In vitro activity of biapenem and comparators against multidrug-resistant and carbapenem-resistant Acinetobacter baumannii isolated from tertiary care hospitals in Thailand

Abstract

Acinetobacter baumannii is one of nosocomial pathogen which emerge as multidrugresistance worldwide. Multidrug-resistant A. baumannii (MDRAB) and carbapenem-resistant A. baumannii (CRAB) are highly concerned due to limitation of therapeutic options. Antibacterial activity of biapenem was explored in order to overcome bacterial resistance. Total of 412 A. baumannii clinical isolates from 13 tertiary care hospitals in Thailand were collected. MIC values of biapenem and comparators; imipenem, meropenem, colistin, sulbactam, ciprofloxacin ceftazidime and fosfomycin sodium, were determined by broth microdilution method in accordance with the Clinical and Laboratory Standards Institute (CLSI) guidelines (2016). In total, 320 isolates (77.67%) were MDRAB and 328 isolates (79.61%) were CRAB and 58 were colistin-resistant AB (14.07%). A. baumannii showed widespread resistance to ceftazidime, ciprofloxacin and carbapenems in more than 90% of the strains; resistance to sulbactam, fosfomycin, and colistin were 85%, 60%, and 15% respectively. By comparison among carbapenems, biapenem showed MIC50/90 of 16/32 which were at least 2-fold lower than imipenem and meropenem (MIC50/90; 32/128, 32/64, respectively). In addition, 15% of imipenem and meropenem-resistant A. baumannii were susceptible to biapenem. Also, 19% of colistin-resistant A. baumannii were susceptible to biapenem. Biapenem showed a good activity over other carbapenems against the MDRAB, CRAB and colistin-resistant AB strains. This drug might be a therapeutic option as alone or combination for highly resistant bacteria.