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The effects of different enrofloxacin dosages on clinical efficacy and resistance development in chickens experimentally infected with Salmonella Typhimurium.

ABSTRACT: To investigate the optimal dosage which can improve clinical efficacy and minimize resistance, pharmacokinetics/pharmacodynamics model of enrofloxacin was established. Effect of enrofloxacin treatments on clearance of Salmonella in experimentally infected chickens and simultaneously resistance selection in Salmonella and coliforms were evaluated in three treatment groups (100, PK/PD designed dosage of 4, 0.1?mg/kg b.w.) and a control group. Treatment duration was three rounds of 7-day treatment alternated with 7-day withdrawal. Results showed that 100?mg/kg b.w. of enrofloxacin completely eradicated Salmonella, but resistant coliforms (4.0-60.8%) were selected from the end of the second round's withdrawal period till the end of the experiment (days 28-42). PK/PD based dosage (4?mg/kg b.w.) effectively reduced Salmonella for the first treatment duration. However upon cessation of medication, Salmonella repopulated chickens and persisted till the end with reduced susceptibility (MIC_CIP?=?0.03-0.25?mg/L). Low frequency (5-9.5%) of resistant coliforms was selected (days 39-42). Enrofloxacin at dosage of 0.1?mg/kg b.w. was not able to eliminate Salmonella and selected coliforms with slight decreased susceptibility (MIC_ENR?=?0.25?mg/L). In conclusion, short time treatment (7 days) of enrofloxacin at high dosage (100?mg/kg b.w.) could be effective in treating Salmonella infection while minimizing resistance selection in both Salmonella and coliforms.

SUBMITTER: Li J

PROVIDER: S-EPMC5601478 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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The effects of different enrofloxacin dosages on clinical efficacy and resistance development in chickens experimentally infected with Salmonella Typhimurium.

Li Jun J Hao Haihong H Cheng Guyue G Wang Xu X Ahmed Saeed S Shabbir Muhammad Abu Bakr MAB Liu Zhenli Z Dai Menghong M Yuan Zonghui Z

Scientific reports 20170915 1

To investigate the optimal dosage which can improve clinical efficacy and minimize resistance, pharmacokinetics/pharmacodynamics model of enrofloxacin was established. Effect of enrofloxacin treatments on clearance of Salmonella in experimentally infected chickens and simultaneously resistance selection in Salmonella and coliforms were evaluated in three treatment groups (100, PK/PD designed dosage of 4, 0.1 mg/kg b.w.) and a control group. Treatment duration was three rounds of 7-day treatment ...[more]

PMID: 28916830

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Project description:In recent years, pathogenic strains of Enterococcus cecorum (EC) have emerged as a causing agent of septicemia and skeletal infection in broiler chickens with a high economic impact worldwide. Although research has been conducted, many aspects of the pathogenesis of the EC-associated disease are still unknown. In the present study, an experimental infection model was established in broiler chickens. Two different EC strains (EC14 and EC15) were compared in two different concentrations of each strain (2 × 106 and 2 × 108 colony-forming units per milliliter (CFU/mL)) after oral infection of one-day-old chicks. Clinical signs and gross lesions of the EC-associated disease were monitored in the following seven weeks. Although both EC strains were originally isolated from clinical disease outbreaks and had a high embryonic lethality, only EC14 successfully induced the typical course of the EC-associated disease with characteristic clinical signs and gross lesions. In total, 23% of the birds in the two EC14-groups were EC-positive in extraintestinal organs on culture, and no differences were found between the two infectious doses. EC14 was frequently detected via real-time PCR in the free thoracic vertebra (FTV) and femoral heads without any detectable gross lesions. The number of EC positive spleens from infected broilers was comparable using bacterial isolation and a specific real-time PCR. Interestingly, EC15 was not detected in extraintestinal organs, although birds in the EC15 groups were colonized by EC in the ceca after experimental infection. The present study represents first proof that virulence differs among EC strains in experimentally infected chickens, and emphasizes the need to further characterize virulence factors and pathogenic mechanisms of EC. The strain EC14 at a dose of 106 CFU is suitable for reproduction of the EC-associated disease. The experimental infection model reported here provides the basis for further research on the EC pathogenesis and possible prevention and intervention strategies.

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Project description:BackgroundSalmonella Enteritidis (SE) is one of the major causes of human foodborne intoxication resulting from consumption of contaminated poultry products. Genetic selection of animals that are more resistant to Salmonella carriage and modulation of the gut microbiota are two promising ways to decrease individual Salmonella carriage. The aims of this study were to identify the main genetic and microbial factors that control the level of Salmonella carriage in chickens (Gallus gallus) under controlled experimental conditions. Two-hundred and forty animals from the White Leghorn inbred lines N and 61 were infected by SE at 7 days of age. After infection, animals were kept in isolators to reduce recontamination of birds by Salmonella. Caecal contents were sampled at 12 days post-infection and used for DNA extraction. Microbiota DNA was used to measure individual counts of SE by digital PCR and to determine the bacterial taxonomic composition, using a 16S rRNA gene high-throughput sequencing approach.ResultsOur results confirmed that the N line is more resistant to Salmonella carriage than the 61 line, and that intra-line variability is higher for the 61 line. Furthermore, the 16S analysis showed strong significant differences in microbiota taxonomic composition between the two lines. Among the 617 operational taxonomic units (OTU) observed, more than 390 were differentially abundant between the two lines. Furthermore, within the 61 line, we found a difference in the microbiota taxonomic composition between the high and low Salmonella carriers, with 39 differentially abundant OTU. Using metagenome functional prediction based on 16S data, several metabolic pathways that are potentially associated to microbiota taxonomic differences (e.g. short chain fatty acids pathways) were identified between high and low carriers.ConclusionsOverall, our findings demonstrate that the caecal microbiota composition differs between genetic lines of chickens. This could be one of the reasons why the investigated lines differed in Salmonella carriage levels under experimental infection conditions.

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Dataset Information

The effects of different enrofloxacin dosages on clinical efficacy and resistance development in chickens experimentally infected with Salmonella Typhimurium.

Publications

The effects of different enrofloxacin dosages on clinical efficacy and resistance development in chickens experimentally infected with Salmonella Typhimurium.

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