Emergence of OXA-48 carbapenemase-producing Enterobacter cloacae ST89 infection in Poland.

BACKGROUND

The utility of carbapenems, which are considered 'last-line' agents, is being diminished by the growing incidence of various resistance mechanisms in bacteria. We aimed to investigate the molecular mechanism of carbapenem resistance in Enterobacter cloacae recovered from a 76-year-old patient who had undergone coronary artery bypass grafting and repair of the mitral and tricuspid valves. Interestingly, the patient had no prior history of hospital admission abroad.

METHODS

The Carba-NP test II and synergy testing were performed to confirm carbapenemase activity. PCR was used to detect carbapenemase-encoding genes. Nucleotide and amino acid sequence analysis was performed to identify OXA-48 variants. Moreover, we performed multilocus sequence typing (MLST) of multidrug-resistant (MDR) E. cloacae.

RESULTS

We detected no significant increase in zone diameter around disks with inhibitors. However, the Carba-NP test II revealed carbapenemase activity in all isolates. All isolates showed the presence of the exact OXA-48 carbapenemase variant. Furthermore, MLST analysis revealed that the MDR E. cloacae isolates belonged to ST89.

CONCLUSIONS

We report a case of infection caused by a unique carbapenem-resistant E. cloacae ST89 producing OXA-48 carbapenemase. Interestingly, these pathogens developed resistance to other 'last-resort' agents, namely colistin and tigecycline. There is a crucial need for surveillance programs aimed at screening for carbapenemase-producing Gram-negative bacteria, especially in patients transferred from high-incidence areas.