title: Staphylococcus aureus infections and factors associated with resistance to methicillin in a hospital emergency department.
abstract: OBJECTIVE
  Assessment of the characteristics of patients with Staphylococcus aureus (SA) infections, and factors associated with resistance to methicillin in a hospital emergency department (ED) in Spain.
  
  
  METHODS
  All adult patients admitted between January 2007 and December 2010 with a SA infection confirmed by a positive culture in a sample obtained in the hospital emergency department were selected for enrolment. Epidemiological, clinical, therapeutic and microbiological variables were retrospectively collected from the patients' medical charts. The variable assessed within the primary outcome of the study was the isolation of methicillin resistant Staphylococcus aureus (MRSA). For the purpose of the analysis, the sample was divided in terms of the presence or not of the resistance to methicillin and a logistic regression analysis was performed to identify the factors associated with isolation and empirical antibiotic coverage of MRSA.
  
  
  RESULTS
  A total of 207 patients with a confirmed SA infection were included in the study analysis, with a mean age of 64.7 (SD 20) years. MRSA was isolated in a total of 63 (30.4%) patients, and a linear incremental trend was observed over the course of the study (p=0,047). MRSA was empirically covered in the emergency department on an average rate of one in three patients. Independent factors associated with the isolation of MRSA were: age above 65 years [OR 2.97 (95% CI 1.24 to 7.1), P = 0.014], severe baseline functional dependence [OR 2.41 (95 % 1.02 to 5.69), P = 0.045], chronic obstructive pulmonary disease [OR 4.83 (95% CI 1.88 to 12.42), P = 0.001], history of antibiotic treatment within the previous 2 months [OR 4.94 (95% CI 2.27 to 10.76), P <0.001] and a confirmed urinary infection [OR 5.98 (95% CI 1.65 to 21.69) p = 0.007]. Independent factors associated with empiric coverage of MRSA in the ED were history of antibiotic treatment within the previous 2 months [OR 3.88 (95% CI 1.76 to 8.57), P <0.001] and the presence of a catheter device [OR 6.28 (95% CI 1.64 to 24.07), P = 0.007].
  
  
  CONCLUSIONS
  Resistance to methicillin appears to be increasingly frequent in patients infected with SA admitted in our emergency department and there appears to be a need for a more optimal empiric antibiotic treatment in these patients.
authors.affiliation: Juan González del Castillo, Hospital Clínico San Carlos. Emergency Ward, Profesor Martín Lagos s/n. 28040, Madrid, Spain. jgonzalezcast@wanadoo.es.
authors.forename: Juan
authors.initials: J
authors.lastname: González-Castillo
authors.forename: Caterina
authors.initials: C
authors.lastname: Cenci
authors.forename: Esther
authors.initials: E
authors.lastname: Rodriguez-Adrada
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Candel
authors.forename: Fernando
authors.initials: F
authors.lastname: de la Torre-Misiego
authors.forename: Cristina
authors.initials: C
authors.lastname: Fernández
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Martín-Sánchez
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D002404:Catheterization; D015897:Comorbidity; D024881:Drug Resistance, Bacterial; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008712:Methicillin / Q000494:pharmacology*; D055624:Methicillin-Resistant Staphylococcus aureus; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications; D012189:Retrospective Studies; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*; D016896:Treatment Outcome; D014552:Urinary Tract Infections / Q000150:complications
chemical_list: D008712:Methicillin