Genotype-phenotype correlation in multiresistant Escherichia coli and Klebsiella pneumoniae strains isolated in Western Romania

OBJECTIVE: Bacterial multidrug- resistance (MDR) to antimicrobials has become an important public health issue all over the world and it involves both hospital and commu - nity-acquired strains. MATERIALS AND METHODS: A number of 75 Escherichia coli and 77 Klebsiella pneumoniae (K.) strains identified in biological samples col - lected from community (CA) and hospital-ac - quired (HA) infections were found to be resistant to the third generation cephalosporins. Of these, 93 MDR strains were subjected to microarray analysis to detect the expression of 31 antimi - crobial resistance genes. RESULTS: We found that all HA extended-spec - trum β-lactamase (ESBL) producing E. coli strains had at least one resistance gene to third generation cephalosporins, while in 54% of all CA strains genetic substrates justifying their an - tibiotic resistance were identified. Almost 81% of HA-ESBL (Extended-Spectrum β Lactamase) K. pneumoniae strains had at least one resistance gene to third generation cephalosporins, while in only 6% of the CA strains a similar genotype was identified. In the HA group, the blaCTX-M-15 genotype proved to be most frequent in mul - tidrug-resistant E. coli strains and second most frequent (after ampC ) in K. pneumoniae , while in the CA group, this genotype was the fourth most frequent in ESBL E. col i(after ampC , sul1 , tet(R )). CONCLUSIONS: Overall, in 67% of all ESBL producing Enterobacteriaceae strains a genetic substrate justifying the resistance to beta-lac - tam antibiotics was identified; most of the re - maining 33.33% strains were CA with a predomi - nance of K. pneumoniae , in which a different an - tibiotic resistance genetic substrate (outside the detection limit of the kit used in this study) might have been involved.