High prevalence of hospital-associated methicillin-resistant Staphylococcus aureus in the community in Portugal: evidence for the blurring of community–hospital boundaries

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of infection in the community (CA-MRSA), but in spite of its relevance, no data exist concerning its epidemiology in Portugal. In this study, we aimed to evaluate the prevalence, population structure, and origin of MRSA in the Portuguese community. A total of 527 isolates, both methicillin-susceptible S. aureus (MSSA) and MRSA, were collected from individuals with no healthcare-related risk factors attending 16 healthcare institutions in Portugal. Isolates were characterized for the presence of mecA, Panton-Valentine leukocidin (PVL), and arginine catabolic mobile element (ACME), and by staphylococcal cassette chromosome mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE), spa, and multilocus sequence typing (MLST). Susceptibility to a panel of 13 antibiotics was tested. Isolates relatedness was analyzed by goeBURST and BURP. We found a high frequency (21.6%) of MRSA in the community. However, only 11.4% of the isolates belonged to typical CA-MRSA epidemic clones (USA300, USA400, USA700, Southwest Pacific, European, and ST398). The remaining isolates, which constituted the great majority (88.6%), belonged to hospital-associated MRSA (HA-MRSA) epidemic clones, namely, to the EMRSA-15 clone (77.2%). PVL was rare and carried by 17 isolates only (five MRSA and 12 MSSA). In the whole collection, some MRSA and MSSA were highly related. The high frequency of MRSA in the community in Portugal seems to result mainly from dissemination from the hospital. They might also have emerged from an extant MSSA population, by SCCmec acquisition, or MRSA clonal introduction from abroad.

Methicillin-resistant Staphylococcus aureus nasal colonization in a level III neonatal intensive care unit: Incidence and risk factors

“…6,19,20 However, a meaningful distinction between health-care associated MRSA and community-acquired MRSA strains is increasingly challenging and MRSA strains previously identified as belonging to either group are reported to circulate in both community and health care settings. 14,21 Moreover, highly endemic community settings are likely to promote spilling of MRSA into the NICUs via HCWs or parents.…”

Nasal carriage of sequence type 22 MRSA and livestock-associated ST398 clones in Tangier, Morocco

“…It has been recently reported in healthy individuals (without associated healthcare risk factors) in Italy and the Middle East [22][23][24]. The origin of ST22-MRSA-IV strains circulating in the Tangier community could be HA-EMRSA-15 types, which are disseminated from hospitals to community environments, as several studies have indicated [6,25]. This hypothesis might find its justification in the fact that the discharged patients continue their wound dressing elsewhere in the outpatient care centers.…”

“…These strains cause distinct clinical syndromes, have diverse genetic backgrounds, carry smaller SCCmec elements, most commonly SCCmec type IV or type V, and often harbor the Panton-Valentine leukocidin (PVL) [5]. However, the distinction between HA-MRSA and CA-MRSA remains problematic due to blurred boundaries between them and lack of consistently stable markers [5,6]. Since 2003, MRSA strains from livestock (for example, pigs) or animal products, termed livestock-associated MRSA (LA-MRSA) have emerged worldwide, which reveals the truly zoonotic potential of S. aureus/MRSA [7].…”

Rapid screening of methicillin-resistant Staphylococcus aureus carrying the mecC gene in a Portuguese hospital

“…In the last decades, MRSA infections were limited to hospitals, but the exponential emergence of community-associated MRSA infections shaped the epidemiology of S. aureus leading to the replaced of hospital-associated MRSA (HA-MRSA) clones by community-associated MRSA [7] . Between 2009-2010 Tavares A, et al [8] studied a total of 1,487 S. aureus isolates collected from 16 Portuguese healthcare institutions located in different geographic regions of Portugal, reporting that MRSA clones present in the community were clones typically found in hospitals. This signals Portugal as a region where the transfer of strain between setting can be recognized, valorizing potential risks for public health of a third epidemiological form of MRSA, livestock-associated MRSA (LA-MRSA) [1] .…”