Reconventionalization following antibiotic decontamination in man and animals

Abstract

Antibiotic decontamination of the digestive tract can suppress or eliminate all microorganisms in this tract that are sensitive to the antibiotics used for decontamination. Experimental work in animals has indicated that colonization resistance (CR) decreases to extremely low values during decontamination as a result of the suppression of the anaerobic fraction of the intestinal flora. This renders the decontaminated individual extremely sensitive to colonization by microorganisms that are resistant to the antibiotics used for decontamination. Colonization of the gastrointestinal tract will follow even very low contamination doses and the contaminating microorganisms can then reach abnormally high concentrations. This results in invasion of the host, which can be fatal when the individual has a lowered resistance to infection. Experiments in sublethally irradiated mice indicate that implantation of an anaerobic intestinal flora prior to actual reconventionalization decreases the risk of infection. If recolonization of the intestines by anaerobes that contribute to CR is left to circumstantial contamination, a recently decontaminated individual with a weak defense capacity may become contaminated with pathogenic microorganisms before the CR has become reestablished. These more pathogenic microbes may then establish colonies and cause an infection. Experiences with recolonization of patients and animals with a mixture of anaerobic bacteria are described. Chemicals/CAS: amphotericin, 12633-72-6; natamycin, 52882-37-8, 7681-93-8; nystatin, 1400-61-9, 34786-70-4, 62997-67-5; Antibiotics