Eurosurveillance - Volume 30, Issue 38, 25 September 2025

Data for healthcare-associated infections (HAI) and antibiotic use in long-term care facilities (LTCF) in Switzerland are lacking but are necessary to take actions.

We aimed to estimate HAI prevalence and antibiotic use and to record existing structure and process indicators in the area of infection prevention/antibiotic use in Swiss LTCF.

We invited all Swiss LTCF for this PPS in September 2024 using the adapted Healthcare-Associated Infections in European Long-Term Care Facilities (HALT)-4 protocol. The proportion of residents with HAI and systemic antibiotic treatment was calculated for a representative sample, stratified by language region and size. We assessed resident-level and institutional risk factors for HAI in all participating institutions, using random-effects logistic regression.

We included 94 LTCF (7,244 residents), whereof 49 LTCFs (3,375 residents) belonged to the representative sample. Median age of residents in the representative sample was 87 years (range: 36–107) and 2,334 (69.2%) were female. Prevalence of HAI was 2.2% (95% confidence interval (CI): 1.7–2.7); 2.7% (95% CI: 2.2–3.3) were receiving antibiotic treatment, with highest use in LTCF in French-speaking cantons (5.9%; 95% CI: 4.2–7.5). Urinary tract (46%) and respiratory infections (20%) were most common, aminopenicillins (26%) and nitrofurantoin (19%) the most commonly used antimicrobials. The strongest independent risk factor for HAI was presence of urinary catheters (adjusted odds ratio = 2.65; 95% CI: 1.71–4.11).

Prevalence of HAI and antibiotic use in Swiss LTCFs were comparable to the European average from 2023/24. There are regional differences in antibiotic consumption. Urinary catheterisation, potentially modifiable, was the most important risk factor for HAI.

Hospital-based communicable disease surveillance may be costly during large outbreaks and often misses mild or asymptomatic infections. It can be enhanced by environmental surveillance, which monitors circulating pathogens, even from asymptomatic carriers.

We investigated if tracking viruses in indoor air could be used for their surveillance in a community setting. We also tested the value of untargeted metagenomics to identify viruses in air samples.

Weekly indoor air samples were collected with active air samplers from January until December 2022 from a daycare centre in Leuven, Belgium. Samples were analysed using respiratory and enteric quantitative (q)PCR panels, as well as with untargeted metagenomics, enabling both targeted and agnostic viral detections.

Human-associated viruses were detected in 40 of 42 samples across the study period, with MW polyomavirus being most prevalent (33 samples). Respiratory agents such as rhinoviruses and RSV-B and enteric viruses including rotavirus A, astrovirus, and adenovirus appeared at epidemiologically expected times. Skin-associated viruses were also observed, notably Merkel cell polyomavirus and STL polyomavirus. Metagenomics enabled reconstructing multiple complete genomes, distinguishing viral subtypes and detecting copresence of closely related variants. Additionally, several animal, insect, fungal, and plant viruses were found, reflecting both indoor and outdoor environmental exposure.

Indoor air monitoring, combined with untargeted metagenomics, demonstrates a potential to support virus surveillance. This approach can allow monitoring circulation of viruses in community settings, including those causing asymptomatic or mild infections. By enabling to reconstruct complete viral genomes, it allows detailed variant tracking, facilitating adapted public health responses.