A retrospective study of non-ventilator hospital-acquired pneumonia in a Norwegian hospital: a serious medical condition in need of better and timelier microbiological diagnostics.

Background: Hospital-acquired pneumonia (HAP) is the most common hospital-acquired infection (HAI). HAP is associated with a high burden of morbidity and mortality, but the diagnosis is difficult to establish and the incidence uncertain.

Methods: Patients aged ≥ 18 years hospitalised with radiologically verified non-ventilator hospital acquired pneumonia (NV-HAP) during 2018 were retrospectively identified at Drammen Hospital, a Norwegian general hospital. Infectious Diseases Society of America and the American Thoracic Society's definition of HAP was used.

Results: In total 119 cases of NV-HAP were identified among 27,701 admissions. The incidence was 4.3 per 1000 admissions and 1.2 per 1000 patient-days. The median age was 74 years, 63% were male and median Charlson comorbidity index was 5. Coronary heart disease (42%) was the most common comorbidity. Median length of stay was 17.2 days. A blood culture was obtained in 53.8% of patients, while samples from lower airways were seldom obtained (10.9%). In-hospital mortality was 21%, accumulated 30-day mortality was 27.7% and accumulated 1-year mortality was 39.5%. Thirty-day readmission rate among survivors was 39.4%.

Conclusion: NV-HAP was present in approximately 1 in 250 hospitalisations, most had multiple comorbidities, and 1 in 5 died in hospital. Although thorough microbiological sampling is recommended when NV-HAP is suspected, our data indicate that airway sampling is infrequent in clinical practice. Our findings underscore the need to develop microbiological diagnostic strategies to achieve targeted antimicrobial treatment that may improve patient outcomes and reduce broad-spectrum antibiotic usage.