High Prevalence of EMRSA-15 in Portuguese Public Buses: A Worrisome Finding

Abstract

BackgroundThe nosocomial prevalence of methicillin resistant Staphylococcus aureus (MRSA) in Portugal remains one of the highest in Europe and is currently around 50%. Transmission of S. aureus, including MRSA, occurs principally by direct human-to-human skin contact. However, S. aureus can survive for long periods on inanimate objects, which may represent an important reservoir for dissemination as well.Methodology/Principal FindingsBetween May 2009 and February 2010, handrails of 85 public urban buses circulating in Oporto, Portugal, were screened for the occurrence of MRSA. Twenty-two (26%) buses showed MRSA contamination. The molecular characterization of a total of 55 MRSA, by pulsed-field gel electrophoresis (PFGE), staphylococcal cassette chromosome (SCC) mec typing, spa typing, and multilocus sequence typing (MLST), clustered the isolates into three clonal types. However, the overwhelming majority (n = 50; 91%) of the isolates belonged to a single clone (PFGE A, spa types t747, t032, t025 or t020, ST22, SCCmec type IVh) that exhibits the characteristics of the pandemic EMRSA-15, currently the major lineage circulating in Portuguese hospitals, namely in the Oporto region. Two additional clones were found but in much lower numbers: (i) PFGE B, ST5, spa type t002, SCCmec IVa (n = 3), and (ii) PFGE C, spa type t008, ST8, SCCmec IVa (n = 2). None of the 55 isolates was PVL positive.Conclusions/SignificancePublic buses in Oporto seem to be an important reservoir of MRSA of nosocomial origin, providing evidence that the major hospital-associated MRSA clone in Portugal is escaping from the primary ecological niche of hospitals to the community environment. Infection control measures are urgently warranted to limit the spread of EMRSA-15 to the general population and future studies are required to assess the eventual increase of MRSA in the Portuguese community, which so far remains low.

Contamination of public transports by Staphylococcus aureus and its carriage by biomedical students: point-prevalence, related risk factors and molecular characterization of methicillin-resistant strains

“…Although the difference is not statistically significant, the prevalence of MRSA in buses (16.1%) was higher than the found in trains (8.9%), which is expected if we consider that bus routes circulate closer to the main reservoir (hospital 7 The heavy media coverage regarding MRSA subsequent to our previous study may have influenced cleaning and disinfection practices in the interim, reducing the prevalence of MRSA on the surfaces in buses. A similar study carried out in 2011/12 in buses circulating in Lisbon reported an even higher MRSA prevalence of 36%.…”

“…In fact, among PFGE subtype A1, we found four different spa types, including two new motifs and two motifs already described in Porto buses, t032 and t747. 7 Moreover, these latter spa types were described as the most prevalent types in Portuguese hospitals, including one of the major hospitals in Porto near some of the buses lines included in this study as well as in several other countries, including Germany, Sweden and Norway (http://spa.ridom.de). 26,28 The rate of nasal carriage of S. aureus among biomedical students has been reported to range from 10.6 to 41.7%.…”

“…Additionally, the same suspensions were used to inoculate BBL™ CHROMagar™ Staph aureus plates (Becton, Dickinson & Co, New Jersey, USA) supplemented with oxacillin, as described by Simões et al (2011). 7 PCR amplification of the mecA gene was performed to confirm methicillin resistance as described by Murakami et al 13 …”

“…11 Recently, we reported for the first time a high prevalence of an MRSA of nosocomial origin on the handrails of public buses in Porto (26%) and subsequently in Lisbon (36%). 6,7 In the present study, we analysed the contamination of two different transportation services in Porto (urban buses and trains) by S. aureus and evaluated its carriage in university students in the biomedical sciences. These students (i) commonly travel by public transportation, (ii) are considered at risk of carrying S. aureus 12 and, consequently, (iii) may be vectors of MRSA from the teaching clinical environment to the public transportation vehicles, and vice-versa.…”

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.…”