Bloodstream infections caused by carbapenem-resistant Acinetobacter baumannii: Clinical features, therapy and outcome from a multicenter study

Objectives: bloodstream infections (BSI) due to multidrug-resistant (MDR) Acinetobacter baumannii (AB) have been increasingly observed among hospitalized patients. Methods: prospective, observational study conducted among 12 large tertiary-care hospitals, across 7 Italian regions. From June 2017 to June 2018 all consecutive hospitalized patients with bacteremia due to MDR-AB were included and analyzed in the study. Results: During the study period 281 episodes of BSI due to MDR-AB were observed: 98 (34.8%) episodes were classified as primary bacteremias, and 183 (65.2%) as secondary bacteremias; 177 (62.9%) of them were associated with septic shock. Overall, 14-day mortality was observed in 172 (61.2%) patients, while 30-day mortality in 207 (73.6%) patients. On multivariate analysis, previous surgery, continuous renal replacement therapy, inadequate source control of infection, and pneumonia were independently associated with higher risk of septic shock. Instead, septic shock and Charlson Comorbidity Index >3 were associated with 14-day mortality, while adequate source control of infection and combination therapy with survival. Finally, septic shock, previous surgery, and aminoglycoside-containing regimen were associated with 30-day mortality, while colistin-containing regimen with survival. Conclusions: BSI caused by MDR-AB represents a difficult challenge for physicians, considering the high rates of septic shock and mortality associated with this infection.