Sinusitis and Sinus Infection Are the Same Condition
There is no clinical difference between "sinusitis" and "sinus infection"—these terms are interchangeable and both refer to inflammation of the paranasal sinuses. 1
Understanding the Terminology
Sinusitis is defined as inflammation of one or more of the paranasal sinuses, and the most common cause of sinusitis is infection. 1 When patients or clinicians use the term "sinus infection," they are describing the same pathophysiologic process—inflammation of the sinus cavities, typically triggered by infectious agents (viral or bacterial) or other inflammatory processes. 1
The Modern Terminology Shift
- The medical community has actually suggested replacing both terms with "rhinosinusitis" because rhinitis (nasal inflammation) typically precedes sinusitis, sinusitis without rhinitis is rare, and the mucosa of the nose and sinuses are contiguous. 1
- This reflects the reality that isolated sinus inflammation without nasal involvement is uncommon in clinical practice. 1
Important Clinical Distinction: Not All Sinusitis Is Infectious
While "sinus infection" colloquially implies bacterial infection, sinusitis encompasses both infectious and non-infectious forms: 1
Infectious Sinusitis
- Acute bacterial sinusitis is caused primarily by Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. 2
- Chronic infectious sinusitis may involve anaerobic bacteria (gram-positive streptococcus, bacteroides, Fusobacterium species) or S. aureus, characterized by neutrophilic inflammation. 1, 2
Non-Infectious Sinusitis
- Chronic hyperplastic eosinophilic sinusitis is marked by eosinophils and mononuclear cells with few neutrophils, does not respond to antibiotics, and is often associated with nasal polyps, asthma, and aspirin sensitivity. 1, 3
- Antibiotics should NOT be prescribed for chronic sinusitis unless significant or persistent purulent nasal discharge is present on examination, as chronic sinusitis is primarily inflammatory rather than infectious. 4
Classification by Duration
Both terms apply across the temporal spectrum of disease: 1
- Acute: Symptoms less than 4 weeks (purulent rhinorrhea, postnasal drainage, facial pain, headache, fever, cough). 1
- Subacute: Symptoms 4 to 8 weeks (unresolved acute). 1
- Chronic: Symptoms 8 weeks or longer with abnormal CT or MRI findings. 1, 4
- Recurrent: 3 or more episodes of acute sinusitis per year. 1
Clinical Pitfall to Avoid
The role of bacterial infection in chronic sinusitis is less certain than in acute sinusitis. 1 Many patients labeled with "chronic sinus infection" actually have non-infectious inflammatory disease that will not respond to repeated antibiotic courses. 4, 3 Over 50% of patients with a strong history of chronic sinusitis have normal CT scans, highlighting the complexity of diagnosis. 1