Background: Despite improvements in treatment options, lung abscess remains a complicated infection, often requiring weeks of broad-spectrum antibiotic treatment.

Aims and Objective: To describe real-life treatment strategies for lung abscess, with regard to antibiotic treatment regimen, administration route and treatment duration.

Methods: In a retrospective cohort study, patients diagnosed with lung abscess (LA) in four hospitals across Denmark were identified using the International Classification of Diseases and Related Health Problems 10th revision (ICD-10) diagnostic codes between 2016 and 2021. From hospitalization records, data on demographics and treatment were collected.

Results: A total of 222 patients were included. Mean age was 63 years (SD ± 15 years), 63% male. The most frequent respiratory comorbidity was chronic obstructive pulmonary disease (31%).
In 149 patients (67%), treatment with antibiotics (AB) were initiated prior to the diagnosis of LA, and in 198 patients (89%) treatment with intravenous (IV) AB were given after diagnosis. The median treatment duration of IV AB was 14 days (IQR 8-14). Combining IV and oral administration, the median treatment duration was 38 days (IQR 30-51).
The three most frequent AB regimens were high-dose benzylpenicillin and metronidazole (27%), cefuroxime and metronidazole (17%) and piperacillin/tazobactam and metronidazole (17%). Shifts in IV AB across the three treatments were conducted in 23%, 30% and 29%, respectively.

Conclusion: Variable antibiotic treatment strategies were used for LA, and change in AB treatment was common. Prospective trials are warranted to establish the most efficient treatment taking antibiotic stewardship into account.