Bugs and Drugs High Yield Summary (AI)

Vibrio cholerae high yield summary

Gram-negative curved rod; oxidase positive; requires NaCl for growth; serogroups O1 & O139 produce cholera toxin (A-B toxin ↑cAMP → massive watery diarrhea); diagnosis via stool culture, PCR, toxin assays; treatment is aggressive fluid/electrolyte replacement + doxycycline/azithromycin; virulence factors = cholera toxin, toxin co-regulated pilus, accessory toxins; clinical = profuse “rice-water” diarrhea, dehydration, epidemics/pandemics; unique trait = very high infectious dose, endemic in 50+ countries.

Vibrio parahaemolyticus high yield summary

Gram-negative curved rod; halophilic (requires salt); oxidase positive; diagnosis via stool culture, Kanagawa hemolysin detection; treatment supportive, antibiotics shorten course; virulence = thermostable direct hemolysin (Kanagawa toxin), type III secretion system; clinical = seafood-associated gastroenteritis (watery diarrhea), wound infections; unique trait = most common cause of seafood gastroenteritis in US/Japan.

Vibrio vulnificus high yield summary

Gram-negative curved rod; halophilic; oxidase positive; capsule present; diagnosis via wound/blood culture; treatment = doxycycline or minocycline + 3rd gen cephalosporin; virulence = polysaccharide capsule, cytolysins, proteases; clinical = wound infections, rapidly fatal septicemia esp. in liver disease patients; unique trait = very high mortality, associated with raw oysters/saltwater exposure.

Campylobacter jejuni high yield summary

Gram-negative curved “comma-shaped” rod; oxidase positive; grows at 42°C; diagnosis via stool culture, PCR; treatment supportive, macrolides for severe disease; virulence = LOS (lipooligosaccharide) mimics GM1 ganglioside → Guillain-Barré; clinical = inflammatory diarrhea (bloody), fever, abdominal pain; unique trait = leading cause of bacterial gastroenteritis worldwide, post-infectious reactive arthritis.

Helicobacter pylori high yield summary

Gram-negative curved rod with polar flagella; urease positive; diagnosis via urea breath test, stool antigen, biopsy; treatment = triple therapy (PPI + clarithromycin + amoxicillin/metronidazole); virulence = urease, CagA, VacA; clinical = gastritis, peptic ulcers, gastric adenocarcinoma, MALT lymphoma; unique trait = survives acidic stomach via urease, colonizes gastric mucosa.

Escherichia coli (ETEC, EHEC, UPEC, EIEC, EAEC) high yield summary

Gram-negative rod; lactose fermenter, oxidase negative; diagnosis via stool PCR/EIA, urine culture; treatment supportive, antibiotics for UTI; virulence varies: ETEC = CFA adhesins + LT/ST toxins → watery traveler’s diarrhea; EHEC = Shiga toxin + attaching/effacing lesions → bloody diarrhea, HUS (O157:H7, sorbitol negative); UPEC = P fimbriae adhesins → cystitis/pyelonephritis; EIEC = invasion genes like Shigella → dysentery; EAEC = AAF adhesins + SHET-1 toxin → persistent diarrhea, biofilm; unique trait = most versatile enteric pathogen, major cause of UTIs and diarrheal syndromes.

Enterobacter high yield summary

Gram-negative rod; lactose fermenter; opportunistic nosocomial pathogen; diagnosis via culture; treatment = carbapenems or resistant-directed therapy; virulence = capsule, antimicrobial resistance; clinical = hospital-acquired pneumonia, UTI, bacteremia esp. in neonates/immunocompromised; unique trait = frequent cause of catheter-related infections.

Klebsiella pneumoniae high yield summary

Gram-negative rod; large capsule → mucoid colonies; lactose fermenter; diagnosis via culture; treatment = carbapenems unless KPC (carbapenemase) resistant; virulence = capsule, siderophores, resistance genes; clinical = lobar pneumonia with “currant jelly” sputum, UTI, wound infections; unique trait = KPC resistance mechanism, prominent capsule.

Proteus vulgaris high yield summary

Gram-negative rod; highly motile “swarming” colonies; urease positive; diagnosis via urine culture; treatment = antibiotics guided by susceptibility; virulence = urease → ↑pH → struvite stones; clinical = UTI, pyelonephritis, staghorn calculi; unique trait = produces large amounts of urease, stone formation.

