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Rigby J, Elmerhebi E, Diness Y, Mkwanda C, Tonthola K, Galloway H, Miles R, Henrion MYR, Edwards T, Gauld J, Msefula C, Johnston R, Nair S, Feasey N, Elviss NC. Optimized methods for detecting Salmonella Typhi in the environment using validated field sampling, culture and confirmatory molecular approaches. J Appl Microbiol 2021; 132:1503-1517. [PMID: 34324765 DOI: 10.1111/jam.15237] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/07/2021] [Accepted: 07/08/2021] [Indexed: 11/30/2022]
Abstract
AIMS This study evaluated detection methods for Salmonella Typhi (S. Typhi) in the environment, to establish a novel pathway from field sampling to isolation of viable organisms and molecular confirmation from complex environmental samples, thus enabling environmental surveillance of typhoid. METHODS AND RESULTS Multiple media were assessed using clinical isolates from the Public Health England's (PHE) Culture collection. The culture pathway selected consisted of a primary 2% bile broth and secondary Selenite F broth, followed by modified Chromogenic Agar for Salmonella Esterase (mCASE). A qPCR assay was adapted from a validated S. Typhi PCR panel for confirmation of isolates, with comparison to biochemical and serological tests showing good specificity. Sampling locations in Blantyre, Malawi were used to compare sampling methods. Viable S. Typhi were isolated from a mixture of trap and grab river water samples on six occasions. CONCLUSIONS Culture of viable S. Typhi from environmental samples was possible using effective capture and culture techniques. SIGNIFICANCE AND IMPACT OF STUDY Whilst several studies have attempted to detect S. Typhi from the environment, this is the first successful attempt to isolate the organism from river water since the 1980s. Supplementing clinical data with environmental screening offers the potential for enhanced surveillance, which might inform interventions and assess vaccination programmes.
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Affiliation(s)
- Jonathan Rigby
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK.,Malawi-Liverpool-Wellcome Research Programme, The College of Medicine, Blantyre, Malawi
| | | | - Yohane Diness
- Malawi-Liverpool-Wellcome Research Programme, The College of Medicine, Blantyre, Malawi
| | - Charity Mkwanda
- Malawi-Liverpool-Wellcome Research Programme, The College of Medicine, Blantyre, Malawi
| | - Katalina Tonthola
- Malawi-Liverpool-Wellcome Research Programme, The College of Medicine, Blantyre, Malawi
| | - Heather Galloway
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK.,Malawi-Liverpool-Wellcome Research Programme, The College of Medicine, Blantyre, Malawi
| | - Rory Miles
- Centre for Enzyme Innovation, University of Portsmouth, Portsmouth, UK
| | - Marc Y R Henrion
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK.,Malawi-Liverpool-Wellcome Research Programme, The College of Medicine, Blantyre, Malawi
| | - Thomas Edwards
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Jillian Gauld
- Faculty of Health and Medicine, University of Lancaster, Lancaster, UK
| | - Chisomo Msefula
- Department of Microbiology, The College of Medicine, University of Malawi, Blantyre, Malawi
| | - Rob Johnston
- National Infection Service, Public Health England, London, UK
| | - Satheesh Nair
- National Infection Service, Public Health England, London, UK
| | - Nicholas Feasey
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK.,Malawi-Liverpool-Wellcome Research Programme, The College of Medicine, Blantyre, Malawi.,Department of Microbiology, The College of Medicine, University of Malawi, Blantyre, Malawi
| | - Nicola C Elviss
- National Infection Service, Public Health England, London, UK
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