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Every organism and topic in PetriKey — 182 organisms and 159 topics across eight categories. Filter by category or gram stain, or type to search. All free.
16S rRNA sequencing
Bacterial gene sequencing ID concept
Acanthamoeba species
Contact-lens keratitis free-living amoeba
Acid-fast stain
Mycolic-acid wall staining concept
Acinetobacter baumannii
Healthcare-associated nonfermenting coccobacillus
Gram −Actinomyces israelii
Sulfur-granule filamentous anaerobe
Gram +Adenovirus
Nonenveloped double-stranded DNA virus
Aeromonas hydrophila
Freshwater rod, wound and gut infection
Gram −AIDS
Advanced HIV: CD4 <200 and opportunistic infections
Amebiasis
Bloody dysentery plus liver abscess
Aminoglycosides
30S protein-synthesis class concept
Gram −Anaplasma phagocytophilum
Intracellular tick-borne bacterium of granulocytes
Gram −Antibody isotypes
IgG, IgM, IgA, IgE, IgD and their roles
Antigen test concept
Detects microbial protein or polysaccharide target
Antigenic drift vs shift
Gradual mutation vs abrupt reassortment
Antimalarial mechanism concepts
How antimalarials hit the parasite (concepts only)
Antimicrobial stewardship
Coordinated effort to optimize antimicrobial use
Ascaris lumbricoides
Large intestinal nematode
Aseptic technique
Practices that prevent contamination
Aspergillus fumigatus
Septate hyphae with acute-angle branching
Autoclave and moist heat
Pressurized steam sterilization
Azoles
Ergosterol-synthesis antifungal concept
Babesia microti
Tick-borne intraerythrocytic piroplasm
Bacillus anthracis
Spore-forming aerobic Gram-positive rod
Gram +Bacillus cereus
Reheated-rice food poisoning rod
Gram +Bacitracin (A disk) test
A-disk: Group A strep sensitive, Group B resistant
Gram +Bacterial conjugation
Gene transfer through cell-to-cell contact
Bacterial flagella
Rotary appendages for motility
Bacterial growth curve
Four phases of a batch culture
Bacterial meningitis
Inflammation of meninges with rapid onset
Bacteriophage
Virus that infects bacteria
Bacteroides fragilis
Anaerobic Gram-negative rod with capsule clue
Gram −Balantidium coli
Only ciliated protozoan that infects humans
Bartonella henselae
Cat-scratch disease, bacillary angiomatosis
Gram −Benzimidazole antiparasitics
Bind parasite beta-tubulin
Beta-lactamase
Enzyme that breaks the beta-lactam ring
Beta-lactams
Cell-wall synthesis drug class concept
Bile solubility test
Pneumococcus dissolves in bile; viridans does not
Gram +Biofilm
Surface-attached microbial community
BK virus
Transplant nephropathy and cystitis
Blastomyces dermatitidis
Dimorphic fungus with broad-based budding
Blood agar hemolysis
Alpha, beta, and gamma hemolysis vocabulary
Bordetella pertussis
Small respiratory coccobacillus with toxin vocabulary
Gram −Borrelia burgdorferi
Tick-borne spirochete
Botulism
Toxin-driven descending flaccid paralysis
Brucella species
Undulant fever, unpasteurized dairy zoonosis
Gram −Burkholderia cepacia complex
Non-fermenter, cystic fibrosis lung pathogen
Gram −Burkholderia pseudomallei
Soil non-fermenter causing melioidosis
Gram −Calcofluor white stain
Fluorochrome binding fungal chitin
CAMP test
Arrowhead synergy = Group B strep / Listeria
Gram +Campylobacter jejuni
Curved motile Gram-negative rod
Gram −Candida albicans
Yeast with germ-tube clue
Candida auris / Candidozyma auris
Emerging multidrug-resistant yeast
Candidiasis / thrush
White oral plaques that scrape off
Capnocytophaga species