Salmonella (S. typhi, S. paratyphi) high yield summary

Gram-negative rod; non-lactose fermenter; motile; diagnosis via stool/blood culture, serotyping; treatment = fluoroquinolones, ceftriaxone, azithromycin; virulence = type III secretion systems, Vi capsule (S. typhi); clinical = gastroenteritis (watery diarrhea, fever), enteric fever (typhoid: fever, rose spots, relative bradycardia, hepatosplenomegaly), bacteremia; unique trait = chronic gallbladder carriage with S. typhi.

Shigella high yield summary

Gram-negative rod; non-motile; non-lactose fermenter; very low infectious dose (10–100); diagnosis via stool culture, PCR; treatment = ciprofloxacin or TMP-SMX; virulence = type III secretion system, Shiga toxin (esp. S. dysenteriae); clinical = dysentery (bloody diarrhea, cramps, tenesmus), fever; unique trait = epidemic dysentery with Sd1, post-infectious reactive arthritis.

Yersinia pestis high yield summary

Gram-negative rod; bipolar “safety pin” staining; zoonotic (rats, fleas); diagnosis via stain/culture; treatment = gentamicin + fluoroquinolone; virulence = T3SS Yop proteins, capsule; clinical = bubonic plague (painful buboes, fever), pneumonic plague (cough, hemoptysis, dyspnea); unique trait = >90% mortality untreated pneumonic plague.

Yersinia enterocolitica high yield summary

Gram-negative rod; cold tolerant, grows at 4°C; loves iron; diagnosis via stool culture, PCR; treatment supportive, antibiotics for severe cases; virulence = T3SS Yop proteins; clinical = gastroenteritis in children, mesenteric adenitis mimicking appendicitis, post-infectious arthritis/erythema nodosum; unique trait = transfusion-related bacteremia/endotoxic shock.

Listeria monocytogenes high yield summary

Gram-positive coccobacillus; tumbling motility; cold tolerant, grows at 4°C; diagnosis via culture, PCR; treatment = ampicillin + gentamicin; virulence = internalins, listeriolysin O, ActA for actin motility; clinical = neonatal sepsis/meningitis, meningitis in immunocompromised, gastroenteritis; unique trait = survives in refrigerated foods, transplacental spread.

Streptococcus pyogenes (Group A beta hemolytic) high yield summary

Gram-positive cocci in chains; catalase negative; beta-hemolytic; virulence = M protein, hyaluronic acid capsule, streptolysins, streptokinase, DNases, pyrogenic exotoxins; diagnosis via throat swab culture, rapid antigen, ASO titers; treatment = beta-lactams; clinical = pharyngitis, scarlet fever, cellulitis, necrotizing fasciitis, toxic shock; nonsuppurative = rheumatic fever (antigenic mimicry), post-strep glomerulonephritis; unique trait = “flesh-eating bacteria.”

Streptococcus agalactiae (Group B beta hemolytic) high yield summary

Gram-positive cocci in chains; catalase negative; beta-hemolytic; virulence = polysaccharide capsule, sialic acid surface; diagnosis via PCR/culture of vaginal/rectal swab; treatment = beta-lactams; clinical = neonatal sepsis, pneumonia, meningitis; infections in pregnant women (UTI, endometritis); unique trait = neonatal disease due to lack of maternal antibodies.

Enterococcus (Gamma hemolytic) high yield summary

Gram-positive cocci in pairs/chains; catalase negative; gamma (no hemolysis); NaCl and bile resistant; virulence = biofilm formation, adhesins, intrinsic antibiotic resistance; diagnosis via culture/PCR; treatment = penicillin/ampicillin + aminoglycoside synergy, vancomycin; clinical = nosocomial infections: UTI, bacteremia, endocarditis, intra-abdominal infections; unique trait = VRE (vancomycin-resistant enterococcus), “cockroach” of hospital pathogens.

Viridans streptococci (Alpha hemolytic) high yield summary

Gram-positive cocci in chains; catalase negative; alpha-hemolytic; optochin resistant; virulence = dextran polysaccharides for adherence; diagnosis via culture; treatment = beta-lactams, vancomycin; clinical = dental caries, periodontal disease, endocarditis (native/prosthetic valves), head/neck infections; unique trait = normal oral flora, can seed bloodstream during dental procedures.

