Moraxella catarrhalis

Definition

Moraxella catarrhalis is a Gram-negative, aerobic, diplococcus bacterium that is commonly found as part of the normal microbiota of the human upper respiratory tract. It is an opportunistic pathogen that can cause various respiratory tract infections in certain populations.

5 Must Know Facts For Your Next Test

1. Moraxella catarrhalis is a common colonizer of the human upper respiratory tract, particularly the nasopharynx and oropharynx.
2. It is an opportunistic pathogen that can cause infections in individuals with compromised immune systems, such as the elderly, young children, and those with chronic respiratory conditions.
3. Moraxella catarrhalis is a leading cause of otitis media (middle ear infection) and sinusitis, especially in children.
4. The bacterium can also cause lower respiratory tract infections, such as bronchitis and pneumonia, in susceptible individuals.
5. Moraxella catarrhalis has developed resistance to various antibiotics, making some infections more challenging to treat.

Review Questions

• Describe the role of Moraxella catarrhalis in the normal microbiota of the respiratory tract.
  • Moraxella catarrhalis is a common member of the normal microbiota of the upper respiratory tract, particularly the nasopharynx and oropharynx. As an opportunistic pathogen, it is typically harmless in healthy individuals but can cause infections in those with compromised immune systems or underlying respiratory conditions. Its presence in the respiratory tract is generally considered part of the normal microbial community, but it can become an opportunistic pathogen when the host's defenses are weakened.
• Explain how Moraxella catarrhalis can contribute to respiratory tract infections.
  • Moraxella catarrhalis is a leading cause of various respiratory tract infections, such as otitis media (middle ear infection), sinusitis, bronchitis, and pneumonia. The bacterium can take advantage of a weakened immune system or other predisposing factors to cause these infections. For example, in young children or the elderly, Moraxella catarrhalis may overgrow and invade the middle ear or sinuses, leading to otitis media or sinusitis. In individuals with chronic respiratory conditions, the bacterium can also cause lower respiratory tract infections like bronchitis or pneumonia. The increasing antibiotic resistance of Moraxella catarrhalis further complicates the treatment of these respiratory infections.
• Evaluate the clinical significance of Moraxella catarrhalis in the context of respiratory tract infections.
  • Moraxella catarrhalis is a clinically significant opportunistic pathogen in the context of respiratory tract infections. As a common colonizer of the upper respiratory tract, it can cause significant morbidity, particularly in vulnerable populations such as young children, the elderly, and those with weakened immune systems or chronic respiratory conditions. Moraxella catarrhalis is a leading cause of otitis media and sinusitis, which can have serious complications if left untreated. Additionally, its ability to cause lower respiratory tract infections like bronchitis and pneumonia in susceptible individuals highlights its potential to contribute to significant respiratory disease. The growing antibiotic resistance of Moraxella catarrhalis further underscores the clinical importance of understanding its role in respiratory tract infections and developing effective treatment strategies.

Related terms

Opportunistic Pathogen: An opportunistic pathogen is a microorganism that is normally harmless but can cause disease in individuals with a weakened immune system or other predisposing factors.

Respiratory Tract Infections: Respiratory tract infections are a group of illnesses that affect the upper or lower respiratory system, such as the nose, sinuses, pharynx, larynx, trachea, bronchi, and lungs.

Diplococcus: A diplococcus is a bacterium that divides in one plane, resulting in pairs of cocci (spherical cells).