Biomedical subjects

E B Shotts

Publications and source records attributed to E B Shotts.

79 records · Page 5Linked to original sources

PubMedDate not supplied

Inhibition of Salmonella typhimurium in the chicken intestinal tract by a transformed avirulent avian Escherichia coli.

An avirulent, wild-type avian Escherichia coli (E. coli Av) was electrotransformed with a plasmid coding for the production of microcin 24 (pGOB18) and was designated E. coli AvGOB18. The transformant inhibited the growth of seven serotypes of Salmonella commonly associated with colonization and contamination of poultry products and seven strains of E. coli O157:H7 in the in vitro colicin/microcin assay. The transformant did not inhibit the replication of multiple isolates of Listeria monocytogenes or Campylobacter jejuni in similar assays. The transformant is nonconjugative, indicating that the plasmid would not be transmitted to other intestinal microflora in the environment. The transformant also survived in sterile tap and deionized water incubated at 25 C and 37 C in the laboratory for 30 days and was recovered from drinkers and birds in in vivo floor pen studies. In in vivo studies, E. coli AvGOB18 did not colonize the intestinal tract of broiler chicks when given as a single or multiple dose and did not reduce the Salmonella load in the broilers. But Salmonella typhimurium was reduced significantly in the intestinal tracts of broiler chickens when E. coli AvGOB18 was administered continually in the water supply.

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PubMedDate not supplied

A growth medium for the production of a bacterin for immunization against infectious coryza.

A serum-free modified Casman broth medium was developed to grow Haemophilus gallinarum to titers of 10-8 organisms per ml. Formalin-inactivated bacterins prepared form the broth culture were used to immunize chickens. A single dose of bacterin containing adjuvant protected 6 of 7 chickens against a homologous challenge 4 weeks postvaccination. A second dose given 3 weeks after the first offered no better protection than a single dose.

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PubMedDate not supplied

Effect of feeding selected short-chain fatty acids on the in vivo attachment of Salmonella typhimurium in chick ceca.

Two groups of 20 chicks each were fed 1% fatty acid continuously starting at 1 day of age, while a control group of 20 chicks received unsupplemented feed. At 2 days of age, chicks were inoculated orally with 1 ml of Salmonella typhimurium (1 x 10(6) colony-forming units/ml). Ceca were obtained from six chicks of each group at 7, 14, and 21 days of age. At 14 days of age, formic and propionic acids had statistically reduced Salmonella recovery by 2.56 logs and 3.09 logs, respectively, compared with controls. At 21 days of age, both test groups showed significant reductions of approximately 3.6 logs compared with controls. There were no statistical differences in body weights among the groups at 21 days of age.

Animal Feed↗

PubMedDate not supplied

Comparison of a quantitative microtiter method, a quantitative automated method, and the plate-count method for determining microbial complement resistance.

A quantitative microtiter method for determining the degree of complement resistance or sensitivity of microorganisms is described. The microtiter method is compared with a quantitative automated system and the standard plate-count technique. Data were accumulated from 30 avian Escherichia coli isolates incubated at 35 C with either chicken plasma or heat-inactivated chicken plasma. Analysis of data generated by the automated system and plate-count techniques resulted in a classification of the microorganisms into three groups: those sensitive to the action of complement; those of intermediate sensitivity to the action of complement; and those resistant to the action of complement. Although the three methods studied did not agree absolutely, there were statistically significant correlations among them.

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PubMedDate not supplied

Effect of feeding selected carbohydrates on the in vivo attachment of Salmonella typhimurium in chick ceca.

Two-day-old chicks were orally inoculated with 1 ml of Salmonella typhimurium (10(5) colony-forming units/ml) and divided into four groups. Three groups were fed 2.5% carbohydrates starting on day 1 (arabinose, galactose, and lactose), while the fourth group served as the control. Ceca were obtained from each group at 7, 14, and 21 days. At the end of 14 days, all three carbohydrates statistically reduced Salmonella recovery. However, lactose failed to reduce recovery between day 14 and day 21. Arabinose and galactose continued to show significant reductions of recovery through 21 days. No statistical difference was found between Salmonella recovery from whole ceca (with cecal material) and inverted ceca (washed free of cecal material).

Animal Feed↗

PubMedDate not supplied

Effect of short-chain fatty acids on the growth of Salmonella typhimurium in an in vitro system.

Previous studies have revealed a reduction of cecal Salmonella carriage from feeding either carbohydrate or short-chain fatty acids (SCFAs). This in vitro study presents a profile of the relative SCFA content of the ceca when chicks are fed an unmedicated diet with 2.5% carbohydrate. Subsequent incorporation of these acids into culture medium was used to demonstrate their antagonistic activity toward in vitro growth of Salmonella typhimurium. Commonly found concentrations of SCFAs based upon the above findings reduced in vitro Salmonella growth by at least 50%, and 10 x concentrations inhibited growth more than 80%. An explanation of the mechanism(s) involved in growth reduction is offered.

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PubMedDate not supplied

Mutation rate of avian intestinal coliform bacteria when pressured with fluoroquinolones.

The purpose of this study was to determine the rate at which resistance developed in avian coliform bacteria when exposed to nalidixic acid, sarafloxacin, or enrofloxacin. In in vitro studies, the rates of mutation of avian isolates of Escherichia coli and Salmonella were determined following nalidixic acid, sarafloxacin, or enrofloxacin pressure. The rates of mutation were similar for nalidixic acid and sarafloxacin, whereas a lower rate of mutation was seen after enrofloxacin pressure. In in vivo studies, the quinolones were administered in the drinking water to broiler chickens at a concentration of 40 ppm for five consecutive days. Samples of feces were inoculated onto appropriate media and the frequency of resistance was determined. The frequency rates of resistance to nalidixic acid and sarafloxacin were similar. Enrofloxacin-medicated birds did not develop enrofloxacin-resistant coliform bacteria. The in vitro and in vivo data appear to correlate.

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