Streptococcus pneumoniae (Pneumococcus, alpha hemolytic) high yield summary

Gram-positive “lancet-shaped” diplococci; catalase negative; alpha-hemolytic; optochin sensitive; virulence = polysaccharide capsule, pneumolysin, IgA protease, teichoic acid; diagnosis via Gram stain/culture, urine antigen, PCR; treatment = beta-lactams, macrolides, fluoroquinolones; clinical = lobar pneumonia with “rust-colored” sputum, sinusitis, otitis media, meningitis, bacteremia; unique trait = major risk in asplenic patients; prevention = polysaccharide/conjugate vaccines.

Haemophilus influenzae high yield summary

Gram-negative coccobacilli; fastidious, requires chocolate agar with factors X (hemin) and V (NAD); virulence = PRP capsule (type b most virulent), pili, IgA protease, beta-lactamase; diagnosis via Gram stain, culture, PCR; treatment = beta-lactamase stable beta-lactams, macrolides, fluoroquinolones; clinical = pneumonia, meningitis, epiglottitis, sinusitis, otitis media, conjunctivitis; unique trait = Hib vaccine dramatically reduced invasive disease in children.

Moraxella catarrhalis high yield summary

Gram-negative diplococci; resembles H. influenzae clinically; less virulent; diagnosis via culture; treatment = beta-lactams, macrolides; clinical = otitis media, sinusitis, bronchitis, pneumonia (esp. COPD exacerbations); unique trait = “H. flu want-to-be.”

Legionella pneumophila high yield summary

Gram-negative slender rods; poor staining; fastidious, requires BCYE agar with cysteine and iron; virulence = facultative intracellular in macrophages, type IV secretion, proteolytic enzymes; diagnosis via urine antigen (serogroup 1), culture; treatment = macrolides, fluoroquinolones, rifampin; clinical = Legionnaires’ disease (severe pneumonia, diarrhea, CNS dysfunction, high mortality), Pontiac fever (self-limited flu-like illness); unique trait = water-based transmission (cooling towers, hot tubs, biofilms in amoebae).

Bordetella pertussis high yield summary

Gram-negative coccobacilli; fastidious, grows on Bordet-Gengou or Regan-Lowe agar; virulence = pertussis toxin (↑cAMP, mucus), adenylate cyclase toxin, tracheal cytotoxin, fimbriae, pertactin, BrkA; diagnosis via PCR, culture difficult; treatment = macrolides; clinical = whooping cough: catarrhal → paroxysmal (severe cough, inspiratory “whoop,” post-tussive emesis, lymphocytosis) → convalescent; unique trait = highly contagious, no animal reservoir, cyclical epidemics.

Corynebacterium diphtheriae high yield summary

Gram-positive club-shaped rods; non-spore forming; grows on selective media; virulence = diphtheria toxin (inhibits EF-2 → protein synthesis arrest); diagnosis via culture, toxin detection (Elek test, PCR); treatment = antitoxin + antibiotics; clinical = pharyngitis with pseudomembrane, bull neck, myocarditis, neuropathy; unique trait = vaccine-preventable (DTaP/Tdap).

Pseudomonas aeruginosa high yield summary

Gram-negative aerobic rod; non-fermenter; produces pyocyanin (green pigment), grape-like odor; virulence = quorum sensing, biofilm (alginate), exotoxin A, elastases, hemolysins, type III secretion; diagnosis via culture, PCR; treatment = advanced anti-pseudomonal agents (piperacillin-tazobactam, ceftazidime, carbapenems, fluoroquinolones, aminoglycosides); clinical = nosocomial pneumonia, UTI, bacteremia, wound/burn infections, otitis externa, hot-tub folliculitis, ecthyma gangrenosum; unique trait = opportunistic pathogen, high mortality in immunocompromised.

Staphylococcus aureus high yield summary

Gram-positive cocci in clusters; catalase positive, coagulase positive, beta-hemolytic; virulence = Protein A, MSCRAMMs, capsule, PVL toxin, enterotoxins, TSST-1, exfoliative toxins; diagnosis via Gram stain, culture (mannitol salt agar turns yellow), PCR for MRSA; treatment = beta-lactams, vancomycin for MRSA; clinical = skin abscesses, impetigo, pneumonia (post-influenza), endocarditis, osteomyelitis, food poisoning, toxic shock, scalded skin syndrome; unique trait = grape-like clusters, golden colonies, “spider bite” MRSA outbreaks.

