Co-Production of OXA-48 and NDM-1 Carbapenemases in Providencia rettgeri: the First Report

Our country is the epicenter of the OXA-48-like carbapenemase-producing Klebsiella and Escherichia coli; and in the recent years, the concern has been increasing due to both spreading of this resistance to other members of Enterobacteriaceae family and acquiring other carbapenemases by the OXA-48-producing strains. In this study, OXA-48 and NDM-1 co-production was presented in Providencia rettgeri. Two P.rettgeri strains that were resistant to all antimicrobials except colistin and tigecyclin, were isolated from two patients in the burn unit of our hospital, including one from the urine sample of a 68 years female in April 2017, and the other from a burn wound swab of a 35 years old male, in November 2017. Minimal inhibitory concentrations (MICs) of the isolates for imipenem and meropenem were measured as >= 32 mu g/ml; and for colistin and tigecyclin were 1 ve 0.5 mu g/ml, respectively. Multiplex PCR analysis showed that both strains were carrying bla(oxA-48 )and bla(NDM-1 )carbapenemases, and bla(TEM) extended spectrum beta-lactamase genes. By using DNA sequence analysis, the TEM gene was typed as bla(TEM-1). The Pulsed Field Gel Electrophoresis (PFGE) analysis indicated that these two strains which were consecutively isolated from two different patients in a single unit within about seven months were genetically indistinguishable. No significant data that could explain the spread of these isolates was obtained from our retrospective analysis of the medical records including the results of environmental surveillance cultures, and patients' history. Nevertheless, hospital infection control committee enforced the infection control measures in that unit, and no further isolation was observed within three months period following the last isolation, neither from environmental nor from clinical samples. With this study, it was emphasized that the co-production of OXA-48 and NDM-1 carbapenemases which was reported from only three Enterobacteriaceae species up to date was ongoing for spreading to other species by using horizontal route, and also showing a potential to be a growing problem in the hospitals, by clonal expansion (vertical route). Effectively using of the molecular epidemiological methods will provide useful data to better understand the transmission dynamics of such rare, but problematic species in hospitals.