Wastewater-based surveillance as a tool for public health action: SARS-CoV-2 and beyond

EU surveys insights: analytical tools, future directions, and the essential requirement for reference materials in wastewater monitoring of SARS-CoV-2, antimicrobial resistance and beyond

BACKGROUND

Wastewater surveillance (WWS) acts as a vigilant sentinel system for communities, analysing sewage to protect public health by detecting outbreaks and monitoring trends in pathogens and contaminants. To achieve a thorough comprehension of present and upcoming practices and to identify challenges and opportunities for standardisation and improvement in WWS methodologies, two EU surveys were conducted targeting over 750 WWS laboratories across Europe and other regions. The first survey explored a diverse range of activities currently undertaken or planned by laboratories. The second survey specifically targeted methods and quality controls utilised for SARS-CoV-2 surveillance.

RESULTS

The findings of the two surveys provide a comprehensive insight into the procedures and methodologies applied in WWS. In Europe, WWS primarily focuses on SARS-CoV-2 with 99% of the survey participants dedicated to this virus. However, the responses highlighted a lack of standardisation in the methodologies employed for monitoring SARS-CoV-2. The surveillance of other pathogens, including antimicrobial resistance, is currently fragmented and conducted by only a limited number of laboratories. Notably, these activities are anticipated to expand in the future. Survey replies emphasise the collective recognition of the need to enhance the accuracy of results in WWS practices, reflecting a shared commitment to advancing precision and effectiveness in WWS methodologies.

CONCLUSIONS

These surveys identified a lack of standardised common procedures in WWS practices and the need for quality standards and reference materials to enhance the accuracy and reliability of WWS methods in the future. In addition, it is important to broaden surveillance efforts beyond SARS-CoV-2 to include other emerging pathogens and antimicrobial resistance to ensure a comprehensive approach to protecting public health.

Poliomyelitis and COVID-19: a repeated history

The measurement of the enterovirus and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in sewage water is relevant in the early detection of the introduction or disappearance of these viruses in the ecosystem. We evaluated the co-circulation of the enteroviruses and SARS-CoV-2 in 81 sewage water samples collected between September 2021 and April 2023 from different regions of north and southeast Romania, at the border with Ukraine. We used, for the molecular detection of the pathogens, the multiplex real-time polymerase chain reaction (PCR) assay produced for respiratory samples and the Respiratory 2.1 Plus panel Biofire Film array. The isolation of enteroviruses was performed on cell culture lines, in accordance with the World Health Organization (WHO) recommendations. By molecular investigations, we detected the SARS-CoV-2 in 22 (27%) samples, and the human rhinovirus/enterovirus in 64 (79%) samples. By isolation on cell culture lines, 27 samples (33,33%) were positive for non-polio enteroviruses, and no poliovirus strains were isolated, proving the maintenance of the polio-free status in Romania. In an emergency situation, the molecular detection of the pathogens in sewage water using a PCR system integrating sample preparation, amplification, detection, and analysis in 1 h could be implemented.

Enterococci, Van Gene-Carrying Enterococci, and Vancomycin Concentrations in the Influent of a Wastewater Treatment Plant in Southeast Germany

Vancomycin-resistant (VR) Enterococcus spp. can be detected in high concentrations in wastewaters and pose a risk to public health. During a one-year study (September 2022-August 2023), 24 h composite raw wastewater samples (n = 192) of a municipal wastewater treatment plant were investigated for cultivable enterococci. After growth on Slanetz-Bartley agar (SBA), a mean concentration of 29,736 ± 9919 cfu/mL was calculated. Using MALDI-TOF MS to characterize randomly picked colonies (n = 576), the most common species were found to be Enterococcus faecium (72.6%), E. hirae (13.7%), and E. faecalis (8.0%). Parallel incubation of wastewater samples on SBA and VRESelect agar resulted in a mean rate of VR enterococci of 2.0 ± 1.5%. All the tested strains grown on the VRESelect agar (n = 172) were E. faecium and carried the vanA (54.6%) or vanB gene (45.4%) with limited sequence differences. In susceptibility experiments, these isolates showed a high-level resistance to vancomycin (>256 µg/mL). Concentration of vancomycin was determined in 93.7% of 112 wastewater samples (mean: 123.1 ± 64.0 ng/L) and varied between below 100 ng/L (the detection limit) and 246.6 ng/L. A correlation between the concentration of vancomycin and the rate of VR strains among the total enterococci could not be found. The combination of incubation of samples on SBA and a commercial vancomycin-containing agar applied in clinical microbiology with a multiplex PCR for detection of van genes is an easy-to-use tool to quantify and characterize VR Enterococcus spp. in water samples.