Extensive Dissemination of Methicillin-Resistant Staphylococcus Aureus (MRSA) Between the Hospital and the Community in a Country With a High Prevalence of Nosocomial MRSA

PLoS One. 2013 Apr 3;8(4):e59960. doi: 10.1371/journal.pone.0059960. Print 2013.

Abstract

According to the EARS-Net surveillance data, Portugal has the highest prevalence of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) in Europe, but the information on MRSA in the community is very scarce and the links between the hospital and community are not known. In this study we aimed to understand the events associated to the recent sharp increase in MRSA frequency in Portugal and to evaluate how this has shaped MRSA epidemiology in the community. With this purpose, 180 nosocomial MRSA isolates recovered from infection in two time periods and 14 MRSA isolates recovered from 89 samples of skin and soft tissue infections (SSTI) were analyzed by pulsed-field gel electrophoresis (PFGE), staphylococcal chromosome cassette mec (SCCmec) typing, spa typing and multilocus sequence typing (MLST). All isolates were also screened for the presence of Panton Valentine leukocidin (PVL) and arginine catabolic mobile element (ACME) by PCR. The results showed that ST22-IVh, accounting for 72% of the nosocomial isolates, was the major clone circulating in the hospital in 2010, having replaced two previous dominant clones in 1993, the Iberian (ST247-I) and Portuguese (ST239-III variant) clones. Moreover in 2010, three clones belonging to CC5 (ST105-II, ST125-IVc and ST5-IVc) accounted for 20% of the isolates and may represent the beginning of new waves of MRSA in this hospital. Interestingly, more than half of the MRSA isolates (8/14) causing SSTI in people attending healthcare centers in Portugal belonged to the most predominant clones found in the hospital, namely ST22-IVh (n = 4), ST5-IVc (n = 2) and ST105-II (n = 1). Other clones found included ST5-V (n = 6) and ST8-VI (n = 1). None of the MRSA isolates carried PVL and only five isolates (ST5-V-t179) carried ACME type II. The emergence and spread of EMRSA-15 may be associated to the observed increase in MRSA frequency in the hospital and the consequent spillover of MRSA into the community.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Evolution
  • Community-Acquired Infections / epidemiology
  • Cross Infection / epidemiology
  • Humans
  • Methicillin-Resistant Staphylococcus aureus / classification
  • Methicillin-Resistant Staphylococcus aureus / genetics*
  • Methicillin-Resistant Staphylococcus aureus / isolation & purification
  • Multilocus Sequence Typing
  • Portugal / epidemiology
  • Prevalence
  • Staphylococcal Infections / epidemiology*

Grant support

DE was supported by a fellowship from project TROCAR-FP7-HEALTH-2007-B project n° 223031 from the European Commission and project PTDC/BIA-EVF/117507/2010 from Fundação para a Ciência e Tecnologia (FCT), Portugal. NAF was supported by a grant SFRH/BPD/66514/2009 from FCT. This work was funded by project Ref. P-99911 from Fundação Calouste Gulbenkian; CONCORD-FP7-HEALTH-2007-B project n° 222718 and TROCAR-FP7-HEALTH-2007-B project n° 223031 from the European Commission. The work was supported additionally by FCT through grant #Pest-OE/EQB/LAO004/2011. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.