Title
Surface sampling collection and culture methods for Escherichia coli in household environments with high fecal contamination
Date Issued
22 August 2017
Access level
open access
Resource Type
journal article
Author(s)
Publisher(s)
MDPI
Abstract
Empiric quantification of environmental fecal contamination is an important step toward understanding the impact that water, sanitation, and hygiene interventions have on reducing enteric infections. There is a need to standardize the methods used for surface sampling in field studies that examine fecal contamination in low-income settings. The dry cloth method presented in this manuscript improves upon the more commonly used swabbing technique that has been shown in the literature to have a low sampling efficiency. The recovery efficiency of a dry electrostatic cloth sampling method was evaluated using Escherichia coli and then applied to household surfaces in Iquitos, Peru, where there is high fecal contamination and enteric infection. Side-by-side measurements were taken from various floor locations within a household at the same time over a three-month period to compare for consistency of quantification of E. coli bacteria. The dry cloth sampling method in the laboratory setting showed 105% (95% Confidence Interval: 98%, 113%) E. coli recovery efficiency off of the cloths. The field application demonstrated strong agreement of side-by-side results (Pearson correlation coefficient for dirt surfaces was 0.83 (p < 0.0001) and 0.91 (p < 0.0001) for cement surfaces) and moderate agreement for results between entrance and kitchen samples (Pearson (0.53, p < 0.0001) and weighted Kappa statistic (0.54, p < 0.0001)). Our findings suggest that this method can be utilized in households with high bacterial loads using either continuous (quantitative) or categorical (semi-quantitative) data. The standardization of this low-cost, dry electrostatic cloth sampling method can be used to measure differences between households in intervention and non-intervention arms of randomized trials.
Volume
14
Issue
8
Language
English
OCDE Knowledge area
Biología celular, Microbiología
Salud pública, Salud ambiental
Subjects
Scopus EID
2-s2.0-85028298539
PubMed ID
Source
International Journal of Environmental Research and Public Health
ISSN of the container
16617827
Sponsor(s)
Acknowledgments: We wish to thank the families of the MAL-ED households and the fieldworkers for their enthusiasm, patience, and humor. We also thank Jason Bishai and Nicholas Jennings for their technical assistance with the laboratory experiments. This publication was made possible by support from the Sherrilyn and Ken Fisher Center for Environmental Diseases, Division of Infectious Diseases of the Johns Hopkins School of Medicine. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of the Fisher Center or Johns Hopkins University School of Medicine. Funding was obtained from The National Science Foundation Integrative Graduate Education and Research Traineeship Grant 1069213, The Osprey Foundation of Maryland Grant 1602030014, the Johns Hopkins Water Institute, Johns Hopkins Fisher Center Discovery Program Grant 010 KOS2015, The Kazuyoshi Kawata fund in Sanitary Engineering and Science, and the C. W. Kruse Memorial Fund Scholarship. M.F.D. was supported by NIH ORIP grant 1K01OD01991. The Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development Project (MAL-ED) is carried out as a collaborative project supported by the Bill & Melinda Gates Foundation, the Foundation for the National Institutes of Health, and the National Institutes of Health, Fogarty International Center.
Sources of information:
Directorio de Producción Científica
Scopus