Memly's USMLE Step 1 Microbiology: 300 Organism Cards
300 organisms by structure, virulence and how they are identified.
300枚のカード
収録カードを見る（30枚）
全300枚から30枚を抜粋して表示しています。
| 表 | 裏 |
|---|---|
| Gram stain principle — what is it? | A differential stain separating bacteria by how well the cell wall retains crystal violet after an alcohol wash. The result is a property of wall structure, so it also predicts susceptibility to agents that act on the wall. |
| Catalase test — what is it? | Detection of the enzyme converting hydrogen peroxide to water and oxygen, seen as bubbling. |
| Chocolate agar — what is it? | Blood agar heated to lyse the red cells, releasing factor V and factor X. |
| Staphylococcus aureus — what is it? | Gram-positive cocci in clusters, catalase positive and coagulase positive, beta hemolytic. |
| Streptococcus pyogenes — what is it? | Gram-positive cocci in chains, catalase negative, beta hemolytic, bacitracin sensitive, Lancefield group A. |
| Bacillus anthracis — what is it? | Gram-positive spore-forming aerobic rod with a polypeptide capsule of D-glutamate. |
| Clostridium tetani — what is it? | Gram-positive spore-forming obligate anaerobe with a terminal spore. |
| Neisseria meningitidis — what is it? | Gram-negative diplococci, oxidase positive, maltose and glucose fermenting, grown on Thayer-Martin. |
| Enterobacteriaceae common features — what is it? | Gram-negative rods that are oxidase negative, ferment glucose, and reduce nitrate. A negative oxidase result on a gram-negative rod points to this family, which is the first branch in enteric identification. |
| Vibrio cholerae — what is it? | Comma-shaped gram-negative rod, oxidase positive, growing in alkaline media. |
| Brucella — what is it? | Small gram-negative coccobacillus, facultative intracellular within macrophages. Intracellular survival produces an undulating fever pattern and a prolonged course. |
| Endotoxin — what is it? | Lipopolysaccharide in the outer membrane of gram-negative bacteria, released on cell lysis. Exotoxin, which is secreted, protein, heat labile, and often has a specific molecular target. |
| Mycobacterium tuberculosis — what is it? | Acid-fast rod, obligate aerobe, slow growing on Lowenstein-Jensen medium. |
| Treponema pallidum — what is it? | Spirochete too thin to be seen on Gram stain, visualized by darkfield microscopy, not culturable on artificial media. Its outer membrane carries few surface proteins, which is one explanation offered for its persistence despite an antibody response. |
| Mycoplasma pneumoniae — what is it? | The smallest free-living bacteria, with no cell wall and sterols in the membrane, growing slowly on enriched media. Having no peptidoglycan, it is unaffected by agents acting on the cell wall and is invisible on Gram stain. |
| Biofilm — what is it? | A community of bacteria embedded in a self-produced polysaccharide matrix on a surface. Organisms inside divide slowly and are shielded from both phagocytes and diffusion, so the state rather than the species explains persistence. |
| Viral genome classification — what is it? | Viruses grouped by nucleic acid type, strandedness, and sense, since those determine what must happen before proteins can be made. The grouping predicts whether the virus must carry its own polymerase, which is a structural requirement rather than a naming convention. |
| DNA virus general features — what is it? | Most are double stranded, linear or circular, and replicate in the nucleus using host machinery. The exceptions are the examinable part, since the general rule follows from needing host nuclear enzymes. |
| RNA virus general features — what is it? | Most replicate in the cytoplasm and lack proofreading, so mutation rates are far higher than for DNA viruses. High mutation rate underlies antigenic change, quasispecies diversity, and rapid emergence of resistance. |
| Influenza genome segmentation — what is it? | Eight separate RNA segments packaged together in one particle. Co-infection of one cell by two strains allows whole segments to be exchanged, which is the mechanism of antigenic shift and of pandemic emergence. |
| Arbovirus transmission — what is it? | Transmission by an arthropod vector in which the virus replicates before being passed on. Vector distribution and season determine where and when infection occurs, which is why these infections are geographically bounded. |
| Fungal cell wall — what is it? | A wall of chitin and glucans, with ergosterol rather than cholesterol as the principal membrane sterol. Both the wall polysaccharide and the membrane sterol are absent from human cells, which is why they are the two selective targets. |
| Histoplasma capsulatum — what is it? | Dimorphic fungus appearing as small yeasts within macrophages. |
| Giardia lamblia — what is it? | Flagellated protozoan with trophozoite and cyst forms. |
| Nematodes — what is it? | Roundworms with a cylindrical unsegmented body and separate sexes. Most intestinal species are acquired by ingesting eggs or by larvae penetrating skin, so the entry route separates them into two groups. |
| Definitive versus intermediate host — what is it? | The definitive host harbours the sexually reproducing stage, while an intermediate host carries larval or asexual stages. For malaria the mosquito is definitive and the human intermediate, which reverses the assumption that the human is the main host. |
