Background and importance The pervasive use of antibiotics has been identified as a major public health threat due to the emergence of antibiotic resistant bacteria. Antibiotics are among the most commonly prescribed drugs in nursing homes (NHs) and up to 75% of these are considered inappropriate.

Aim and objectives To characterise antibiotic therapy in NHs and evaluate adequacy.

Material and methods A prospective study was conducted in a NHs (264 residents) over a 3 month period (July–September 2019). All residents with antibiotic prescriptions for suspected infections were included. Data were collected by review of medical and pharmacy records: demographic and clinical characteristics, risk factors for infection, antibiotic prescribed, indication and microbiology data.

Inadequate antibiotic therapy was defined as: (1) conditions without an antibiotic indication; (2) non-adherence to therapeutic guidelines; (3) incorrect dose, route of administration or duration; (4) no microbiology sample collection when needed; and (5) microbiological evidence of infection not covered by the chosen antibiotics, or no antibiotic de-escalation.

Results We included 62 residents, mean age 81.7±10.7 years, 69.4% women, and 6.5% had an antibiotic allergy. Mean Charlson comorbidity index age adjusted was 5.8±1.9. The majority of residents presented risk factors for infection (RFF) (95.2%), mean 3.1±1.4. RFF included functional dependency (6.9% of patients), previous antibiotic therapy (59.7%) and cognitive impairment (53.2%).

The most commonly prescribed antibiotics were amoxicillin/clavulanic (24.2%), quinolones (19.4%), fosfomycin–trometamol (19.4%), cephalosporins (11.2%), fosmomycin calcium (9.7%), cloxacillin (9.7%) and other (6.4%). Mean duration was 5.6±3.5 days. Most treatments were empirical (75.8%), 21% were targeted treatment and 3.2% were prophylactic. Combination therapy was found in only one case; three intravenous route.

The most common infection was urinary tract infection (48.4%), followed by skin and soft tissue infection (22.6%) and lower respiratory tract infection (21%). Sample collection was carried out in 41.9% (76.9% before initiating antibiotic): 65.4% uroculture, 11.5% exudate culture and 23.1% others. Most of the cultures were positive (80.8%; 71.4% were monomicrobial infections). The most prevalent microorganisms isolated were gram negative isolates (85.7%); methicillin resistant Staphylococcus aureus was isolated in three cases (14.3%).

Antibiotic therapy was inadequate in 51.6%: (1) 9.3%; (2) 56.3%; (3) 12.5%; (4) 3.2%; and (5) 18.7%.

Conclusion and relevance Broad spectrum antibiotics are often prescribed. There was a high number of inadequate antibiotic prescriptions. Pharmacy teams are well placed to support prudent selection of antibiotic therapy in NHs.

References and/or acknowledgements No conflict of interest.