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.
Highlights
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important hospital-associated (HA-methicillin resistant Staphylococcus aureus (MRSA)) pathogens, responsible for increased patient morbidity and mortality, length of hospitalization and higher healthcare costs
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
In a study performed in 2006 in 11 Portuguese hospitals scattered all over the country, EMRSA-15 accounted for 54% of the total isolates [25]
Summary
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important hospital-associated (HA-MRSA) pathogens, responsible for increased patient morbidity and mortality, length of hospitalization and higher healthcare costs. The current prevalence of HA-MRSA in Portugal (49.1%) is among the highest in the continent (EARSS Annual report 2009 http://www.ecdc.europa.eu/en/publications/Publications/ 1011_SUR_annual_EARS_Net_2009.pdf). Considering this problematic situation in Portuguese hospitals, different investigations have been performed to evaluate the extension of CA-MRSA in the country. The nosocomial prevalence of methicillin resistant Staphylococcus aureus (MRSA) in Portugal remains one of the highest in Europe and is currently around 50%. S. aureus can survive for long periods on inanimate objects, which may represent an important reservoir for dissemination as well
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