Carbapenem-Resistant Klebsiella pneumoniae Strains: Susceptibility to Novel Antibiotics and Molecular Detection of the Resistance Mechanisms - A Study from Two Greek Tertiary Teaching Hospitals

Objectives: We evaluated the carbapenem resistance mechanisms of Klebsiella pneumoniae strains isolated in two Greek tertiary teaching hospitals and their susceptibility to currently used and novel antimicrobial agents. Materials and methods: Forty-seven carbapenem resistant K. pneumoniae strains were collected in G. Papanikolaou and Ippokrateio hospital of Thessaloniki from 1/11/2016 to 5/1/2018 and 26/1/2017 to 19/4/2017 respectively. Strain identification and antimicrobial susceptibility was conducted by Vitek 2 system (Biomerieux France). Susceptibility against new antimicrobial agents was examined by disk diffusion method. Polymerase chain reaction (PCR) was used for the detection of blaKPC, blaVIM, blaNDM and blaOXA-48 genes. Results: The EDTA-boronic acid disk synergy test performed on the 24 K. pneumoniae strains from G. Papanikolaou hospital demonstrated that 8 (33.3%) yielded positive for metallo-b-lactamases (MBL) and 16 (66.6%) for K. pneumoniae carbapenemases (KPC) production. Gentamycin demonstrated the highest in vitro activity (82.6%) among the 23 K. pneumoniae strains from Ippokrateio hospital followed by colistin (73.9%) and tigecycline (69.5%). All strains from G. Papanikolaou hospital were sensitive to colistin whereas the 70.8% of them displayed susceptibility to gentamycin. Ceftazidime/ avibactam showed the highest sensitivity (76.6%) in all strains followed by eravacyclin (66.6%). The blaKPC gene was present in 30 strains (63.8%), the blaNDM in 11 (23.4%) and the blaVIM in 6 (12.8%). The blaOXA-48 gene was not detected. Conclusions: Well established antimicrobial agents such as colistin, gentamycin and tigecycline and novel antibiotics like ceftazidime/avibactam and eravacycline may be reliable options for the treatment of invasive infections caused by KPC-producing pathogens.