Bacteria

Overview of Gram-Negative Rods – Respiratory Illnesses (non-enterobacteriaceae)

Anisha ValliLeave a comment

RESPIRATORY ILLNESSES CAUSED BY GRAM-NEGATIVE RODS

Haemophilus influenzae

  • Transmitted via respiratory droplets.
  • Two key types of Haemophilus influenzae: Nonencapsulated and Encapsulated.
  • Haemophilus influenzae non-encapsulated, aka, Non-typeable colonizes the upper respiratory tract of many people.
    – The bacteria can migrate to other parts of the respiratory tract and cause:
    Sinusitis and otitis
    Bronchitis and pneumonia; patients can develop bronchial inflammation and/or pneumonia with consolidation. Patients with chronic obstructive pulmonary disease (COPD) are at especially high risk of pneumonia from Haemophilus influenzaemigration.
  • Encapsulated Haemophilus influenzae, especially type B, causes serious, life-threatening infections in unvaccinated children.
    Meningitis and septic arthritis
    Epiglottitis is characterized by a swollen epiglottis that can obstruct the airways and esophagus. Patients have a sore throat, and may drool due to the inability to swallow saliva; may be life-threatening.

Bordetella pertussis and Bordetella parapertussis

  • Transmitted via respiratory droplets.
  • These bacteria cause pertussis, aka, whooping cough.
  • Infection is highly contagious, and is most severe in infants, who experience respiratory failure.
  • Clinicians are seeing an increasing number of cases in adolescents and adults.
  • DTaP vaccine protects children from infection.

Stages of Pertussis

  • Incubation period lasts approximately one week.
  • Catarrhal stage lasts one to two weeks.
    – This stage is characterized by non-specific symptoms of fever, runny nose, sneezing, and cough.
  • Paroxysmal stage can last for several weeks.
    – Characterized by episodes of forceful expirations followed by a loud inspiration – the “whoop!” of “whooping cough”.
    – Because the fits are prolonged, oxygen levels can drop, leading to cyanosis, and post-pertussive vomiting can occur.
  • Convalescent stage is characterized by reduced coughing; complications are possible, including pneumonia and encephalopathy.

Legionella pneumophila

  • Transmitted via aerosolized water.
    – For example, in the mist from air humidifiers, shower heads, etc.
  • Legionnaire’s disease is characterized by severe pneumonia and fever; older and less healthy individuals are more susceptible to disease.
  • Pontiac fever is characterized by fever, myalgias, and other flu-like symptoms.

Francisella tularensis

  • Transmitted via infected rabbits or bites from ticks and deerflies; thus, tularemia is a zoonotic disease.
  • Tularemia can manifest in different forms:
    – Ulceroglandular tularemia produces skin lesions, often with black areas; the lymph nodes also become infected and produce tender, painful bulges in the skin – it is sometimes said to resemble the bubonic plague.
    – Pneumonia*
    – Tularemia can also affect other organs, including the eye, mouth, and throat.

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