Staphylococcus epidermidis high yield summary

Gram-positive cocci in clusters; catalase positive, coagulase negative; gamma/non-hemolytic; virulence = thick biofilm/slime layer; diagnosis via culture (often contaminant); treatment = resistant to many beta-lactams, vancomycin; clinical = infections of prosthetic joints, valves, catheters, pacemakers; unique trait = ubiquitous skin flora, opportunistic device-related pathogen.

Staphylococcus saprophyticus high yield summary

Gram-positive cocci in clusters; catalase positive, coagulase negative; virulence = adherence to uroepithelium; diagnosis via urine culture; treatment = antibiotics for UTI; clinical = cystitis in young sexually active women; unique trait = second most common cause of UTI after E. coli.

Neisseria meningitidis high yield summary

Gram-negative diplococci; oxidase and catalase positive; grows on chocolate agar; encapsulated; virulence = polysaccharide capsule, LOS endotoxin, pili, IgA protease; diagnosis via Gram stain/PCR of CSF/blood, culture; treatment = ceftriaxone/cefotaxime; prevention = vaccines (A, C, Y, W135, B), chemoprophylaxis for contacts; clinical = meningitis (fever, headache, neck stiffness), meningococcemia with petechial/purpuric rash, Waterhouse-Friderichsen syndrome; unique trait = epidemics in “meningitis belt,” risk ↑ in asplenia/complement deficiency.

Neisseria gonorrhoeae high yield summary

Gram-negative diplococci; oxidase and catalase positive; grows on chocolate/Thayer-Martin agar; no capsule; virulence = pili, Opa proteins, Por proteins, LOS endotoxin, IgA protease, antigenic variation; diagnosis via NAAT (PCR), Gram stain of urethral exudate; treatment = ceftriaxone + doxy/azithro for chlamydia coverage; prevention = condoms, silver nitrate/erythromycin eye drops for neonates; clinical = urethritis in men, cervicitis/PID in women, neonatal conjunctivitis, disseminated infection → septic arthritis, tenosynovitis, skin lesions; unique trait = most common cause of septic arthritis in young adults.

Treponema pallidum (syphilis) high yield summary

Thin spirochete; not visible on Gram stain, seen by dark field or DFA; cannot be cultured; virulence = immune evasion, fibronectin binding, hemolysins; diagnosis via dark field microscopy, serology (RPR/VDRL, FTA-ABS, TP-PA); treatment = penicillin (desensitize if allergic); clinical = primary (painless chancre), secondary (rash incl. palms/soles, condyloma lata), latent, tertiary (tabes dorsalis, aortitis, gummas, Argyll Robertson pupil), congenital (Hutchinson teeth, saddle nose, saber shins); unique trait = causes vasculitis of vasa vasorum.

Lyme borreliosis (Borrelia burgdorferi) high yield summary

Spirochete; poor Gram stain, seen with dark field; transmitted by Ixodes tick; virulence = OspA (tick midgut binding), OspC (transmission to mammals), complement regulator binding proteins; diagnosis = clinical (erythema migrans), ELISA + Western blot for IgM/IgG; treatment = doxycycline/amoxicillin (early), ceftriaxone (late/neuro); clinical = early localized (erythema migrans, flu-like), early disseminated (Bell’s palsy, AV block, meningitis, migratory arthritis), late (chronic arthritis, neuropathy); unique trait = erythema migrans “bull’s-eye” rash, Bell’s palsy, AV block.

Leptospira interrogans (leptospirosis) high yield summary

Tightly coiled spirochete; seen by dark field, DFA, silver stain; grows slowly in special media; zoonotic, shed in urine of mammals (dogs, rats, livestock); virulence = immune-mediated damage; diagnosis via serology (microscopic agglutination test), culture of blood/CSF/urine; treatment = doxycycline, ceftriaxone; clinical = biphasic illness: flu-like fever, myalgias, conjunctival suffusion → Weil’s disease (jaundice, renal failure, hemorrhage, thrombocytopenia); unique trait = survives in water/soil for weeks, infection via contaminated water/urine.

Clostridium difficile (C. diff) high yield summary

Gram-positive spore-forming anaerobic rod; virulence = Toxin A (enterotoxin, neutrophil chemotaxis, ↑ permeability, diarrhea), Toxin B (cytotoxin, actin depolymerization, cell death); diagnosis = stool toxin PCR/ELISA; treatment = oral vancomycin, fecal transplant for recurrence; clinical = watery diarrhea, pseudomembranous colitis, toxic megacolon; unique trait = recent antibiotic exposure main risk, spores survive in environment.

