Competitive Exclusion

Thoughts for Thinking People – 12/10/01


Is infectious disease caused by the germ or the terrain? This debate has raged since the time of Pasteur. Although the germ-as-villain paradigm has won the war of popularity in modern medical practice, there is increasing evidence that it is the fertility of the host “soil” that plays the most significant role in whether the “weeds” of disease take root.

Obviously the pathogen is not the whole answer; otherwise life would have long ago been annihilated. Even during highly virulent plagues, there are some of the population who only get mildly ill and recover, and others who develop no signs or symptoms whatsoever. It is not a matter of sporadic or selective contact, since microbes have the ability to spread with ease and can ubiquitously expose populations. Efforts to eliminate pathogens by washing, aerosolizing and disinfecting cannot hope to remove the possibility of contact. Only under the most rigorous laboratory conditions can gnotobiotic (microbial-free) organisms be grown. When this is done, however, such sterile creatures are unsuitable for free living since their immune systems have been untested and thus are unprepared to resist street microbes.

In an attempt to solve the problem of food-borne pathogens in food animals, rigorous methods have been attempted such as sterilizing environments and eradication in situ through extensive use of antibiotics and chemotherapeutic agents. The results of this microbial warfare have not been good. We are losing the war. Nature has its own checks and balances. The more we learn of these important relationships, the more likely it is we will be able to take advantage of natural mechanisms developed over eons of time to assure the survival of species. One such mechanism is competitive exclusion (CE) of pathogens by probiotic organisms. If the digestive tract is populated with sufficient numbers of “friendly” microorganisms, the pathogens cannot as easily take root.

Competitive exclusion is now being used in chickens, cattle, and swine to decrease pathogens that can infect humans. In effect, it involves the treatment of young animals with fecal material from healthy adults that is either defined or undefined. The FDA has recently (1998) approved the first CE product for use in poultry production. The usual method of treatment is spraying the material on young animals or inoculating the drinking water. Although the exact mechanism of action is not known, it is believed that probiotic organisms within CE material act through nutrient exclusion, competition for attachment sites, creating volatile fatty acids and fermentative gases that inhibit pathogens, and by decreasing the oxidation-reduction potential.

Modern food-animal production practices, which separate the young from natural contact with the mother, increase vulnerability to infection. Better hygiene and aggressive antibiotic use has not solved the problem of escalating food-borne pathogens. Restoring natural balances with competitive exclusion holds great promise in helping to curb this threat.

There is also a lesson here in that we, too, should be using probiotic cultures on a prophylactic basis (it is only by such preventive measures that competitive exclusion works) and thus help guard ourselves against disease-causing organisms. (Wysong offers probiotic supplements for humans and their companion animals including ProbiosynT, Pet InoculantT, BioticT and PDGT ?

There is also a lesson in child rearing. Rather than concentrating on the sterility of the birthing theatre, removal of children to sterile incubators and bassinets, treating them with various antimicrobials and then feeding them with a processed and denatured synthetic milk via a sterile nipple and bottle, it would be much better to put the child in the mother’s arms to suckle. Continued nursing and body contact with the mother help inoculate children with competitive exclusion probiotic organisms and thus best prepare the child against a world of pathogens that will always be present. Assuming the parents are healthy, the practice in primitive societies of pre-chewing foods to feed to weaning children is an additional method of inoculating the digestive tract of the young with competitive exclusion organisms.


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