1. Respiratory System Infections
Chapter 22

2. Respiratory System Most common entry point for infections Upper tract
Mouth, nasal cavity, sinuses, pharynx
Lower tract
epiglottis, larynx, trachea, bronchi, bronchioles and lung tissue

5. Protection Nasal hair Tonsils (adenoids) Mucus Ciliated mucus membrane
Involuntary responses (coughing, etc.)
Alveolar macrophages

6. Normal flora Limited to the upper tract Mostly Gram positive
S. aureus, alpha and non-hemolytic streptococci, diptheriods, Haemophilus influenzae and Moraxella catarrhalis

7. Streptococcal Pharyngitis
Strep throat
Causative agent
Streptococcus pyogenes
Β-hemolytic group A streptococcus

8. Signs & Symptoms Difficulty swallowing Fever, malaise, headache
Red throat with pus patches
Enlarged tender lymph nodes
Localized to neck
Most patients recover in a week or so

9. Complications of infection can occur during acute illness
Laryngitis
Bronchitis
Scarlet fever (Scarlatina)

10. Scarlet fever Strains infected with specific phage Erythrogenic toxin
Sandpaper-like rash
Spreads from chest across body
Strawberry red tongue with white coating
Skin peels away similar to scaled skin syndrome
Children are at higher risk

11. Complications that can develop later
Rheumatic fever
Glomerulonephritis
Necrotizing fasciitis

12. Rheumatic fever M protein in cell wall allows pathogen to persist
Autoimmune response
Antibodies cross react with heart cell antigens
Damage heart valves (endocarditis) and muscle
Arthritis, nodules over bony surfaces under skin

13. Glomerulonephritis Body fails to remove antigen-antibody complexes
Accumulate in glomeruli of the kidneys
Triggers inflammation obstructing blood flow
High blood pressure and low urine output
Irreversible kidney damage possible

14. Epidemiology (of Strep throat)
Humans only host
Spread by respiratory droplets
Sore throats (with fever) should be cultured
Beta hemolysis and serotype determination should be made for streptococci
Peak incidence occurs in winter or spring
Highest in grade school children

15. Prevention Treatment No vaccine available Adequate ventilation
Avoid crowds
Treatment
Penicillin, erythromycin or cephalosporin

16. Diphtheria Causative agent Corynebacterium diphtheria Gram variable
Pleomorphic
Non-spore forming
Metachromatic granules

17. Signs & Symptoms mild sore throat, slight fever, fatigue and malaise
Dramatic neck swelling
Pseudo-membrane forms in mouth, on tonsils or pharynx
Phage infected strains release diphtheria toxin
Toxin is produced in low iron environments

18. Not very invasive bacteria
Exotoxin released into bloodstream
Results in damage to heart, nerves and kidneys
Very potent toxin
Small amount inactivates large population of cells which explains potency
Even with treatment 1 in 10 patents die

19. Epidemiology Humans primary reservoir
Spread through direct/droplet contact transmission
Reservoir of infection include
Recovered and asymptomatic carriers
People with active disease
Diagnosed by immunoassay to detect circulating toxins

20. Prevention Treatment Immunization Immunity not lifelong
DTaP
Immunity not lifelong
Booster should be given every 10 years
Treatment
Open blocked airways
Antitoxin must be given early
No effect on absorbed toxin
Penicillin and erythromycin to eliminate bacteria

21. Sinusitis and Otitis Media
Bacterial infection
Streptococcus pneumoniae; Haemophilus influenza; Moraxella catarrhalis; Staphylococcus aureus
Viral infections
Non-infectious allergies are the cause of many sinus infections

22. Signs & Symptoms Mild fever Extreme ear pain (ear drum may rupture)
Effusion
Severe malaise
Headache

23. Epidemiology Begins with infection of nasopharynx
Spreads upward to sinuses or up Eustachian tubes
Sinusitis occurs in more in adults
Otitis Media occurs more often in children
Predisposing factors
damage to the ciliated mucus membrane

24. Prevention and treatment
No proven prevention for sinusitis
Prevention of otitis media involves influenza and pneumococcal vaccines
Tubes installed to avoid recurrent infections
Antibiotics for established bacterial cause
Penicillin like Amoxicillin

25. Common Cold Rhinitis Causative agent 30% to 50% caused by rhinovirus
More than 100 types of rhinovirus
Member of picornavirus family

26. Signs & Symptoms Malaise, scratchy mild sore throat, runny nose
Cough and hoarsness (laryngitis)
Nasal secretion
Initially profuse and watery
Later, thick and purulent
No fever

27. Injured cells produce inflammation which stimulates profuse nasal secretion, sneezing and tissue swelling
Infection halted by inflammation, interferon release and immune response
Increased risk for secondary bacterial infections!

28. Epidemiology Humans are only reservoir
Aerosols, fomites, direct contact transmission
Close contact with infected person or secretions necessary
No proven relationship between exposure to cold temperature and disease

29. Prevention Treatment No vaccine Hand washing Keep hands away from face
Avoid crowds during times when colds are prevalent
Treatment
Certain antiviral medications showing promise
Pleconaril
Must be taken at first onset of symptoms