Capnophilic gliding rod of dog and human oral flora
Gram −Capsule
Antiphagocytic surface structure
Carbapenems
Broadest-spectrum beta-lactam cell-wall class
Catalase test
Staph vs strep study branch
Cellulitis
Spreading skin and subcutaneous infection
Chickenpox and shingles
Primary varicella vs zoster reactivation
Chikungunya virus
Aedes alphavirus, disabling arthralgia
Chlamydia trachomatis
Obligate intracellular bacterium
Chloramphenicol
50S peptidyl-transferase inhibitor
Chocolate agar X/V factors
Enriched media vocabulary for fastidious bacteria
Cholera
Toxin-mediated profuse watery diarrhea
Citrate utilization test
Prussian blue = citrate positive (Klebsiella)
Gram −Citrobacter species
Citrate-using enteric rods, E. coli mimics
Gram −Clonorchis sinensis
Chinese liver fluke from raw freshwater fish
Clostridioides difficile
Spore-forming anaerobic rod
Gram +Clostridium botulinum
Flaccid-paralysis canned-food anaerobe
Gram +Clostridium perfringens
Anaerobic spore-forming rod
Gram +Clostridium tetani
Terminal-spore tetanus rod
Gram +Coagulase test
S. aureus clue among staphylococci
Coccidioides immitis/posadasii
Dimorphic fungus with spherules
Colonization vs contamination vs infection
Interpretation vocabulary for coursework
Community-acquired pneumonia
Lung infection acquired outside healthcare settings
Complement system
Cascade of opsonization, inflammation, and lysis
Corynebacterium diphtheriae
Club-shaped Gram-positive rod with toxin clue
Gram +COVID-19 illness
SARS-CoV-2 respiratory illness with anosmia
Coxiella burnetii
Q fever, aerosol zoonosis, no vector needed
Gram −Coxsackievirus
Enteroviruses of HFMD and myocarditis
CRE
Carbapenem-resistant Enterobacterales
Crimean-Congo hemorrhagic fever virus
Nairovirus, Hyalomma tick, livestock
Cryptococcal meningitis
Subacute AIDS meningitis, India ink positive
Cryptococcus gattii
Encapsulated yeast affecting immunocompetent hosts
Cryptococcus neoformans
Encapsulated yeast
Cryptosporidium
Acid-fast oocyst protozoan
Cutibacterium acnes
Acne & prosthesis anaerobe (formerly Propionibacterium)
Gram +Cyclospora cayetanensis
Produce-linked acid-fast coccidian
Cystoisospora belli
Large elliptical oocyst coccidian (former Isospora)
Cytomegalovirus
Herpesvirus with owl-eye inclusion clue
Dengue fever
Aedes-borne 'breakbone' fever
Dengue virus
Aedes-borne flavivirus, breakbone fever
Dermatophytes
Keratin-loving molds
Dermatophytosis / ringworm
Annular scaly plaque with central clearing
Dientamoeba fragilis
Binucleate intestinal flagellate with no classic cyst
Diphyllobothrium latum
Fish tapeworm linked to B12 deficiency
Direct antiglobulin (Coombs) test
Detects antibody/complement coating red cells
DNase test
Clearing on DNA agar = S. aureus positive
Gram +Dracunculus medinensis
Guinea worm from copepod-contaminated water
Ebola virus
Filamentous filovirus, bat reservoir, VHF
Echinocandins
Fungal cell-wall class concept
Echinococcus granulosus
Hydatid cyst tapeworm of dogs and sheep
Efflux pump
Membrane transporter that expels drugs
Ehrlichia chaffeensis
Obligate intracellular tick-borne bacterium of monocytes
Gram −Eikenella corrodens
HACEK fight-bite Gram-negative rod
Gram −ELISA
Antigen-antibody assay concept
EMB agar concept
Green metallic sheen = E. coli
Gram −Endospore
Durable bacterial survival structure
Entamoeba histolytica
Amebic trophozoite with RBC clue
Enterobacter cloacae
Motile enteric rod with inducible AmpC
Gram −Enterobius vermicularis
Pinworm with perianal tape-test clue
