Thymine bases on one strand of DNA, next to each other, are covalently linked together to form a thymine dimer.

Adenine and thymine bases on opposing DNA strands are linked together by hydrogen bonds.

Thymine bases on the opposing DNA strands are covalently linked together to form a thymine dimer.

Adenine and thymine bases on opposing DNA strands are covalently linked together to form an AT dimer.

FMT stimulates host macrophages to phagocytose C. difficile spores more efficiently, preventing recurrence.

FMT introduces donor antibodies that directly neutralize C. difficile toxins in the recipient’s intestine.

FMT restores microbial diversity that outcompetes C. difficile for nutrients and niches, re-establishes metabolic by-products that inhibit pathogen growth, and strengthens colonization resistance.

FMT supplies bacteriophages that specifically lyse C. difficile, acting similarly to targeted antimicrobial therapy.

9

1

7

5

Staphylococcus and Escherichia coli

Halobacterium and Staphylococcus

Cyanobacteria and Green algae

Halobacterium and Sulfolobus

Dry heat

Pasteurization

Ethylene oxide

Autoclave

Forming a biofilm that masks surface antigens and blocks phagocyte access

Producing urease to neutralize stomach acid, allowing survival of H. pylori

Releasing leukocidins that directly kill neutrophils and macrophages

Allowing opsonization but blocking complement-mediated lysis

The uncontrolled muscle contractions in Clostridium tetani infection

The hemolysis of red blood cells in a staphylococcal infection

The fever, nausea, and low blood pressure in a Salmonella infection

The invasion and lysis of intestinal cells by E. coli