Brent J. Skura

Impact of Feed Supplementation with Antimicrobial Agents on Growth Performance of Broiler Chickens, Clostridium perfringens and Enterococcus Counts, and Antibiotic Resistance Phenotypes and Distribution of Antimicrobial Resistance Determinants in Escherichia coli Isolates

ABSTRACT The effects of feed supplementation with the approved antimicrobial agents bambermycin, penicillin, salinomycin, and bacitracin or a combination of salinomycin plus bacitracin were evaluated for the incidence and distribution of antibiotic resistance in 197 commensal Escherichia coli isolates from broiler chickens over 35 days. All isolates showed some degree of multiple antibiotic resistance. Resistance to tetracycline (68.5%), amoxicillin (61.4%), ceftiofur (51.3%), spectinomycin (47.2%), and sulfonamides (42%) was most frequent. The levels of resistance to streptomycin, chloramphenicol, and gentamicin were 33.5, 35.5, and 25.3%, respectively. The overall resistance levels decreased from day 7 to day 35 (P < 0.001). Comparing treatments, the levels of resistance to ceftiofur, spectinomycin, and gentamicin (except for resistance to bacitracin treatment) were significantly higher in isolates from chickens receiving feed supplemented with salinomycin than from the other feeds (P < 0.001). Using a DNA microarray analysis capable of detecting commonly found antimicrobial resistance genes, we characterized 104 tetracycline-resistant E. coli isolates from 7- to 28-day-old chickens fed different growth promoters. Results showed a decrease in the incidence of isolates harboring tet(B), blaTEM, sulI, and aadA and class 1 integron from days 7 to 35 (P < 0.01). Of the 84 tetracycline-ceftiofur-resistant E. coli isolates, 76 (90.5%) were positive for blaCMY-2. The proportions of isolates positive for sulI, aadA, and integron class 1 were significantly higher in salinomycin-treated chickens than in the control or other treatment groups (P < 0.05). These data demonstrate that multiantibiotic-resistant E. coli isolates can be found in broiler chickens regardless of the antimicrobial growth promoters used. However, the phenotype and the distribution of resistance determinants in E. coli can be modulated by feed supplementation with some of the antimicrobial agents used in broiler chicken production.

Antibiotic resistance and virulence genes in commensal Escherichia coli and Salmonella isolates from commercial broiler chicken farms.

Antibiotic resistance patterns and the presence of antibiotic and virulence determinants in 74 sorbitol-negative Escherichia coli and 62 Salmonella isolates from nine different broiler chicken farms were investigated. Each farm was supplied by one of three companies that used different antimicrobial agents in feed for growth promotion. The isolates were identified by API 20E for E. coli and by serological tests for Salmonella. The susceptibility of the isolates to antibiotics was determined by Sensititre using the Clinical and Laboratory Standards Institutes breakpoints. Fifty-two E. coli isolates (70.3%) and nine Salmonella isolates (14.52%) were multiresistant to at least nine antibiotics. The multiresistant isolates were evaluated for the presence of tetracycline resistance, integron class 1, and blacMY 2 genes by PCR. Of the 74 E. coli isolates, 55 were resistant to amoxicillin and ceftiofur. Among these 55 resistant E. coli isolates, 45 (81.8%) and 22 (40.0%) were positive for blacMY-2 and qacEdeltal-Sull genes, respectively. Tetracycline resistance was found in 56 isolates (75.8%) among which 12 (21.4%) and 24 (42.9%) gave positive results for tetA and tetB, respectively. Virulence genes (iss, tsh, and traT), aerobactin operon (iucC), and the eaeA gene were detected in some E. coli strains. Among the 27 amoxicillin- and ceftiofur-resistant Salmonella isolates, the blacMY-2 gene was detected in 22 isolates. The class 1 integron gene (qacEdeltal-Sull) was not detected in any Salmonella isolates, whereas the invasin (inv) and virulence (spy) genes were found in 61 (98.4%) and 26 (42%) of the Salmonella isolates, respectively. This study indicated that multiple antibiotic-resistant commensal E. coli and Salmonella strains carrying virulence genes can be found on commercial broiler chicken farms and may provide a reservoir for these genes in chicken production facilities. Except for the presence of tetB, there was no significant effect of feed formulations on the phenotypic or genotypic characteristics of the isolates.

Modified Atmosphere Packaging of Fruits and Vegetables

Consumer appeal for fresh, low-calorie, healthy, nutritious and high quality foods has grown steadily in the last 10 years. Such food trends may be attributed to consumer attitudes on lifestyle, nutrition, fitness, health and food quality [7, 103, 128, 239]. The 1990 Grocery Attitudes of Canadians study [104] indicated that 68% of grocery shoppers considered nutrition as extremely or very important. North Americans are concerned about foods in their diet in relation to weight control and chronic disease risks. Government agencies and health-promoting organizations are recommending a reduction of fat, cholesterol and salt in the diet and a greater consumption of fruits, vegetables and cereals with the view that such dietary changes may reduce the risk of heart disease and cancer incidence [7, 285]. Fresh commodities are now considered by consumers to be more nutritious than canned products and more flavourful [128].

