Major Bacterial Infections of Humans – Vocabulary Flashcards

A set of vocabulary flashcards covering essential bacterial pathogens, diseases, and key virulence terms discussed in the lecture on major bacterial infections of humans.

Propionibacterium acnes

Anaerobic Gram-positive bacillus that causes acne.

Bacillus anthracis

Spore-forming Gram-positive bacillus responsible for anthrax (woolsorter disease).

Clostridium perfringens

Anaerobic, spore-forming Gram-positive bacillus most commonly causing gas gangrene (myonecrosis).

Mycobacterium leprae

Acid-fast bacillus causing leprosy (Hansen disease).

Staphylococcus aureus

Gram-positive coccus linked to folliculitis, furuncles, abscesses, cellulitis, and toxin-mediated illnesses such as TSS, scalded-skin syndrome, and food poisoning.

Streptococcus pyogenes

Beta-hemolytic Gram-positive coccus causing impetigo, erysipelas, strep throat, scarlet fever, necrotizing fasciitis, rheumatic fever, and post-streptococcal glomerulonephritis.

Otitis externa

External ear canal infection (swimmer’s ear) commonly due to E. coli, Pseudomonas aeruginosa, Proteus spp., or Staphylococcus aureus.

Otitis media

Middle ear infection most often caused by Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis; may also be viral.

Haemophilus influenzae biogroup aegyptius

Gram-negative bacillus frequently responsible for bacterial conjunctivitis (pinkeye).

Chlamydia trachomatis serotypes A–C

Obligate intracellular Gram-negative bacteria causing trachoma (chlamydial keratoconjunctivitis).

Chlamydia trachomatis serotypes D–K

Cause inclusion (chlamydial) conjunctivitis and genital chlamydiasis.

Neisseria gonorrhoeae

Gram-negative diplococcus causing gonorrhea and gonococcal conjunctivitis (ophthalmia neonatorum).

Corynebacterium diphtheriae

Pleomorphic Gram-positive bacillus producing diphtheria toxin that causes diphtheria of the upper respiratory tract.

Streptococcus pneumoniae

Gram-positive diplococcus; leading cause of community-acquired pneumonia, otitis media, and conjunctivitis.

Legionella pneumophila

Poorly staining Gram-negative bacillus spread via environmental water aerosols; causes Legionnaires’ disease and Pontiac fever.

Mycoplasma pneumoniae

Cell wall-less bacterium causing primary atypical (walking) pneumonia transmitted by respiratory droplets.

Mycobacterium tuberculosis

Acid-fast bacillus causing tuberculosis; spread by airborne droplets.

Bordetella pertussis

Encapsulated Gram-negative coccobacillus producing toxins that cause whooping cough (pertussis).

Fusobacterium nucleatum

Anaerobic Gram-negative bacillus commonly involved with Treponema vincentii in acute necrotizing ulcerative gingivitis (trench mouth).

Helicobacter pylori

Curved microaerophilic Gram-negative bacillus associated with gastritis and peptic ulcers.

Campylobacter jejuni

Curved or spiral Gram-negative bacillus causing campylobacter enteritis acquired from poultry and other animals.

Vibrio cholerae O1

Curved Gram-negative bacillus that secretes cholera toxin causing profuse watery diarrhea via fecal-oral transmission.

Salmonella spp.

Gram-negative enteric bacilli causing salmonellosis through intestinal invasion, endotoxin release, and toxin production.

Salmonella typhi

Gram-negative bacillus causing typhoid fever; humans are the principal reservoir and carriers may persist.

Shigella dysenteriae

Non-motile Gram-negative bacillus causing shigellosis (bacillary dysentery); related species include S. flexneri, S. boydii, S. sonnei.

Enterohemorrhagic E. coli (EHEC) O157:H7

Strain of E. coli producing potent cytotoxins that cause hemorrhagic colitis and HUS; often linked to cattle feces.

Enterotoxigenic E. coli (ETEC)

E. coli strains producing heat-labile or heat-stable enterotoxins that cause traveler’s diarrhea; spread by fecal-oral route.

Urinary tract infection (UTI)

Infection of the urinary system most commonly caused by E. coli; can be healthcare-associated or community-acquired.

Treponema pallidum

Thin, tightly coiled spirochete causing syphilis; transmitted sexually, transplacentally, or via blood.

Haemophilus ducreyi

Gram-negative coccobacillus that causes chancroid, a genital ulcer disease.

Calymmatobacterium granulomatis

Gram-negative bacterium responsible for granuloma inguinale (donovanosis).

Lymphogranuloma venereum

STD caused by Chlamydia trachomatis serotypes L1–L3 that produces genital ulcers and inguinal lymphadenitis.

Rickettsia rickettsii

Obligate intracellular Gram-negative bacterium transmitted by ticks causing Rocky Mountain spotted fever (spotted fever rickettsiosis).

Rickettsia typhi

Flea-borne Gram-negative rickettsia causing endemic (murine) typhus.

Rickettsia prowazekii

Louse-borne rickettsia responsible for epidemic typhus fever.

Ehrlichia chaffeensis

Obligate intraleukocytic Gram-negative bacterium causing human monocytic ehrlichiosis transmitted by ticks.

Borrelia burgdorferi

Loosely coiled spirochete transmitted by Ixodes ticks that causes Lyme disease.

Yersinia pestis

Nonmotile bipolar-staining Gram-negative coccobacillus causing plague (bubonic, septicemic, pneumonic) transmitted by rodent fleas.

Francisella tularensis

Pleomorphic Gram-negative coccobacillus causing tularemia, often acquired from rabbits through tick bites.

Listeria monocytogenes

Gram-positive coccobacillus acquired from contaminated foods causing listeriosis, particularly meningitis in neonates and immunocompromised.

Clostridium tetani

Motile anaerobic spore-forming Gram-positive bacillus producing tetanospasmin toxin that causes tetanus (lockjaw).

Clostridium botulinum

Anaerobic spore-forming Gram-positive bacillus whose neurotoxin causes botulism and wound botulism.

Clostridium difficile

Anaerobic spore-forming Gram-positive bacillus causing antibiotic-associated diarrhea and pseudomembranous colitis.

Endotoxin

Lipopolysaccharide component of Gram-negative cell walls that triggers fever, inflammation, and shock.

Exotoxin

Protein toxin secreted by bacteria (e.g., cytotoxins, enterotoxins, neurotoxins) that damages host tissues.

Enterotoxin

Type of exotoxin that targets intestinal mucosa, leading to secretory diarrhea (e.g., cholera toxin, ETEC toxins).

Biofilm

Structured microbial community within a self-produced polymeric matrix attached to a surface; associated with persistent infections.

Necrotizing fasciitis

Rapidly progressive soft-tissue infection with widespread necrosis, commonly due to Streptococcus pyogenes or mixed flora.

Immunosuppression (bacterial factor)

Virulence mechanism whereby bacteria suppress host immune responses to enhance their survival and spread.

Complement evasion

Strategies used by bacteria to prevent activation or action of the complement cascade, aiding resistance to serum killing.

Phagocytic escape

Bacterial ability to avoid ingestion or killing by white blood cells, often via capsules, toxins, or intracellular survival.