Comprehensive Pathogen Vocabulary

43 vocabulary flashcards summarizing key pathogens, their microbe type, major virulence, transmission, treatment, and associated disease.

Haemophilus influenzae type b (Hib)

Gram-negative coccobacillus; encapsulated, crosses the blood–brain barrier to cause meningitis; spread by respiratory droplets; treated with third-generation cephalosporins.

Neisseria meningitidis

Gram-negative diplococcus with capsule and endotoxin; infects blood and CNS producing meningitis; transmitted via droplets; therapy is cephalosporin plus vancomycin.

Listeria monocytogenes

Gram-positive rod; listeriolysin O and actin rocket-tails let it invade CNS and placenta; food-borne; ampicillin ± gentamicin for listeriosis.

Clostridium botulinum

Gram-positive anaerobe; botulinum toxin blocks acetylcholine at neuromuscular junctions causing flaccid paralysis (botulism); from improperly canned food; give antitoxin and supportive care.

Clostridium tetani

Gram-positive anaerobe; tetanospasmin blocks inhibitory neurotransmitters leading to spastic paralysis (tetanus); enters via dirty wounds; prevented by vaccine, treated with TIG and wound care.

Mycobacterium leprae

Acid-fast rod that invades Schwann cells causing peripheral neuropathy (leprosy); spread by prolonged skin contact; treated with dapsone plus rifampin.

Trypanosoma brucei

Hemoflagellate protozoan; antigenic variation allows persistence in blood and CNS (African sleeping sickness); transmitted by tsetse fly; treated with antiparasitic drugs (e.g., suramin, melarsoprol).

Naegleria fowleri

Free-living amoeba entering via cribriform plate to brain, leading to primary amebic meningoencephalitis (PAM); contracted from warm freshwater; almost uniformly fatal, no reliable therapy.

Rabies virus

Enveloped ssRNA-negative rhabdovirus; travels retrograde by axons to CNS causing fatal encephalitis; from animal bites; post-exposure prophylaxis with rabies immunoglobulin and vaccine.

Prion (PrP^Sc)

Misfolded protein that templates further misfolding, producing spongiform degeneration of neurons (CJD/vCJD); transmitted by contaminated tissue; no effective treatment.

Streptococcus pyogenes – Rheumatic fever

Gram-positive group A streptococcus; M-protein cross-reactivity and SPEs trigger autoimmune attack on heart and joints; follows untreated strep throat; penicillin prevents rheumatic fever.

Francisella tularensis

Gram-negative intracellular rod; survives in macrophages causing ulceroglandular tularemia; caught from ticks or rabbits; treated with streptomycin or gentamicin.

Brucella species

Gram-negative coccobacilli; facultative intracellular within RES producing undulant fever (brucellosis); acquired from unpasteurized dairy or livestock; doxycycline plus rifampin therapy.

Bacillus anthracis

Gram-positive spore-forming rod; edema (EF), lethal (LF) and protective antigen (PA) toxins cause cutaneous, inhalational or GI anthrax; spores inhaled or through skin; treated with ciprofloxacin or doxycycline.

Clostridium perfringens

Gram-positive anaerobe; α-toxin (lecithinase) destroys muscle leading to gas gangrene; introduced via traumatic wounds; requires surgical debridement and hyperbaric O₂.

Bartonella henselae

Gram-negative rod inhabiting RBCs; causes granulomatous lymphadenitis (cat-scratch disease); transmitted by cat scratches; usually self-limited but azithromycin speeds recovery.

Yersinia pestis

Gram-negative rod with capsule, Yops and Pla proteins; infects lymph nodes and lungs producing bubonic or pneumonic plague; spread by flea bites; doxycycline or streptomycin used for treatment.

Borrelia burgdorferi

Spirochete; immune complex deposition leads to arthritis and neurologic signs in Lyme disease; transmitted by Ixodes deer tick; first-line therapy is doxycycline.

Rickettsia rickettsii

Obligate intracellular bacterium; replicates in endothelium causing vasculitis and rash of Rocky Mountain spotted fever; acquired via tick bite; doxycycline is drug of choice.

Trypanosoma cruzi

Protozoan that invades cardiac and GI smooth muscle causing Chagas disease; vector is reduviid (kissing) bug; treated with benznidazole or nifurtimox.

Toxoplasma gondii

Protozoan forming tissue cysts; reactivation in CNS or congenital infection; contracted from cat feces or undercooked meat; prophylaxis/therapy with TMP-SMX or pyrimethamine-sulfadiazine.

