Microbiology confusion pairs
35 Microbiology topics students commonly mix up on Step 1, each with the fastest separator, a side-by-side comparison, and a free practice question.
- Pneumococcus and viridans streptococci vs Group A and Group B StreptococcusAlpha hemolysis splits by optochin; beta hemolysis splits by Group A pharyngitis versus Group B neonate.
- Staphylococcus aureus vs Coagulase-negative staphylococciCoagulase positive means aureus; coagulase negative splits by novobiocin and clinical setting.
- Escherichia coli vs Klebsiella and EnterobacterE coli is indole-positive UTI; Klebsiella is capsule mucoid pneumonia; Enterobacter is hospital AmpC resistance.
- Salmonella vs ShigellaSalmonella is motile and H2S-positive; Shigella is nonmotile, H2S-negative, and low-dose contagious.Video
- Salmonella Typhi vs Nontyphoidal SalmonellaTyphi is systemic enteric fever and human reservoir; nontyphoidal Salmonella is animal-food gastroenteritis.
- Vibrio cholerae vs Other pathogenic Vibrio speciesCholera is water plus rice-water diarrhea; vulnificus is raw oysters/seawater plus sepsis or wounds; parahaemolyticus is seafood…
- Campylobacter jejuni vs Salmonella and ShigellaCampylobacter is curved/poultry/GBS; Salmonella is H2S-positive; Shigella is low-dose nonmotile dysentery.
- Helicobacter pylori vs Campylobacter jejuniH pylori is urease-positive stomach ulcer disease; Campylobacter is poultry-associated inflammatory diarrhea.
- Clostridioides difficile and C perfringens vs C botulinum and C tetaniDifficile is pseudomembranes, perfringens is gas/alpha toxin, botulinum is flaccid, tetani is spastic.
- Listeria monocytogenes vs Group B StreptococcusListeria is foodborne rod with tumbling motility; GBS is maternal-colonization coccus with CAMP positivity.
- Neisseria meningitidis vs Neisseria gonorrhoeaeMeningitidis ferments glucose and maltose and causes meningitis; gonorrhoeae ferments glucose only and causes STI disease.Video
- Haemophilus influenzae type b vs Nontypeable Haemophilus influenzaeHib: encapsulated and invasive (meningitis, epiglottitis), vaccine-preventable; nontypeable H influenzae: unencapsulated, causes mucosal…
- Bordetella pertussis vs Mycoplasma pneumoniaePertussis: paroxysmal whooping cough with lymphocytosis; Mycoplasma: gradual walking pneumonia with cold agglutinins.
- Pseudomonas aeruginosa vs Stenotrophomonas maltophiliaPseudomonas is oxidase-positive blue-green fruity water/burn/CF pathogen; Stenotrophomonas is broad-antibiotic ICU nonfermenter…
- Legionella vs Mycoplasma and Chlamydia pneumoniaeLegionella is severe water-linked pneumonia with GI/CNS signs and hyponatremia; Mycoplasma is walking pneumonia with cold agglutinins;…Video
- Mycobacterium tuberculosis vs Mycobacterium leprae and avium complexTuberculosis is airborne granulomatous lung disease; leprae is skin-nerve disease; MAC is environmental disseminated disease in very low…
- Chlamydia trachomatis A-C vs Chlamydia trachomatis D-K and L1-3A-C is eye scarring trachoma; D-K is mucosal urogenital or neonatal infection; L1-3 is invasive lymphogranuloma venereum with painful nodes.
- Treponema pallidum vs Borrelia and LeptospiraTreponema is sexual or congenital syphilis; Borrelia is tick-linked Lyme or relapsing fever; Leptospira is animal-urine or freshwater…
- Rickettsia vs Coxiella and BartonellaRickettsia is arthropod vasculitic rash disease; Coxiella is aerosol livestock Q fever without classic vector bite; Bartonella is cat or…
- Plasmodium falciparum vs Other Plasmodium speciesFalciparum is severe high-parasitemia malaria; vivax and ovale relapse from hypnozoites; malariae is chronic quartan disease; knowlesi is…Video
- Trypanosoma cruzi vs Trypanosoma bruceiCruzi is Latin America reduviid bug Chagas with heart and GI dilation; brucei is tsetse fly African sleeping sickness with lymph nodes and…
- Visceral leishmaniasis vs Cutaneous and mucocutaneous leishmaniasisVisceral leishmaniasis is fever, pancytopenia, and huge spleen; cutaneous disease is skin ulcer; mucocutaneous disease destroys nasal or…
- Toxoplasma gondii vs CryptosporidiumToxoplasma is cat or meat exposure with brain or congenital disease; Cryptosporidium is acid-fast waterborne watery diarrhea, severe in…
- Entamoeba histolytica vs Giardia and CryptosporidiumEntamoeba is invasive dysentery and liver abscess; Giardia is greasy malabsorption; Cryptosporidium is watery acid-fast diarrhea in…
- Taenia solium vs Taenia saginataSolium is pork and cysticercosis risk; saginata is beef intestinal tapeworm without neurocysticercosis.
- Schistosoma haematobium vs Schistosoma mansoni and japonicumHaematobium is urinary hematuria and bladder cancer; mansoni and japonicum are intestinal liver-portal disease.
- Echinococcus vs TaeniaEchinococcus is dog-linked hydatid liver/lung cysts; Taenia is pork/beef intestinal tapeworm or solium neurocysticercosis.
- Candida vs CryptococcusCandida is pseudohyphae mucosal or catheter yeast; Cryptococcus is encapsulated yeast causing meningitis with antigen or India ink clues.
- Aspergillus vs MucoralesAspergillus is septate acute-angle hyphae and cavity/neutropenia disease; Mucor is broad right-angle hyphae with DKA and necrotic eschar.Video
- Pneumocystis jirovecii vs CryptococcusPneumocystis is low-CD4 diffuse hypoxemic pneumonia; Cryptococcus is encapsulated yeast meningitis with high opening pressure.
- HSV and VZV vs CMV and EBVHSV/VZV are sensory-neuron vesicle viruses; CMV is owl-eye immunosuppression/congenital disease; EBV is CD21 B-cell mono and malignancy.
- High-risk HPV vs Low-risk HPVHigh-risk HPV causes dysplasia and cancer through E6/E7; low-risk HPV causes warts and papillomas.
- Hepatitis B virus vs Hepatitis A, C, D, and E virusesHBV is DNA with reverse transcriptase and serology staging; HAV/HEV are fecal-oral acute RNA; HCV is chronic bloodborne RNA; HDV requires…
- Norovirus vs RotavirusNorovirus is abrupt outbreak vomiting in all ages; rotavirus is severe infant watery diarrhea with segmented dsRNA and vaccine prevention.
- DNA viruses vs RNA virusesDNA viruses mostly replicate in nucleus; RNA viruses mostly replicate in cytoplasm, with poxvirus, influenza, and retrovirus as key…