Progress 09/15/04 to 09/14/08
Outputs
OUTPUTS: For the duration of the study, the antimicrobial usage information was attained for the six different animal populations studied. The purpose was to establish the extent of antimicrobial treatment for each study group and to determine if antimicrobial drug use affected the ability to recover resistant organisms. The livestock sampling was divided into three phases based on antibiotic usage to examine the effect of ceftiofur use on the microflora of the animal populations. Weekly ground meat samples of beef and pork were obtained from the system's slaughterhouse. This plant butchered the majority of the finished animals as well as the cull animals from throughout the system. A single 10 pound package of ground product was used to screen for the bacteria of interest. From each weekly 10 pound package, 10 subsamples were taken for microbiological analysis. Microbial analysis included E. coli with reduced susceptibility to ceftriaxone and Salmonella spp. For E. coli isolation, a 10 g fecal sample was aseptically mixed with 90 ml nutrient broth containing 4 microng/ml cefoxitin and incubated at 37oC for 18-24 hours. On the following day, each sample was plated on to a MacConkey agar plate containing 8 microng/ml ceftriaxone (Mac-cef) and incubated at 37oC for 18-24 hours. Isolated pink lactose-fermenting colonies were picked off of the Mac-cef plate and placed into Tryptophan broth at 37oC for 18-24 hours. Following the incubation, Kovac's reagent was added to the Tryptophan broth to confirm E. coli. Biotyping was performed on the E. coli isolates. It was thought the isolates could be grouped based on their ability to ferment six different types of sugars, D-raffinose, L-sorbose, L-rhamnose, sucrose, dulcitol, and 2-deoxy-D-ribose. Each E. coli isolate was grown on a MacConkey agar plate and 3 colonies were picked and placed into sterile distilled water. The diluted colonies were then plated in triplicate on a 96 well plate, with each well containing media with one of the six sugars. Each of the E. coli isolate's fermentation pattern was recorded, and the results were categorized dichotomously as either utilizing the sugar or not utilizing the sugar. PARTICIPANTS: Dr. Wittum is a professor at Ohio State University. Dr. Funk is on faculty at Michigan State University TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
During the study, 1637 of the 4101 (0.40) livestock samples and 9 of the 89 (0.10) ground meat samples furnished E. coli isolates. As for the Salmonella spp. results, 312 isolates came from the livestock samples (0.08), and 4 isolates came from the ground meat samples (0.04). Of the three livestock populations sampled, the beef cattle samples consistently contained the highest amount of E. coli isolates, and the dairy cattle samples furnished most of the Salmonella spp. isolates. The swine samples presented minimal amounts of both E. coli and Salmonella spp. isolates; however, of the fresh meat products cultured for these two bacterial groups of interest, the ground pork provided nearly all the isolates of both E. coli and Salmonella spp. Farm A had a known history of multidrug resistant Salmonella enterica serovar Newport. A total of 117 Salmonella isolates were collected from farm A, and when plated on a MacConkay agar plate containing 16 micronl/ml ceftriaxone, 88 of the 117 (0.75) isolates grew. All of the 88 Salmonella isolates that grew on the antibiotic plate reacted positively to the polyvalent antisera test. The growth on the plate and agglutination of the antisera test indicate the Salmonellas recovered could potentially be multidrug resistant Salmonella enterica serovar Newport. Resistance trends for the three animal groups during each phase were as follows: For both beef and dairy cattle, the period of time associated with the highest level of E. coli isolates recovered was during phase 2, which was the phase when ceftiofur products were withheld. Dissimilarly, the period of time associated with the lowest proportion of E. coli isolates recovered was phase 3 where ceftiofur products were introduced back into the animal populations. After looking at the biotyping results, there were 8 biotypes associated with the meat isolates. These meat biotypes were compared to the biotyping results from the animal isolates. Frequently, the animal biotyping patterns matched those from the meat isolates. Of the 1637 E. coli isolates recovered, 1577 (0.96) were biotyped. Microbial analysis included E. coli with reduced susceptibility to ceftriaxone and Salmonella spp. For E. coli isolation, a 10 g fecal sample was aseptically mixed with 90 ml nutrient broth containing 4 microng/ml cefoxitin and incubated at 37oC for 18-24 hours. On the following day, each sample was plated on to a MacConkey agar plate containing 8 microng/ml ceftriaxone (Mac-cef) and incubated at 37oC for 18-24 hours. Isolated pink lactose-fermenting colonies were picked off of the Mac-cef plate and placed into Tryptophan broth at 37oC for 18-24 hours. Following the incubation, Kovac's reagent was added to the Tryptophan broth to confirm E. coli.
Publications
- No publications reported this period
|