An ST405 NDM-4-producing Escherichia coli isolated from a Danish patient previously hospitalized in Vietnam.

Sir, Recently, a novel New Delhi metallo-b-lactamase (NDM) variant was described by Nordmann et al. This variant, designated NDM-4, differs from NDM-1 by a single amino substitution and an increased carbapenemase activity. NDM-4 was first detected in an Escherichia coli isolated from a urinary sample from a patient previously hospitalized in India. A second finding of the NDM-4 variant was reported in an E. coli rectal isolate from a patient transferred from Cameroon to France. This patient reported no previous travel to India. Here, we describe the first NDM-4-producing E. coli isolate in Denmark. The isolatewasobtainedfromamalepatient inhis50stransferred from Vietnam to Denmark. The patient was hospitalized in two Vietnamese hospitals in late 2012 before being transferred to Aalborg University Hospital, Denmark. Nasal, throat and perineal swabs were obtained for routine screening for multiresistant bacteria (extended-spectrum b-lactamaseand carbapenemase-producing Gram-negative bacteria, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus spp.). A carbapenemresistant E. coli from the perineal swab was detected. Consequently, the patient stayed in isolation during the entire hospital stay. The isolate was sent to Statens Serum Institut and tested for antimicrobial susceptibility to 27 antimicrobial agents by microbroth dilution (Sensititre, Trek Diagnostics System, East Grinstead, UK) as devised by the CLSI, with the exception of tigecycline and ertapenem, which were tested using MIC Test Strips (Liofilchem, Roseto degli Abruzzi, Italy) (Table 1). E. coli ATCC 25922 was used for quality control. The MIC results were interpreted using CLSI guidelines. The E. coli isolate was resistant to all b-lactam antimicrobial agents tested, including carbapenems (MICs of imipenem and ertapenem were .16 and .32 mg/L, respectively) (Table 1). Additionally, the isolate was resistant to gentamicin and fluoroquinolones, but remained susceptible to neomycin, colistin, sulfamethoxazole, trimethoprim and tigecycline. The resistance profile of the NDM-4 E. coli was similar to that of the NDM-4 isolates from India and Cameroon. PCR and sequencing were performed in search of different carbapenemase and extended-spectrum b-lactamase genes. Results showed that the E. coli isolate harboured the blaNDM-4, blaCTX-M-15 and blaTEM-1 genes. The isolate was PCR negative for the 16S rRNA methylase genes armA and rmtC conferring high-level resistance to aminoglycosides. The bleMBL gene, a novel gene reported to encode a bleomycin resistance protein coexpressed with the blaNDM-1 gene, was also detected using PCR. 7 Bleomycin is a glycopeptide antibiotic used as an anticancer agent to induce DNA strand breaks. It has been speculated that bleomycin chemotherapy may drive the emergence of NDM producers; even so, the patient had no history of such treatment. However, during the hospital stay in Vietnam the patient was treated with cefoperazone+ sulbactam, which may have contributed to the selection of the NDM-4-producing E. coli later isolated. Interestingly, blaNDM-1producing E. coli and Klebsiella pneumoniae have previously been reported from two Vietnamese surgical patients without history of travel outside Vietnam and as well as from two sites (3 km apart) in the Kim Nguu river running through Hanoi. The reservoir of such bacteria may not be limited to the hospital environment. To investigate the mobility of blaNDM-4, conjugation experiments were carried out in Luria–Bertani (LB) broth with streptomycinresistantE.coli MG1655astherecipient, asdescribed previously. Transconjugants were selected on LB agar plates supplemented with streptomycin (50 mg/L) and ertapenem (4 mg/L). PCR amplification and sequence analysis confirmed successful transfer of Table 1. Antimicrobial resistance profile of an ST405 blaNDM-4-producing E. coli isolated from a Danish patient and the blaNDM-4-positive transconjugant E. coli MG1655