title: Inhibition of in vitro Salmonella Typhimurium colonization in porcine cecal bacteria continuous-flow competitive exclusion culturest.
abstract: Continuous-flow (CF) chemostate cultures were used as models to determine the potential usefulness of undefined porcine cecal bacteria as competitive exclusion (CE) cultures against colonization by Salmonella Typhimurium. One culture, pCF1, was derived from cecal bacteria of an animal maintained on antibiotic-free feed, while the other culture, pCF4, was derived from cecal bacteria of an animal maintained on feed containing chlortetracycline. The effectiveness against a chlortetracycline-resistant Salmonella Typhimurium was examined in CF cultures maintained in the absence (pCF1 and pCF4) and presence (cpCFl and cpCF4) of chlortetracycline. CF cultures were inoculated with each of 10(2), 10(4), and 10(6) Salmonella Typhimurium CFU/ml. Chemostat inocula of 10(2) Salmonella CFU/ml resulted in no Salmonella Typhimurium being detected at 2 and 3 days postinoculation in pCF1 and pCF4, respectively, and after 2 days in both cpCF1 and cpCF4. Inoculations of 10(4) Salmonella Typhimurium CFU/ml resulted in clearance from pCF1 and pCF4 within 4 days and within 3 days from cpCF1 and cpCF4. Following inoculation with 10(6) CFU/ml, no Salmonella Typhimurium were detected in all CF cultures by 6 days postinoculation. The results indicated that in vitro CF cultures of porcine cecal bacteria were able to inhibit the growth of Salmonella Typhimurium. The ability to limit Salmonella Typhimurium growth was not restricted by prior exposure of the cecal bacteria to the feed additive chlortetracycline. The present study demonstrates the potential application of CF cultures as models to aid in the identification of CE cultures against salmonellosis in pigs.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, College Station, Texas 77845, USA. hume@ffsru.tamu.edu
authors.forename: M E
authors.initials: ME
authors.lastname: Hume
authors.forename: D J
authors.initials: DJ
authors.lastname: Nisbet
authors.forename: S A
authors.initials: SA
authors.lastname: Buckley
authors.forename: R L
authors.initials: RL
authors.lastname: Ziprin
authors.forename: R C
authors.initials: RC
authors.lastname: Anderson
authors.forename: L H
authors.initials: LH
authors.lastname: Stanker
mesh_terms: D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000494:pharmacology; D002432:Cecum / Q000382:microbiology*; D002751:Chlortetracycline / Q000008:administration & dosage / Q000494:pharmacology; D015169:Colony Count, Microbial; D066298:In Vitro Techniques; D008403:Mass Screening / Q000662:veterinary; D012481:Salmonella Infections, Animal / Q000188:drug therapy / Q000517:prevention & control*; D012486:Salmonella typhimurium / Q000187:drug effects / Q000254:growth & development*; D013552:Swine; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D002751:Chlortetracycline