Clostridium perfringens high yield summary

Gram-positive anaerobic rod, weak spore former; double zone beta hemolysis; virulence = alpha toxin (lecithinase → massive hemolysis, tissue destruction), beta toxin (necrotizing enteritis), enterotoxin (superantigen, fluid loss); diagnosis = Gram stain/culture; treatment = high-dose penicillin, surgical debridement, hyperbaric oxygen; clinical = gas gangrene (myonecrosis, shock, death

Clostridium tetani (tetanus) high yield summary

Gram-positive spore-forming anaerobic rod; virulence = tetanospasmin (blocks inhibitory neurotransmitters GABA/glycine → spastic paralysis); diagnosis = clinical; treatment = TIG (tetanus immunoglobulin), penicillin, benzodiazepines; prevention = toxoid vaccine (Tdap, boosters q10y); clinical = generalized tetanus (lockjaw, risus sardonicus, opisthotonus), localized tetanus, neonatal tetanus; unique trait = spores in soil, “rusty nail” injury.

Clostridium botulinum (botulism) high yield summary

Gram-positive spore-forming anaerobic rod; virulence = botulinum toxin (cleaves SNARE proteins → blocks ACh release → flaccid paralysis); diagnosis = clinical, toxin detection, EMG; treatment = antitoxin, supportive care; prevention = food safety, avoid honey in infants; clinical = foodborne botulism (descending paralysis, blurred vision, dry mouth), infant botulism (floppy baby), wound botulism; unique trait = most potent toxin known, used in bioterrorism.

Anaerobic colonic gram negative rods high yield summary

Gram-negative short rods; obligate anaerobes; normal colonic flora (~90%); virulence = LPS endotoxin; diagnosis = culture under anaerobic conditions; treatment = metronidazole, beta-lactam/beta-lactamase inhibitor; clinical = intra-abdominal abscesses, bite infections, head/neck infections; unique trait = Bacteroides, Fusobacterium, Porphyromonas, Prevotella common genera.

Actinomyces high yield summary

Gram-positive branching anaerobic rods; normal oral flora; virulence = chronic infection with sulfur granules; diagnosis = culture, microscopy; treatment = penicillin, surgical drainage; clinical = cervicofacial infections (“lumpy jaw”), slow-growing abscesses, sinus tracts; unique trait = produces sulfur granules in pus.

Mycoplasma pneumoniae high yield summary

No cell wall, sterol-containing membrane; stains poorly; extracellular pathogen; virulence = P1 adhesin → ciliostasis, superantigen activity; diagnosis = PCR, serology; treatment = macrolides, tetracyclines, fluoroquinolones; clinical = tracheobronchitis, “walking pneumonia” (atypical, prolonged cough, mild x-ray findings), complications = myringitis, encephalitis, hemolytic anemia; unique trait = epidemics every 6–8 years, resistant to beta-lactams.

Genital mycoplasma high yield summary

No cell wall; species = M. genitalium, M. hominis, Ureaplasma; virulence = adhesins, immune evasion; diagnosis = NAAT; treatment = macrolides, tetracyclines, fluoroquinolones; clinical = nongonococcal urethritis, cervicitis, PID, pyelonephritis, postpartum fever, spontaneous abortion; unique trait = similar presentation to Chlamydia, colonization common in sexually active individuals.

Chlamydia (general) high yield summary

Obligate intracellular Gram-negative; unique biphasic life cycle (elementary body infectious, reticulate body replicative); virulence = intracellular survival, immune evasion; diagnosis = NAAT; treatment = macrolides, tetracyclines; clinical = conjunctivitis, pneumonia, urogenital infections; unique trait = cannot synthesize ATP, requires host cell.

Chlamydophila pneumoniae high yield summary

Obligate intracellular Gram-negative; virulence = intracellular survival; diagnosis = PCR, serology; treatment = macrolides, tetracyclines; clinical = atypical pneumonia, bronchitis, pharyngitis, sinusitis; unique trait = person-to-person respiratory transmission, possible association with atherosclerosis.

Chlamydia trachomatis high yield summary

Obligate intracellular Gram-negative; virulence = MOMP serovars, intracellular life cycle; diagnosis = NAAT; treatment = macrolides, tetracyclines; clinical = trachoma (A–C serovars, blindness), urogenital infections (D–K serovars, NGU, cervicitis, PID), neonatal conjunctivitis/pneumonia, lymphogranuloma venereum (L1–L3 serovars, painless ulcer → lymphadenitis); unique trait = #1 bacterial STD worldwide.

