Background: Long-term care facility (LTCF) residents are twice as likely to receive antibiotics compared with elderly living in the community, and studies have reported up to half of prescriptions in LTCFs as inappropriate.

Aim: To identify factors contributing to general and inappropriate antibiotic prescription among LTCF residents with lower respiratory tract infections (LRTIs).

Methods: In this prospective, multicentric, observational study, residents with LRTIs were recruited among 32 LTCFs in Western Switzerland during winter 2022-2023. Residents underwent lung ultrasound (LUS) within three days of LRTI onset, serving as the pneumonia diagnosis reference standard. Multivariate logistic regression and backward selection were used with P < 0.1 cut-off to identify factors among demographics, vital signs, diagnostic tests, and LTCF characteristics associated with (i) antibiotic prescription and (ii) inappropriate prescription.

Findings: A total of 114 residents were included, 63% female, median age 87 years. Fifty-nine (52%) residents underwent diagnostic tests: 50 (44%) polymerase chain reaction (PCR) for respiratory viruses and 16 (14%) blood test with C-reactive protein and/or blood count. Sixty-three (55%) residents received antibiotics. Factors associated with antibiotic prescriptions were Rockwood Clinical Frailty Scale score ≥7, oxygen saturation <92%, performing a blood test, rural LTCFs, and female physician. Among residents receiving antibiotics, 48 (74%) had inappropriate prescriptions, with performance of respiratory virus PCR test as the only protective factor.

Conclusion: Whereas half of LRTI residents received antibiotics, falling within lower ranges of European LTCFs prescription rates (53-80%), most antibiotic prescriptions were inappropriate. Utilization of diagnostic tests correlates with lower overall and inappropriate prescription, advocating for their use to optimize prescription practices in LTCFs.