Introduction: Hospital-acquired infections caused by Enterobacteriaceae producing different types of carbapenem- hydrolizing enzymes are now commonly observed and represent a great limitation for antimicrobial therapy. The purpose of the study was to evaluate the emergence of carbapenem-resistant Enterobaceriaceae among the strains isolated from hospitalized patients to the National Institute of Infectious Diseases, Bucharest (NIID) and the identification of different types of carbapenemases, using phenotypic methods.
Materials and methods: Between January - June 2014, 587 strains of Klebsiella pneumoniae, Enterobacter species and E.coli were isolated from various clinical specimens. We were included all non-susceptible strains to carbapenems, according to EUCAST 2014 clinical breakpoints, as determined by using microdilution MicroScan Panels (Siemens Healthcare Diagnostics). The modified Hodge test (MHT) was performed as phenotypic confirmatory test for carbapenemase production according to CLSI guidelines and the combination disk test (KPC, MBL , OXA-48 Confirm kit, Rosco Diagnostica) according to EUCAST guidelines.
Results: A total of 45 non-repeat Enterobaceriaceae (32 strains Klebsiella pneumoniae, 5 strains E.coli, 8 strains Enterobacter spp) were identified as non-susceptibile to one or more carbapenems (93,33% ertapenem, 53,33% meropenem, 48,88% imipenem). Most strains were isolated from urine (75,55%). MHT was positive in 55,6% (25/45) of carbapenem-resistant strains; in 24 cases the carbapenem-hydrolizing enzyme was identified as: OXA-48-like (n=16), KPC (n=4), MBL (n=1), KPC + MBL (n=2) and MBL + OXA-48-like (n=1). All carbapenemase- positive strains were 100% resistant to 3rd and 4th generation cephalosporins, showing less resistance to tigecycline (12,5% resistant and 25% intermediate), colistin (37,5%) and fosfomycin (41,6%).
Conclusion: During 6 months period, there were isolated 7,66% (45/587) carbapenem-resistant Enterobacteriaceae (K. pneumoniae 21,47%, E. coli 1,23%). Twenty four strains were carbapenemase-producers. The most frequent carbapenemase isolated in our study was OXA-48-like.