Multi-country cross-sectional study of colonization with multidrug-resistant organisms: protocol and methods for the Antibiotic Resistance in Communities and Hospitals (ARCH) studies.

<bold>Background: </bold>Antimicrobial resistance is a global health emergency. Persons colonized with multidrug-resistant organisms (MDROs) are at risk for developing subsequent multidrug-resistant infections, as colonization represents an important precursor to invasive infection. Despite reports documenting the worldwide dissemination of MDROs, fundamental questions remain regarding the burden of resistance, metrics to measure prevalence, and determinants of spread. We describe a multi-site colonization survey protocol that aims to quantify the population-based prevalence and associated risk factors for colonization with high-threat MDROs among community dwelling participants and patients admitted to hospitals within a defined population-catchment area.<bold>Methods: </bold>Researchers in five countries (Bangladesh, Chile, Guatemala, Kenya, and India) will conduct a cross-sectional, population-based prevalence survey consisting of a risk factor questionnaire and collection of specimens to evaluate colonization with three high-threat MDROs: extended-spectrum cephalosporin-resistant Enterobacteriaceae (ESCrE), carbapenem-resistant Enterobacteriaceae (CRE), and methicillin-resistant Staphylococcus aureus (MRSA). Healthy adults residing in a household within the sampling area will be enrolled in addition to eligible hospitalized adults. Colonizing isolates of these MDROs will be compared by multilocus sequence typing (MLST) to routinely collected invasive clinical isolates, where available, to determine potential pathogenicity. A colonizing MDRO isolate will be categorized as potentially pathogenic if the MLST pattern of the colonizing isolate matches the MLST pattern of an invasive clinical isolate. The outcomes of this study will be estimates of the population-based prevalence of colonization with ESCrE, CRE, and MRSA; determination of the proportion of colonizing ESCrE, CRE, and MRSA with pathogenic characteristics based on MLST; identification of factors independently associated with ESCrE, CRE, and MRSA colonization; and creation an archive of ESCrE, CRE, and MRSA isolates for future study.<bold>Discussion: </bold>This is the first study to use a common protocol to evaluate population-based prevalence and risk factors associated with MDRO colonization among community-dwelling and hospitalized adults in multiple countries with diverse epidemiological conditions, including low- and middle-income settings. The results will be used to better describe the global epidemiology of MDROs and guide the development of mitigation strategies in both community and healthcare settings. These standardized baseline surveys can also inform future studies seeking to further characterize MDRO epidemiology globally. [ABSTRACT FROM AUTHOR]