Rickettsia rickettsii (RMSF) high yield summary

Gram-negative obligate intracellular; poor Gram stain, seen with Giemsa; virulence = phospholipase to escape phagosome, infects vascular endothelium → vasculitis; diagnosis = serology (IFA), PCR; treatment = doxycycline; clinical = fever, headache, myalgia, rash (palms/soles), complications = meningitis, myocarditis, septic shock; unique trait = tick vector (Dermacentor), most severe spotted fever.

Rickettsia parkeri high yield summary

Gram-negative obligate intracellular; virulence = similar to RMSF but milder; diagnosis = serology, PCR; treatment = doxycycline; clinical = mild spotted fever, sparse rash, eschar at tick bite; unique trait = Amblyomma maculatum tick vector, SE US and South America.

Rickettsia prowazekii high yield summary

Gram-negative obligate intracellular; virulence = infects endothelium, causes vasculitis; diagnosis = serology, PCR; treatment = doxycycline; clinical = epidemic typhus (fever, rash spreading trunk → extremities, meningoencephalitis), recrudescent typhus, sporadic typhus; unique trait = louse-borne, associated with refugee populations, flying squirrels in US.

Ehrlichia chaffeensis (Human Monocytic Ehrlichiosis, HME) high yield summary

Gram-negative obligate intracellular; infects monocytes; virulence = morulae in mononuclear cells; diagnosis = PCR, serology; treatment = doxycycline; clinical = fever, headache, myalgia, rash (30%, esp. children), cytopenias, ↑ LFTs; unique trait = Lone Star tick vector, more severe in elderly/immunocompromised/splenectomy.

Ehrlichia ewingii high yield summary

Gram-negative obligate intracellular; infects granulocytes; virulence = morulae in granulocytes; diagnosis = PCR, serology; treatment = doxycycline; clinical = similar to HME but less severe, rash uncommon; unique trait = Lone Star tick vector, rare in US.

Anaplasma phagocytophilum (Human Granulocytic Anaplasmosis, HGA) high yield summary

Gram-negative obligate intracellular; infects neutrophils; virulence = morulae in granulocytes, cytokine release; diagnosis = PCR, serology; treatment = doxycycline; clinical = fever, headache, myalgia, cytopenias, ↑ LFTs, rash rare; unique trait = Ixodes tick vector, Upper Midwest/NE US endemic.

Brucellosis (Brucella spp.) high yield summary

Gram-negative coccobacilli; facultative intracellular; difficult to culture; virulence = survival in macrophages, granulomatous response; transmission = unpasteurized milk/cheese, animal contact; diagnosis = serology, culture (slow); treatment = doxycycline + rifampin; clinical = undulating fever, sweats, weight loss, hepatosplenomegaly, lymphadenopathy; unique trait = chronic relapsing course, occupational hazard (farmers, abattoir workers).

Tularemia (Francisella tularensis) high yield summary

Gram-negative coccobacillus; facultative intracellular; highly virulent; transmission = rabbits, ticks, deer flies, inhalation, ingestion; diagnosis = serology, PCR, culture (special media); treatment = streptomycin, gentamicin; clinical = ulceroglandular (skin ulcer + lymphadenopathy), typhoidal, oculoglandular, pneumonic; unique trait = potential bioterrorism agent, “rabbit fever.”

Q Fever (Coxiella burnetii) high yield summary

Small pleomorphic Gram-negative, obligate intracellular; phase I antigen highly infectious; transmission = aerosols from birthing animals (sheep, goats, cattle, cats); diagnosis = serology (phase I/II antibodies), PCR; treatment = doxycycline; clinical = flu-like illness, pneumonia, hepatitis, chronic endocarditis; unique trait = extremely infectious (single organism sufficient), bioterrorism potential.

Plague (Yersinia pestis) high yield summary

Gram-negative coccobacillus, bipolar “safety pin” staining; virulence = capsule, type III secretion system; reservoir = rodents, fleas; transmission = flea bites, direct animal contact, pneumonic person-to-person; diagnosis = culture, PCR; treatment = aminoglycosides, doxycycline; clinical = bubonic plague (painful buboes), septicemic plague, pneumonic plague (hemoptysis, high mortality); unique trait = historical pandemics, bioterrorism agent.

