The role of Staphylococcus aureus carriage in the pathogenesis of bloodstream infection

Marshall, Caroline, and McBryde, Emma (2014) The role of Staphylococcus aureus carriage in the pathogenesis of bloodstream infection. BMC Research Notes, 7. 428. pp. 1-6.

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Background: Staphylococcus aureus (SA) colonisation is associated with development of bloodstream infection (BSI), with the majority of colonising and infecting strains identical by pulsed-field gel electrophoresis (PFGE). We examined SA colonisation in patients with SABSI to delineate better the relationship between the two.

Methods: Patients with SABSI were swabbed in the nose, throat, groin, axilla and rectum. Isolates were typed using PFGE. Logistic regression was performed to determine factors associated with positive swabs.

Results: 79 patients with SABSI had swabs taken. 46 (58%) had ≥ 1 screening swab positive for S. aureus; of these 37 (80%) were in the nose, 11 (24%) in the throat, 12 (26%) in the groin, 11 (24%) in the axilla and 8 (17%) in the rectum. On multivariate analysis, days from blood culture to screening swabs (OR 0.5, 95% CI 0.32-0.78, P = 0.003) and methicillin resistance (OR 9.5, 95% CI 1.07-84.73, P = 0.04) were associated with having positive swabs. Of 46 participants who had a blood sample and 1 other sample subtyped, 33 (72%, 95% CI 57-84%) had all identical subtypes, 1 (2%) had subtypes varying by 1–3 bands and 12 (26%) had subtypes ≥ 3 bands different. 30/36 (83%) blood-nose pairs were identical.

Conclusion: Overall, 58% of patients with SABSI had positive screening swabs. Of these, only 80% had a positive nose swab ie less than half (37/79, 47%) of all SABSI patients were nasally colonised. This may explain why nasal mupirocin alone has not been effective in preventing SA infection. Measures to eradicate non-nasal carriage should also be included.

Item ID: 39739
Item Type: Article (Research - C1)
ISSN: 1756-0500
Keywords: Staphylococcus aureus; blood stream infection; colonisation
Additional Information:

© 2014 Marshall and McBryde; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

Funders: CASS Foundation, Royal Australasian College of Physicians (RACP)
Projects and Grants: RACP Robert and Elizabeth Albert Study Grant
Date Deposited: 16 Sep 2015 01:05
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1103 Clinical Sciences > 110309 Infectious Diseases @ 40%
11 MEDICAL AND HEALTH SCIENCES > 1117 Public Health and Health Services > 111706 Epidemiology @ 40%
16 STUDIES IN HUMAN SOCIETY > 1605 Policy and Administration > 160508 Health Policy @ 20%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920109 Infectious Diseases @ 50%
92 HEALTH > 9202 Health and Support Services > 920207 Health Policy Evaluation @ 50%
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