Whole-genome sequencing shows that patient-to-patient transmission rarely accounts for acquisition of Staphylococcus aureus in an intensive care unit

Price, James R, Golubchik, Tanya, Cole, Kevin, Wilson, Daniel J, Crook, Derrick W, Thwaites, Guy E, Bowden, Rory, Walker, A Sarah, Peto, Timothy E A, Paul, John and Llewelyn, Martin J (2014) Whole-genome sequencing shows that patient-to-patient transmission rarely accounts for acquisition of Staphylococcus aureus in an intensive care unit. Clinical Infectious Diseases, 58 (5). pp. 609-618. ISSN 1058-4838

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Abstract

BACKGROUND

Strategies to prevent Staphylococcus aureus infection in hospitals focus on patient-to-patient transmission. We used whole-genome sequencing to investigate the role of colonized patients as the source of new S. aureus acquisitions, and the reliability of identifying patient-to-patient transmission using the conventional approach of spa typing and overlapping patient stay.

METHODS

Over 14 months, all unselected patients admitted to an adult intensive care unit (ICU) were serially screened for S. aureus. All available isolates (n = 275) were spa typed and underwent whole-genome sequencing to investigate their relatedness at high resolution.

RESULTS

Staphylococcus aureus was carried by 185 of 1109 patients sampled within 24 hours of ICU admission (16.7%); 59 (5.3%) patients carried methicillin-resistant S. aureus (MRSA). Forty-four S. aureus (22 MRSA) acquisitions while on ICU were detected. Isolates were available for genetic analysis from 37 acquisitions. Whole-genome sequencing indicated that 7 of these 37 (18.9%) were transmissions from other colonized patients. Conventional methods (spa typing combined with overlapping patient stay) falsely identified 3 patient-to-patient transmissions (all MRSA) and failed to detect 2 acquisitions and 4 transmissions (2 MRSA).

CONCLUSIONS

Only a minority of S. aureus acquisitions can be explained by patient-to-patient transmission. Whole-genome sequencing provides the resolution to disprove transmission events indicated by conventional methods and also to reveal otherwise unsuspected transmission events. Whole-genome sequencing should replace conventional methods for detection of nosocomial S. aureus transmission.

Item Type: Article
Schools and Departments: Brighton and Sussex Medical School > Global Health and Infection
Subjects: R Medicine
Depositing User: Sandy Gray
Date Deposited: 15 Sep 2014 12:05
Last Modified: 11 Aug 2017 14:57
URI: http://sro.sussex.ac.uk/id/eprint/49931

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