Coli Loads Research Articles

Cecal Populations of Lactobacilli and Bifidobacteria and Escherichia coli Populations After In Vivo Escherichia coli Challenge in Birds Fed Diets with Purified Lignin or Mannanoligosaccharides

Two experiments were conducted to evaluate lignin and mannanoligosaccharides as alternatives to antibiotic growth promoters in broilers. Dietary treatments for the 2 studies were 1) negative control (CTL−, antibiotic free); 2) positive control (CTL+, diet 1 + 11 mg of virginiamycin/kg); 3) mannanoligosaccharide (MOS; diet 1 + BioMos: 0.2% to 21 d and 0.1% thereafter); 4) LL (diet 1 + 1.25% Alcell lignin); and 5) HL (diet 1 + 2.5% Alcell lignin). In experiment 1, each treatment was assigned to 4 pen replicates (52 birds each). Body weight and feed intake were recorded weekly for 38 d. At 28 and 38 d, cecal contents were assayed for lactobacilli and bifidobacteria. Body weight and feed intake did not differ among dietary treatments. At d 38, the lactobacilli population was greatest (P < 0.05) in birds fed MOS, whereas LL-fed birds had greater (P < 0.05) lactobacilli load than those fed CTL+. Bifidobacteria load was greater (P < 0.05) in birds fed MOS or LL compared with those fed CTL+ at both d 28 and 38. However, at d 28 and 38, lactobacilli and bifidobacteria loads were lowest (P < 0.05) in CTL+ or HL-fed birds. In experiment 2, 21-d-old birds from the initial flock were transferred to cages for oral Escherichia coli (O2 and O88 serotypes) challenge (12 birds/treatment). After 3, 6, and 9 d, cecal loads of E. coli were determined. Birds fed HL had a lower E. coli load (P < 0.05) than birds fed CTL− or CTL+ at d 3, and lower than birds fed CTL− at d 6. At d 9, the E. coli load was lower (P < 0.05) in birds fed MOS or HL than in those fed the CTL− or CTL+ diets; LL-fed birds had lower E. coli load than those fed CTL−. Birds fed MOS or LL had a comparative advantage over CTL+ birds in increasing populations of lactobacilli and bifidobacteria and lowering E. coli loads after challenge.

Development of a process-based model to predict pathogen budgets for the Sydney drinking water catchment

In drinking water catchments, reduction of pathogen loads delivered to reservoirs is an important priority for the management of raw source water quality. To assist with the evaluation of management options, a process-based mathematical model (pathogen catchment budgets - PCB) is developed to predict Cryptosporidium, Giardia and E. coli loads generated within and exported from drinking water catchments. The model quantifies the key processes affecting the generation and transport of microorganisms from humans and animals using land use and flow data, and catchment specific information including point sources such as sewage treatment plants and on-site systems. The resultant pathogen catchment budgets (PCB) can be used to prioritize the implementation of control measures for the reduction of pathogen risks to drinking water. The model is applied in the Wingecarribee catchment and used to rank those sub-catchments that would contribute the highest pathogen loads in dry weather, and in intermediate and large wet weather events. A sensitivity analysis of the model identifies that pathogen excretion rates from animals and humans, and manure mobilization rates are significant factors determining the output of the model and thus warrant further investigation.

Enterobacteriaceae in ground meats

Presumptive Escherichia coli counts for 312 samples of non-frozen ground beef were determined and compared with proposed Canadian standards. Results for frozen pork sausages, packaged at manufacturer level, indicated little difference in distribution of presumptive E. coli loads compared with retail ground beef. Use of solid media and direct inoculation of EC broth at 45 °C did not give alternative, rapid methods of estimating E. coli loads in ground beef. Counts on violet red bile agar (VRBA) within 18–24 h incubation at 35 °C gave reliable estimates of coliform bacteria (bile-precipitating colonies) and Enterobacteriaceae (total count), with only 1.3 and 10.7% false positives, respectively. Bile-precipitating isolates from VRBA were primarily E. coli, also Serratia liquefaciens, aerogenic Enterobacter agglomerans, Enterobacter cloacae, Citrobacter freundii, and Klebsiella pneumoniae. Non-bile-precipitating colonies were primarily aerogenic E. agglomerans and S. liquefaciens; however, in the most probable number technique E. agglomerans was screened out. In addition to E. coli, E. agglomerans and S. liquefaciens were the principal types of Enterobacteriaceae in these samples. Enterobacter agglomerans gave a variety of IMViC reactions, including the type I (++−−) reaction, whereas S. liquefaciens were predominantly IMViC type −−++. Incubating EC broth at 45.5 °C, as opposed to 44.5 °C, reduced the number of false positives.