Microbiology: A Systems Approach, 2nd ed'

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Microbiology A Systems Approach, 2nd ed.

• Chapter 21 Infectious Diseases Affecting the
  Respiratory System

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21.1 The Respiratory Tract and Its Defenses

• Most common place for infectious agents to gain
  access to the body
• Upper respiratory tract mouth, nose, nasal
  cavity, sinuses, pharynx, epiglottis, larynx
• Lower respiratory tract trachea, bronchi,
  bronchioles, lungs, alveoli
• Defneses
• Nasal hair
• Cilia
• Mucus
• Involuntary responses such as coughing, sneezing,
  and swallowing
• Macrophages
• Secretory IgA against specific pathogens

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Figure 21.1
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21.2 Normal Biota of the Respiratory Tract

• Generally limited to the upper respiratory tract
• Gram-positive bacteria (streptococci and
  staphylococci) very common
• Disease-causing bact4eria are present as normal
  biota can cause disease if their host becomes
  immunocompromised or if they are transferred to
  other hosts (Streptococcus pyogenes, Haemophilus
  influenza, Streptococcus pneumonia, Neisseria
  meningitides, Staphylococcus aureus)
• Normal biota perform microbial antagonism

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21.3 Upper Respiratory Tract Diseases Caused by
Microorganisms

• Rhinitis, or the Common Cold
• Symptoms sneezing, scratchy throat, runny nose
  (rhinorrhea)
• Symptoms begin 2-3 days after infection
• Generally not accompanied by fever

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Sinusitis

• Commonly called a sinus infection
• Most commonly caused by allergy
• Can also be caused by infections or structural
  problems
• Generally follows a bout with the common cold
• Symptoms nasal congestion, pressure above the
  nose or in the forehead, feeling of headache or
  toothache
• Facial swelling and tenderness common
• Discharge appears opaque with a green or yellow
  color in case of bacterial infection
• Discharge caused by allergy is clear and may be
  accompanied by itchy, watery eyes

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Acute Otitis Media (Ear Infection)

• Also a common sequel of rhinitis
• Viral infections of the upper respiratory tract
  lead to inflammation of the Eustachian tubes and
  buildup of fluid in the middle ear- can lead to
  bacterial multiplication in the fluids
• Bacteria can migrate along the eustachian tube
  from the upper respiratory tract, multiply
  rapidly, leads to pu production and continued
  fluid secretion (effusion)
• Chronic otitis media when fluid remains in the
  middle ear for indefinite periods of time (may be
  caused by biofilm bacteria)
• Symptoms sensation of fullness or pain in the
  ear, loss of hearing
• Untreated or severe infections can lead to
  eardrum rupture

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Figure 21.2
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Pharyngitis

• Inflammation of the throat
• Pain and swelling, reddened mucosa, swollen
  tonsils, sometime white packets of inflammatory
  products
• Mucous membranes may swell, affecting speech and
  swallowing
• Often results in foul-smelling breath
• Incubation period 2-5 days

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Figure 21.5
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Figure 21.7
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Diphtheria

• Symptoms initially experienced in the upper
  respiratory tract
• Sore throat, lack of appetite, low-grade fever
• Pseudomembrane forms on the tonsils or pharynx

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Figure 21.8
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Figure 21.9
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Figure 21.10
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