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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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Respiratory System

Figure 22.2

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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