A Longitudinal Study of Prevalence, Antibiotic Resistance and Strain Types of Campylobacter Isolates in Turkeys

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Title: A Longitudinal Study of Prevalence, Antibiotic Resistance and Strain Types of Campylobacter Isolates in Turkeys
Author: Joshi, Shilpa
Advisors: Dr. Fred Breidt, Committee Member
Dr. James Brown, Committee Member
Dr. Brian Sheldon, Committee Member
Dr. Sophia Kathariou, Committee Chair
Abstract: Campylobacter has been recognized as a leading bacterial cause of human gastroenteritis in the United States, with ca. 2.4 million cases each year. Epidemiological data suggest that contaminated products of animal origin, especially raw poultry contributes significantly to campylobacteriosis with C. jejuni being the most prevalent species accounting for 90% of the infections. Research has been primarily focused on Salmonella in broilers and little information is available on colonization of Campylobacter in turkeys. Due to the growing popularity of turkey as a food commodity in the US, and North Carolina being a leading turkey producing state, it is important to focus attention on this zoonotic pathogen and its sources of colonization in turkey flocks. In an effort to address these issues, a longitudinal study was conducted on the prevalence, antibiotic resistance and strain types of Campylobacter isolates obtained from twelve turkey farms in Eastern North Carolina. Fecal samples were collected at 5, 7, 10, 13 and >13 weeks of age during the lifetime of the flock. Samples were tested for resistance to antibiotics following the National Committee for Clinical Laboratory Standards (NCCLS) guidelines and genotyping methods, including fla typing and Pulsed Field Gel Electrophoresis (PFGE) were employed to investigate the genetic diversity among these isolates. Farms involved in the study were chosen based on prevalence data for C. jejuni, which suggested high prevalence of this organism at different time points during the lifetime of the flock. The first study focused on C. jejuni isolates in a brooder/grow-out facility. It was of particular interest due to the trends seen in resistance of brooder isolates to fluoroquinolones (FQs) and persistence of a particular genotype in the brooder and the grow-outs. 92.3% of the C. jejuni isolates in house #1 (brooder) were sensitive to FQs while 50% of the isolates in house #2 (brooder) were resistant to FQs. TAK and TAKQ were the two main categories of antibiotic resistance seen in house #1 and #2 respectively. Genotyping showed the presence of one predominant fla and SmaI type in both the houses with a small fraction of isolates from the grow-out flocks having this strain type. These findings suggested that isolates of the same genotype may differ in FQ resistance and that diversity can be observed even within the same farm. The objectives of the second study were to determine the prevalence of Campylobacter in twelve turkey farms and antibiotic resistance patterns among the isolates in these farms. Even though our focus was on C. jejuni isolated from these farms, information about C. coli isolates was also obtained. Resistance of Campylobacter isolates to clinically relevant antibiotics such as erythromycin and FQs was substantially high with multi-resistance more commonly observed in C. coli. Almost 100% of the isolates were resistant to tetracycline and ampicillin. A mean of 28.2% C. jejuni isolates and mean of 63.4% C. coli isolates had a FQ MIC of >160 μg/ml. The third study evaluated the genetic diversity among Campylobacter isolates and determined whether particular strain types persist throughout the lifetime of the flock. It was found that 3 of the 8 brooder/grow-out pairs showed the presence of one persistent fla and PFGE type with certain strain types being found at more than one sampling timepoint. Genetic diversity was seen with 3-11 fla and 2-10 PFGE types in each flock. In 3 of the 6 brooder/grow-out pairs, C. jejuni strain types from the brooders were found in grow-outs. Genotyping techniques were effective in subtyping the isolates with a mean of 14.8 isolates per flock being subtyped (Total N=296). In conclusion, data collected in such research studies will contribute to further understand Campylobacter colonization in turkeys, especially in regards to elucidating prevalence, antibiotic resistance, and population diversity patterns of the pathogen in commercial turkey farms.
Date: 2005-11-21
Degree: MS
Discipline: Food Science
URI: http://www.lib.ncsu.edu/resolver/1840.16/160


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