Coli Challenge Research Articles

Effect of feeding organic acids on gastrointestinal digesta measurements at various times postweaning in pigs challenged with enterotoxigenic Escherichia coli

In Study 1, pigs (n = 54) weaned at 21 ± 2 d were fed a 20% CP corn-soybean meal based diet only (control) or with 1.5% fumaric or 1.5% citric acid. One half of the pigs on each treatment were orally challenged on days 3, 7 or 14 postweaning with 1010E. coli (0157:K88+) to observe the effects on scouring and on intestinal digesta pH, Cl− concentration, VFA and non-volatile acid profiles, and microflora concentrations in the stomach, jejunum, cecum and lower colon when pigs were necropsied 5, 9 or 16 d postweaning. The E. coli challenge increased (P < 0.05) the severity of scouring. Organic acids had no appreciable effects on severity of scouring and intestinal measurements except for fumaric and succinic acid concentrations which were greater in the stomach (P < 0.001) and jejunum (P < 0.05) of pigs fed fumaric acid. The E. coli challenge had no significant effect on pH, Cl− concentration, and lactobacillus or E. coli concentrations, but did increase (P < 0.05) the concentration of lactic acid in the jejunum, and total VFA in the lower colon. From days 5 to 16 postweaning, pH decreased (P < 0.002) in the cecum, Cl− concentration increased (P < 0.03) in the jejunum, lactobacillus counts decreased (P < 0.001) in the jejunum and increased (P < 0.004) in the lower colon, and E. coli counts decreased in the jejunum (P < 0.07), cecum (P < 0.02) and lower colon (P < 0.001). In Study 2, pigs (n = 96) weaned at 21 ± 2 d were similarly fed organic acids as in Study 1 and half of the animals in each treatment were orally challenged with E. coli on day 3 postweaning. During the 15-d experiment, E. coli challenge decreased (P < 0.05) ADG by 20% and increased F:G 19% from 7 to 15 d postweaning and increased (P < 0.001) the severity of scouring between days 4 and 11 postweaning. Feeding organic acids had no measurable effect on growth performance or scouring and did not modify the effects of the postweaning E. coli challenge. Key words: Pigs, pH, organic acids, volatile fatty acids, lactobacillus, Escherichia coli

Classification of newly calved cows into moderate and severe responders to experimentally induced Escherichia coli mastitis.

In the present study newly calved cows were tentatively classified as moderate and severe responders to experimentally induced Escherichia coli mastitis based upon the reactive oxygen species (ROS)-generating capacity of their blood neutrophils before infection. The groups differed in blood and milk composition prior to infection. This initial classification was supported by the corresponding variation in clinical symptoms and in the changes in milk production and composition measured during mastitis. Responses of newly calved cows to Esch. coli challenge varied from mild to severe symptoms of inflammation in infected glands and differed in the intensity of systemic disturbances and general illness. Losses in milk yield and compositional changes were most pronounced in inflamed glands and in severe responders. In inflamed glands milk yield and composition did not return to preinfection level in either moderate or severe responders. The yields of lactose, alpha-lactalbumin, casein and fat followed the same pattern as milk yield. It is concluded that the severe and long lasting systemic disturbances observed in severe responders can be ascribed to absorption of endotoxin from infected glands into circulation, indicating the important role of endotoxin in the pathology of coliform mastitis in periparturient cows. Evaluation of the ROS-generating capacity of blood neutrophils and blood and milk composition before infection might help to predict the cow's sensitivity to Esch. coli mastitis.

Controlling acute Escherichia coli mastitis during the periparturient period with recombinant bovine interferon gamma

The efficacy of recombinant bovine interferon (rBoIFN)-gamma against experimentally induced Escherichia coli mastitis during the periparturient period was investigated. Dairy cows intramammarily treated with rBoIFN-gamma 24 h before the E. coli challenge had fewer infected quarters, lower clinical scores, and infections of shorter duration when compared to placebo-treated animals. All rBoIFN-gamma treated cows survived the experimental E. coli challenge. However, placebo treated cows had a 42% mortality rate attributed to coliform mastitis with 3 days of the challenge. Results from this study suggest that intramammary infusion of rBoIFN-gamma can prevent the rapid, unrestricted growth of E. coli within the mammary gland and inhibit the subsequent development of an unlimited inflammatory response under experimental conditions. It is likely that controlling severe local inflammatory reactions may also decrease the pathological alterations to mammary parenchymal tissue that often accompanies acute coliform mastitis during the periparturient period. The potential for prophylactic of perinatal dairy cows with rBoIFN-gamma to regulate the rate, severity, and duration of naturally occurring coliform mastitis during periods of heightened susceptibility is discussed.

