Chapter 26 Upper and Lower RT Infections

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Chapter 26 Upper and Lower RT Infections

• MLAB 2434 Clinical Microbiology
• Cecile Sanders Keri Brophy-Martinez

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Concepts

• Normal Respiratory Flora
• Exists in symbiotic relationship with host
• In absence of disease, presence of bacteria is
  called colonization
• Prevents proliferation and invasion by pathogenic
  bacteria through competition for nutrients and
  receptors sites on host cells

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Concepts (contd)

• Normal Respiratory Flora (contd)
• Normal flora also produces bacteriocins, which
  are toxic to other bacteria
• Patients receiving broad-spectrum antibiotics,
  hospitalized, or with chronic illnesses may have
  altered normal flora

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Concepts (contd)

• Immune Status of Host
• Age as a risk factor (infants and elderly more
  susceptible)
• Reduced clearance of secretions
• Immature anatomical development (e.g., eustachian
  tube)
• Reduced function of respiratory cilia after viral
  infection
• Obstruction by foreign body
• Disease that alters RT anatomy (tumors)
• Alterations in viscosity of mucus (e.g., cystic
  fibrosis)

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Concepts (contd)

• Immune Status of Host (contd)
• Infection-induced airway obstruction (e.g.,
  epiglottitis)
• Seasonal and Community Trends in Infections
• Empiric Antimicrobial Therapy

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Anatomy of RT

• Upper RT (p. 883)
• Nasal cavity (sinuses)
• Nasopharynx
• Oropharynx
• Epiglottis
• Larynx

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Anatomy of RT

• Lower RT
• Trachea
• Bronchi
• Lungs, alveoli

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Barriers to Infection

• Lower RT environment normally sterile
• Barriers
• Nasal hairs
• Cilliary cells
• Coughing
• Normal flora
• Phagocytes/Inflammatory cells
• Tracheobronchial tree secretes immunoglobulins

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Virulence Factors of Pathogenic Organisms

• Adherence
• Toxin Elboration
• Evasion of Host Defenses

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URT Infections

• Pharyngitis
• Most common bacterial cause S. pyogenes (Group
  A)
• Viruses
• Unusual pathogens
• N. gonorrhoeae
• C. diphtheriae

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URT Infections (contd)

• Pharyngitis (contd)
• Laboratory diagnosis
• Rapid strep screening
• Culture with A disk or PYR positive
• Gram stain from throats NOT helpful
• Sinusitis
• S. pneumoniae and H. influenzae are most common
  bacterial pathogens

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URT Infections (contd)

• Sinusitis (contd)
• Less common bacteria
• S. pyogenes
• M. catarrhalis
• S. aureus
• Symptoms
• Purulent nasal discharge
• Pain in face

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URT Infections (contd)

• Sinusitis (contd)
• Laboratory diagnosis
• Nasal secretions are not reliable culture sources
• Best culture material is from sinus puncture and
  aspirates
• X-rays and CT scans are reliable indicators of
  infection

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URT Infections (contd)

• Sinusitis (contd)
• Treatment since specimens are difficult to
  obtain, most sinus infections are treated with
  antibiotics known to be effective against the
  most common pathogens (empiric treatment)
• Complications
• Spread of infection to adjacent sites
• Anaerobic infection

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URT Infections (contd)

• Otitis Media
• Middle ear infection
• Seen mostly in pre-school age children due to
  crowded conditions and immature eustachian tube
• Most common pathogens are S. pneumoniae and H.
  influenzae

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URT Infections (contd)

• Otitis Media (contd)
• Uncommon pathogens
• S. pyogenes
• M. catarrhalis
• S. aureus
• Complications
• Damage to ear drum and possible hearing loss
• Infection spread to adjacent areas
• Treatment usually empiric

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URT Infections (contd)

• Epiglottitis
• Epiglottis is a fleshy structure at the opening
  of the trachea which protects the airway from
  aspiration during swallowing
• Infection causes the epiglottis to swell which is
  a serious condition due to potential airway
  obstruction
• Very painful swallowing

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URT Infections (contd)

• Epiglottitis (contd)
• Most common pathogen is H. influenzae type B
• Laboratory diagnosis direct smear and culture
  with swab

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URT Infections (contd)

• Pertussis
• Respiratory illness with severe whooping cough
• Most common pathogens
• Bordetella pertussis
• Bordetella parapertussis
• Laboratory diagnosis
• Nasopharyngeal swabs for FA direct staining and
  culture

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LRT Infections

• Bronchitis and Bronchiolitis
• Most common pathogens respiratory viruses
• Most common bacteria
• M. pneumoniae
• C. pneumoniae
• B. pertussis

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LRT Infections (contd)

• Bronchitis and Bronchiolitis (contd)
• Peaks in winter months
• Cough and fever cough is productive later in
  illness
• X-rays do NOT show radiographic findings
• Laboratory diagnosis
• Gram stain
• Culture

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LRT Infections (contd)

• Community-Acquired Pneumonia
• Children
• Most common pathogens
• RSV
• Parainflunzae virus
• Adenovirus
• M. pneumoniae

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LRT Infections (contd)

• Community-Acquired Pneumonia (contd)
• Children
• Less common pathogens
• S. pneumoniae
• H. influenzae
• Grp B. Strep (neonates)

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LRT Infections (contd)

• Community-Acquired Pneumonia (contd)
• Adults
• Most common pathogens
• S. pneumoniae
• M. pneumoniae (walking pneumonia)
• Less common pathogens
• H. influenzae
• G- Rods
• S. aureus
• Legionella sp.

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LRT Infections (contd)

• Community-Acquired Pneumonia (contd)
• Adults
• Symptoms
• Rapid onset of fever with chills
• Cough of purulent sputum may be blood-tinged

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LRT Infections (contd)

• Nosocomial Pneumoniae
• Common pathogens
• G Rods (60) Klebsiella, Enterobacter,
  Escherichia, Serratia, and Pseudomonas sp.
• G Organisms (16)
• Anaerobes
• Legionella sp.
• Caused by compromise of barriers and colonization
  with pathogens

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LRT Infections (contd)

• Aspiration Pneumonia
• Aspiration of oropharyngeal or gastric contents
  into LRT
• Common pathogens mixed anaerobes and aerobes
• May lead to respiratory distress syndrome

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LRT Infections (contd)

• Chronic Pneumonia
• Mycobacterium
• Fungi
• Empyema
• Localized extension of a lung infection between
  lung and chest wall (usually requires drainage)
• Common pathogens
• S. aureus
• S. pneumoniae
• S. pyogenes
• G - Rods