Anaerobic Gram-Positive Anaerobes – Vocabulary Review

Fifty vocabulary flashcards covering Clostridium species, their virulence factors, laboratory identification tests, associated diseases, and related anaerobic bacteria for exam review.

Clostridium

Genus of obligate anaerobic, catalase-negative, spore-forming Gram-positive bacilli.

Obligate anaerobe

Organism that cannot grow in the presence of oxygen and thrives only under anaerobic conditions.

Catalase negative

Lacking the enzyme catalase; unable to decompose hydrogen peroxide—typical of Clostridium spp.

Spore-forming bacilli

Rod-shaped bacteria capable of producing heat-resistant endospores for survival.

Collagenase

Clostridial enzyme that degrades collagen, facilitating bacterial spread through tissues.

Hyaluronidase

Virulence enzyme that breaks down hyaluronic acid in connective tissue, aiding invasion.

Lecithinase

Phospholipase C produced by C. perfringens; major toxin that lyses cell membranes.

Phospholipase

Lipid-degrading enzyme contributing to tissue destruction in Clostridial infections.

Terminal spore

Endospore located at the extreme end of a bacterial cell.

Subterminal spore

Spore situated near the end but not at the extreme pole of the cell.

Central spore

Endospore positioned in the middle of the bacterial cell.

Peritrichous flagella

Flagella distributed over the entire cell surface, providing motility to most Clostridia.

Swollen sporangium

Enlarged bacterial cell body caused by endospore formation, seen in many Clostridia.

Carbohydrate fermenter

Bacterium that metabolizes sugars anaerobically; most Clostridia except C. tetani & C. histolyticum.

Gas gangrene bacillus

Common name for Clostridium perfringens, the main agent of gas gangrene.

Alpha toxin

Lethal phospholipase produced by C. perfringens causing cell lysis and tissue necrosis.

Enterotoxin (C. perfringens)

Toxin produced during sporulation that leads to food-borne illness.

Box-shaped bacilli

Microscopic square-ended appearance characteristic of C. perfringens cells.

Double zone hemolysis

Inner β-hemolysis and outer α-hemolysis around C. perfringens colonies on blood agar.

Stormy fermentation

Violent gas production and curd disruption of milk by C. perfringens in litmus milk.

Lecithinase positive

Production of an opaque halo on egg yolk agar; diagnostic for C. perfringens.

Nagler’s test

Egg-yolk agar assay detecting lecithinase activity to identify C. perfringens.

Reverse CAMP test

Identification test where C. perfringens enhances hemolysis of Streptococcus agalactiae.

Gas gangrene

Life-threatening myonecrosis with gas formation and tissue necrosis caused by C. perfringens.

Hyperbaric oxygen therapy

Treatment delivering high-pressure oxygen to inhibit anaerobes in gas gangrene.

Type A C. perfringens food poisoning

Mild, self-limiting diarrhea and cramps 8–30 h after ingesting enterotoxin.

Enteritis necroticans

Severe Type C disease with β-toxin–mediated necrosis of the small intestine.

Tetanospasmin

Potent neurotoxin of C. tetani that blocks inhibitory neurotransmitter release.

Drumstick appearance

Microscopic look of C. tetani cells with terminal spores and swollen sporangia.

Trismus

Lockjaw—painful masseter muscle spasm seen in tetanus.

Risus sardonicus

Sardonic grin due to facial muscle spasm characteristic of tetanus.

Botulinum toxin A

Most potent C. botulinum neurotoxin; causes botulism and marketed as Botox.

Foodborne botulism

Intoxication from preformed toxin in improperly preserved foods, often toxin A.

Infant botulism

Infection in infants after ingesting C. botulinum spores, classically from honey.

Toxin A (C. difficile)

Enterotoxin responsible for antibiotic-associated diarrhea.

Toxin B (C. difficile)

Cytotoxin causing pseudomembranous colitis in hospitalized patients.

Pseudomembranous colitis

Severe colonic inflammation marked by plaques, linked to C. difficile toxins.

Cycloserine-cefoxitin-fructose agar (CCFA)

Selective medium giving yellow, ground-glass colonies of C. difficile.

Chartreuse fluorescence

Bright yellow-green glow of C. difficile colonies under long-wave UV light.

Pre-reduced anaerobically sterilized (PRAS) medium

Transport medium that maintains specimens under strict anaerobic conditions.

Catalase test for Clostridium

Assay that differentiates aerotolerant strains; bubbling indicates a positive result.

Mouse neutralization test

Bioassay confirming C. botulinum neurotoxin in serum or feces.

Cell culture cytotoxicity test

Gold-standard assay for detecting C. difficile toxin B in specimens.

Lipase test

Mother-of-pearl sheen on egg yolk agar indicating lipase production by C. botulinum or C. noyvi.

Actinomycosis

Chronic, suppurative infection with sulfur granules caused by Actinomyces israelii.

Molar tooth colony

Rough, heaped colony morphology of older Actinomyces israelii cultures.

Propionibacterium acnes

Skin commensal diphtheroid bacillus often recovered as a contaminant in blood cultures.

Tomato juice agar

Acidic (pH 3–4) medium used for the isolation of Lactobacillus species.

Bacterial vaginosis

Vaginal infection associated with reduced Lactobacillus, replaced by mixed flora.

Pleomorphic Gram-positive rods

Variable-shaped, non-motile rods typical of Lactobacillus species.