Liver abscesses in Southern Europe: clinical and microbiological characterization of a retrospective cohort

BACKGROUND: Liver abscess is a potentially life-threatening condition and differentiating between pyogenic (PLA) and amoebic liver abscess (ALA) can be challenging. Besides, increasing antimicrobial resistance and the lack of standardized guidelines complicate its management. METHODS: We conducted an observational study of adult individuals diagnosed with liver abscess at Vall d’Hebron University Hospital (Barcelona) from 2016 to 2020. Patients were classified as cryptogenic (CLA) or non-cryptogenic (NCLA) based on presumed pathophysiology. Data on demographics, microbiology, treatment and outcomes were collected. Multivariate logistic regression identified predictors of ALA, recurrence, and mortality. RESULTS: 145 patients were included. Median age was 71 years; 74% were male. NCLA represented 72% of cases, mainly due to biliary tract disease (65%). Microbiological diagnosis was obtained in 117 (80%) cases, with Enterobacterales present in 75/103 (73%) of PLA. Enterobacterales showed high resistance rates, with amoxicillin-clavulanate resistance of 56% in NCLA vs. 29% in CLA, and to piperacillin-tazobactam 49% vs. 14%, respectively. ALA accounted for 14/40 (35%) of CLA. Migration or recent international travel was the only predictor (OR 11.2, p = 0.01), but 4/14 (29%) had no risk factors. Recurrence occurred in 7/92 (8%) NCLA cases. Thirty-day mortality for pyogenic abscesses was 14/106 (12%). Solid (OR 6.5, p = 0.003) and hematologic malignancies (OR 6.1, p = 0.043) were independently associated with early mortality. CONCLUSION: CLA and NCLA differ significantly in presentation and microbiological isolations with high antimicrobial resistance among NCLA. In CLA cases, amoebic aetiology should be considered, even in the absence of classical risk factors.