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Chapter 22Chapter 22Infections of the Respiratory Infections of the Respiratory
SystemSystem
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Clinical Science
• Diagnosis– Anatomical– Etiological
• Prognosis and Treatment
• Types of infections– Acute– Chronic– Persistent– Symptomatic– Asymptomatic– Local– Systemic– Primary– Secondary– mixed
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Clinical Science
• Progress of Infections– Incubation– Prodromal– Active– convalescent
Figure 22.1
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Epiglottitis
• Haemophilus influenzae– require components of blood– capsule
• pathogenic strains• resistant to phagocytosis• resistant to complement lysis
– children most vulnerable– vaccine
• Hib
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Streptococcal pharyngitis
• Streptococcus pyogenes– group A beta-hemolytic streptococcus
• group A--type of polysaccharide antigen• beta-hemolytic--type of hemolysis of blood agar
– clinical syndrome• whitish exudate covering tonsils• inflammation of pharynx• fever
– identification of bacteria• throat culture• latex agglutination detect antigens
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Complications of S. pyogenes
• scarlet fever– toxin kills cells
• septicemia– spread in the bloodstream
• Rheumatic fever– inflammation in organs/joints– heart valve damage– prevention if Strep throat is treated
• Acute poststreptococcal glomerulonephritis– inflammation in glomeruli
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Diphtheria
• Diphtheria--Corynebacterium diptheriae
– Protein toxin– Symptoms
• localized inflammatory response• membranous pharyngitis• difficulty in swallowing• swelling of lymph glands
– Vaccine• acellular• portion of DTP
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Anthrax
• Bacillus anthracis• Toxins
– Edema factor (EF) – Lethal factor (LF) – Protective antigen (PA) macrophages
• Receptor
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The Common Cold– Rhinoviruses
• 25-50% of the colds• 100+ serotypes• transmission by respiratory droplets• pathogenesis
– replication in epithelial cells– stimulate kinins-secretions– immune response clears virus
• restoration of epithelium--months• treatment: symptoms only
– other viruses• Coronaviruses (SARS)
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Pneumococcal pneumonia• Streptococcus pneumoniae
– pneumococcus• pathogenic strains--capsule• 80 serotypes
– clinical syndrome• difficult to recover from clinical samples• inhaling respiratory droplets• intense inflammation
– pneumonia
– treatment• antibiotics
– prevention• vaccine (Pneumovax)
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Other pneumonias
• Various bacteria• S. aureus, H. influenzae, Klebsiella spp, E. coli, Proteus
spp.
– secondary infection after other disease– Pathogenesis
• replication/inflammation in alveoli• inflammation leading to fluid in lungs• need healthy breathing to facilitate normal cleansing
– Treatment--antibiotic
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Atypical pneumonias
• Primary atypical pneumonia– Mycoplasma pneumoniae– no cell wall
• Chlamydial Pneumonia– Chlamydia psitacci– exposure to sick birds
• Q Fever– Coxiella burnetii– Rare, almost never causes death
• Legionellosis– Legionella pneumophila– natural and artificial water supplies– multiplies intracellularly
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Pertussis
• Whooping cough• Bordatella pertussis
– Pathogenesis• replication of bacteria• production of toxins
– Symptoms• characteristic cough (whooping)• cold symptoms• vomiting (intense cough)
– vaccine• acellular vaccine (DPT)
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Tuberculosis• Mycobacterium tuberculosis
– pathogenesis• inflammation and lesions of lung
tissue• cellular immune (TC) response• slow growth rate
– Symptoms• varies• primary lesions• can spread to various tissues
– Treatment• prolonged multiple antibiotics (6
months)
– Increase incidence (drug resistance)
Figure 22.9
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Influenza (flu)
• Influenza virus types A, B, C– Epidemiology
• annual epidemics and occasional pandemics– antigenic drift and antigenic shift
– Symptoms• virus inhaled• 1-3 days after exposure• sudden onset of fever 102-104oF• malaise, headache, muscle ache, cough
– Treatment• uncomplicated recovery in few weeks• prevent secondary infections--pneumonia, • immunization
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Bronchitis
• Croup– Parainfluenza virus– Symptoms
• loud, barking cough
• Bronchiolitis– Respiratory syncytial virus– Paramyxovirus
• Subtype B: asymptomatic strains
• Subtype A: predominate in most outbreaks
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Hantavirus Pulmonary Syndrome
• May 1993 outbreak– Four corners area of Southwest US– 70% victims died
• many healthy• lung failure
– capillaries leaked-filling air space
– Identified virus• Sin Nombre virus• new strain of Hantavirus
– reservoir• deer mice and other rodents
– isolates• worldwide
Figure 22.12
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Fungal Infections
• Histoplasmosis– Histoplasma
capsulatum– dimorphic– distribution
• worldwide• certain areas
– 1% infected become ill
Figure 22.13
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Fungal Infections
• Coccidioidomycosis– semiarid climates– spores inhaled into
alveoli
Figure 22.14
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Fungal infections
• Blastomycosis– humans and animals– clinical syndrome
• resembles tuberculosis
• distant organs--skin, bone, testes
• Pneumocystic pneumonia (PCP)– AIDS associated
• rarely seen before 1980’s
• most common cause of death with AIDS
– cysts in lung