title: Prolonged outbreak of Staphylococcus aureus surgical site infection traced to a healthcare worker with psoriasis.
abstract: BACKGROUND
  Meticillin-sensitive Staphylococcus aureus (MSSA) is a frequent cause of surgical site infection (SSI), but point-source outbreaks are rarely recognized.
  
  
  OBJECTIVE
  To describe an outbreak of MSSA SSI in a thoracic surgical unit.
  
  
  METHODS
  An outbreak investigation was started following two postoperative bacteraemias with MSSA resistant to fusidic acid (MSSA FusR). Patients with MSSA FusR were identified from microbiology records and through prospective case finding. Healthcare workers (HCWs) were screened. Isolates were characterized by phage typing, spa typing, pulsed-field gel electrophoresis and toxin gene profiling. A case-control study examined the association between one HCW with MSSA FusR and the patients involved in the outbreak.
  
  
  RESULTS
  Nineteen patients were identified with MSSA FusR over 16 months. Four isolates were available for typing and all belonged to the same lineage. Seventy-six HCWs were screened. One was a carrier of the outbreak strain (a nurse with psoriasis). All 19 cases were exposed to this HCW compared with only 40/66 controls (P = 0.003) and cases had a greater duration of exposure (P = 0.00001, chi-squared for trend). Direct patient contact was documented in 15 cases. The outbreak was halted by thorough cleaning of the ward and removal of the HCW from clinical duty.
  
  
  CONCLUSIONS
  The HCW with psoriasis was the source of this outbreak. MSSA FusR may be a marker for strains associated with skin conditions. HCWs with significant skin conditions may pose an infection risk in surgical settings. Recommendations are made for occupational health teams regarding screening of HCWs with dermatitis.
authors.affiliation: Department of Clinical Microbiology, Nottingham University Hospital, Nottingham, UK.
authors.forename: S A
authors.initials: SA
authors.lastname: Crusz
authors.affiliation: Department of Clinical Microbiology, Nottingham University Hospital, Nottingham, UK.
authors.forename: C
authors.initials: C
authors.lastname: Yates
authors.affiliation: Department of Clinical Microbiology, Nottingham University Hospital, Nottingham, UK.
authors.forename: S
authors.initials: S
authors.lastname: Holden
authors.affiliation: Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, Colindale, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Kearns
authors.affiliation: Department of Clinical Microbiology, Nottingham University Hospital, Nottingham, UK. Electronic address: tim.boswell@nuh.nhs.uk.
authors.forename: T
authors.initials: T
authors.lastname: Boswell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology; D016022:Case-Control Studies; D003428:Cross Infection / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D005260:Female; D006282:Health Personnel; D006761:Hospitals; D006801:Humans; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000150:complications*; D012189:Retrospective Studies; D013207:Staphylococcal Skin Infections / Q000382:microbiology / Q000635:transmission*; D013211:Staphylococcus aureus / Q000302:isolation & purification; D013530:Surgical Wound Infection / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology; D013903:Thoracic Surgery
keywords: Fusidic acid resistance; Healthcare workers; Meticillin-sensitive Staphylococcus aureus; Psoriasis; Surgical site infection; Thoracic