Selecting for development of fluoroquinolone resistance in a Campylobacter jejuni strain 81116 in chickens using various enrofloxacin treatment protocols

Abstract

Aims: To determine the effect of various enrofloxacin dose regimes on the colonization and selection of resistance in Campylobacter jejuni strain 81116P in experimentally colonized chickens. Methods and Results: Two experiments were undertaken, in which 14‐day‐old chickens were colonized with 1 × 107–1 × 109 CFU g−1Camp. jejuni strain 81116P and then treated with enrofloxacin at 12–500 ppm in drinking water for various times. Caecal colonization levels were determined at various time‐points after start‐of‐treatment, and the susceptibility of recovered isolates to ciprofloxacin was monitored. Resistance was indicated by growth on agar containing 4 μg ml−1 ciprofloxacin, MICs of 16 μg ml−1 and the Thr86Ile mutation in gyrA. Enrofloxacin at doses of 12–250 ppm reduced Camp. jejuni colonization over the first 48–72 h after start‐of‐treatment. The degree of reduction in colonization was dose, but not treatment time, dependent. In all cases, maximal colonization was re‐established within 4–6 days. Fluoroquinolone‐resistant organisms were recoverable within 48 h of start‐of‐treatment; after a further 24 h all recovered isolates were resistant. In contrast, a dose of 500 ppm enrofloxacin reduced colonization to undetectable levels within 48 h, and the treated birds remained Campylobacter negative throughout the remaining experimental period. By high pressure liquid chromatography, for all doses, the maximum concentrations of enrofloxacin and ciprofloxacin in the caecal contents were detected at the point of treatment completion. Thereafter, levels declined to undetectable by 7 days post‐treatment withdrawal. Conclusions: In a model using chickens maximally colonized with Camp. jejuni 81116P, treatment with enrofloxacin, at doses of 12–250 ppm in drinking water, enables the selection, and clonal expansion, of fluoroquinolone‐resistant organisms. However, this is preventable by treatment with 500 ppm of enrofloxacin. Significance and impact of the study: Treatment of chickens with enrofloxacin selects for resistance in Camp. jejuni in highly pre‐colonized birds. However, a dose of 500 ppm enrofloxacin prevented the selection of resistant campylobacters.

Antibiotic Resistance in Campylobacter spp. Isolated from Broiler Chicken Meat and Human Patients in Estonia

“…1831/2003, antimicrobials as growth promoters in food animal production have been banned since 2006 [ 30 ]. Antimicrobials are still used intensively in poultry for therapy and infection prophylaxis, which has caused the spread of resistant strains to humans [ 31 , 32 ]. However, some countries are showing positive trends, for example, antimicrobial use in poultry in Scandinavian countries is generally low.…”

Antimicrobial Resistance and Genotypic Diversity of Campylobacter Isolated from Pigs, Dairy, and Beef Cattle in Tanzania

“…However, enrofloxacin is licensed for therapeutic use in poultry against colibacilliosis, pasteurellosis, and mycoplasmosis (Mubito et al, 2014 ), which may result in the selection of resistance of Campylobacter to fluoroquinolones. These resistant isolates might be transmitted to other food animals that are in the proximity of poultry via a variety of vehicles, including common farm workers and/or flies or other critters (McDermott et al, 2002 ; Van Boven et al, 2003 ; Stapleton et al, 2010 ). Furthermore, it is possible that Cip resistant isolates might have originated from humans where this antimicrobial is commonly used.…”

Scientific Opinion onCampylobacterin broiler meat production: control options and performance objectives and/or targets at different stages of the food chain

“…However, the treatment of flocks with certain antibiotics, for health reasons such as bacterial respiratory infections, during rearing, can affect the dynamics of colonization in birds already colonized by Campylobacter (Stapleton et al, 2010). However, the treatment of flocks with certain antibiotics, for health reasons such as bacterial respiratory infections, during rearing, can affect the dynamics of colonization in birds already colonized by Campylobacter (Stapleton et al, 2010).…”