Ghassan M. Matar
American University of Beirut and Medical Center, Lebanon
Title: Assessment of MIC levels in carbapenem resistant Enterobacteriaceae in relation to carbapenemases, ESBLs and bacterial intrinsic factors
Biography
Biography: Ghassan M. Matar
Abstract
Background - The surge of multidrug-resistant Enterobacteriaceae increased dependence on carbapenems resulting in the rise of carbapenem resistant Enterobacteriaceae (CRE). This study aimed at correlating carbapenem resistance and outer membrane proteins (OMPs) encoding genes to MIC levels among clinical isolates of Escherichia coli and Klebsiella pneumoniae. Methods- The MICs of E. coli (n= 76) and K. pneumoniae (n=54), collected between July 2008 and July 2014, were determined against ertapenem (ERT), imipenem (IMP) and meropenem (MER). PCR was performed on all 130 isolates to amplify the resistance and OMPs encoding genes: bla OXA-48, blaNDM-1, blaCTXM-15, OMPC and OMPF. Electroporation, efflux pump and PFGE were performed on selected isolates harboring the resistance and OMPs encoding genes. Results- The prevalence of resistance genes encoding for bla OXA-48, blaNDM-1or blaCTXM-15 among E. coli isolates were 36%, 12% and 80%, respectively, while among K. pneumoniae were 37%, 28%, and 72%, respectively. K. pneumoniae isolates positive for any of the three resistance encoding genes: bla OXA-48, blaNDM-1 and blaCTXM-15 had an MIC90 > 32µg/ml against ERT, IPM and MER. While in E. coli isolates harboring any of the three genes, there was a variation in the MIC90 values. Porin impermeabilities due to loss of OMPC and OMPF genes in K. pneumoniae, enhanced MIC90 values in these clinical isolates. Electroporation confirmed the sole role of the resistance encoding genes in conferring carbapenem resistance. Conclusion- Levels of MIC in CRE may largely depend on the type of resistance encoding genes, and porin loss. Such information can be helpful for antimicrobial treatment and stewardship