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Respiratory System Infections

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Presentation on theme: "Respiratory System Infections"— Presentation transcript:

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

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