title: Multi-site and nasal swabbing for carriage of Staphylococcus aureus: what does a single nose swab predict?
abstract: BACKGROUND
  Carriage of Staphylococcus aureus is a risk for infections. Targeted decolonization reduces postoperative infections but depends on accurate screening.
  
  
  OBJECTIVE
  To compare detection of S. aureus carriage in healthy individuals between anatomical sites and nurse- versus self-swabbing; also to determine whether a single nasal swab predicted carriage over four weeks.
  
  
  METHODS
  Healthy individuals were recruited via general practices. After consent, nurses performed multi-site swabbing (nose, throat, and axilla). Participants performed nasal swabbing twice-weekly for four weeks. Swabs were returned by mail and cultured for S. aureus. All S. aureus isolates underwent spa typing. Persistent carriage in individuals returning more than three self-swabs was defined as culture of S. aureus from all or all but one self-swabs.
  
  
  RESULTS
  In all, 102 individuals underwent multi-site swabbing; S. aureus carriage was detected from at least one site from 40 individuals (39%). There was no difference between nose (29/102, 28%) and throat (28/102, 27%) isolation rates: the combination increased total detection rate by 10%. Ninety-nine patients returned any self-swab, and 96 returned more than three. Nasal carriage detection was not significantly different on nurse or self-swab [28/99 (74%) vs 26/99 (72%); χ2: P=0.75]. Twenty-two out of 25 participants with first self-swab positive were persistent carriers and 69/71 with first self-swab negative were not, giving high positive predictive value (88%), and very high negative predictive value (97%).
  
  
  CONCLUSIONS
  Nasal swabs detected the majority of carriage; throat swabs increased detection by 10%. Self-taken nasal swabs were equivalent to nurse-taken swabs and predicted persistent nasal carriage over four weeks.
authors.affiliation: Nuffield Department of Medicine, University of Oxford, Oxford, UK. Electronic address: bernadette.young@ndm.ox.ac.uk.
authors.forename: B C
authors.initials: BC
authors.lastname: Young
authors.affiliation: Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: A A
authors.initials: AA
authors.lastname: Votintseva
authors.affiliation: Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: D
authors.initials: D
authors.lastname: Foster
authors.affiliation: Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: H
authors.initials: H
authors.lastname: Godwin
authors.affiliation: Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: R R
authors.initials: RR
authors.lastname: Miller
authors.affiliation: Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: L W
authors.initials: LW
authors.lastname: Anson
authors.affiliation: Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: A S
authors.initials: AS
authors.lastname: Walker
authors.affiliation: Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: T E A
authors.initials: TEA
authors.lastname: Peto
authors.affiliation: Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: D W
authors.initials: DW
authors.lastname: Crook
authors.affiliation: Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK.
authors.forename: K
authors.initials: K
authors.lastname: Knox
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002353:Carrier State / Q000175:diagnosis*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D058889:Molecular Typing; D013048:Specimen Handling / Q000379:methods*; D013203:Staphylococcal Infections / Q000175:diagnosis*; D013211:Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D055815:Young Adult
keywords: Carriage; Multi-site screening; Staphylococcus aureus; spa typing