Enterococcus faecalis/faecium
Bile-esculin and VRE vocabulary
Gram +Enterotoxigenic E. coli (ETEC)
Toxin-driven watery traveler's diarrhea pathotype
Gram −Enterovirus group
Nonenveloped positive-sense RNA picornaviruses
Epstein-Barr virus
B-cell tropic herpesvirus
ESBL
Extended-spectrum beta-lactamase concept
Escherichia coli
Gram-negative lactose-fermenting rod
Gram −Ethambutol
Arabinogalactan synthesis inhibitor
Exotoxin vs endotoxin
Protein toxin versus LPS lipid A concept
Gram −Fasciola hepatica
Sheep liver fluke from watercress
Flucytosine
5-FC converted to antifungal 5-FU
Fluoroquinolones
DNA gyrase/topoisomerase concept
Fonsecaea (chromoblastomycosis)
Dematiaceous mold; copper-penny sclerotic bodies
Fosfomycin
MurA inhibitor of early cell-wall synthesis
Francisella tularensis
Tularemia, rabbit/tick zoonosis, cysteine need
Gram −Fusarium species
Hyaline mold; keratitis and neutropenic fungemia
Fusobacterium necrophorum
Lemierre-syndrome anaerobe
Gram −Gardnerella vaginalis
Clue-cell bacterial vaginosis rod
Gas gangrene
Clostridial myonecrosis with tissue gas
Germ tube test
Sprout with no constriction = C. albicans
Giardia duodenalis
Flagellated protozoan with cysts
Giardiasis
Fatty, foul, floating diarrhea from water
Giemsa stain
Romanowsky stain for blood and intracellular organisms
Glycylcyclines (tigecycline)
Tetracycline derivative evading tet resistance
GMS silver stain
Silver stain making fungi and Pneumocystis black
Gram stain
First-pass bacterial sorting tool
Gram +Griseofulvin
Microtubule-disrupting keratin-depositing antifungal
Haemophilus influenzae
Small Gram-negative coccobacillus with X/V factors
Gram −Hantavirus
Bunyavirus, deer mouse, pulmonary syndrome
Healthcare-associated infection
Infection acquired in a care setting
Helicobacter pylori
Curved urease-positive gastric rod
Gram −Hepatitis A virus
Nonenveloped positive-sense RNA hepatitis virus
Hepatitis B virus
Partially double-stranded DNA virus
Hepatitis C virus
Enveloped positive-sense RNA virus
Hepatitis D virus
Defective satellite virus needing HBV
Hepatitis E virus
Waterborne enteric hepatitis, risk in pregnancy
Herd immunity
Indirect protection at high population immunity
Herpes simplex virus
Enveloped double-stranded DNA virus
Hippurate hydrolysis test
Purple color = GBS, C. jejuni, Listeria, Gardnerella
Gram +Histoplasma capsulatum
Dimorphic fungus with macrophage clue
HIV
Retrovirus with reverse transcriptase
Hookworm (Ancylostoma/Necator)
Skin-penetrating cause of iron-deficiency anemia
Horizontal gene transfer
Gene sharing between cells, not offspring
HTLV-1
Oncogenic retrovirus, ATLL and HAM/TSP
Human herpesvirus 6
Roseola infantum (sixth disease)
Human herpesvirus 8
Kaposi sarcoma-associated herpesvirus
Human metapneumovirus
RSV-like bronchiolitis and pneumonia
Human papillomavirus
Nonenveloped circular DNA virus
Immunofluorescence assay
Fluorophore-tagged antibody detection
Impetigo
Superficial crusting skin infection of children
Incubation period
Exposure-to-symptom-onset interval
India ink preparation
Negative stain that reveals a capsule halo
Indole test
Cherry-red ring = E. coli (indole positive)
Gram −Infectious mononucleosis
EBV triad: fever, pharyngitis, lymphadenopathy
Infective endocarditis
Infection of heart valves with vegetations
Influenza illness
Abrupt seasonal respiratory illness
Influenza virus
Segmented negative-sense RNA virus
Innate vs adaptive immunity
Fast nonspecific defense vs slow specific memory
