Notes
Respiratory Illnesses - Gram-Negative Rods
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Respiratory Illnesses caused by Gram-Negative Rods
Here we'll learn an overview of key non-enterobacteriaceae Gram-Negative rods that cause respiratory illnesses.
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 influenzae migration.
Encapsulated Haemophilus influenzae, especially type B, causes serious, life-threatening infections in unvaccinated children.
Infections include:
Meningitis
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
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
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.