Monitoring of verotoxigenic Escherichia coli (VTEC) and identification of human pathogenic VTEC types 1 Scientific Opinion of the Panel on Biological Hazards

Salmonella is a human pathogen that is commonly found in poultry products. It is possible to decrease chicken carcass and egg contaminations by adding organic acids to the feed or drinking water at appropriate times. Medium-chain fatty acids are more antibacterial against Salmonella than short-chain fatty acids. The antibacterial effect of these acids is species specific. Bacteria that are unable to decrease intracellular pH accumulate organic acid anions in accordance with the pH gradient across their cell membranes. The short-chain fatty acid butyrate specifically down-regulates expression of invasion genes in Salmonella spp. at low doses. Also medium-chain fatty acids and propionate decrease the ability of Salmonella spp. to invade epithelial cells, in contrast to acetic acid. Because not all bacteria are affected in a similar fashion by organic acids, it may be possible to use probiotic and prebiotic bacteria to achieve beneficial effects. If diets can be designed to stimulate organic acid production in the caecum, it may be possible to control Salmonella spp. via even easier and more cost-effective measures, compared with addition of acids to feed or drinking water.

https://www.tandfonline.com/doi/pdf/10.1080/03079450600711045

The use of organic acids to combat Salmonella in poultry: a mechanistic explanation of the efficacy

A lytic bacteriophage, which was previously isolated from sewage and which attaches to the K1 capsular antigen, has been used to prevent septicemia and a meningitis-like infection in chickens caused by a K1 1 bacteremic strain of Escherichia coli. Protection was obtained even when administration of the phage was delayed until signs of disease appeared. The phage was able to multiply in the blood. In newly borne colostrum-deprived calves given the E. coli orally, intramuscular inoculation of phage delayed appearance of the bacterium in the blood and lengthened life span. With some provisos there is considerable potential for this approach to bacterial-disease therapy.

https://cvi.asm.org/content/cdli/5/3/294.full.pdf

Use of Lytic Bacteriophage for Control of Experimental Escherichia coli Septicemia and Meningitis in Chickens and Calves

Fowl typhoid and pullorum disease are two distinct septicaemic diseases largely specific to avian species and caused by Salmonella Gallinarum and Salmonella Pullorum, respectively. They were first described more than one century ago. Since their discovery, many efforts have been made to control and prevent their occurrence in commercial farming of birds. However, they remain a serious economic problem to livestock in countries where measures of control are not efficient or in those where the climatic conditions favour the environmental spread of these microorganisms. During the past 15 to 20 years there has been an explosion of genetic and immunological information on the biology of these two organisms, which is beginning to contribute to a better understanding of the organisms and their interaction with the host. However, it is not enough simply to understand the pathology in greater and greater detail. What is needed, in addition to this increase in basic knowledge, is creative thinking to challenge existing paradigms and to develop really novel approaches to infection control.

https://www.tandfonline.com/doi/pdf/10.1080/03079457.2010.542575

Pullorum disease and fowl typhoid--new thoughts on old diseases: a review.

A total number of 189 one d-old Hubbard broiler chicks were randomly divided into seven treatment groups of three replicates, 9 chicks each. The first group was served as control and fed the basal diets. While, the other six groups were received the basal diet supplemented with acetic acid (AC), citric acid (CA) or lactic acid (LA) at different levels of 1.5 and 3.0 % of diet, respectively. The experiment was lasted when chicks were 42 d old. Thyroid gland activity, some blood components, organ morphology, pH level of some gastrointestinal tract (GI-tract) segments and performance were measured. The results showed that dietary acidification elevated significantly concentration of T as well as T :T ratio, but T level was not significantly 3 3 4 4 affected. Moreover, the effect was clearly notable with CA and AC. Chicks fed acidified diets had better immune response as indicated by their higher serum globulin and relative lymphoid organs than the control. Similarly, higher calcium and phosphorus concentrations were noted. On the other hand, significant reduction in abdominal fat and serum level of cholesterol and total lipid was achieved due to dietary acidification. The liver functions did not adversely alter, in response to addition of organic acidifiers. Addition of any level and source of organic acids increased feed digestion and absorption as a result of increasing relative pancreas weight and small intestine density (indication of the intestinal villi dimension). The pH values in different GI-tract segments were insignificantly decreased with supplemental all types and doses of AC, CA and LA. Broiler chicks of dietary organic acids had superior improvement in live body weight (LBW), body weight gain (BWG) and feed conversion ratio (FCR) as compared to those of unsupplemented diet. No remarkable differences were noted between the addition of 1.5 and 3% of either AC, CA or LA in most studied traits.

Thyroid activity, some blood constituents, organs morphology and performance of broiler chicks fed supplemental organic acids

Summary Experiments were carried out on the antibacterial effects of a commercial formic acid‐propionic acid mixture (Bio‐add™) against different Salmonella serotypes. The preparation exerted a strong antibacterial effect on S. typhimurium strain F98 in artificially contaminated feed. After 28 days storage, the bactericidal effect was still considerable. When chickens were reared on feed that had been treated with Bio‐add™ and artificially contaminated with different serotypes, S. enteritidis, S. typhimurium and S. agona were not isolated from the caecal contents, but S. infantis was. No organisms of this strain were isolated when a lower feed‐contamination rate of bacteria was used.

https://www.tandfonline.com/doi/pdf/10.1080/03079459508419071

Studies on the use of a formic acid-propionic acid mixture (Bio-add) to control experimental Salmonella infection in broiler chickens.

The effect of colonisation of the alimentary tract of newly hatched chicks by different Salmonella serotypes on the establishment in the gut by other Salmonella strains inoculated afterwards was assessed. Although profound inhibition of colonisation had been found previously to be genus-specific, considerable variation was found within the Salmonella genus. Some strains were found to be much more inhibitory than others and some were more easily inhibited than were others. There was not an absolute relationship between inhibitory activity and colonisation ability. No relationship was seen between inhibition and serotype or phage types within serotypes. There was no correlation between in vivo inhibition and the extent of inhibition that occurred in early stationary phase cultures in rich, undefined broth cultures.

Interference between Salmonella serotypes in intestinal colonisation of chickens: correlation with in vitro behaviour.

Summary An indirect ELISA using soluble whole cell antigen was used to screen serum samples obtained from breeder and layer flocks some of which had shown clinical or bacteriological evidence of infection with Salmonella Gallinarum or 5”. Pullorum. There was good correlation between Salmonella infection and the presence of serum samples showing high optical density (OD) values. Sera from seven flocks showing high values were retested using group D (0–1, 9, 12) lipopolysaccharide (LPS) and g,m‐H flagella as detecting antigens. Sera from six flocks produced high OD values with LPS and low values with flagella confirming infection with a non‐flagellate, group D Salmonella while one produced high values with both antigens indicating mixed infection with another group D serotype.

Ana Maria Iba

Papers

Studies on the use of a formic acid-propionic acid mixture (Bio-add) to control experimental Salmonella infection in broiler chickens.

Interference between Salmonella serotypes in intestinal colonisation of chickens: correlation with in vitro behaviour.

Examination by ELISA of sera obtained from chicken breeder and layer flocks showing evidence of fowl typhoid or pullorum disease.