Development of Moore Swab and Ultrafiltration Concentration and Detection Methods for Salmonella Typhi and Salmonella Paratyphi A in Wastewater and Application in Kolkata, India and Dhaka, Bangladesh

• Type of Material: Article
• Authors: Pengbo Liu, Emory University; Makoto Ibaraki, Emory University; Renuka Kapoor, Emory University; Nuhu Amin, International Centre for Diarrhoeal Disease, Bangladesh (ICDDR, B); Abhishek Das, Indian Council Med Res ICMR; Rana Miah, International Centre for Diarrhoeal Disease, Bangladesh (ICDDR, B); Asish K Mukhopadhyay, Indian Council of Medical Research (ICMR), National Institute of Cholera and Enteric Diseases (NICID); Mahbubur Rahman, International Centre for Diarrhoeal Disease, Bangladesh (ICDDR, B); Shanta Dutta, National Institute of Cholera and Enteric Diseases (NICID); Christine Moe, Emory University
• Language: English
• Date: 2021-07-15
• Publisher: FRONTIERS MEDIA SA
• Publication Version: Final Published Version
• Copyright Statement: © 2021 Liu, Ibaraki, Kapoor, Amin, Das, Miah, Mukhopadhyay, Rahman, Dutta and Moe.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.3389/fmicb.2021.684094
• Title of Journal or Parent Work: FRONTIERS IN MICROBIOLOGY
• Volume: 12
• Start Page: 684094
• End Page: 684094
• Grant/Funding Information: This study was funded by The Bill and Melinda Gates Foundation (BMGF) grant OPP1150697. BMGF was the funding and management agency for this project. Funds are available for open access publication fees.
• Keywords: HOLLOW-FIBER ULTRAFILTRATION; Microbiology; Salmonella Typhi; ultrafiltration; SIMULTANEOUS RECOVERY; ENVIRONMENTAL SURVEILLANCE; Moore swab; Salmonella Paratyphi A; wastewater; Life Sciences & Biomedicine; OUTBREAK; DIVERSE MICROBES; surveillance; SURFACE-WATER; Science & Technology; FEVER
• Research Categories: Health Sciences, Hygiene

Abstract

Enteric fever is a severe systemic infection caused by Salmonella enterica serovar Typhi (ST) and Salmonella enterica serovar Paratyphi A (SPA). Detection of ST and SPA in wastewater can be used as a surveillance strategy to determine burden of infection and identify priority areas for water, sanitation, and hygiene interventions and vaccination campaigns. However, sensitive and specific detection of ST and SPA in environmental samples has been challenging. In this study, we developed and validated two methods for concentrating and detecting ST/SPA from wastewater: the Moore swab trap method for qualitative results, and ultrafiltration (UF) for sensitive quantitative detection, coupled with qPCR. We then applied these methods for ST and SPA wastewater surveillance in Kolkata, India and Dhaka, Bangladesh, two enteric fever endemic areas. The qPCR assays had a limit of detection of 17 equivalent genome copies (EGC) for ST and 25 EGC for SPA with good reproducibility. In seeded trials, the Moore swab method had a limit of detection of approximately 0.05–0.005 cfu/mL for both ST and SPA. In 53 Moore swab samples collected from three Kolkata pumping stations between September 2019 and March 2020, ST was detected in 69.8% and SPA was detected in 20.8%. Analysis of sewage samples seeded with known amount of ST and SPA and concentrated via the UF method, followed by polyethylene glycol precipitation and qPCR detection demonstrated that UF can effectively recover approximately 8, 5, and 3 log10 cfu of seeded ST and SPA in 5, 10, and 20 L of wastewater. Using the UF method in Dhaka, ST was detected in 26.7% (8/30) of 20 L drain samples with a range of 0.11–2.10 log10 EGC per 100 mL and 100% (4/4) of 20 L canal samples with a range of 1.02–2.02 log10 EGC per 100 mL. These results indicate that the Moore swab and UF methods provide sensitive presence/absence and quantitative detection of ST/SPA in wastewater samples.