Plasmodium species

Protozoan; cyclic RBC lysis and cerebral sequestration cause malaria; spread by Anopheles mosquitoes; treated with artemisinin-based combination therapy (ACT).

Schistosoma species

Blood flukes; eggs trigger granulomas in liver or bladder (schistosomiasis); cercariae penetrate skin in freshwater; praziquantel is curative.

Streptococcus pyogenes – Pharyngitis

Gram-positive group A coccus; streptolysins and capsule inflame pharynx leading to strep throat; droplet spread; penicillin prevents suppurative and rheumatic complications.

Corynebacterium diphtheriae

Gram-positive club-shaped rod; diphtheria toxin inhibits EF-2 causing pharyngeal pseudomembranes and myocarditis; respiratory spread; antidiphtheria antitoxin plus penicillin or erythromycin.

Bordetella pertussis

Gram-negative coccobacillus; pertussis toxin disables Gi, paralyzing cilia and producing whooping cough; transmitted via droplets; macrolides shorten course; vaccination prevents.

Mycobacterium tuberculosis

Acid-fast rod; caseating granulomas form in lungs causing TB; airborne transmission; treated with RIPE (rifampin, isoniazid, pyrazinamide, ethambutol).

Streptococcus pneumoniae

Gram-positive lancet diplococcus; capsule and pneumolysin lead to lobar pneumonia and meningitis; spread via droplets; β-lactams (e.g., penicillin, ceftriaxone) used.

Chlamydia psittaci

Obligate intracellular bacterium; causes atypical pneumonia (psittacosis) from inhaling bird droppings; tetracycline is treatment.

Influenza virus

Segmented ssRNA enveloped orthomyxovirus; HA/NA proteins undergo antigenic drift/shift causing seasonal and pandemic flu; spread by droplets; neuraminidase inhibitors (oseltamivir) useful early.

SARS-CoV-2

+ssRNA enveloped coronavirus; binds ACE2 in lungs producing COVID-19; transmitted by respiratory droplets/aerosols; mainstay is supportive care and antivirals when indicated.

Histoplasma capsulatum

Dimorphic fungus; inhaled spores convert to intramacrophage yeast causing histoplasmosis; linked to bat/bird droppings; treated with itraconazole (or amphotericin for severe).

Pneumocystis jirovecii

Opportunistic fungus; foamy alveolar exudate leads to PCP pneumonia in immunocompromised; airborne; prophylaxis/therapy with TMP-SMX.

Escherichia coli – UTI

Gram-negative rod with P-fimbriae enabling ascension of urinary tract causing cystitis/pyelonephritis; treated with nitrofurantoin or fluoroquinolones depending on severity.

Leptospira interrogans

Spirochete; biphasic illness, severe form is Weil’s disease with jaundice, renal failure, hemorrhage; acquired from water contaminated by animal urine; doxycycline for prophylaxis and treatment.

Neisseria gonorrhoeae

Gram-negative diplococcus; pili and antigenic variation aid mucosal invasion causing gonorrhea; sexually transmitted; treated with ceftriaxone (plus azithromycin for chlamydial coinfection).

Chlamydia trachomatis

Obligate intracellular bacterium with elementary/reticulate bodies; causes cervicitis, urethritis, PID; sexually transmitted; doxycycline or azithromycin cures.

Treponema pallidum

Spirochete with stealthy outer membrane enabling immune evasion; causes syphilis (primary, secondary, tertiary, congenital); transmitted sexually or transplacentally; long-acting penicillin G is definitive therapy.

Herpes simplex virus type 2

Enveloped dsDNA virus establishing latency in sacral ganglia; reactivation causes painful genital ulcers; sexually transmitted; acyclovir/valacyclovir shorten outbreaks.

Human papillomavirus 6/11/16/18

Non-enveloped DNA virus; E6/E7 oncoproteins inactivate p53/Rb, producing warts and cervical/anal cancers; spread sexually; prevented by recombinant vaccine.

Gardnerella vaginalis

Gram-variable rod forming vaginal biofilm; overgrowth after dysbiosis yields bacterial vaginosis (fishy discharge, clue cells); treated with metronidazole.

Candida albicans

Opportunistic yeast; overgrowth on mucosal surfaces causes vulvovaginal candidiasis (thick white discharge); endogenous flora imbalance; fluconazole therapy.

Trichomonas vaginalis

Flagellated protozoan; proteases damage vaginal epithelium producing foul-smelling green discharge; sexually transmitted; metronidazole treats patient and partners.