Abstract

Background/Aim: Extended spectrum β-lactamases (ESBL) in Escherichia coli constitutes one of the major threads to modern medicine, and the increasing pollution with quaternary ammonium compounds (QACs) has been suspected to contribute to the spread of ESBL producing bacteria. The present report aimed to investigate the co-resistance to QACs in E. coli isolated at Uppsala University Hospital, Sweden.
Materials/Methods: Co-resistance in E. coli with production of ESBL enzymes of the type blaCTX-M (n = 23) were compared to E. coli producing AmpC type ESBL enzymes blaCMY and blaDHA (n = 27). All isolates were tested for susceptibility to antibiotics and QACs, and high-quality whole genome sequences were analyzed for resistance determinants.
Results: The plasmid-borne small multidrug resistance efflux pump sugE(p) was solely present in blaCMY producing E. coli (n = 9), within the same genetic environment blaCMY – blc – sugE(p). Other small multidrug efflux pumps were found without association for ESBL-types: emrE (n = 5) and the truncated qacE1 (n = 18).
Conclusions: Co-resistance of ESBL enzymes and small multidrug resistance efflux pumps in E. coli was common, and might indicate that other substances than antibiotics contribute to the spread and emergence of antibiotic resistance.

Key words: Biocides, ESBL, Escherichia coli, quaternary ammonium compounds