Gram-Negative Rods: 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. 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.

• 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.