Molecular Epidemiology of OXA-48 and NDM-1 Producing Enterobacterales Species at a University Hospital in Tehran, Iran, Between 2015 and 2016

Carbapenem-resistantEnterobacterales(CRE) is an increasing problem worldwide. Here, we examined the clonal relatedness of 71 non-repetitive CRE isolates collected in a university hospital in Tehran, Iran, between February 2015 and March 2016. Pulsed-field gel electrophoresis (PFGE) and MLST were used for epidemiological analysis. Screening for antibiotic resistance genes, PCR-based replicon typing, conjugation experiments, and optical DNA mapping were also performed. Among all 71 isolates, 47 isolates ofKlebsiella pneumoniae(66.2%), eightEscherichia coli(11.2%), fiveSerratia marcescens(7%), and twoEnterobacter cloacae(2.8%) harboredbla(NDM-1)andbla(OXA-48)genes together or alone. PFGE analysis revealed that most of the OXA-48- and NDM-1-producingK. pneumoniaeand all of OXA-48-producingS. marcescenswere clonally related, while all eightE. coliand twoE.cloacaeisolates were clonally unrelated. The predominant clones of carbapenemase-producingK. pneumoniaeassociated with outbreaks within the hospital were ST147 (n= 13) and ST893 (n= 10). Plasmids carryingbla(NDM-1)andbla(OXA-48)were successfully transferred to anE. coliK12-recipient strain. Thebla(OXA-48)gene was located on an IncL/M conjugative plasmid, while thebla(NDM-1)gene was located on both IncFII similar to 86-kb to similar to 140-kb and IncA/C conjugative plasmids. Our findings provide novel epidemiologic data on carbapenemase-producingEnterobacterales(CPE) in Iran and highlight the importance of horizontal gene transfer in the dissemination ofbla(NDM-1)andbla(OXA-48)genes. The occurrence and transmission of distinctK. pneumoniaeclones call for improved infection control to prevent further spread of these pathogens in Iran.