title: Restoring the selectivity of modified charcoal cefoperazone deoxycholate agar for the isolation of Campylobacter species using tazobactam, a β-lactamase inhibitor.
abstract: Extended spectrum β-lactamase (ESBL) producing Escherichia coli have emerged as a contaminant on modified charcoal cefoperazone deoxycholate agar (mCCDA) when attempting to selectively isolate Campylobacter spp. from poultry. E. coli are particularly problematic given their ability to grow under microaerophilic conditions and have been shown to outcompete Campylobacter species making Campylobacter detection or enumeration difficult. This paper recommends a novel method for restoring the selectivity of mCCDA using tazobactam, a β-lactamase inhibitor. The method significantly inhibited ESBL E. coli growth in spiked or naturally contaminated broiler caecal samples (p≤0.01) when compared to conventional mCCDA. This effect was seen at concentrations as low as 1mg/L tazobactam. TmCCDA(1) was found to inhibit up to 8 log10 CFU/mL of ESBL E. coli in mixed pure cultures and 7.5 log10 CFU/mL in caecal samples. Furthermore TmCCDA concentrations up to 10 mg/L had no statistically significant inhibitory effect (p≥0.05) on the recovery of a panel of 27 Campylobacter jejuni and 5 Campylobacter coli isolates when compared to conventional mCCDA. From this study it is suggested that tazobactam, which is more chemically stable than clavulanic acid or sulbactam, is more suitable for restoring the selectivity of mCCDA for the detection or isolation of campylobacters.
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, The Republic of Ireland.
authors.forename: Shaun
authors.initials: S
authors.lastname: Smith
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, The Republic of Ireland.
authors.forename: Joseph
authors.initials: J
authors.lastname: Meade
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, The Republic of Ireland.
authors.forename: Kevina
authors.initials: K
authors.lastname: McGill
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, The Republic of Ireland.
authors.forename: James
authors.initials: J
authors.lastname: Gibbons
authors.affiliation: Teagasc Food Research Centre, Ashtown, Dublin 15, The Republic of Ireland.
authors.forename: Declan
authors.initials: D
authors.lastname: Bolton
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, The Republic of Ireland. Electronic address: paul.whyte@ucd.ie.
authors.forename: Paul
authors.initials: P
authors.lastname: Whyte
mesh_terms: D000362:Agar / Q000737:chemistry; D000818:Animals; D001431:Bacteriological Techniques / Q000379:methods*; D002167:Campylobacter / Q000187:drug effects / Q000254:growth & development* / Q000302:isolation & purification; D002438:Cefoperazone / Q000494:pharmacology*; D002606:Charcoal / Q000737:chemistry / Q000494:pharmacology; D002645:Chickens / Q000382:microbiology; D003470:Culture Media / Q000737:chemistry; D003840:Deoxycholic Acid / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects*; D008460:Meat / Q000382:microbiology; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D015203:Reproducibility of Results; D000078142:Tazobactam; D065093:beta-Lactamase Inhibitors / Q000494:pharmacology*
chemical_list: D003470:Culture Media; D065093:beta-Lactamase Inhibitors; D003840:Deoxycholic Acid; D002606:Charcoal; D002438:Cefoperazone; D010397:Penicillanic Acid; D000362:Agar; D000078142:Tazobactam
keywords: Broiler caecal samples; Contamination; ESBL Escherichia coli; Selective isolation; Tazobactam