Microbiology Bacteria Tests and Structures: Catalase, Coagulase, Endospores, Toxins, Biofilms, Hemolysis, Capsules, and Oxygen Requirements

Catalase test

Determines if bacteria can break down hydrogen peroxide → bubbles = catalase positive

Coagulase

Enzyme that clots blood plasma (Staph aureus is +)

Endospores

Tough, dormant survival form (Bacillus & Clostridium)

Exotoxin

Protein toxin secreted by bacteria (e.g., Staph aureus)

Endotoxin

Lipopolysaccharide in Gram-negative bacteria → triggers inflammation

Biofilm

Sticky bacterial layer that sticks to surfaces (prosthetics, catheters)

Hemolysis

Destruction of red blood cells (alpha = partial, beta = full, gamma = none)

Capsule

Protective coating around bacteria → prevents phagocytosis

Facultative anaerobe

Can survive with or without oxygen

Obligate aerobe

Needs oxygen

Anaerobe

Cannot survive with oxygen