ST405 NDM-5 Producing Escherichia coli in Northern Italy: The First Two Clinical Cases

Background: NDM positive bacteria are now on the top list of carbapenemase producers in some European countries. Dissemination predominantly involves transfer of the blaNDM-1 gene, within bacteria resistant to nearly all antibiotics. NDM-1 and -4 have been rarely reported in Italy. Methods: Three MDR E. coli were recovered, from rectal swab/wound drainage samples of a 60-years-old man and a blood sample of 72-years-old oncological woman. The patients were admitted on March and December 2015 respectively at the surgical unit of Desenzano Hospital, Italy. Although the first patient reported a history of vacation in Thailand, the second one was previously admitted to an Hospital in Verona, where a rectal colonization by a carbapenemase positive strain was ascertained. Identification and antibiotic-susceptibilities were obtained using Autoscan4 System (Beckman Coulter). Phenotypic tests (RoscoDiagnostica), PCR and sequencing for blaNDM/CTX-M/ArmA/CMY-type genes were performed. PFGE, MLST and PBRT KIT replicon typing have been assessed.Results: The three E. coli isolates resulted resistant to β-lactams, aminoglycosides, fluoroquinolones, nitrofurantoin, sulfonamides and colistin, retaining susceptibility to tigecycline and fosfomycin (EUCAST breakpoints). Phenotypic test results were confirmed for all the isolates by PCR and sequencing, the latter identifying blaNDM-5/TEM-1/CMY-42 genes. Neither armA nor blaCTX-M-type genes were found. The strains were identical by PFGE. MLST revealed an ST405 lineage; replicon typing indicated IncI1; IncFII groups.Conclusions: This is the first report in Italy of three NDM-5/TEM-1/CMY-42 positive ST405 E. coli isolates. NDM-5 E. coli have already been found in few countries, but never linked to the ST405. The hypothesis of a foreign origin of the first strain is reinforced by the fact that no other similar MDR E. coli strains have been isolated in the same period at Desenzano Hospital, but the identification of a second strain from a different patient could be related to the presence of an ST405 hot spot area in Italy.