Arrival of carbapenem-hydrolyzing-oxacillinases in Acinetobacter baumannii in Bosnia and Herzegovina

Multidrug-resistant Acinetobacter baumannii (MDR-AB) is an important threat for critically ill patients. It can infect the respiratory tract, blood, soft tissues, urinary tract and central nervous system. Recently, carbapenem-resistance was observed in A. baumannii clinical isolates from Bosnia and Herzegovina. This prompted us to analyze these isolates with regards to genotypic diversity, antibiotic susceptibility and occurrence of acquired carbapenem resistance genes. Twelve carbapenem-resistant isolates were collected at a University hospital during two different periods of 2011 and 2015-2016: four isolates in 2011 and eight isolates 2015-2016 and compared to determine the dynamic changes in carbapenemase resistance mechanisms and population structure. All twelve isolates were positive for intrinsic bla(OXA-51-like), nine for bla(OXA-40-like) and one for the bla(OXA-23-like) gene. ISAba1 was found upstream of bla(OXA-51) in all and upstream of bla(OXA-23-like) gene in one isolate. Sequencing of the selected PCR products revealed the presence of OXA-72 beta-lactamase (strain 1) and OXA-23 beta-lactamase (strain 41). WGS of the selected isolate (AB 5) revealed the presence of bla(OXA-72), chromosomal genes bla(OXA-69) and bla(ADC). Moreover, the aac (3)-1a and aadA1 genes encoding aminogly-coside resistance, and sul1encoding sulphonamide resistance were identified. PFGE and rep-PCR revealed two clones containing highly similar isolates positive for OXA-40-like; one from 2011 and the other from 2015 to 2016. Implementation of hospital hygiene measures, screening of the patients on admission for carriage of MDR-AB, and the early and accurate detection, with restriction of antibiotic use should be recommended to control the spread of these important hospital pathogenes. To our knowledge, this is the first report of A. baumannii isolates producing carbapenem-hydrolyzing oxacillinases (CHDL) from Bosnia and Herzegovina.