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Every organism and topic page, category and gram-stain browse, and full-text search are free and crawlable — no account, no paywall. That's 341 reference cards you can reach the moment you search a name.
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78 entries
Bacteria
Gram-stain, morphology, and biochemical clues for the high-yield bacterial organisms.
48 entriesViruses
Genome type, structure, and disease associations across the core viral families.
19 entriesFungi
Dimorphism, morphology, and lab clues for the medically important fungi.
37 entriesParasites
Life cycles, vectors, and diagnostic clues for protozoa and helminths.
45 entriesLab & diagnostics
Stains, media, and biochemical tests — what they show and how to read them.
36 entriesAntimicrobials
Drug classes, mechanisms of action, and resistance vocabulary.
46 entriesConcepts
Core microbiology concepts that tie the organisms and methods together.
32 entriesDiseases & syndromes
Syndromes and presentations mapped back to their causative organisms.
High-yield organisms
Start with the classics
Bacterium
Staphylococcus aureus
Gram-positive cocci in clusters
Gram +Bacterium
Streptococcus pyogenes
Group A beta-hemolytic streptococcus
Gram +Bacterium
Escherichia coli
Gram-negative lactose-fermenting rod
Gram −Bacterium
Pseudomonas aeruginosa
Oxidase-positive nonfermenting rod
Gram −Bacterium
Mycobacterium tuberculosis
Acid-fast rod
Fungus
Candida albicans
Yeast with germ-tube clue
Virus
Influenza virus
Segmented negative-sense RNA virus
Parasite
Giardia duodenalis
Flagellated protozoan with cysts
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PetriKey is an educational study reference for microbiology coursework — not medical advice and not a tool for diagnosis, treatment, or specimen handling.