Interplay of efflux, impermeability, and AmpC activity contributes to cefuroxime resistance in clinical, non-ESBL-producing isolates of Escherichia coli.
Cefuroxime resistance in Escherichia coli strains susceptible to extended-spectrum cephalosporins is not uncommon, but the resistance mechanisms have so far not been elucidated. Therefore, 14 clinical non-extended-spectrum beta-lactamase isolates of E. coli were examined, 11 of which were cefuroxime resistant. Quantitative RT-PCR was used to examine the transcription levels of the genes acrA (encoding AcrA, part of the AcrAB-TolC efflux pump system) and ompF (encoding the porin OmpF). Isoelectric focusing was used for detection of beta-lactamases, and a spectrophotometric assay was used to measure AmpC activity. Among the 11 cefuroxime-resistant isolates, 7 had increased acrA transcription (from 2.4 to 38 times the ATCC strain), 3 isolates had very low ompF transcription levels (<or=0.01 times the ATCC strain), and 2 isolates showed increased AmpC activity (confirmed by 3-aminophenylboronic acid inhibition). We suggest that efflux, impermeability, and increased AmpC activity all contribute to cefuroxime resistance in E. coli.
Källman
Owe
O
Clinical Microbiology, MTC, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden. owe.kallman@karolinska.se
Giske
Christian G
CG
Samuelsen
Ørjan
Ø
Wretlind
Bengt
B
Kalin
Mats
M
Olsson-Liljequist
Barbro
B
D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001897:Boronic Acids / Q000494:pharmacology; D002444:Cefuroxime / Q000493:pharmacokinetics*; D002463:Cell Membrane Permeability; D024881:Drug Resistance, Bacterial; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D008074:Lipoproteins / Q000096:biosynthesis / Q000235:genetics; D026901:Membrane Transport Proteins / Q000096:biosynthesis / Q000235:genetics; D008826:Microbial Sensitivity Tests; D018272:Porins / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000378:metabolism*
C083497:AcrA protein, E coli; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001897:Boronic Acids; D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; D008074:Lipoproteins; D026901:Membrane Transport Proteins; C109237:OmpF protein; D018272:Porins; D065093:beta-Lactamase Inhibitors; C028592:3-aminobenzeneboronic acid; C048795:AmpC beta-lactamases; D001618:beta-Lactamases; D002444:Cefuroxime