1490. Serious Infections Caused by Carbapenem Susceptible and Carbapenem Resistant Acinetobacter baumannii-calcoaceticus Complex - A Retrospective Review

Background Increasing resistance to available antibiotics, including carbapenems, is limiting effective treatment options for serious Acinetobacter baumannii-calcoaceticus (ABC) complex infections that are associated with high mortality. This multi-center retrospective analysis is to describe the natural history and outcomes of serious ABC infections. Methods This was a retrospective review of 125 cases of ABC infections from United States (US), Israel, Turkey and Russia. Baseline, microbiologic, treatment and outcomes data were collected from patients with hospital-acquired (HABP, n=23) or ventilator-associated bacterial pneumonia (VABP, n=26), bacteremia (n=36), urinary tract infections/acute pyelonephritis (n=16), and wound ABC infections (n=24) between 2017-2019. Results Fifty percent of cases reviewed were from the US. The median age of patients was 63 years (range 18-93), 46% were > 65 years old, 69% were male, 31% had renal failure, and 22% had septic shock. The most common co-morbidities observed were cardiac disease (41%), diabetes (32%) and moderate or severe renal disease (26%). Rates of resistance were observed as follows: ciprofloxacin 74%, ceftazidime 67%, amikacin 52% and colistin 0%. Carbapenem resistance (CR) was observed in 49% of patients. Most patients (73%) received combination therapy with 37% receiving at least 4 antibiotics. Carbapenems (40%) and penicillin/b-lactamase inhibitors (42%) were mostly used for treatment. Polymyxins were used in 18% of cases. Overall, the 28-day mortality was 34% and was highest in bacteremia (56%) and VABP (50%). CR appears to be a factor in mortality and other outcomes, as well as hospital days (table). In patients who received monotherapy, all 5 patients with CR infection died compared to 29% mortality in patients with carbapenem sensitive (CS) infection. Mortality was 70% in 20 cases when colistin was used for treatment. Conclusion Serious ABC infections are associated with substantial comorbidities and a high mortality rate despite treatment with combination therapy. CR appears to be a major factor in mortality. New antibiotics are urgently needed to treat serious ABC infections. Disclosures Khurram Rana, PharmD, Entasis Therapeutics (Employee) Galia Rahav, MD, AstraZeneca (Scientific Research Study Investigator) Kathleen Maloney, CCRP, Entasis Therapeutics (Employee) Subasree Srinivasan, MD MPH, Entasis therapeutics (Employee)