Isoniazid
KatG-activated mycolic acid synthesis blocker
Japanese encephalitis virus
Culex flavivirus, pigs and birds, Asia
JC virus
Cause of PML in immunosuppression
Kingella kingae
Fastidious HACEK coccobacillus of young children
Gram −Kirby-Bauer disk diffusion
Susceptibility testing concept
Klebsiella pneumoniae
Encapsulated lactose-fermenting rod
Gram −KOH preparation
Alkali clears keratin to reveal fungal elements
Lac operon
Model of inducible gene regulation
Lactobacillus species
Doderlein vaginal-flora acid producer
Gram +Lactophenol cotton blue
Mounting stain for mold morphology
Lassa virus
Arenavirus, Mastomys rat, West Africa
Lateral flow assay
Rapid immunochromatographic strip test
Legionella pneumophila
Water-associated intracellular rod
Gram −Leishmania species
Sandfly-borne macrophage parasite
Leptospira interrogans
Question-mark spirochete; rat-urine water exposure
Lincosamides (clindamycin)
50S peptidyl-transferase blocker, anaerobe-active
Gram +Lipoglycopeptides
Lipid-tailed glycopeptides for Gram-positives
Gram +Lipopeptides (daptomycin)
Calcium-dependent membrane depolarizer
Gram +Listeria monocytogenes
Tumbling motility Gram-positive rod
Gram +Loa loa
African eye worm with Calabar swellings
Lyme disease
Tick-borne multistage spirochetal illness
Lymphocytic choriomeningitis virus
Arenavirus, house mouse, aseptic meningitis
Lysogenic vs lytic cycle
Two paths a phage can take
MacConkey agar concept
Lactose-fermentation sorting vocabulary
Gram −Macrolides
50S protein-synthesis class concept
Malaria
Anopheles-borne cyclic fever with hemolysis
Malassezia furfur
Lipophilic yeast of tinea versicolor
MALDI-TOF MS
Protein fingerprint ID concept
Marburg virus
Filovirus, cave/mine bat exposure, VHF
Measles
Rubeola: 3 C's, Koplik spots, descending rash
Measles virus
Enveloped negative-sense RNA paramyxovirus
Methyl red / Voges-Proskauer test
MR+ E. coli vs VP+ Klebsiella
Gram −Metronidazole
Anaerobe/protozoa DNA-damage concept
Minimum inhibitory concentration
MIC susceptibility vocabulary
Molluscum contagiosum virus
Umbilicated papules from a poxvirus
Monobactams (aztreonam)
Monocyclic beta-lactam, Gram-negative only
Gram −Moraxella catarrhalis
Oxidase-positive Gram-negative diplococcus
Gram −Morganella morganii
Urease- and indole-positive nosocomial enteric rod
Gram −Motility test concept
Diffuse growth from the stab = motile
MRSA
Methicillin-resistant S. aureus vocabulary
Mucor/Rhizopus group
Broad aseptate/pauci-septate hyphae clue
Mumps virus
Parotitis, orchitis, aseptic meningitis
Mycobacterium avium complex
Nontuberculous mycobacteria; disseminated in advanced HIV
Mycobacterium leprae
Acid-fast leprosy bacillus (cannot be cultured)
Mycobacterium marinum
Photochromogen of fish-tank granuloma
Mycobacterium tuberculosis
Acid-fast rod
Mycoplasma pneumoniae
No cell wall atypical bacterium
NAAT
Nucleic acid amplification test concept
Naegleria fowleri
Freshwater brain-eating free-living amoeba
Necrotizing fasciitis
Rapidly spreading deep fascial infection
Neisseria gonorrhoeae
Oxidase-positive Gram-negative diplococcus
Gram −Neisseria meningitidis
Gram-negative diplococci
Gram −Neuraminidase inhibitors
Block influenza virion release
Nitrate reduction test
Red after reagents = nitrate reduced
Gram −Nitrofurantoin
Reactive-intermediate urinary agent
Nocardia species
Branching weakly acid-fast aerobic rods
Normal flora / microbiota
Resident microbial community concept
Norovirus
Nonenveloped positive-sense RNA GI virus
