Selective decontamination and the anaerobic faecal flora

Area of Science:

• Microbiology
• Pharmacology
• Gastroenterology

Background:

• Selective decontamination of the gastrointestinal tract using non-absorbable antibiotics is a strategy to prevent infections in immunocompromised patients.
• Gram-negative facultatively anaerobic rods are common pathogens in these vulnerable populations.

Purpose of the Study:

• To evaluate the in vivo effects of antibiotics on human intestinal flora.
• To determine the efficacy of selective decontamination in preventing infections.

Main Methods:

• Experiments were conducted using ex-germ-free mice colonized with human intestinal flora.
• The impact of polymyxin B on obligate anaerobes and Enterobacteriaceae was assessed.

Main Results:

• Polymyxin B selectively eliminated Enterobacteriaceae without altering the human obligate anaerobic flora.
• In vitro antibiotic sensitivity differences correlated with in vivo efficacy.
• Antibiotic binding to intestinal contents influenced dosing and release dynamics.

Conclusions:

• Selective decontamination with polymyxin B is effective in eliminating target pathogens while preserving the host's anaerobic gut microbiota.
• Antibiotic binding and release are critical factors for optimizing selective decontamination protocols.