly lower than in those without masks (p 0.007). Using PFGE, 10 clusters and 14 singletons were identified among the MRSA isolates. In this regard, most of the MRSA isolates recovered from health-care carriers and patients in intensive care wards, especially general intensive care units, were grouped in certain clusters, indicating intra-ward transmission of the mentioned isolates in these restricted areas. We concluded that screening and decolonization of carriers, contact precautions, prudent use of antibiotics and implementation of active surveillance are recommended strategies for the prevention and control of MRSA transmission in hospital settings.

Keywords: Health-care workers; methicillin-resistant Staphylococcus aureus; patients; pulsed-field gel electrophoresis; risk factors.

Fig. 1

The prevalence of antimicrobial resistance of methicillin-resistant Staphylococcus aureus (MRSA) isolates among personnel carriers and patients. CHL, chloramphenicol; CLI, clindamycin; CXT, cefoxitin; DOX, doxycycline; ERT, erythromycin; GEN, gentamicin; LZD, linezolid; MUP, mupirocin; RIF, rifampin; SXT, trimethoprim-sulfamethoxazole; SYN, quinupristin-dalfopristin (synercid); TEI, teicoplanin.

Fig. 2

SmaI macrorestriction fragments of methicillin-resistant Staphylococcus aureus (MRSA) isolates on pulsed-field gel electrophoresis (PFGE) gels. Lanes 2 to 8, different PFGE patterns of MRSA isolates; M, PFGE marker.

Fig. 3

The UPGMA dendrogram of methicillin-resistant Staphylococcus aureus (MRSA) isolates based on pulsed-field gel electrophoresis profiles. Isolate code, source of sample and the related ward are also given for each MRSA isolates.