Nucleoside analog antivirals
Fake nucleosides cause chain termination
Onchocerca volvulus
River blindness from blackfly bites
Optochin test
P-disk: pneumococcus sensitive, viridans resistant
Gram +Oxazolidinones (linezolid)
50S initiation-complex inhibitor for Gram-positives
Gram +Oxidase test
Cytochrome c oxidase clue
Gram −Oxygen requirement classes
How bacteria relate to oxygen
Paracoccidioides brasiliensis
Latin American dimorphic 'mariner's wheel' fungus
Paragonimus westermani
Lung fluke from undercooked crab
Parainfluenza virus
Leading cause of croup in children
Parvovirus B19
Small nonenveloped single-stranded DNA virus
Pasteurella multocida
Cat/dog bite coccobacillus, rapid cellulitis
Gram −Pasteurization
Mild heat to reduce pathogen load
PCR
Amplifies target nucleic acid
Pediculus (lice)
Blood-feeding lice; body louse is a disease vector
Pili and fimbriae
Surface appendages for attachment and transfer
Plasmid
Extrachromosomal self-replicating DNA loop
Plasmodium falciparum
Severe/cerebral malaria species
Plasmodium species
Malaria parasite with RBC stage clue
Pneumocystis jirovecii
Opportunistic fungal pneumonia vocabulary
Pneumocystis pneumonia
PCP: dry cough and hypoxia in AIDS
Poliovirus
Enterovirus of paralytic poliomyelitis
Polyenes
Ergosterol-binding antifungal concept
Polymyxins (colistin)
Cationic outer-membrane detergent
Gram −Porin
Outer-membrane channel of Gram-negatives
Gram −Prions
Misfolded protein, spongiform encephalopathy
Protease inhibitors
Block viral polyprotein cleavage
Proteus mirabilis
Urease-positive swarming rod
Gram −Pseudomonas aeruginosa
Oxidase-positive nonfermenting rod
Gram −PYR test
Red = Group A strep and Enterococcus
Gram +Pyrazinamide
Acid-pH prodrug via pncA activation
Quellung reaction
Antibody-induced capsular swelling
Quorum sensing
Cell-density chemical communication
Rabies virus
Bullet-shaped negative-sense RNA virus
Respiratory syncytial virus
Enveloped negative-sense RNA virus
Reverse transcriptase inhibitors
Block viral RNA-to-DNA copying
Rhinovirus
Nonenveloped positive-sense RNA virus
Rickettsia rickettsii
Obligate intracellular tick-borne bacterium
Rifamycins
RNA polymerase antimicrobial concept
Rocky Mountain spotted fever
Tick-borne rickettsial vasculitis with rash
Rotavirus
Segmented double-stranded RNA virus
Rubella virus
German measles and congenital rubella
Salmonella enterica
Motile non-lactose fermenting enteric rod
Gram −Sarcoptes scabiei
Burrowing mite that causes scabies
SARS-CoV-2
Enveloped positive-sense RNA coronavirus
Scedosporium species
Near-drowning mold; brain abscess opportunist
Schistosoma species
Blood flukes with snail intermediate host
Seasonal human coronaviruses
229E, NL63, OC43, HKU1 common-cold agents
Serotype and serotyping
Antigen-based strain classification
Serratia marcescens
Red-pigmented healthcare-associated rod
Gram −Shiga toxin-producing E. coli (STEC/EHEC)
Shiga-toxin pathotype linked to HUS
Gram −Shigella species
Nonmotile non-lactose fermenting rod
Gram −Sporothrix schenckii
Rose-gardener dimorphic fungus, cigar-shaped yeast
Staphylococcus aureus
Gram-positive cocci in clusters
Gram +Staphylococcus epidermidis
Coagulase-negative skin flora clue
Gram +Staphylococcus saprophyticus
Coagulase-negative, novobiocin-resistant clue
Gram +Stenotrophomonas maltophilia
Multidrug-resistant nosocomial non-fermenter
Gram −Sterilization vs disinfection
Killing all life vs reducing most microbes
Streptococcus agalactiae
