Reviving the “Moore Swab”: a Classic Environmental Surveillance Tool Involving Filtration of Flowing Surface Water and Sewage Water To Recover Typhoidal Salmonella Bacteria

Abstract

The “Moore swab” is a classic environmental surveillance tool whereby a gauze pad tied with string is suspended in flowing water or wastewater contaminated with human feces and harboring enteric pathogens that pose a human health threat. In contrast to single volume “grab” samples, Moore swabs act as continuous filters to “trap” microorganisms, which are subsequently isolated and confirmed using appropriate laboratory methods. Continuous filtration is valuable for the isolation of transiently present pathogens such as human-restricted Salmonella enterica serovars Typhi and Paratyphi A and B. The technique was first proposed (1948) to trace Salmonella Paratyphi B systematically through sewers to pinpoint the residence of a chronic carrier responsible for sporadic outbreaks of paratyphoid fever. From 1948 to 1986, Moore swabs proved instrumental to identify long-term human reservoirs (chronic carriers) and long-cycle environmental transmission pathways of S. Typhi and Paratyphi, for example, to decipher endemic transmission in Santiago, Chile, during the 1980s. Despite limitations such as intermittent shedding of typhoidal Salmonella by humans and the effects of dilution, S. Typhi and S. Paratyphi have been recovered from sewers, surface waters, irrigation canals, storm drains, flush toilets, and septic tanks by using Moore swabs. Driven by the emergence of multiple antibiotic-resistant S. Typhi and S. Paratyphi A strains that limit treatment options, several countries are embarking on accelerated typhoid control programs using vaccines and environmental interventions. Moore swabs, which are regaining appreciation as important components of the public health/environmental microbiology toolbox, can enhance environmental surveillance for typhoidal Salmonella, thereby contributing to the control of typhoid fever.

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

“…21,26 Moore swabs were instrumental in the detection of ST in sewage canals near Santiago, Chile that were used to irrigate vegetable crops typically eaten without cooking. 6 These findings indicate risk of ST transmission via drinking water and raw produce, but these samples and methods do not provide quantitative information that could be used to estimate the burden of typhoid infection in the population. Quantitative detection of ST and SPA in wastewater samples collected from sites where the population catchment can be estimated allows modeling approaches to estimate prevalence of typhoid and paratyphoid infection in the catchment population.…”

“…18 "Moore swabs" have been used for decades by public health professionals around the world to detect and isolate enteric pathogens from wastewater and environmental waters, and their use to recover typhoidal Salmonella bacteria has recently been reviewed by Sikorski and Levine. 6 Consisting of a strip of cotton gauze tied with string and suspended in flowing water, this All rights reserved. No reuse allowed without permission.…”

“…11 The Moore swab was first introduced for Salmonella detection from sewage in 1948 in England during a paratyphoid epidemic. 6 Subsequently, this method has been successfully used to isolate Vibrio Cholerae 12 , poliovirus 13 and Burkholderia pseudomallei 14 from sewage. In contrast to the Moore swab method that only shows the presence or absence of a target pathogen, UF is a quantitative method that can simultaneously concentrate multiple pathogens from large volumes of water or wastewater, [15][16][17] and we recently reported the application of this method to detect S. Typhi in wastewater samples.…”

Giants On Clay Feet – COVID-19, infection control, and public health laboratory networks in England, the US, and (West-)Germany (1945-2020)

“…In the case of war, it was decided to establish a centralized emergency laboratory network In the absence of bacteriological attacks, EPHLS research also produced effective new surveillance technologies: national phage-typing schemes were rolled out for typhoid, paratyphoid, Salmonella enterica serovar Typhimurium, and Staphylococcus aureus; 'Moore swabs' were developed to isolate and trace bacteria in sewer and water systems; centralized 'finger print registries' for typhoid carriers were established; and microbial taxonomies were refined 28,[53][54][55][56] . Its track record secured the EPHLS a post-war future.…”

A Novel COVID-19 Early Warning Tool: Moore Swab Method for Wastewater Surveillance at an Institutional Level

“…The Moore swab was first proposed by Brendan Moore in 1948 to trace Salmonella Paratyphi B from effluent sewage water in North Devon, England to determine the sources of infection responsible for sporadic outbreaks of paratyphoid fever. 10 Since the first application to detect typhoidal Salmonella in sewage water, the Moore swab method has been utilized throughout the world to detect several fecal borne pathogens such as coxsackieviruses, 11 poliovirus (26-29), 12-15 human norovirus, 16 Escherichia coli O157:H7 16, 17 Vibrio cholerae O1. 18-20 Over the years, the technique once used for tracing the chronic carriers of Salmonella Paratyphi B has expanded to environmental surveillance, investigation of ongoing outbreaks, and bacterial enumeration in surface water.…”