Microbiology reference
PetriKey is a free microbiology reference for nursing, pre-med and micro students: gram stain, morphology, lab clues, and disease links for 182 organisms and 159 topics as fast, searchable reference cards, with flashcards and quizzes to make it stick.
Browse by category
Gram-stain, morphology, and biochemical clues for the high-yield bacterial organisms.
48 entriesGenome type, structure, and disease associations across the core viral families.
19 entriesDimorphism, morphology, and lab clues for the medically important fungi.
37 entriesLife cycles, vectors, and diagnostic clues for protozoa and helminths.
45 entriesStains, media, and biochemical tests - what they show and how to read them.
36 entriesDrug classes, mechanisms of action, and resistance vocabulary.
46 entriesCore microbiology concepts that tie the organisms and methods together.
32 entriesSyndromes and presentations mapped back to their causative organisms.
High-yield organisms
Gram-positive cocci in clusters
Gram +Group A beta-hemolytic streptococcus
Gram +Gram-negative lactose-fermenting rod
Gram −Oxidase-positive nonfermenting rod
Gram −Acid-fast rod
Yeast with germ-tube clue
Segmented negative-sense RNA virus
Flagellated protozoan with cysts
Free forever
Every organism and topic page, the identification flowcharts, the study guides, the Gram-positive and Gram-negative browse, category 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.
Go deeper
Flashcard decks, a daily quiz across 5 question modes, a study streak and mastery tracking, and per-organism notes turn passive reading into active recall.
PetriKey is an educational study reference for microbiology coursework - not medical advice and not a tool for diagnosis, treatment, or specimen handling.