Final answer:
Chronic sinusitis is a persistent inflammation of the sinuses lasting more than 12 weeks, often caused by bacteria like Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. These bacteria typically take hold following a viral infection that weakens the immune defenses. Viral infections in the cooler nasal cavity allow these pathogens to flourish and contribute to the symptoms of sinusitis.
Step-by-step explanation:
Chronic sinusitis is characterized by prolonged inflammation of the sinuses, typically lasting more than 12 weeks. This condition can cause a range of symptoms, including nasal congestion, facial pain, and a reduction in the sense of smell. While chronic sinusitis can have various triggers, a common causal pathogen is the bacteria Streptococcus pneumoniae. Other bacteria such as Haemophilus influenzae and Moraxella catarrhalis also frequently contribute to this condition. These organisms can overpower the immune system, particularly after a preceding viral upper respiratory infection, leading to sinusitis. The inflammation of the sinuses is often part of a more general inflammation of the nasal mucosa, hence the term rhinosinusitis.
Bacterial rhinosinusitis not only stems from the action of these common bacteria but can also result from impaired mucociliary clearance or immune deficiencies that may facilitate bacterial growth. Considering that the nasal cavity is cooler than the rest of the respiratory system, this provides an ideal breeding ground for these pathogens. The subsequent immune response to the infection leads to symptoms such as congestion and nasal discharge, which are recognized signs of sinusitis. Secondary infections are common after an initial viral infection, such as the common cold, as the virus can weaken the mucosal defenses, paving the way for opportunistic bacteria to establish an infection.