Prevention of Diarrhea Caused by Enterotoxigenic Escherichia coli: Lessons Learned with Volunteers

The effectiveness of bismuth subsalicylate in the prevention and treatment of diarrhea induced in volunteers by a single strain of enterotoxigenic Escherichia coli and a standard inoculum size was evaluated. Bismuth subsalicylate (500 mg in a solid dosage form) was administered 8 hours and 2 hours before and 2 hours and 4 hours after the E. coli challenge; treatment was continued four times a day for three additional days. Volunteers experiencing diarrhea were re-randomized to receive placebo or bismuth subsalicylate (300 mg every 30 minutes, for a total of 2.4 g of bismuth subsalicylate, in eight doses). Diarrhea occurred in nine (56%) of the 16 volunteers receiving placebo and in two (13%) of the 15 volunteers receiving bismuth subsalicylate (P less than .03). In vitro studies revealed that bismuth subsalicylate and its components each were bactericidal at concentrations possibly attained during the clinical trial. The effect of the dosage form (solid vs. liquid), the relation of drug administration to meals, and how these variables might greatly influence the effectiveness of bismuth subsalicylate prophylaxis for travelers' diarrhea were considered.

Pathogenicity of Escherichia coli in Aerosols for Young Chickens

The relative pathogenicity of Esherichia coli isolates from poultry was determined by aerosol exposure of young chickens. Evidence of colisepticemia with airsacculitis and/or pericarditis and perihepatitis was evaluated. A system was devised that included the intratracheal (IT) inoculation of strain SE-17 infectious bronchitis virus (IBV) of chicks at 7 days of age followed by their aerosol exposure to E. coli culture suspensions 2 days later. Each experiment was terminated 6 days later. For comparative purposes in some studies, chicks were housed at 17 C and others at 27 C. The IBV-E. coli challenge procedure proved to be an effective way to determine the relative ability of E. coli isolates to cause death and/or gross lesions in young chickens. With some E. coli isolates, there were minimal or no obvious adverse effects from exposure except when chickens were previously inoculated with IBV. When chicks were housed at 17 C instead of 27 C, slight increases in mortality and decreases in gross lesions were generally observed, probably because the earlier deaths did not allow time for the lesions to become as evident. The E. coli isolate #18344 (Congo Red-positive) was consistently more pathogenic than the Congo Red-negative version of that isolate. Cultures of E. coli previously demonstrated to be pathogenic (VA O1:K1 and DL #29) were among the most pathogenic isolates evaluated in these experiments and were similar to the Congo Red-positive #18344 isolate.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental Escherichia coli peritonitis in immunosuppressed mice: the role of specific and non-specific immunity.

An experimental Escherichia coli septicaemia-peritonitis model was adapted to immunosuppressed mice. The mice were made neutropenic by a sublethal dose of cyclophosphamide, which resulted in a 100-fold increase in their susceptibility to intraperitoneal injection of E. coli O18:K1. A lethal infection could be prevented by passive immunisation with anti-K1 capsular or anti-O18 LPS antibodies but not with anti-J5 bacterial antibodies. The anti-K1 and anti-O18 antisera were able to increase the LD50 of the E. coli challenge by factors of 50 and 5, respectively. The role of non-specific, lipopolysaccharide (LPS)-mediated resistance to infection was also investigated in this model, in which only long-living phagocytic cells such as macrophages are believed to be functional. Pretreatment of mice with LPS was shown to prevent growth of the bacterial challenge in the peritoneal cavity and blood and to result in a five-fold increase in the LD50 of the challenge strain. These findings suggest an important role for macrophages as effector cells in defence against E. coli infection.

Semisoluble aminated glucan: Long-term efficacy against an intraperitonealE. coli challenge and its effect on formation of abdominal adhesions

The first part of this study in the rat was designed to assess the immediate and, in particular, the long-term effects of semisoluble aminated glucan (SAG) with regard to an intraperitoneal (i.p.) E. coli challenge and side-effects. The severity of the E. coli peritonitis was evaluated by quantification of the concomitant bacteremia. The animals randomly received either 10 ml normal saline i.p. (controls) or 10 ml (50 mg) SAG i.p. (experimental groups). It was found that SAG had no immediate protective effect against the infectious challenge as no difference was detected in the bacterial clearance between saline- and SAG-treated rats at day 0. However, 2 days after injection of saline/SAG a substantial protection of SAG was noted as no blood-borne bacteria could be detected at 1, 2, 3, 4 and 5 h after the E. coli challenge in SAG-treated animals, whereas by contrast matching blood cultures were positive in all controls. A likewise protective effect against E. coli bacteremia of a single i.p. injection of SAG was demonstrated at 7, 21, and 49 days after the administration of the compound. During the 7-week experimental period no clinical side-effects of SAG were observed. At autopsy (days 0, 2, 7, 21, and 49, respectively) no gross pathologic conditions were found. Lung, spleen, and kidney sections from SAG-treated rats were normal, whereas tiny granulomas were exhibited in liver sections, possibly related to the hyperfunctional macrophage state which SAG induced. The second main object of the study was to evaluate SAG's effect on adhesion formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Fasting, Water Deprivation, and Adrenal-Blocking Chemicals on Resistance to Escherichia coli Challenge

