Amoxicillin therapy of poultry flocks: effect upon the selection of amoxicillin-resistant commensal Campylobacter spp.

Background: The aim of this study was to investigate the effect of amoxicillin therapy of poultry flocks upon the persistence of commensal Campylobacter spp. and the incidence of antibiotic resistance.

Methods: Four poultry flocks naturally colonized with Campylobacter were treated with amoxicillin and monitored before, during and up to 4 weeks post-treatment.

Beta-lactamase-mediated beta-lactam resistance in Campylobacter species: prevalence of Cj0299 (bla OXA-61) and evidence for a novel beta-Lactamase in C. jejuni.

Fifty-two percent of 1,288 poultry isolates of campylobacters were ampicillin resistant, and resistance was more common among Campylobacter coli isolates (67.4%) than among Campylobacter jejuni isolates (47.5%).

Incidence and mechanism of ciprofloxacin resistance in Campylobacter spp. isolated from commercial poultry flocks in the United Kingdom before, during, and after fluoroquinolone treatment.

Five commercial broiler flocks were treated with a fluoroquinolone for a clinically relevant infection. Fresh feces from individual chickens and environmental samples were cultured for campylobacters before, during, and weekly posttreatment until slaughter. Both Campylobacter jejuni and C.

Prevalence and subtypes of ciprofloxacin-resistant Campylobacter spp. in commercial poultry flocks before, during, and after treatment with fluoroquinolones.

Five commercial broiler chicken flocks were treated with either difloxacin or enrofloxacin for a clinically relevant infection, as instructed by a veterinarian. Campylobacters were isolated from individual fecal samples and from samples associated with the broiler environment before, during, and after treatment. Ciprofloxacin-resistant Campylobacter jejuni and/or C.

Selection of moxifloxacin-resistant Staphylococcus aureus compared with five other fluoroquinolones.

Fluoroquinolone-resistant mutants were selected from Staphylococcus aureus NCTC 8532 (F77), and two GrlA mutants of F77 (F193 and F194) with moxifloxacin, sparfloxacin, ofloxacin, grepafloxacin, levofloxacin and trovafloxacin. For mutants selected from F77, moxifloxacin, grepafloxacin and sparfloxacin selected preferentially for mutations in gyrA (Glu-88-->Lys). Ofloxacin and trovafloxacin selected most commonly for mutations in grlA, conferring substitutions for Ser-80.

Fluoroquinolone resistance in Campylobacter species from man and animals: detection of mutations in topoisomerase genes.

Consecutive isolates of quinolone-resistant campylobacter isolated over a 5 year period (1990-1995) from the faeces of patients with enteritis in Plymouth, UK, were examined for the epidemiology of mutations in gyrA (n = 127). In addition, clinical isolates and poultry isolates from Germany, The Netherlands and other regions of the UK collected before 1995 were examined for mutations in the quinolone resistance-determining region of gyrA by single-stranded conformational polymorphism analysis and direct sequencing of a 270 bp fragment of PCR-generated DNA. The majority of isolates (173/208) carried a mutation at codon 86 in gyrA resulting in substitution of Ile for Thr; all of these were resistant to ciprofloxacin (MIC > or = 2 mg/L).