Bacteremia and meningitis caused by OXA-23-producing Acinetobacter baumannii – molecular characterization and susceptibility testing for alternative antibiotics

Kamile Francine Schuertz, Felipe Francisco Tuon, Jussara Kasuko Palmeiro, Danieli Conte, João Paulo Marochi Telles, Lucas Eduardo Trevisoli, Libera Maria Dalla-Costa

Carbapenem-resistant Acinetobacter baumannii infection is a concern in developing countries due to high incidence, few therapeutic options, and increasing costs. Characterize and analyze the antibiotic susceptibility patterns of carbapenem-resistant A. baumannii isolates and evaluate clinical data of meningitis and bacteremia caused by this microorganism. Twenty-six A. baumannii isolates from 23 patients were identified by MALDI-TOF and automated methods and genotyped using pulsed field genotyping electrophoresis. Clinical data and outcomes were evaluated. Susceptibility of isolates to colistin, tigecycline, meropenem, imipenem, and doxycycline was determined. Mortality due to A. baumannii infections was 73.91%; all patients with meningitis and 7/8 patients with ventilator-associated pneumonia died. All isolates were susceptibility to polymyxin (100%; MIC50, MIC90: 1μg/mL, 1μg/mL) and colistin (100%; MIC50, MIC90: 2μg/mL, 2μg/mL), and 92% were susceptible to tigecycline (MIC50, MIC90: 1μg/mL, 1μg/mL) and doxycycline (MIC50, MIC90: 2μg/mL, 2μg/mL). blaOXA-23 was identified in 24 isolates. Molecular typing showed 8 different patterns: 13 isolates belonged to pattern A (50%). Carbapenem-resistant A. baumannii infections mortality is high. Alternative antimicrobial therapy (doxycycline) for selected patients with carbapenem-resistant A. baumannii infection should be considered.