Multi-site and nasal swabbing for carriage of Staphylococcus aureus : what does a single nose swab predict?

Abstract

SummaryBackgroundCarriage of Staphylococcus aureus is a risk for infections. Targeted decolonization reduces postoperative infections but depends on accurate screening.AimTo 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.MethodsHealthy 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.FindingsIn 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%).ConclusionNasal 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.

Prevalence of Staphylococcus aurues carriage in patients with chronic kidney disease: A preliminary cross-sectional study of outpatients at the National Hospital of Sri Lanka

“…This highlights the possible utility of testing for skin carriage or nasal carriage alone to detect a possible carrier status. Prior studies have con rmed this and shown that nasal swabbing alone is adequate (8,9). This is in keeping with the results from our study.…”

“…This is in keeping with the results from our study. A few studies have higher detection rates using throat swabbing (8,9). We did not adopt this due to inconvenience to the patient.…”

Pathogens Causing Respiratory Tract Infections in Children Less Than 5 Years of Age in Senegal

“…19,21,24 They used nasal/nasopharyngeal swabs, but the literature does not mention major differences in detection of S aureus between nose or throat. 34 Another explanation is the use of PCR for detection of bacteria.…”

Increased Staphylococcus aureus Nasal Carriage Rates in Rheumatoid Arthritis Patients on Biologic Therapy

“…This study has certain limitations. Cultures were only obtained by nasal swab, as the association with surgical site infections is strongest with nares cultures; however, while the addition of other sites such as the throat or the surgical site might increase in culture yield, the increase is unlikely to be large (4,(32)(33)(34). Moreover, a difference in carriage would likely affect all three tested groups equally.…”