title: Clinical impact and prevalence of MRSA CC398 and differences between MRSA-TetRand MRSA-TetSin an area of Spain with a high density of pig farming: a prospective cohort study.
abstract: OBJECTIVE
  Tetracycline resistance (TetR) is a phenotypic marker of the livestock-associated methicillin-resistant Staphylococcus aureus (MRSA) CC398 clone. The aim of this study was to analyse the prevalence of MRSA CC398 in patients in contact with healthcare facilities and differences between patients with MRSA-TetRand MRSA tetracycline-susceptible (TetS) strains.
  
  
  METHODS
  Patients diagnosed with MRSA from January 2012 to December 2015 were divided into two groups, MRSA-TetRand MRSA-TetS. Epidemiologic and clinical data were evaluated. Molecular analysis was performed (multilocus sequence typing, spa typing) on MRSA-TetRstrains.
  
  
  RESULTS
  Data from 288 MRSA patients were obtained, and 106 (36.8%) carried MRSA-TetR(93 typed as CC398 (87.7%); the remaining 13 isolates were ascribed to CC9, CC1, CC121, CC30, CC97, CC146 and CC152). The most frequent spa type was t011 (56.6%, 61/106). Detection of MRSA-TetRincreased over the years (21.9%, 16/73, in 2012; 50.7%, 36/71, in 2015; p <0.001). Hospital acquisition was found in 16.7% (19/114) of MRSA-TetRpatients vs. 83.3% (95/114) in MRSA-TetSpatients (p <0.001). Frequency of MRSA-TetRpatients in nursing homes was lower than in MRSA-TetSpatients (4.7%, 5/106, vs. 27.5%, 50/182, p <0.001). MRSA-TetRas distinct from MRSA-TetSwas associated with workers on pig farms (49.0%, 52/106, vs. 1.0%, 2/182; p <0.001), fewer admissions to hospital (46.2%, 49/106, vs. 68.1%, 124/182; p <0.001) and fewer comorbidities (81.1%, 86/106, vs. 59.9%, 109/182; p <0.001). Sixty cases of MRSA-CC398 infection were diagnosed, including, among others, endocarditis, septic arthritis, prosthetic joint infection, pneumonia and bacteraemia.
  
  
  CONCLUSIONS
  Prevalence of MRSA-TetR(especially CC398) at the hospital level in a Spanish region with intensive pig farming activity is high and is responsible for severe infections. Significant differences were detected in clinical and epidemiologic characteristics among MRSA-TetRand MRSA-TetSpatients.
authors.affiliation: Department of Internal Medicine, Hospital Universitari de Vic, Spain; Department of Medicine, Universitat Autònoma de Barcelona, Spain. Electronic address: eareynaga@chv.cat.
authors.forename: E
authors.initials: E
authors.lastname: Reynaga
authors.affiliation: Area de Bioquímica y Biología Molecular, Universidad de La Rioja, Logroño, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Torres
authors.affiliation: Infectious Diseases Unit, Health Sciences Research Institute of the Germans Trias i Pujol Foundation, Badalona, Barcelona, Spain; CIBER de Enfermedades Respiratorias, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Garcia-Nuñez
authors.affiliation: Microbiology Department, Hospital Universitari de Vic, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Navarro
authors.affiliation: Microbiology Department, Hospital Universitari de Vic, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Vilamala
authors.affiliation: Epidemiology Department, Hospital Universitari de Vic, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Puigoriol
authors.affiliation: Department of Internal Medicine, Hospital Universitari de Vic, Spain.
authors.forename: G E
authors.initials: GE
authors.lastname: Lucchetti
authors.affiliation: Department of Medicine, Universitat Autònoma de Barcelona, Spain; Infectious Diseases Unit, Health Sciences Research Institute of the Germans Trias i Pujol Foundation, Badalona, Barcelona, Spain; CIBER de Enfermedades Respiratorias, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Sabrià
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000072480:Farms; D005260:Female; D006801:Humans; D058751:Livestock; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics*; D008875:Middle Aged; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D015995:Prevalence; D011446:Prospective Studies; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D034421:Sus scrofa; D013552:Swine; D013753:Tetracycline Resistance / Q000235:genetics*
keywords: Colonization; Community-acquired infection; LA-MRSA; MRSA-CC398; MRSA-Tet(R); Spain; Staphylococcus aureus