Water-borne typhoid fever caused by an unusual Vi-phage type in Edinburgh

Conn, Nancy K.; Heymann, C. S.; Jamieson, A. F.; McWilliam, Joan M.; Scott, Taylor

doi:10.1017/s0022172400022300

Cited by 13 publications

(7 citation statements)

References 2 publications

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“…The Moore swab was first deployed by Brendan Moore in 1948 to trace Salmonella Paratyphi B from sewage in North Devon, England to determine the sources of contamination responsible for sporadic outbreaks of paratyphoid fever. Since the first application to detect typhoidal Salmonella in sewage, the Moore swab method has been utilized in several studies throughout the world to detect Salmonella Typhi in irrigation water, surface water, municipal sewers, and storm drains (Bowmer et al, 1959;Callaghan and Brodie, 1968;Conn et al, 1972;Sears et al, 1984). Given its effectiveness, simplicity, and affordability, we adapted this method for use in typhoid environmental surveillance of wastewater in Kolkata, India.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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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.

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Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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“…Since the first application to detect typhoidal Salmonella in sewage, the Moore swab method has been utilized in several studies throughout the world to detect Salmonella Typhi in irrigation water, surface water, municipal sewers, and storm drains. 11,[30][31][32] Given its effectiveness, simplicity, and affordability, we adapted this method for use in typhoid environmental surveillance of wastewater in Kolkata, India. We found that the Moore swab method has several advantages over UF in terms of greater sensitivity, simplicity, shorter processing time, less labor, and lower cost.…”

Section: Discussionmentioning

confidence: 99%

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

Liu

Ibaraki

Kapoor

et al. 2021

Preprint

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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 to 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 log10 cfu, 5 log10 cfu, and 3 log10 cfu of seeded ST and SPA in 5 L, 10 L, 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, and these two methods can be used jointly or separately for Salmonella Typhi environmental surveillance.

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“…Phage typing has been particularly important in support of epidemiological investigations of Salm. typhi (Conn et al 1972 Although phage typing is essential for the primary subdivision of serovars, the method can prove insufficiently discriminatory in serovars in which a small number of phage types predominate. For example, from 1981 to 1986, 86% of strains of Salm.…”

Section: A P P L I C a T I O N O F P H E N O T Y P I C T Y P I N G M mentioning

confidence: 99%

The identification, typing and fingerprinting of Salmonella: laboratory aspects and epidemiological applications

Threlfall¹,

Frost²

1990

Journal of Applied Bacteriology

136

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Since the 1930s, traditional methods of strain identification based on serotyping and phage typing have been the foundation of salmonella epidemiology. Although the incidence of diseases such as typhoid and paratyphoid has decreased in recent years, food-poisoning caused by non-typhoidal salmonella strains has now reached epidemic proportions in many countries, despite improvements in sanitation and hygiene. Precise strain identification is an essential prerequisite for epidemiological investigations aimed at combating the spread of these strains and eradicating the sources of infection. Modern methods of genotypic typing, particularly those based on physical characterization of the plasmid content of the organism have already proved invaluable for the identification and differentiation of strains in many outbreaks. These plasmid typing methods are now increasingly used with serotyping and phage typing for many epidemiological investigations. Other methods of genotypic typing, particularly those based on recognition of small differences in chromosome structure, are not yet practical for the examination of large numbers of strains. Nevertheless, improvements in small-scale methods for chromosomal DNA extraction coupled with the increasing use of non-isotopic labels for identification of restriction fragment length polymorphisms may provide a new dimension to Salmonella epidemiology.

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Water-borne typhoid fever caused by an unusual Vi-phage type in Edinburgh

Cited by 13 publications

References 2 publications

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

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

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

The identification, typing and fingerprinting of Salmonella: laboratory aspects and epidemiological applications

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