Bacillus anthracis (Anthrax) high yield summary

Gram-positive spore-forming rod; non-motile; virulence = poly-D-glutamate capsule, exotoxins (protective antigen, edema factor, lethal factor); transmission = spores from hides, wool, meat; diagnosis = culture, PCR; treatment = ciprofloxacin, doxycycline; clinical = cutaneous anthrax (black eschar), inhalational anthrax (mediastinal widening, pleural effusion, shock), GI anthrax; unique trait = spores survive for months, bioterrorism agent.

Cat Scratch Fever (Bartonella henselae) high yield summary

Gram-negative bacillus; transmission = cat bite/scratch, kittens; diagnosis = serology, PCR; treatment = azithromycin; clinical = papule at inoculation site, regional lymphadenopathy, fever; rare dissemination = liver/spleen abscesses, encephalitis, retinitis; unique trait = most common zoonotic infection in US.

Pasteurella multocida high yield summary

Gram-negative coccobacillus; facultative anaerobe; virulence = capsule, endotoxin, iron requirement; transmission = dog/cat bites, scratches, licking wounds; diagnosis = culture; treatment = penicillin, doxycycline; clinical = rapidly progressive cellulitis, abscesses, septicemia in immunocompromised, pneumonia in chronic lung disease; unique trait = common bite wound pathogen.

Lyssavirus (Rabies) high yield summary

Bullet-shaped rhabdovirus; transmission = saliva from infected mammals (bats in US, dogs worldwide); pathogenesis = retrograde axonal transport to CNS; diagnosis = DFA of brain tissue, PCR; treatment = post-exposure prophylaxis (vaccine + immunoglobulin); clinical = encephalitis, hydrophobia, agitation, paralysis, coma, death; unique trait = nearly 100% fatal once symptomatic.

Mycobacterium tuberculosis (TB) high yield summary

Acid-fast bacillus; waxy cell wall (mycolic acids); virulence = cord factor, sulfatides (inhibit phagolysosome fusion); transmission = airborne droplets; diagnosis = AFB smear/culture, PCR (GeneXpert), TST/IGRA for latent; treatment = RIPE regimen (rifampin, isoniazid, pyrazinamide, ethambutol); clinical = pulmonary TB (cough, hemoptysis, cavitary upper lobe lesions, night sweats, weight loss), extrapulmonary TB (meningitis, Pott’s disease, miliary TB); unique trait = latent vs active disease, synergy with HIV.

Leprosy (Hansen’s Disease, Mycobacterium leprae) high yield summary

Acid-fast bacillus; obligate intracellular; prefers cooler tissues (skin, peripheral nerves); transmission = prolonged close contact; diagnosis = clinical, biopsy, PCR; treatment = dapsone + rifampin ± clofazimine (long-term); clinical = tuberculoid (few hypoesthetic plaques, low bacterial load), lepromatous (diffuse, leonine facies, high bacterial load), borderline; unique trait = nerve damage → loss of sensation, infections from unnoticed injuries.

Nontuberculous Mycobacteria (NTM, e.g. M. avium complex MAC) high yield summary

Acid-fast bacilli; environmental reservoirs (soil, water); no person-to-person spread; virulence = intracellular survival; diagnosis = repeated positive AFB cultures, PCR; treatment = macrolides + ethambutol + rifampin (species-dependent); clinical = pulmonary disease (bronchiectasis, fibrocavitary lesions), disseminated disease in HIV (fever, weight loss, diarrhea, lymphadenitis), skin/soft tissue infections; unique trait = >180 species, MAC common in AIDS patients.

Superficial Fungal Infections (Tineas) high yield summary

Caused by dermatophytes (Trichophyton, Microsporum, Epidermophyton); infect keratinized tissues (skin, hair, nails); diagnosis = KOH prep of skin scraping → branching septate hyphae; treatment = topical azoles/terbinafine, oral agents for severe cases; clinical = tinea pedis (athlete’s foot), tinea capitis, tinea corporis (ringworm), tinea cruris (jock itch), tinea unguium (onychomycosis); unique trait = superficial, non-invasive, common worldwide.

Blastomycosis (Blastomyces dermatitidis) high yield summary

Dimorphic fungus; endemic in SE/central US, Great Lakes, St. Lawrence River; transmission = inhalation of conidia from soil/decaying vegetation; diagnosis = broad-based budding yeast (8–15 µm, thick walls), urine antigen; treatment = amphotericin B for severe, itraconazole for mild/moderate; clinical = pneumonia (acute/chronic), disseminated disease to skin (ulcerative lesions), bone, GU tract; unique trait = mimics malignancy, broad-based buds.

