Effect of chitosan on Salmonella Typhimurium in broiler chickens.

Public concern with the incidence of antibiotic-resistant bacteria, particularly among foodborne pathogens such as Salmonella, has been challenging the poultry industry to find alternative means of control. The purposes of the present study were to evaluate in vitro and in vivo effects of chitosan on Salmonella enterica serovar Typhimurium (ST) infection in broiler chicks. For in vitro crop assay experiments, tubes containing feed, water, and ST were treated with either saline as a control or 0.2% chitosan. The entire assay was repeated in three trials. In two independent in vivo trials, 40 broiler chicks were assigned to an untreated control diet or dietary treatment with 0.2% chitosan for 7 days (20 broiler chicks/treatment). At day 4, chicks were challenged with 2×105 colony-forming units (CFU) ST/bird. In a third in vivo trial, 100 broiler chicks were assigned to untreated control diet or dietary treatment with 0.2% chitosan for 10 days (50 broiler chicks/treatment) to evaluate ST horizontal transmission. At day 3, 10 birds were challenged with 105 CFU ST/bird, and the remaining nonchallenged birds (n=40) were kept in the same floor pen. In all three in vitro trials, 0.2% chitosan significantly reduced total CFU of ST at 0.5 and 6 h postinoculation compared with control (p<0.05). In two in vivo trials, at 7 days, dietary 0.2% chitosan significantly reduced total CFU of recovered ST in the ceca in both experiments. Dietary 0.2% chitosan significantly reduced total ST CFU recovered in the ceca of horizontally challenged birds in the third in vivo trial. Chitosan at 0.2% significantly reduced the CFU of recovered ST in vitro and in vivo, proving to be an alternative tool to reduce crop, ceca, and consequently carcass ST contamination as well as decreasing the amount of ST shed to the environment.

Evidence for Clostridium septicum as a primary cause of cellulitis in commercial turkeys.

Etiology and methods of immunoprophylaxis against common field cellulitis in commercial turkeys were evaluated. It was determined that intravenous administration ( approximately 10(8) cells/ml) of 1 of 4 isolates of Clostridium septicum from cellulitis lesions rapidly caused the classic lesions of cellulitis followed by death within 36 hr at high doses. When the supernatant alone was injected into turkey poults, signs of depression and ataxia were temporarily observed for up to 20 hr after injection, but no cellulitis lesions were detected. An enzyme-linked immunosorbent assay was developed to measure antibody levels against the isolated C. septicum. This assay was used to predict susceptibility to infection. An experimental formalin-killed bacterin/toxoid was produced from the challenge strain of C. septicum with inactivation timed to allow toxin accumulation and approximately 10(8) cells/ml. This bacterin/toxoid given at day of hatch generated a rapid and persistent antibody response against the homologous C. septicum in the vaccinated birds at 9 weeks (P < 0.001). The ability of this experimental vaccine to protect birds in the field as well as its ability to evaluate unvaccinated flocks to establish the time of seroconversion and the relationship to clinical disease are currently under evaluation.

Identification and characterization of lactic Acid bacteria in a commercial probiotic culture.

The aim of the present study was to describe the identification and characterization (physiological properties) of two strains of lactic acid bacteria (LAB 18 and 48) present in a commercial probiotic culture, FloraMax(®)-B11. Isolates were characterized morphologically, and identified biochemically. In addition, the MIDI System ID, the Biolog ID System, and 16S rRNA sequence analyses for identification of LAB 18 and LAB 48 strains were used to compare the identification results. Tolerance and resistance to acidic pH, high osmotic concentration of NaCl, and bile salts were tested in broth medium. In vitro assessment of antimicrobial activity against enteropathogenic bacteria and susceptibility to antibiotics were also tested. The results obtained in this study showed tolerance of LAB 18 and LAB 48 to pH 3.0, 6.5% NaCl and a high bile salt concentration (0.6%). Both strains evaluated showed in vitro antibacterial activity against Salmonella enterica serovar Enteritidis, Escherichia coli (O157:H7), and Campylobacter jejuni. These are important characteristics of lactic acid bacteria that should be evaluated when selecting strains to be used as probiotics. Antimicrobial activity of these effective isolates may contribute to efficacy, possibly by direct antimicrobial activity in vivo.

Physiological Properties and Salmonella Growth Inhibition of Probiotic Bacillus Strains Isolated from Environmental and Poultry Sources.

The objective of the present study was to describe the physiological properties of seven potential probiotic strains of Bacillus spp. Isolates were characterized morphologically, biochemically, and by 16S rRNA sequence analyses for identification. Tolerance to acidic pH, high osmotic concentrations of NaCl, and bile salts were tested. Isolates were also evaluated for their ability to metabolize different carbohydrates sources. The antimicrobial sensitivity profiles were determined. Inhibition of gastrointestinal Salmonella colonization in an avian model was also evaluated. Five strains of Bacillus were tolerant to acidic conditions (pH 2.0) and all strains were tolerant to a high osmotic pressure (NaCl at 6.5%). Moreover, all strains were able to tolerate concentration of 0.037% bile salts after 24 h of incubation. Three strains were able to significantly reduce Salmonella Typhimurium levels in the crop and in the ceca of broiler-type chickens. Among the 12 antibiotics tested for antibiotic resistance, all strains were resistant to bacitracin and susceptible to gentamycin, neomycin, ormethoprim, triple sulfa, and spectinomycin. Bacterial spore formers have been shown to prevent gastrointestinal diseases in animals and humans. The results obtained in this study show important characteristics to be evaluated when selecting Bacillus spp. candidates to be used as probiotics.