A landmark trial presented at ESCMID Global 2026 shows that improving oral hygiene for hospital patients can reduce the risk of non-ventilator-associated hospital-acquired pneumonia (NV-HAP) by 60%.

The study, involving over 8,000 patients, is the only multicenter randomized controlled trial (RCT) in a hospital setting to evaluate this approach and the largest RCT in this setting to date.

NV-HAP is a form of pneumonia that develops at least 48 hours after hospital admission in patients who are not receiving mechanical ventilation. It is a common health care-associated infection linked to longer hospital stays, higher health care costs and increased mortality.

Despite occurring more frequently and being equally as dangerous as ventilator-associated pneumonia (VAP), it has historically received far less research attention.

To address this gap, researchers conducted the Hospital Acquired Pneumonia Prevention (HAPPEN) Study, a multicenter, stepped-wedge cluster RCT across nine wards in three Australian hospitals over a 12-month period, concluding in August 2025. Each ward introduced the intervention every three months. In total, 8,870 patients were included in the study, of whom 4,347 were in wards during the intervention period.

In the intervention phase, patients were provided on admission with a toothbrush, toothpaste, educational materials and access to additional online resources. Health care staff received onsite training, access to online resources and practical support to improve the delivery of oral care. Control was usual practice.

The program led to a substantial improvement in oral hygiene practices among hospital patients. The proportion of patients receiving oral care increased from 15.9% in the control to 61.5% in the intervention, with audits showing oral care was undertaken an average of 1.5 times per day.

Importantly, exposure to the intervention was associated with a statistically significant reduction in NV-HAP risk. Incidence fell from 1.00 to 0.41 cases per 100 admission days-at-risk – representing an approximately 60% reduction.

“One of the most encouraging findings from this study was the scale of improvement we were able to achieve,” commented lead study author Professor Brett Mitchell, Avondale University, Australia.

“Through earlier work, we identified several barriers in hospitals, including limited access to suitable products, low awareness of the link with pneumonia and competing clinical priorities. By addressing these through education, practical resources and conversations with patients on admission, we were able to substantially increase oral care in hospital wards.”

Explaining why improved oral hygiene can reduce pneumonia risk, Professor Mitchell said, “Typically, NV-HAP is the result of fluids from the mouth or throat entering the lungs, with hospital-associated respiratory pathogens more frequently detected in patients who are unable to clear oral secretions.

These infections are thought to arise largely from a patient’s own microbiota rather than person-to-person transmission. Improving oral hygiene helps reduce these pathogens in the mouth, potentially lowering the risk of subsequent infection.”

Looking ahead, Professor Mitchell commented, “Guidelines already recognize the role of oral care in preventing NV-HAP, but the evidence supporting these recommendations has been limited. Our study now provides robust evidence from a hospital setting. The next step is to better understand how structured programs can be effectively implemented and sustained across hospital wards.”

Provided by
European Society of Clinical Microbiology and Infectious Diseases