A study conducted at a hospital in Ireland highlights the potential for hospital wastewater systems to serve as a reservoir for clinically relevant antibiotic-resistant pathogens, researchers reported last week in the Journal of Hospital Infection.

In the study, which was conducted at University Hospital Limerick, researchers performed a large-scale metagenomic analysis of wastewater pipes from a soon-to-be refurbished ward that has experienced multiple multidrug-resistant healthcare-associated infection outbreaks. For the analysis, they processed biofilm and extracted DNA from 20 pipe samples from patient rooms, including toilet u-bends and sink and shower drains. They also analyzed clinical isolates from patients who had been on the ward prior to refurbishment and were known to be colonized with antibiotic-resistant bacteria.

if we can stop these reservoirs from being established by improved infection control practices, we can hopefully stop patients from acquiring difficult-to-treat infections.

Sequencing of DNA from the pipe samples revealed a diverse reservoir of antibiotic-resistance genes (ARGs), and the most ARGs observed were those encoding resistant to commonly used antibiotics, including tetracyclines, fluoroquinolones, beta-lactams, and macrolides. Similarly, a diverse range of ARGs was identified in the clinical isolates, and a comparison of the clinical isolates with DNA from the wastewater pipes revealed a considerable number of identical ARGs.

"Whilst these data do not enable us to determine if resistance genes were transferred from patient to the wastewater system or indeed vice versa, they do allow us to confirm crossover in the resistome of clinically-relevant pathogens and the microbiome of the wastewater environment," the study authors wrote.

Wastewater highway

Since all pipes and drains from the hospital's wastewater system connect to the same sewage system, the authors say the findings suggest the system forms a "wastewater highway" that could spread the resistant bacteria from sinks, shower drains, and toilets throughout the hospital—a finding they believe could influence the hospital's infection control and cleaning strategies going forward.

"Such sites pose a risk for healthcare-associated infections, and if we can stop these reservoirs from being established by improved infection control practices, we can hopefully stop patients from acquiring difficult-to-treat infections," study co-author Nuala O'Connell, MD, of the University of Limerick said in a university press release.

Penn State researchers will use a $4.5 million grant from the US Department of Agriculture (USDA) to test for SARS-CoV-2 in 58 wildlife species, with the goal of tracking potential human spillback.

In a news release yesterday, Penn State said the researchers will collect more than 20,000 samples from wildlife such as eastern chipmunks, gray squirrels, raccoons, coyotes, white-footed mice, moose, wolverines, three species of deer, and several bat species. SARS-CoV-2 has already been found in 29 species, such as white-tailed deer, but most species haven't been tested.

Kurt Vandegrift, PhD, principal investigator and associate research professor of biology, cited recent evidence from deer in New York that showed the continued circulation of SARS-CoV-2 variants long absent from humans. "Viral persistence is important because it not only poses a looming risk of spillback to humans, but also allows for viral evolution and the emergence of highly divergent variants for which our diagnostics, therapeutics, and vaccines could be ill prepared," he said in the release.

The presence of the virus in wild animals also carries a risk of spillover to agricultural animals, which could threaten the food supply, he added.

Repeat sampling surveillance

The researchers will sample the same animals in the same region multiple times to determine whether and how transmission is occurring. They will then use a model-informed process to distinguish between dead-end hosts (which don't spread the virus) and those that do spread it, within and between species.

Three countries reported a total of six vaccine-derived polio cases this week, according to the latest update from the Global Polio Eradication Initiative (GPEI), while the group also published the Independent Monitoring Board's annual assessment of progress toward polio eradication, which it said will not happen in 2023 as previously hoped.

"Despite recent progress toward eradication, remaining challenges make stopping transmission of WPV1 [wild poliovirus type 1] this year unlikely, while ending all variant poliovirus outbreaks will take even more time," the monitoring board said.

Wild poliovirus is endemic in only two countries, Afghanistan and Pakistan, several other countries battle outbreaks from three strains of vaccine-derived polio, which is linked to oral polio vaccine use.

Though protected from the virus, recipients of oral polio vaccine shed the weakened virus in their stool, which can then spread to unvaccinated children in unhygienic conditions. In ordinary circumstances, this can actually extend immunization coverage, but in areas with low polio vaccine uptake, the circulating virus can mutate and cause vaccine-derived polio. Newer vaccines, however, are designed to make the vaccine virus less likely to mutate and cause disease.

Despite recent progress toward eradication, remaining challenges make stopping transmission of WPV1 [wild poliovirus type 1] this year unlikely.

Six new cases in 3 countries

The Central African Republic recorded 1 new case this past week of vaccine-derived polio, raising the year's total to 11, the GPEI said in its weekly update. In Chad, 4 cases in two regions raise the 20203 total to 33 cases. One new case was reported in Yemen; that case is just the second reported in 2023. In 2022, Yemen recorded 162 cases.