Bacterial Infections

Question 1

What makes Listeria monocytogenes unique among foodborne pathogens?

Answer 1

Gram+, grows in cold (fridge risk)

Targets: Pregnant (amnionitis/stillbirth), neonates (granulomatosis infantiseptica), immunocompromised (meningitis)

Question 2

How does Listeria present in neonates?

Answer 2

Granulomatosis infantiseptica: Rash + sepsis

Meningitis (exudative)

Question 3

What type of inflammation does Listeria cause?

Answer 3

Suppurative inflammation (neutrophil-dominated)

Question 4

What are the CSF findings in Listeria meningitis?

Answer 4

Acute pyogenic pattern with Gram(+) bacilli

Question 5

What are the 3 key neonatal manifestations of Listeria?

Answer 5

Papular red rash (extremities)

Placental abscesses

Meconium with Gram(+) bacilli

Question 6

Which populations are most vulnerable to severe Listeria?

Answer 6

Pregnant women (amnionitis/stillbirth)

Neonates (granulomatosis infantiseptica)

Immunocompromised (meningitis)

Question 7

What is the mechanism of diphtheria toxin?

Answer 7

ADP-ribosylation of EF-2 → inhibits protein synthesis → cell death

Question 8

What characterizes the respiratory form of diphtheria?

Answer 8

Gray-black pseudomembrane (fibrinosuppurative exudate) that can obstruct airways

Question 9

What are the 5 main organs affected in systemic diphtheria?

Answer 9

Heart (fatty change/myofiber necrosis)

Nerves (demyelination)

Liver (fatty change)

Kidneys (necrosis)

Adrenals (necrosis)

Question 10

How does cutaneous diphtheria present?

Answer 10

Chronic ulcers with dirty gray membrane

Question 11

What bacterium causes whooping cough?

Answer 11

Bordetella pertussis

Question 12

What are the 3 clinical stages of pertussis?

Answer 12

Catarrhal (mild cold symptoms)

Paroxysmal (severe coughing fits with “whoop”)

Convalescent (gradual recovery)

Question 13

What pathological change occurs in the airways?

Answer 13

Laryngotracheobronchitis with mucosal erosion and inflammation

Question 14

What are 5 key infections caused by P. aeruginosa?

Answer 14

CF pulmonary infections

Burn wound sepsis

Contact lens keratitis

Swimmer’s ear (otitis externa)

Ecthyma gangrenosum

Question 15

What is the characteristic lung pathology?

Answer 15

“Fleur-de-lis” necrotizing pneumonia (pale necrotic centers + hemorrhagic rims)

Question 16

What skin lesion suggests pseudomonal sepsis?

Answer 16

Ecthyma gangrenosum (oval necrotic-hemorrhagic lesions)

Question 17

What immune cells are crucial for TB defense?

Answer 17

CD4+ T cells (Th1 response)

Question 18

What’s the difference between TB pathology in immunocompetent vs immunocompromised?

Answer 18

Normal immunity: Caseating granulomas

Weak immunity: No granulomas, unchecked bacterial growth

Question 19

What characterizes Primary TB lesions?

Answer 19

Ghon focus: Consolidation (lower part of upper lobe or upper part of lower lobe)

Ghon complex: Ghon focus + pulmonary hilar node involvement

Ranke complex: Healed, calcified Ghon complex

Question 20

What are Primary TB sequelae?

Answer 20

Healing by fibrosis (in immunocompetent individuals with anti-TB therapy)

Latency → reactivation (with immune compromise)

Progressive primary TB

Question 21

Describe Progressive Primary TB lesions

Answer 21

Resembles acute bacterial pneumonia

Lobar consolidation

Hilar adenopathy

Pleural effusion

Question 22

Progressive Primary TB sequelae?

Answer 22

Miliary pulmonary TB

Question 23

Secondary TB lesion?

Answer 23

Simon focus: Apical consolidation

Question 24

Secondary TB sequelae?

Answer 24

Healing by fibrosis

Localized cascating destructive lesions

Progressive secondary TB

Question 25

Progressive Secondary TB lesions?

Answer 25

Spread into adjacent lung → erosion into bronchi/vessels → cavitation Pleural involvement: effusions, empyema, obliterative fibrous pleuritis

Question 26

Progressive Secondary TB sequelae?

Answer 26

Healing by fibrosis Miliary pulmonary TB

Question 27

Miliary pulmonary TB lesions?

Answer 27

Scattered small foci of consolidation throughout lungs

Question 28

Miliary pulmonary TB sequelae?

Answer 28

Systemic Miliary TB

Question 29

What is the most common extrapulmonary TB manifestation?

Answer 29

Lymphadenitis (Scrofula)

Question 30

What is TB osteomyelitis called when it affects vertebrae?

Answer 30

Pott disease

Question 31

Which part of the GI tract is most commonly affected by TB?

Answer 31

Ileum

Question 32

What are the two forms of hematogenously spread TB?

Answer 32

Disseminated TB (multiple organs) Miliary TB (specific pattern)

Question 33

How is miliary TB pathologically identified?

Answer 33

Multiple small, yellow-white foci scattered throughout organ parenchyma

Question 34

What patient population gets disseminated MAI infection?

Answer 34

Profoundly immunocompromised patients

Question 35

Histologic hallmark of MAI infection?

Answer 35

Macrophages filled with acid-fast bacilli

Question 36

What organism causes leprosy?

Answer 36

Mycobacterium leprae

Question 37

Compare tuberculoid vs lepromatous leprosy immunity

Answer 37

Tuberculoid: Intact cell-mediated immunity Lepromatous: Depressed cell-mediated immunity

Question 38

Nerve involvement in both leprosy forms

Answer 38

Tuberculoid: Asymmetric Lepromatous: Symmetric

Question 39

Lepromin skin test results

Answer 39

Tuberculoid: Positive Lepromatous: Negative

Question 40

Histology of tuberculoid leprosy

Answer 40

Granulomatous inflammation around nerves

Question 41

Histology of lepromatous leprosy

Answer 41

Macrophages (Lepra cells) filled with acid-fast bacilli (Globi)

Question 42

Causative organism of syphilis

Answer 42

Treponema pallidum

Question 43

Two key histologic features of syphilis

Answer 43

Plasma cell-rich inflammation Obliterative endarteritis

Question 44

What is the hallmark lesion of primary syphilis?

Answer 44

Painless anogenital chancre (heals spontaneously)

Question 45

Name 3 features of secondary syphilis

Answer 45

Mucocutaneous lesions Condyloma lata (broad-based plaques) Systemic symptoms (fever, malaise, lymphadenopathy)

Question 46

What is condyloma lata?

Answer 46

Broad-based, painless plaques in secondary syphilis

Question 47

What organs are affected in tertiary syphilis?

Answer 47

Aorta, CNS, Liver, Bones, Testes

Question 48

What is a gumma?

Answer 48

Granuloma with central coagulative necrosis surrounded by plasma cells

Question 49

When does congenital syphilis occur?

Answer 49

During maternal primary/secondary syphilis (high organism burden)

Question 50

Name 3 classic congenital syphilis stigmata

Answer 50

Saddle nose deformity Hutchinson teeth Saber shin

Question 51

What triad makes up Hutchinson's syndrome?

Answer 51

Interstitial keratitis + Hutchinson teeth + 8th nerve deafness

Question 52

What are the screening tests for syphilis?

Answer 52

Non-treponemal tests (RPR, VDRL)

Question 53

When are false-positive RPR/VDRL results seen?

Answer 53

Pregnancy, autoimmune disorders, other infections

Question 54

What causes false-negative RPR/VDRL?

Answer 54

Prozone phenomenon (antibody excess prevents flocculation)

Question 55

What are the confirmatory tests for syphilis?

Answer 55

Treponemal tests (FTA-ABS, MHA-TP)

Question 56

What organisms are included in Rickettsial diseases?

Answer 56

Rickettsia, Orientia, Ehrlichia, Anaplasma

Question 57

Match the disease to its vector: Epidemic typhus Scrub typhus RMSF Ehrlichiosis Anaplasmosis

Answer 57

Lice Chigger mites Dog tick Lone star tick Deer tick

Question 58

What is the main pathogenic mechanism of Rickettsial infections?

Answer 58

Endothelial cell infection → vasculitis → endothelial injury

Question 59

What are the histologic findings in Rickettsial infections?

Answer 59

Vasculitis with mononuclear inflammation ± necrosis, thrombosis, hemorrhage

Question 60

What is the major fatal complication of RMSF?

Answer 60

ARDS from pulmonary vasculitis

Question 61

What causes Lemierre syndrome?

Answer 61

Fusobacterium necrophorum → thrombophlebitis of jugular vein

Question 62

What anaerobes commonly cause: Head/neck infections Abdominal infections Female genital infections

Answer 62

Prevotella/Porphyromonas Bacteroides + E. coli Prevotella + E. coli/GBS

Question 63

What does C. perfringens cause?

Answer 63

Gas gangrene (wounds/uterus), food poisoning, bowel sepsis

Question 64

Why is C. septicum gangrene concerning?

Answer 64

Associated with underlying malignancy

Question 65

How does tetanus present?

Answer 65

Spastic paralysis from toxin in wounds/neonatal stumps

Question 66

What disease does C. botulinum cause and what type of paralysis?

Answer 66

Botulism - flaccid paralysis

Question 67

How does C. botulinum typically grow to cause disease?

Answer 67

In inadequately cooked/preserved foods (anaerobic conditions)

Question 68

What condition does C. difficile cause?

Answer 68

Pseudomembranous colitis

Question 69

When does C. difficile proliferate to cause disease?

Answer 69

When normal gut bacteria are reduced by antibiotics

Question 70

Compare C. botulinum vs C. difficile:

Answer 70

Botulinum: Foodborne, neurotoxin → flaccid paralysis Difficile: Antibiotic-associated, colon toxin → pseudomembranous colitis