Evidence for Community Transmission of Community-Associated but Not Health-Care-Associated Methicillin-Resistant Staphylococcus Aureus Strains Linked to Social and Material Deprivation: Spatial Analysis of Cross-sectional Data

Abstract

BackgroundIdentifying and tackling the social determinants of infectious diseases has become a public health priority following the recognition that individuals with lower socioeconomic status are disproportionately affected by infectious diseases. In many parts of the world, epidemiologically and genotypically defined community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) strains have emerged to become frequent causes of hospital infection. The aim of this study was to use spatial models with adjustment for area-level hospital attendance to determine the transmission niche of genotypically defined CA- and health-care-associated (HA)-MRSA strains across a diverse region of South East London and to explore a potential link between MRSA carriage and markers of social and material deprivation.Methods and FindingsThis study involved spatial analysis of cross-sectional data linked with all MRSA isolates identified by three National Health Service (NHS) microbiology laboratories between 1 November 2011 and 29 February 2012. The cohort of hospital-based NHS microbiology diagnostic services serves 867,254 usual residents in the Lambeth, Southwark, and Lewisham boroughs in South East London, United Kingdom (UK). Isolates were classified as HA- or CA-MRSA based on whole genome sequencing. All MRSA cases identified over 4 mo within the three-borough catchment area (n = 471) were mapped to small geographies and linked to area-level aggregated socioeconomic and demographic data. Disease mapping and ecological regression models were used to infer the most likely transmission niches for each MRSA genetic classification and to describe the spatial epidemiology of MRSA in relation to social determinants. Specifically, we aimed to identify demographic and socioeconomic population traits that explain cross-area extra variation in HA- and CA-MRSA relative risks following adjustment for hospital attendance data. We explored the potential for associations with the English Indices of Deprivation 2010 (including the Index of Multiple Deprivation and several deprivation domains and subdomains) and the 2011 England and Wales census demographic and socioeconomic indicators (including numbers of households by deprivation dimension) and indicators of population health. Both CA-and HA-MRSA were associated with household deprivation (CA-MRSA relative risk [RR]: 1.72 [1.03–2.94]; HA-MRSA RR: 1.57 [1.06–2.33]), which was correlated with hospital attendance (Pearson correlation coefficient [PCC] = 0.76). HA-MRSA was also associated with poor health (RR: 1.10 [1.01–1.19]) and residence in communal care homes (RR: 1.24 [1.12–1.37]), whereas CA-MRSA was linked with household overcrowding (RR: 1.58 [1.04–2.41]) and wider barriers, which represent a combined score for household overcrowding, low income, and homelessness (RR: 1.76 [1.16–2.70]). CA-MRSA was also associated with recent immigration to the UK (RR: 1.77 [1.19–2.66]). For the area-level variation in RR for CA-MRSA, 28.67% was attributable to the spatial arrangement of t...

Socioeconomic Factors Explain Racial Disparities in Invasive Community-Associated Methicillin-Resistant Staphylococcus aureus Disease Rates

“…This is also consistent with findings outside the US that persons living in areas of lower socioeconomic status have higher rates of MRSA [19,31]. These social factors are likely to reflect specific drivers such as availability and affordability of medical care, crowding, and poverty, both at the individual and community levels.…”

“…Factors related to lower socioeconomic status, such as prior incarceration, intravenous drug use, and crowding, are known to increase the risk of community-associated MRSA infection [17–19], and lower socioeconomic status in the community has been associated with increased rates of other acute infectious diseases [20]. Furthermore, black persons in the US experience lower socioeconomic status, which has been described to be due to a complex set of historical and current experiences and conditions [21–25].…”

Contribution of whole-genome sequencing to understanding of the epidemiology and control of meticillin-resistant Staphylococcus aureus

“…Sometimes these patients require readmission and there is constant flux between the acute and long-stay sector. Many studies have highlighted this dynamic in terms of the acquisition and transmission of MRSA between these sectors [56][57][58][59][60][61][62]. Furthermore, there has been interest in the role of carriage, including enteric carriage [44,50].…”

Identification of novel risk factors for community-acquired Clostridium difficile infection using spatial statistics and geographic information system analyses

“…GIS and spatial statistics were recently used to evaluate risk factors for MRSA infection among 867,254 people in a three-borough catchment area in London [32]. The risk of CA-MRSA was increased in areas with important socioeconomic factors such as overcrowding, homelessness, low income, and recent immigration.…”