Carbapenem-Resistant Acinetobacter baumannii Isolation and In-Hospital Mortality in Adults Hospitalized with COVID-19 in Romania: A Retrospective Single-Center Cohort Study

Background/Objectives: We assessed the frequency, timing and management of carbapenem-resistant Acinetobacter baumannii (CRAB) isolation and its association with in-hospital mortality in adults hospitalized with COVID-19. Methods: This retrospective single-center cohort study included all 395 adults admitted from 12 July to 25 September 2022. The primary analysis compared in-hospital mortality by CRAB isolation in the full cohort, with Firth-penalized adjustment for age and admission SpO2. Treatment and case-level data, complete for 95 chart-verified patients, were analyzed secondarily; isolates were classified by onset (NHSN criteria) and respiratory isolates adjudicated as infection or colonization. Results: CRAB was isolated in 33/395 patients (8.4%). Mortality was 36.4% (12/33) with CRAB isolation versus 11.6% (42/362) without (crude OR 4.35, 95% CI 1.81–10.02; adjusted OR 3.82, 95% CI 1.62–9.02). In the detailed-data subset (8/95 with CRAB), isolates were first detected on hospital days 2–6 and four were community-onset; four of seven respiratory isolates represented colonization. All eight received empirical carbapenem plus colistin after specimen collection, including full 9–10-day colistin-based courses in the four colonized patients. Conclusions: CRAB isolation was associated with higher in-hospital mortality after adjustment for baseline severity, but selective sampling precludes causal inference. Early detection suggests frequent carriage on admission; treatment of colonization was the main stewardship target, supporting admission screening and diagnostic stewardship.