Date: 21 Apr 2013

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

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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.

CA-MRSA/MSSA working group: José Melo-Cristino and Luís M. Lito, Serviço de Patologia Clínica, Centro Hospitalar Lisboa Norte, Lisboa, Portugal; José Amorim and Rui Campainha, Departamento de Análises Clínicas, Clínica Lab Dr Edgar Botelho Moniz, Santo Tirso, Portugal; Alberta Faustino, Serviço de Patologia Clínica, Hospital de Braga, Portugal; Maria Luísa Gonçalves and Augusto Machado e Costa, Laboratório de Microbiologia and Departamento de Medicina, Hospital SAMS, Lisboa, Portugal; Filomena Martins and Elsa Gonçalves, Laboratório de Microbiologia, Centro Hospitalar Lisboa Ocidental, Lisboa, Portugal; Graça Ribeiro and Luísa Boaventura, Laboratório de Microbiologia, Centro Hospitalar de Coimbra, Coimbra, Portugal; Ana Fonseca and Mafalda Guimarães, Laboratório de Microbiologia, Centro Hospitalar de Cascais, Cascais, Portugal; João Mairos and Sandra Francisco, Serviço de Ginecologia and Serviço de Patologia Clínica, Hospital da Força Aérea, Lisboa, Portugal; M. Augusta Guimarães and Catarina Lameiras, Serviço de Microbiologia, Instituto Português de Oncologia do Porto, Porto, Portugal; Manuela Ribeiro and Lídia Branco, Laboratório de Microbiologia, Hospital de São João do Porto, Porto, Portugal; Maria Teresa Azevedo Vaz and Marília Gião, Serviço de Patologia Clínica, Centro Hospitalar do Barlavento Algarvio, Portimão, Portugal; Paulo Paixão and Natália Marto, Laboratório de Patologia Clínica, Hospital da Luz, Lisboa, Portugal; Maria Antónia Read, Maria João Soares and Filipa Carneiro, Laboratório de Microbiologia, Hospital Pedro Hispano, Matosinhos, Portugal; Teresa Sardinha, Luisa Sancho, and Germano Sousa, Laboratório de Microbiologia, Hospital Professor Dr Fernando da Fonseca, Amadora, Lisboa, Portugal; Paula Correia, Serviço de Pediatria, Hospital Professor Dr Fernando da Fonseca, Amadora, Lisboa, Portugal; Rosa M. Barros, Margarida Pinto and Isabel Daniel, Laboratório de Microbiologia, Centro Hospitalar de Lisboa Central, Lisboa, Portugal; Maria João Brito, Gonçalo Cordeiro Ferreira and Catarina Gouveia, Unidade de Infecciologia, Centro Hospitalar de Lisboa Central, Lisboa, Portugal; Ana Morais and Idalina Valadares, Laboratório Análises Clínicas, ACES-Centro de Saúde Oeiras e Carnaxide, Oeiras, Portugal.