Multiplex polymerase chain reaction detection of enteropathogens in sewage in Norway

Monitoring of enteropathogenic Gram-negative bacteria in wastewater treatment plants: a multimethod approach

The wastewater treatment processes are associated with the emission of microbial aerosols, including enteropathogenic bacteria. Their presence in this work environment poses a real threat to the health of employees, both through the possibility of direct inhalation of the contaminated air and indirectly through the pollution of all types of surfaces with such bioaerosol particles. This study aimed to investigate the prevalence of enteropathogenic bacteria in the air, on surfaces, and in wastewater samples collected in four wastewater treatment plants (WWTPs). The effectiveness of conventional culture-biochemical, as well as spectrometric and molecular methods for the rapid detection of enteropathogenic bacteria at workstations related to particular stages of wastewater processing, was also evaluated. Bioaerosol, surface swab, and influent and effluent samples were collected from wastewater plants employing mechanical-biological treatment technologies. The air samples were collected using MAS-100 NT impactor placed at a height of 1.5 m above the floor or ground, simulating aspiration from the human breathing zone. Surface samples were collected with sterile swabs from different surfaces (valves, handles, handrails, and coveyor belts) at workplaces. The raw influent and treated effluent wastewater samples were aseptically collected using sterile bottles. The identification of bacterial entheropathogens was simultaneously conducted using a culture-based method supplemented with biochemical (API) tests, mass-spectrometry (MALDI TOF MS), and molecular (multiplex real-time PCR) methods. This study confirmed the common presence of bacterial pathogens (including enteropathogenic and enterotoxigenic Escherichia coli, Salmonella spp., Campylobacter spp., and Yersinia enterocolitica) in all air, surface, and wastewater samples at studied workplaces. Higher concentrations of enteropathogenic bacteria were observed in the air and on surfaces at workplaces where treatment processes were not hermetized. The results of this study underline that identification of enteropathogenic bacteria in WWTPs is of great importance for the correct risk assessment at workplaces. From the analytical point of view, the control of enteropathogenic bacterial air and surface pollution using rapid multiplex-PCR method should be routinely performed as a part of hygienic quality assessment in WWTPs.

Molecular Methods for Pathogenic Bacteria Detection and Recent Advances in Wastewater Analysis

With increasing concerns about public health and the development of molecular techniques, new detection tools and the combination of existing approaches have increased the abilities of pathogenic bacteria monitoring by exploring new biomarkers, increasing the sensitivity and accuracy of detection, quantification, and analyzing various genes such as functional genes and antimicrobial resistance genes (ARG). Molecular methods are gradually emerging as the most popular detection approach for pathogens, in addition to the conventional culture-based plate enumeration methods. The analysis of pathogens in wastewater and the back-estimation of infections in the community, also known as wastewater-based epidemiology (WBE), is an emerging methodology and has a great potential to supplement current surveillance systems for the monitoring of infectious diseases and the early warning of outbreaks. However, as a complex matrix, wastewater largely challenges the analytical performance of molecular methods. This review synthesized the literature of typical pathogenic bacteria in wastewater, types of biomarkers, molecular methods for bacterial analysis, and their recent advances in wastewater analysis. The advantages and limitation of these molecular methods were evaluated, and their prospects in WBE were discussed to provide insight for future development.

Molecular Monitoring of Enteropathogens in Sewage During NATO Exercise Trident Juncture 2018: Potential Tool in Early Outbreak Warning?

INTRODUCTION

Outbreaks of gastrointestinal disease among military service personnel can have severe impact on operational effectivity and force readiness. Thus, early outbreak detection is critical to minimize spread. This pilot study aimed to explore field-based molecular screening of sewage as a supplemental tool in early outbreak warning before disease is diagnosed in personnel seeking medical care.

MATERIALS AND METHODS

Sewage from permanent (n = 3) and temporary (n = 3) military camps, hosting national and international military personnel, were sampled during the NATO Exercise TRJE18 taking place in southern Norway during fall 2018. Samples were screened for 22 gastrointestinal pathogens using multiplex PCR.

RESULTS

Markers of multiple enteropathogens were detected in samples from all locations with some variations in diversity. Yersinia enterocolitica, pathogenic Escherichia coli, adenovirus, and Giardia were detected in sewage from all six camps during the exercise. Agent diversity seemed to increase with population size, regardless of nationality. Only a minor outbreak (n = 6) of norovirus was reported in one of the permanent camps. From the same camp, genetic markers of norovirus were detected in sewage 2 days before outbreak notification. No other outbreaks of gastrointestinal disease were reported during the exercise, indicating that markers of several enteropathogens can be normally found in sewage from healthy soldier populations. Thus, discriminating between true outbreaks and nonrelevant "background levels" would be of critical importance for correct decision-making in operational contexts.

CONCLUSIONS

Molecular screening of sewage allows rapid detection of multiple gastrointestinal pathogens in biological waste from military camps. However, background levels of pathogens challenges interpretation of qualitative analyses in outbreak situations. As such, quantitative measures, as well as high-resolution sequence-based methods, which allows strain identification and broader target spectrum, should be further explored in future studies.