Group B beta-hemolytic streptococcus
Gram +Streptococcus anginosus group
Abscess-forming viridans (milleri) streptococci
Gram +Streptococcus gallolyticus (bovis)
Group D strep linked to colon cancer
Gram +Streptococcus mutans
Dental caries viridans streptococcus
Gram +Streptococcus pneumoniae
Lancet diplococci and capsule clue
Gram +Streptococcus pyogenes
Group A beta-hemolytic streptococcus
Gram +Streptogramins
Synergistic 50S protein-synthesis blockers
Gram +Strongyloides stercoralis
Threadworm with autoinfection cycle
Sulfonamides and trimethoprim
Folate-pathway antimicrobial concept
Superantigen
Toxin that mass-activates T cells
Taenia species
Tapeworm with proglottid vocabulary
Talaromyces marneffei
Southeast Asian dimorphic fungus; fission yeast
Terbinafine (allylamine)
Squalene epoxidase inhibitor
Tetanus
Toxin-driven spastic paralysis from wounds
Tetracyclines
30S tRNA-entry class concept
Thayer-Martin agar concept
VCN-selective chocolate agar for Neisseria
Gram −Toxocara species
Dog/cat roundworm causing larva migrans
Toxoplasma gondii
Cat-associated apicomplexan clue
Toxoplasmosis
Cat / undercooked-meat protozoal infection
Transduction
Bacteriophage-carried DNA transfer
Transformation
Uptake of free environmental DNA
Transmission routes
How pathogens move between hosts
Transposon
Mobile jumping DNA element
Treponema pallidum
Spirochete with serology vocabulary
Trichinella spiralis
Encysted muscle larvae from undercooked pork
Trichomonas vaginalis
Motile flagellated protozoan
Trichosporon species
Arthroconidia-forming yeast; white piedra
Trichuris trichiura
Whipworm with barrel-shaped bipolar-plug egg
Triple sugar iron agar
Slant/butt fermentation + H2S blackening
Gram −Tropheryma whipplei
Actinobacterium of PAS-positive Whipple disease
Gram +Trypanosoma brucei
Tsetse-borne cause of African sleeping sickness
Trypanosoma cruzi
Kinetoplastid protozoan with triatomine vector
Tuberculosis
Airborne lung syndrome with latent and active forms
Typhoid fever
Enteric fever from Salmonella Typhi
Ureaplasma urealyticum
Cell-wall-free urease-positive genital mycoplasma
Urease test concept
Urea hydrolysis and pH-change vocabulary
Urinary tract infection
Lower or upper urinary infection syndrome
Vaccine types
Live, inactivated, subunit, toxoid, mRNA, vector
Vancomycin
Glycopeptide cell-wall concept
Gram +Varicella-zoster virus
Herpesvirus with latency/reactivation clue
Variola virus
Smallpox agent, eradicated in 1980
Vector, reservoir, and definitive host
Transmission ecology vocabulary
Vibrio cholerae
Comma-shaped oxidase-positive rod
Gram −Vibrio parahaemolyticus
Salt-loving seafood gastroenteritis vibrio
Gram −Vibrio vulnificus
Marine vibrio, wound and shellfish sepsis
Gram −Viral hepatitis overview
Hepatitis A-E: routes and chronicity
Viridans streptococci
Alpha-hemolytic optochin-resistant oral strep
Gram +VRE
Vancomycin-resistant enterococci
West Nile virus
Culex flavivirus, neuroinvasive, birds
Western blot
Protein-specific antibody detection by size
Whooping cough
Paroxysmal cough illness (pertussis)
Wright stain
Romanowsky blood-film stain, kin to Giemsa
Wuchereria bancrofti
Lymphatic filaria causing elephantiasis
Yellow fever virus
Aedes flavivirus, jaundice, Councilman bodies
Yersinia enterocolitica
Cold-tolerant enteric rod, pseudoappendicitis
Gram −Yersinia pestis
Flea-borne plague, safety-pin bipolar rod
Gram −Zika virus
Aedes flavivirus, congenital microcephaly
Zoonosis
Infection transmitted from animals to humans