The epidemiology and transmission of methicillin-resistant Staphylococcus aureus in the community in Singapore: study protocol for a longitudinal household study

Nivedita Shankar,Desmond B Teo,Clarence C Tam,Junxiong Pang,Paul A Tambyah,Balamurugan Periaswamy,Angela Li Ping Chow,Brenda Ang,Paola Florez De Sessions,Li Yang Hsu,Jolene Oon

doi:10.1186/s12879-017-2793-y

Abstract

Background/aimMethicillin-resistant Staphylococcus aureus (MRSA) is one of the most common multidrug-resistant organisms in healthcare settings worldwide, but little is known about MRSA transmission outside of acute healthcare settings especially in Asia. We describe the methods for a prospective longitudinal study of MRSA prevalence and transmission.MethodsMRSA-colonized individuals were identified from MRSA admission screening at two tertiary hospitals and recruited together with their household contacts. Participants submitted self-collected nasal, axilla and groin (NAG) swabs by mail for MRSA culture at baseline and monthly thereafter for 6 months. A comparison group of households of MRSA-negative patients provided swab samples at one time point. In a validation sub-study, separate swabs from each site were collected from randomly selected individuals, to compare MRSA detection rates between swab sites, and between samples collected by participants versus those collected by trained research staff. Information on each participant’s demographic information, medical status and medical history, past healthcare facilities usage and contacts, and personal interactions with others were collected using a self-administered questionnaire.Discussion/conclusionUnderstanding the dynamics of MRSA persistence and transmission in the community is crucial to devising and evaluating successful MRSA control strategies. Close contact with MRSA colonized patients may to be important for MRSA persistence in the community; evidence from this study on the extent of community MRSA could inform the development of household- or community-based interventions to reduce MRSA colonization of close contacts and subsequent re-introduction of MRSA into healthcare settings. Analysis of longitudinal data using whole-genome sequencing will yield further information regarding MRSA transmission within households, with significant implications for MRSA infection control outside acute hospital settings.

Highlights

Since its emergence in the 1960s, methicillin-resistant Staphylococcus aureus (MRSA) has become one of the most common multidrug-resistant organisms in healthcare settings worldwide, resulting in considerable health and economic burden
We describe the methods for an ongoing longitudinal study to investigate the persistence and transmissibility of MRSA in the community, and to quantify the relationship between healthcare contact and community transmission
The specific objectives are: a) To measure frequency of MRSA colonization among household contacts b) To identify risk factors associated with colonization and prolonged carriage c) To study MRSA transmission in household contacts of MRSA-colonized patients d) To identify factors associated with MRSA persistence in the household e) To quantify importance of healthcare contact, and other personal interactions, in the transmission of MRSA in the community f ) To determine the diversity of MRSA strains

Summary

Introduction

Since its emergence in the 1960s, methicillin-resistant Staphylococcus aureus (MRSA) has become one of the most common multidrug-resistant organisms in healthcare settings worldwide, resulting in considerable health and economic burden. Carriage of MRSA is a major risk factor for invasive MRSA infection [1,2,3,4,5,6,7,8], and patient transfers between acute care hospitals, community hospitals and longterm care facilities have been reported to be important for maintaining MRSA transmission in healthcare settings [9,10,11,12,13,14,15,16,17]. A limited number of longitudinal studies have shown that MRSA transmission to household contacts is common, with 20% - 40% of non-colonized household contacts of MRSA positive individuals acquiring MRSA during the follow-up period [18, 20,21,22]. Identified risk factors for MRSA acquisition among household contacts include older age [20] and providing care to MRSA-colonized individuals [20, 25]

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