Carbapenem-resistant and : characterization of carbapenemase genes and E-test evaluation of colistin-based combinations.

BACKGROUND

Carbapenamase producing and are emerging worldwide limiting the use of carbapenems as effective and safe drugs.

PURPOSE

To characterize different carbapenemase genes carried by carbapenem-resistant (CR) and isolates and to evaluate the in vitro effect of some colistin-based combinations by E-test method in Zagazig University Hospitals ICU isolates.

METHODS

CR and isolated from the surgical intensive care unit (ICU) were tested for carbapenemase genes by polymerase chain reaction and the effect of colistin/meropenem and colistin/tigecycline combinations was evaluated by E-test.

RESULTS

Genes coding for OXA-23, NDM and GES were detected in 90, 66.7 and 50% of CR , respectively, while genes coding for VIM, GES, NDM and IMP were detected in 50, 40.9, 27.3 and 18.2% of CR , respectively. Colistin/tigecycline combination showed synergistic and additive effect in 20% and 60% of isolates, respectively, while colistin/meropenem combination showed synergistic and additive effect in 63.6% and 36.4% of , respectively.

CONCLUSION

Carbapenemase genes carriage accounts for high level carbapenem resistance in our isolates. Colistin/tigecycline and colistin/meropenem combinations can be considered for treatment of severe infections by CR and , respectively.