title: [Significant increase in the colonisation of Staphylococcus aureus among medical students during their hospital practices].
abstract: BACKGROUND
  Staphylococcus aureus is a pathogen of major concern. The emergence of methicillin-resistant S. aureus (MRSA) has increasingly complicated the therapeutic approach of hospital-acquired infections. Surveillance of MRSA and control measures must be implemented in different healthcare settings, including screening programs for carriers. Our first aim was to determine the prevalence of methicillin-susceptible S. aureus (MSSA) and MRSA nasal carriage in medical students from the Clínico San Carlos Hospital (Madrid). As the MRSA carrier rate in healthcare workers is higher than in the general population, we hypothesised that carrier rate could be increased during their clinical practice in their last three years.
  
  
  METHODS
  We performed an epidemiologic al study of the prevalence of S. aureus colonisation among a group of medical students, who were sampled in 2008 in their third-year, and in 2012 when this class was in its sixth year.
  
  
  RESULTS
  We have found a significant increase in MSSA carriage, from 27% to 46%. There were no MRSA colonisations in the third-year, but one was found in the sixth-year group. The large majority of strains (89%) of strains were resistant to penicillin, and 27% to erythromycin and clindamycin. As 19 coagulase-negative Staphylococcus MR were also identified, a horizontal transfer of genes, such as mecA gene to S. aureus, could have occurred.
  
  
  CONCLUSIONS
  Medical students are both, at risk for acquiring, and a potential source of nosocomial pathogens, mainly MSSA. Therefore, they should take special care for hygienic precautions, such as frequent and proper hand washing, while working in the hospital.
authors.affiliation: Departamento de Microbiología, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, España; Servicio de Microbiología, Hospital Clínico San Carlos, Madrid, España. Electronic address: cravial@med.ucm.es.
authors.forename: Carmen
authors.initials: C
authors.lastname: Rodríguez-Avial
authors.forename: Andrea
authors.initials: A
authors.lastname: Alvarez-Novoa
authors.forename: Azucena
authors.initials: A
authors.lastname: Losa
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Picazo
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D003428:Cross Infection / Q000453:epidemiology / Q000635:transmission; D003430:Cross-Sectional Studies; D004197:Disease Reservoirs; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D005500:Follow-Up Studies; D022761:Gene Transfer, Horizontal; D006235:Hand Disinfection; D006786:Hospitals, Urban; D006801:Humans; D017757:Infectious Disease Transmission, Professional-to-Patient; D008297:Male; D016106:Methicillin Resistance; D009017:Morbidity / Q000639:trends; D009296:Nasal Cavity / Q000382:microbiology*; D046915:Penicillin-Binding Proteins; D013030:Spain; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control / Q000635:transmission; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D013337:Students, Medical / Q000523:psychology; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus