Infectious diseases of the respiratory system

Question 1

What is otitis media?

Answer 1

Middle Ear Infection

Streptococcus pneumoniae or Haemophilus influenzae

• primarily children
• tubes for drainage

25% antibiotics prescribed to humans
biofilms & resistance

Prevnar & Hib conjugated vaccines
- appear to have lowered the incidence of infection in some populations

Question 2

What is streptococcal pharyngitis?

Answer 2

Strep Throat

pharyngitis (sore throat) are usually caused by cold viruses
direct or indirect contact with secretions

However, 30% of cases caused by Streptococcus pyogenes

• 15-20% carriers in pharynx (endogenous)
• direct or indirect contact with secretions

Question 3

What are the symptoms of strep throat?

Answer 3

inflamed pharynx & tonsils white pus nodules
fever
headache
nausea

Question 4

What are the complications from strep throat?

Answer 4

scarlet fever

• erythrogenic toxin from bacteriophage
• sandpaper-like rash on neck, chest, elbows, inner thighs
• strawberry tongue

rheumatic fever
- heart and joints

Question 5

How would you treat strep throat?

Answer 5

treat with beta-lactam antibiotic

Question 6

Why does antibiotic therapy for otitis media often fail?

Answer 6

Bacteria produce biofilms that antibiotics cannot penetrate

Question 7

What complication of streptococcal pharyngitis is characterized by a sandpaper-like rash and strawberry tongue?

Answer 7

Scarlet Fever

Question 8

What are the phases of pertussis?

Answer 8

catarrhal stage

• Bordatella pertussis
• filamentous hemagglutinin
• cold symptoms

paroxysmal stage

• tracheal cytotoxin
• severe coughing (whooping cough)
• antibiotic treatment
• pertussis toxin/endotoxin

convalescent phase
- damaged cilia (secondary infections)

Question 9

What is influenza?

Answer 9

influenza virus transmitted via respiratory secretions (direct/indirect)

prolonged cold-like symptoms with fever, aches, chills, and fatigue
“cytokine storm”
secondary bacterial pneumonias are common
36,000 deaths annually in US
mostly very young or old

Question 10

What are the characteristics of influenza?

Answer 10

enveloped RNA virus

• hemagglutinin (H)
• neuramindase (N)

neuraminidase inhibitors
- Tamiflu & Relenza

Question 11

How do viruses change slowly?

Answer 11

Antigenic drift

• seasonal flu (type B)
• accumulate mutations in hemaggluttinin (H) gene during RNA synthesis

Antigenic shift

• mixing of 8 gene segments of different flu strains (co-infection)
• pandemic flu

Question 12

What is tuberculosis?

Answer 12

Mycobacterium tuberculosis

- intracellular acid-fast bacillus

Question 13

What occurs during the primary stage of tuberculosis infection?

Answer 13

tubercles & caseous lesions

• fibroblasts, lymphocytes (granuloma), epithelioid cells
• host defenses are trying to contain the infection

Question 14

What occurs during the secondary stage of tuberculosis infection?

Answer 14

reactivation after treatment
- called consumption

extrapulmonary TB

• called dissemination
• lymph nodes, kidneys, bones, genital tract, brain, meninges

Question 15

What virulence factor causes the severe coughing symptoms, or ‘whooping cough’, associated with pertussis?

Answer 15

Tracheal cytotoxin

Question 16

Why is BCG vaccine not given to healthcare workers in US?

Answer 16

The vaccine interferes with tuberculin skin test