| Type I hypersensitivity — what is it? | An immediate reaction in which antigen cross-links IgE bound to mast cells, releasing histamine and other mediators. It requires previous sensitization, so the first exposure produces the IgE and a later one produces the reaction. |
| Toll-like receptors — what is it? | Innate receptors recognizing conserved microbial patterns such as lipopolysaccharide, flagellin, and unmethylated DNA motifs. They detect classes of organism rather than specific ones, which is why the innate response is immediate but does not improve with repeated exposure. |
| Antibody isotypes — what is it? | IgM as the first response and a strong complement activator, IgG the most abundant and the only one crossing the placenta, IgA in secretions, IgE on mast cells, and IgD on naive B cells. The heavy chain constant region rather than the binding site determines what an antibody can do once bound. |
| B cell defects and organism pattern — what is it? | Impaired antibody production, associated with recurrent infection by encapsulated bacteria and by enteroviruses. Encapsulated organisms need opsonizing antibody to be cleared, so the defect predicts the organism class. |
このデッキについて
Microbiology collapses into a list of names unless each organism carries a small set of features that separate it from the one next to it. Catalase splits the gram-positive cocci, coagulase splits the staphylococci, and novobiocin splits what is left. Non-septate hyphae branching at wide angles is a different mold from septate hyphae branching at acute ones. Narrow-based budding with a capsule is a different yeast from broad-based budding without one. Learn the discriminating feature and the name follows. Learn the name first and you have a list. That is how these 300 cards are built. Every one opens with a classification or a definition, and beyond that the fields follow what the organism actually turns on: where two organisms are routinely mixed up, the card names the other one and says which single feature separates them. The weighting is 146 cards of bacteriology including 31 on laboratory identification alone, 74 on virology, 30 on parasites, 28 on fungi, and 22 on immunology and host defence patterns. Antimicrobials are not here. Mechanism, spectrum and adverse effects live in the Pharmacology Drug Classes deck, so the two fit together without repeating a card: this deck is the organism, that one is the agent. Cards are tagged by group and by sub-group, so you can drill just the gram negatives, just the DNA viruses, or just the helminths. Import it and the deck joins your spaced-repetition schedule, and what you end up with is the thing the subject is really testing: given a stain, a plate, and a growth condition, being able to say what it is and why.
よくある質問
- How is each organism card built?
- It opens with the classification, which for a bacterium means the Gram result, shape, arrangement and the key biochemical results. Under that, on the cards where it matters, comes the organism this one is most often confused with and the single feature that separates them.
- Where do the antimicrobials fit?
- In the Pharmacology Drug Classes deck, deliberately. That deck covers the mechanism and target of every antimicrobial class. Keeping the agent and the organism in separate decks means neither one repeats the other, and you can drill either side on its own. The only drug names here are optochin, bacitracin and novobiocin, which appear as identification discs rather than as therapy.
- Does it cover the laboratory identification tests?
- Yes, as its own block of 31 cards: Gram stain and acid-fast staining, catalase and coagulase, hemolysis patterns, the optochin, bacitracin and novobiocin discs, oxidase, urease, indole and citrate, lactose fermentation on MacConkey, and the special media from chocolate agar to charcoal yeast extract. Each says what the test detects.
- Which groups get the most cards?
- Bacteriology 146, made up of 31 laboratory identification, 35 gram-positive, 35 gram-negative, 23 virulence mechanisms and 22 mycobacteria, spirochetes and atypicals. Then virology 74, parasites 30, fungi 28, and immunology 22. Bacteriology is heaviest because that is where the discriminating features are densest.
- How is it organized for studying one group at a time?
- Every card carries a group tag and a finer sub-group tag, across laboratory identification, gram-positive bacteria, gram-negative bacteria, mycobacteria and spirochetes, bacterial virulence, virology, fungi, parasites and immunology. Filter by a tag to drill one group, or by the finer tag for a single block such as DNA viruses, helminths or biochemical tests.
- Can I import the whole deck on the free plan?
- Yes. Importing a saved deck runs no new AI generation and does not use your AI allowance, so the free plan imports every card. You can study, edit and delete them afterwards.
- Will importing it twice create duplicates?
- No. Cards you already have are skipped and only cards added in a revision come through. Including re-imports after deleting it, one official deck can be imported three times per account.
- Can I edit the cards after importing?
- Yes. Once imported they are your cards: edit either side, delete the ones you already know cold, retag them, or move them into another deck.
No official questions are reproduced, and every card is written by Memly. Compiled 2026-08-21.