Antibacterial activity of lactoferricin, lysozyme and EDTA against Salmonella enteritidis

Abstract The antibacterial activity of a pepsin digest of bovine lactoferrin, containing the peptide lactoferricin B against Salmonella enteritidis was studied under various conditions. The digest had greater antibacterial activity than lactoferrin in 1% peptone, was bactericidal and also increased the permeability of the outer membrane of the bacteria as demonstrated by plating on bile salts agar. The antibacterial activity was inhibited in richer media, such as tryptic soy broth or milk-based or soy-based infant formula. Addition of lysozyme or EDTA or both, to the lactoferrin digest resulted in increased antibacterial activity of the mixture. Lysosyme or EDTA alone had little or no activity against S. enteritidis . The increase in antibacterial activity obtained with the addition of lysozyme and EDTA to the lactoferrin digest was not sufficient to overcome inhibition by components of the richer media.

Potential for immunological supplementation of foods

Infants who do not receive adequate amounts of breast milk are particularly susceptible to infections by intestinal pathogens. The milk of humans and domestic animals carries protective factors such as immunoglobulins and oligosaccharides that provide a significant amount of protection to the recipient. It has been proposed that the diet of infants at risk of intestinal infections could be supplemented with protective factors found in cows ‘ milk or eggs, particularly immunoglobulins. The evidence in support of supplementation of infant formula is reviewed, as well as some of the work in progress.

Sensory, chemical and gas chromatographic evaluation of five raspberry cultivars

Abstract Five raspberry cultivars, ‘Chilcotin’, ‘Chilliwack’, ‘Meeker’, ‘Skeena’ and ‘Tulameen’, were evaluated for sensory attributes, and chemical and flavor volatile compounds. ‘Chilliwack’ and ‘Tulameen’ received high ratings in sweetness and overall impression with high soluble solids, total sugars and sugar:acid ratio. ‘Chilcotin’ rated low in overall impression and sweetness, and high in sourness and astringency, with low soluble solids, sugar:acid ratio and total sugars, and high titratable acidity. Principal factor analysis (PFA) of the sensory results separated the cultivars based on desirable (appearance, color, texture, aroma and sweetness) and less desirable (sourness, bitterness, astringency and off-flavor) attributes. Twenty-eight volatile compounds were analyzed by dynamic headspace and 18 identified by gas chromatography-mass spectrometry (GC-MS), most of which were terpenes which included α-pinene, sabinene, γ-terpinene, α- and β-ionone and caryophyllene. Volatile compounds varied among cultivars, with benzaldehyde (11·1–31·8%), α-pinene (4·0–11·5%), ethyl heptanoate (6·9–15·2%), β-myrcene (13·2–19·6%) and γ-terpinene (12·2–20·0%) as the predominant volatiles. Correlation analysis established no relationships between sensory and chemical data with volatile compounds.

Structure of the glycocalyx polysaccharide of Pseudomonas fragi ATCC 4973

The structure of the exocellular glycocalyx polysaccharide of Pseudomonas fragi ATCC 4973, a bacterium implicated in the spoilage of meat, has been determined using hydrolysis, methylation analysis and 1D- and 2D-n.m.r. spectroscopy. The polysaccharide, which aids in the adhesion of the cells to each other and to the meat tissue, has the regular repeating unit ----4)-3-O-[(R)-1-carboxyethyl]-alpha-D-Glcp-(1----3)-beta-D-ManpNAc+ ++- (1----4)-beta-D-Glcp-(1----. Random partial O-acetylation occurred in some preparations of the polysaccharide.

Relationship between incidence of Salmonella contamination among pre-scalded, eviscerated and post-chilled chickens in a poultry processing plant.

The incidence of Salmonella contamination in 11 flocks of chickens was determined at three sites within a poultry processing plant: A, before scalding; B, after evisceration; C, after chilling. The average incidence of Salmonella contamination of flocks ranged from 1.2 to 74.4%, and flock to flock variability among sites was significant. Incidences of Salmonella ranged from 3 to 96% at site A; 0 to 69% at site B; and 0 to 96% at site C. Flocks with a high incidence of Salmonella contamination at site A were also frequently contaminated at sites B and C. By generating regression equations, it was possible to predict the incidence of Salmonella at one of these sites from the incidence at the other sites. The ability to define the interdependence between internal and external Salmonella contamination of chickens provides a basis for developing effective control measures for decreasing the incidence of Salmonella -contaminated retail chickens.

Antimicrobial effect of lactoferrin digest on spores of a Penicillium sp. isolated from bottled water

Abstract Fungal growth in bottled water has caused the bottled water industry a series of recalls and rejected products. Microorganisms isolated from bottled water were cultured and identified as Penicillum sp. A spore stock suspension was prepared by washing spores after 7 days incubation at 25°C on potato dextrose agar. Lactoferrin (5% w/v), isolated from cheese whey, was digested at 37°C for 4 h using porcine pepsin (3% w/w). For the antimicrobial assay, a 96 well microplate containing peptone yeast glucose medium and known concentrations of pepsin digest containing lactoferricin, was inoculated with the spore suspension (ca. 7×10 4 ml −1 spores). Culture optical density was monitored at 595 nm. Lactoferricin at concentrations of 60 and 300 μg/ml inhibited spore germination and mycelial growth for up to 9 and 21 days at 30°C, respectively, whereas a bovine serum albumin digest, used as a negative control, had no inhibitory effect on the spores. Lactoferricin may have potential as an antifungal agent in bottled water.