Emergence of carbapenemase-producing Gram-negative bacteria in Saint Petersburg, Russia.

The emergence and spread of carbapenemase-producing Gram-negative bacteria represents a serious public health concern. Here we show that of 477 Gram-negative isolates collected from 18 hospitals between November 2011 and February 2013 in Saint Petersburg (Russia), minimum inhibitory concentrations (MICs) were greater than the European Committee on Antimicrobial Susceptibility Testing (EUCAST) epidemiological cut-off value of at least one carbapenem antibiotic in 101 isolates (21.2%). The bla(NDM-1) gene was detected by PCR in 17 Klebsiella pneumoniae and 1 Acinetobacter nosocomialis isolate. Multilocus sequence typing (MLST) revealed that all NDM-1-producing K. pneumoniae isolates belonged to sequence type 340 (ST340) and harboured genes encoding additional β-lactamases; presence of the bla(CTX-M-1-like) gene correlated with aztreonam resistance, whilst its absence correlated with susceptibility. The epidemiological situation in Saint Petersburg can be assessed as regional spread of NDM-1-producers. The bla(KPC-2) gene was detected in two K. pneumoniae isolates (ST258 and ST273) and one Enterobacter cloacae isolate. Two E. cloacae isolates harboured the bla(VIM-4) gene, and one K. pneumoniae (ST395) isolate harboured the bla(OXA-48) gene. In NDM-1-producers, MICs of biapenem were the lowest compared with those of other carbapenems. Most isolates were susceptible to tigecycline and polymyxin, except for one K. pneumoniae isolate that was found to be polymyxin-resistant and one E. cloacae isolate that was tigecycline-resistant. Only one patient with a urinary tract infection caused by KPC-2-producing K. pneumoniae had a history of travel abroad (Southeast Asia). Thus, there is an actual threat of the emergence of an alarming endemic situation with NDM-1-producers in Saint Petersburg.