From the Guidelines
Chronic sinusitis and acute bacterial sinusitis are primarily caused by a combination of viral and bacterial infections, with the most common bacterial culprits being Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, as well as underlying conditions such as allergies, nasal polyps, and deviated septum. The causes of these conditions can be broken down into:
- Viral upper respiratory infections that create conditions favorable for bacterial growth
- Bacterial infections, with the most common organisms being Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, as noted in 1
- Underlying conditions such as allergies, nasal polyps, and deviated septum, which can contribute to chronic inflammation and increase the risk of infection
- Environmental irritants like cigarette smoke, air pollution, and workplace chemicals, which can also contribute to chronic inflammation
- Immune disorders, certain medical conditions like cystic fibrosis, and fungal infections, which can lead to chronic cases as well
- Anatomical abnormalities like nasal polyps or deviated septum, which can increase risk by blocking normal sinus drainage
- Weakened immune systems from conditions like diabetes or HIV, which can make individuals more susceptible to bacterial infections, as discussed in 1 and 1. The most recent and highest quality study, 1, provides guidance on the diagnosis and management of acute bacterial rhinosinusitis, and highlights the importance of using clinical signs and symptoms to differentiate bacterial from viral causes. Some key points to consider when evaluating the causes of chronic sinusitis and acute bacterial sinusitis include:
- The role of bacterial infection in chronic sinusitis is less certain, and the diagnosis is often based on clinical symptoms and imaging studies, as noted in 1
- The most common bacteria isolated from sinus puncture are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, as listed in 1 and 1
- Radiographic imaging has no role in ascertaining a bacterial cause, and clinical guidelines recommend using clinical signs and symptoms to differentiate bacterial from viral causes, as discussed in 1 and 1.
From the Research
Causes of Chronic Sinusitis
- Anatomic factors, such as a deviated nasal septum, can contribute to the development of chronic sinusitis 2
- Disturbances in mucociliary clearance can also play a role in the pathogenesis of chronic sinusitis 3
- Microbial pathogens, including bacteria and fungi, can cause chronic sinusitis 3, 4
- Inflammatory factors, such as the presence of eosinophils and IL-5-producing T lymphocytes, can contribute to the development of chronic sinusitis 3
- Allergic fungal sinusitis is a special type of chronic sinusitis that can occur in some individuals 3
Causes of Acute Bacterial Sinusitis
- Most acute sinus infections are caused by viruses, but a bacterial infection should be considered if symptoms worsen or fail to improve within 7-10 days 4
- Bacterial pathogens, such as Streptococcus pneumoniae and Haemophilus influenzae, can cause acute bacterial sinusitis 4
- Anatomic factors, such as a deviated nasal septum, can increase the risk of developing acute bacterial sinusitis 2
- Immunodeficiency and mucociliary disorders can also increase the risk of developing acute bacterial sinusitis 2