title: Antimicrobial activity of antibiotics in combination with natural flavonoids against clinical extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae.
abstract: Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated class A enzymes commonly found in the family Enterobacteriaceae, mainly in Klebsiella pneumoniae. Flavonoids have also been reported to possess antimicrobial activity. In this study, the in vitro activities of 18 antibiotics and 12 flavonoids against 20 ESBL-producing K. pneumoniae isolates were evaluated. All of these isolates were susceptible to imipenem and cefmetazole, but were resistant to ampicillin, ampicillin/sulbactam, aztreonam, cefazolin, cefoperazone, cefotaxime, ceftazidime, ceftriaxone, cefuroxime, piperacillin and ticarcillin. Susceptibilities to amikacin, amoxicillin/clavulanate, cefoxitin, ciprofloxacin and gentamicin were variable. Myricetin, a flavonol, inhibited ESBL-producing K. pneumoniae isolates at a high minimum inhibitory concentration (MIC) (MIC(90) value 256 mg/mL), but exhibited significant synergic activity against ESBL-producing K. pneumoniae in separate combination with amoxicillin/clavulanate, ampicillin/sulbactam and cefoxitin. Because of the low-toxic nature of flavonoids, the combination of antibiotics and flavonoids is a potential new strategy for developing therapies for infections caused by ESBL-producing bacteria in the future.
authors.affiliation: Department of Internal Medicine, Ho-Ping Branch, Taipei City Hospital, Taipei 100, Taiwan.
authors.forename: Rong-Dih
authors.initials: RD
authors.lastname: Lin
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Chin
authors.forename: Mei-Hsien
authors.initials: MH
authors.lastname: Lee
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D004359:Drug Therapy, Combination; D005419:Flavonoids / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D010946:Plants, Medicinal; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D005419:Flavonoids; D010936:Plant Extracts; D001618:beta-Lactamases