Bacteria study sheet

78 rows - free sample of the first 6

Gram positive

Gram positive - Bacteria study sheet. Gram-stain, morphology, and biochemical clues for the high-yield bacterial organisms.
Bacterium	Classification	Lab and identification clues	High-yield clue	Associations
Actinomyces israelii	Gram-positive; Branching filamentous rod; Anaerobe; Not acid-fast	Sulfur granules (yellow filament colonies); Branching filaments on Gram stain; Anaerobic growth; Not acid-fast (contrast with Nocardia)	Yellow 'sulfur granules' draining from sinus tracts and cervicofacial 'lumpy jaw' after dental trauma are the core clues; unlike Nocardia it is anaerobic and not acid-fast.	Cervicofacial 'lumpy jaw'; Dental trauma / poor oral hygiene; IUD-associated pelvic study association
Bacillus anthracis	Gram-positive; Rod; Spore-former; Aerobe	Nonmotile teaching distinction; Capsule concept; Spore-forming rod vocabulary	Aerobic spore-forming rod + capsule + toxin vocabulary.	Zoonotic/public-health vocabulary; Biothreat awareness as a concept; Toxin mechanism framing
Bacillus cereus	Gram-positive; Rod (bacillus); Spore-forming; Facultative/aerobic; Beta-hemolytic	Large box-car Gram-positive rods; Endospore-forming; Beta-hemolytic colony vocabulary; Motile teaching distinction	Reheated rice held warm is the classic clue: the heat-stable emetic toxin cereulide causes vomiting, while a separate heat-labile enterotoxin causes watery diarrhea.	Reheated fried rice food poisoning; Emetic (cereulide) vs diarrheal enterotoxin syndromes; Ocular/keratitis study association
Clostridioides difficile	Gram-positive; Rod; Anaerobe; Spore-former	Toxin testing vocabulary; Spore-forming rod; Anaerobic growth concept	Spore-forming anaerobe + toxin + antibiotic-associated colitis vocabulary.	Pseudomembranous colitis vocabulary; Normal flora disruption; Infection-control concepts
Clostridium botulinum	Gram-positive; Rod; Obligate anaerobe; Spore-forming	Spore-forming anaerobe; Toxin detection concept; Grows in low-oxygen sealed containers vocabulary	Botulinum toxin blocks acetylcholine release at the neuromuscular junction to cause descending flaccid paralysis; home-canned foods and honey in infants are the classic sources.	Improperly home-canned foods; Infant botulism linked to honey ('floppy baby' vocabulary); Descending flaccid paralysis and diplopia presentation vocabulary
Clostridium perfringens	Gram-positive; Rod; Anaerobe; Spore-former	Double-zone hemolysis vocabulary; Spore-forming rod concept; Anaerobe vocabulary	Spore-forming anaerobic rod + alpha-toxin vocabulary.	Gas gangrene vocabulary; Food poisoning vocabulary; Clostridium comparison drills

Assembled from the free PetriKey reference. Every row is published in full on its own reference page, with that page's own sources. Educational study reference only - not medical advice, and not for diagnosis, treatment, dosing, specimen handling, or any clinical decision-making.

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