monensin and Salmonella-Infections--Animal

The effect of continuous in-feed administration of anticoccidial agents on antimicrobial sensitivity and the level of bacterial shedding in poultry experimentally infected with Salmonella enterica subsp. enterica serotype Typhimurium definitive type 104 (DT104) were investigated. On day 0, 1,200 1-day-old Salmonella-free broiler chicks were placed into 50 pens, and the pens were randomly allocated to one of five treatments: nonsupplemented (negative control; T1), monensin at 120 mg/kg of diet (T2), salinomycin at 60 mg/kg of diet (T3), semduramicin at 20 mg/kg of diet (T4), or semduramicin at 25 mg/kg of diet (T5). Each bird was inoculated with a well-characterized strain of serotype Typhimurium DT104 on day 10. On day 49, the birds were euthanatized humanely. Bulk fecal samples were collected on days 13, 43, and 48 and were examined for organisms which had acquired resistance. The genetic basis of acquired resistance was determined from representative samples of isolates. Of 784 Salmonella-selective plates supplemented with antimicrobial agents, only 33 showed growth. These isolates came from all treatment regimens, including the nonsupplemented control. A number of phenotypic changes were observed; these included changes in motility, phage type, and agglutination properties. Supplementation of the diet with an anticoccidial drug does not appear to affect antimicrobial resistance or the level of excretion of salmonellae. Most of the changes observed do not seem to be related to the presence of a supplement in feed. Salmonellae appear to be capable of acquiring antimicrobial resistance and phenotypic changes independently of specific antimicrobial selection pressures.

Topics: Animal Feed; Animals; Anti-Bacterial Agents; Chickens; Dietary Supplements; Feces; Genotype; Intestinal Mucosa; Monensin; Nigericin; Phenotype; Pyrans; Salmonella Infections, Animal; Salmonella typhimurium

Ninety Holstein bulls were used in a complete randomized design to study the effect of a blend of plant extract (PE) supplementation on jejunum, cecum, and rectum microbiota (Escherichia coli and lactic acid bacteria [LAB]) and hide and carcass contamination (identification of E. coli O157:H7 and Salmonella). Three treatments--control (CTR), monensin (MON), and PE--were tested. Bulls were offered straw and concentrate ad libitum during 108 d. In the cecum, the percentage of LAB counts below 5 log CFU/ml was greater (P < 0.01) in MON (68.1%) than in CTR (34.6%) and PE (28.0%) treatments. On hide, Salmonella was detected (P < 0.05) in CTR (13.3%) and MON (10.0%) treatments, in contrast to PE (0%) treatment. In bulls fed high-concentrate diets supplemented with PE, no increase of carcass E. coli O157:H7 and Salmonella identification was observed.

Topics: Animals; Carrier State; Cattle; Cattle Diseases; Cecum; Colony Count, Microbial; Escherichia coli Infections; Escherichia coli O157; Food Contamination; Food Microbiology; Jejunum; Male; Monensin; Plant Extracts; Random Allocation; Rectum; Salmonella; Salmonella Infections, Animal

Escherichia coli O157:H7 and Salmonella are widely recognized as important agents of foodborne disease with worldwide distribution. The use of ionophores in feeding growing ruminants is widespread in the United States and has attracted recent interest due to the apparent temporal relationship between initial ionophore use and the increase in human E. coli O157:H7 cases. Two experiments were conducted to evaluate the effects of short-term feeding of ionophores on fecal shedding, intestinal concentrations, and antimicrobial susceptibility of E. coli O157:H7 and S. typhimurium in growing lambs. Sixteen lambs were used in each experiment, four lambs per treatment group: monensin, laidlomycin propionate, bambermycin, and a control treatment. Lambs were fed a grain and hay (50:50) diet with their respective ionophore for 12 d before experimental inoculation with E. coli O157:H7 or S. typhimurium. Animals were maintained on their respective diets an additional 12 d, and fecal shedding of inoculated pathogens was monitored daily. Lambs were killed and tissues and contents were sampled from the rumen, cecum, and rectum. No differences (P > 0.05) in fecal shedding of Salmonella or E. coli O157:H7 were observed due to treatment. Occurrence of Salmonella or E. coli in luminal contents and tissue samples from the rumen, cecum, and rectum did not differ (P > 0.05) among treatments. Feeding monensin decreased (P < 0.05) the incidence of scours in sheep infected with Salmonella compared with the other treatments. No differences in antimicrobial susceptibility were found in any of Salmonella or E. coli O157:H7 isolates. Results from these studies indicate that short-term ionophore feeding had very limited effects on E. coli and Salmonella shedding or on antimicrobial susceptibility in experimentally infected lambs.

Topics: Animals; Anti-Bacterial Agents; Bambermycins; Carrier State; Colony Count, Microbial; Diarrhea; Drug Resistance, Bacterial; Escherichia coli Infections; Escherichia coli O157; Feces; Female; Food Microbiology; Ionophores; Male; Monensin; Random Allocation; Salmonella Infections, Animal; Salmonella typhimurium; Sheep; Sheep Diseases

The influence of growth additives on the duration of salmonella shedding has been variously reported. The different conclusions reached were mainly because of the different experimental systems used. In this paper a naturally infected chicken model for evaluating this problem is described. It simulates commercial conditions and proved to be reproducible in 13 groups, each of 125 birds, over a two-year period.

Topics: Age Factors; Animals; Anti-Bacterial Agents; Cecum; Chickens; Cloaca; Female; Food Additives; Glycopeptides; Male; Monensin; Poultry Diseases; Salmonella; Salmonella Infections, Animal; Species Specificity

In two experiments (Experiments A and B) chickens experimentally infected with S. infantis at 7 days of age and fed diets containing both avoparcin (10 ppm) and monensin (90 ppm) showed a higher frequency of Salmonella-positive livers and higher caecal counts of Salmonella 1 and 2 weeks after challenge than similarly infected chickens fed only avoparcin (10 ppm). The results may indicate a synergistic action between the two drugs on the ability of chickens to withstand Salmonella infections.

Topics: Animals; Anti-Bacterial Agents; Cecum; Chickens; Female; Food Additives; Furans; Glycopeptides; Liver; Male; Monensin; Poultry Diseases; Salmonella; Salmonella Infections, Animal