Histoplasmosis (Histoplasma capsulatum) high yield summary

Dimorphic fungus; endemic in Ohio/Mississippi River valleys, Mexico, Central America; transmission = inhalation of spores from bird/bat droppings (spelunking, construction); diagnosis = small yeast with narrow-based budding inside macrophages, urine antigen; treatment = amphotericin B (severe), itraconazole (mild/moderate); clinical = mostly asymptomatic, pneumonia, disseminated disease (esp. HIV, immunocompromised); unique trait = intracellular yeast in macrophages.

Coccidioidomycosis (Coccidioides immitis/posadasii) high yield summary

Dimorphic fungus; endemic in SW US (Arizona, California), Mexico, South America; transmission = inhalation of arthroconidia from desert soil (dust storms, archaeology, military maneuvers); diagnosis = spherules with endospores on histology, serology (complement fixation); treatment = amphotericin B or azoles (itraconazole, fluconazole for CNS); clinical = pneumonia, disseminated disease (skin, bone, CNS), erythema nodosum; unique trait = “Valley fever,” spherules with endospores.

Paracoccidioidomycosis (Paracoccidioides brasiliensis/lutzii) high yield summary

Dimorphic fungus; endemic in Central/South America; transmission = inhalation; diagnosis = yeast with multiple buds in “captain’s wheel” or “Mickey Mouse ears” pattern; treatment = itraconazole, amphotericin B, TMP-SMX; clinical = pulmonary disease, mucocutaneous lesions, disseminated disease; unique trait = “pilot wheel” appearance.

Sporotrichosis (Sporothrix schenckii) high yield summary

Dimorphic fungus; transmission = inoculation via trauma (rose gardening, landscaping, cats, armadillos); diagnosis = cigar-shaped yeast on histology, culture; treatment = itraconazole (cutaneous), amphotericin B for disseminated; clinical = nodular lymphangitis (lesions spread along lymphatics), disseminated disease in immunocompromised; unique trait = “rose gardener’s disease.”

Candida (Candida albicans + non-albicans spp.) high yield summary

Yeast; normal flora (GI, skin); virulence = pseudohyphae, biofilm formation; diagnosis = budding yeast + pseudohyphae (“sausage links”), culture; treatment = echinocandins (empiric), azoles, amphotericin B; clinical = mucosal infections (oral thrush, esophagitis, vaginitis), invasive candidemia, hepatosplenic abscesses; unique trait = most common invasive fungal infection in hospitalized patients, C. auris emerging MDR pathogen.

Cryptococcus (Cryptococcus neoformans, gattii) high yield summary

Encapsulated yeast; transmission = inhalation of spores from soil/bird droppings, eucalyptus trees; virulence = polysaccharide capsule, neurotropism; diagnosis = India ink stain (encapsulated yeast, narrow-based budding), cryptococcal antigen (CSF, serum); treatment = amphotericin B + flucytosine, then fluconazole; clinical = meningitis (esp. HIV), pneumonia, cutaneous lesions; unique trait = encapsulated yeast, India ink positive.

Aspergillus (A. fumigatus, flavus, terreus, niger) high yield summary

Mold; ubiquitous spores; virulence = angioinvasion → infarction; diagnosis = septate hyphae with acute angle branching, galactomannan antigen; treatment = voriconazole (first-line), amphotericin B, echinocandins; clinical = invasive pulmonary aspergillosis (fever, cough, hemoptysis, halo sign, air crescent sign), allergic bronchopulmonary aspergillosis, aspergilloma (fungus ball); unique trait = halo sign on CT, angioinvasion.

Mucormycosis (Rhizopus, Mucor, etc.) high yield summary

Mold; ubiquitous spores; risk factors = diabetes (DKA), hematologic malignancy, neutropenia; diagnosis = broad, non-septate hyphae with right-angle branching; treatment = lipid amphotericin B, posaconazole/isavuconazole, surgical debridement; clinical = rhinocerebral infection (sinusitis, orbital involvement, CNS), pneumonia, disseminated disease; unique trait = “ribbon-like” hyphae, sinusitis in DKA patients.

Pneumocystis jirovecii (PCP) high yield summary

Opportunistic fungus; transmission = inhalation, latent infection common; risk = HIV (CD4