Fasting for 2 days plus 1 day of feeding resulted in increased resistance to Escherichia coli challenge. If feed during the postfasting period contained metyrapone (a blocker of adrenal synthesis of corticosterone), resistance to E. coli challenge was reduced. Fasting for 1.75 days or water deprivation for 2 days resulted in decreased resistance to E. coli challenge. Deprivation of water for two days of chickens with blocked adrenals resulted in an E. coli challenge response similar to that of controls.

Resistance of C3H/HeJ mice to the effects of Haemophilus pleuropneumoniae.

Comparisons were made in the mortality associated with an inhaled dose of viable Haemophilus pleuropneumoniae type 5, strain J45, between adult C3H/HeN and C3H/HeJ mice. Mice of both strains were also challenged with Escherichia coli strains O111:B4 and J5. The 50% lethal dose (LD50) of H. pleuropneumoniae in C3H/HeN mice was calculated to be 10(6.5) CFU. At a mean dose of 10(6.7) CFU a 46% mortality rate occurred in C3H/HeN mice, whereas only 10% of the C3H/HeJ mice died (P less than 0.01). Deaths occurred significantly earlier in C3H/HeN mice (P less than 0.01). No deaths occurred later than 12 h postinfection in either group. Pulmonary lesions in the mice that died were similar to those in pigs that die during the acute phase of H. pleuropneumoniae infection. In surviving mice of both strains, a mild resolving interstitial and bronchopneumonia was present which was not typical of subacute H. pleuropneumoniae infections in swine. Quantitative bacterial isolations from the lungs, liver, and spleen indicate that H. pleuropneumoniae did not multiply in the lungs, was rapidly cleared, and did not become systemic. No deaths occurred in the mice inoculated with E. coli J5 or O111:B4 at mean doses of 10(6.3), 10(7.2), and 10(8.5) CFU, and 10(6.4), 10(7.5), and 10(8.2) CFU, respectively. The difference in the mortality rate between the C3H/HeN and C3H/HeJ mice suggests that endotoxin may be involved in acute deaths in pigs infected with H. pleuropneumonia. As indicated by the E. coli challenge, however, other factors are also likely to be involved. Because of the differences in the pathology and microbiology following H. pleuropneumoniae pulmonary infections in mice and pigs, mice do not appear to be an accurate model of the overall disease in swine.

Double-Blind Comparison of Bismuth Subsalicylate and Placebo in the Prevention and Treatment of Enterotoxigenic Escherichia coli-Induced Diarrhea in Volunteers

Enterotoxigenic Escherichia coli cause most traveler's diarrhea in Third World countries. We tested bismuth subsalicylate as prophylactic therapy and as treatment for enterotoxigenic E. coli-induced diarrhea. Thirty-two healthy hospitalized volunteers were challenged orally with enterotoxigenic E. coli, strain H10407 (serotype 078:K80:H11). Administration of 600-mg doses of bismuth subsalicylate or placebo was begun 8 h before bacterial challenge. Doses were taken at 8 h and 2 h before, and at 2 h and 4 h after, the E. coli challenge and were continued four times a day for 3 additional days. The maximum prophylactic bismuth subsalicylate dose was 9.6 g. Those experiencing diarrhea were rerandomized to receive bismuth subsalicylate or placebo, given as 300 mg every 30 min for a total of 2.4 g of bismuth subsalicylate, in eight doses. Diarrhea occurred in 9 of the 16 (56%) subjects receiving placebo and in 2 of the 15 (13%) subjects receiving bismuth subsalicylate, p less than 0.03. This study confirms the effectiveness of bismuth subsalicylate in preventing traveler's (enterotoxigenic E. coli) diarrhea, and shows that bismuth subsalicylate in other than liquid form is effective. Enterotoxigenic E. coli were recovered less frequently from those receiving bismuth subsalicylate than from those receiving placebo, suggesting that bismuth subsalicylate prevents diarrhea by reducing the number or multiplication of enterotoxigenic E. coli. In vitro studies revealed that bismuth subsalicylate and its components each were bactericidal at concentrations possibly attained during the clinical trial.