From the Guidelines
Bacterial sinusitis typically develops as a sequela to viral sinusitis rather than beginning as a bacterial infection. Most cases of sinusitis start with a viral upper respiratory infection that causes inflammation of the nasal passages and sinuses, as noted in the clinical practice guideline update on adult sinusitis 1. This inflammation leads to obstruction of the sinus drainage pathways, creating an environment where bacteria can proliferate. The trapped secretions and impaired drainage allow normal nasal flora like Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis to overgrow and cause a secondary bacterial infection.
Key points to consider in the management and understanding of sinusitis include:
- The incidence of acute viral rhinosinusitis (VRS) is high, estimated to occur from 2 to 5 times per year in the average adult 1.
- Secondary bacterial infection is believed to complicate only 0.5% to 2.0% of these events, highlighting that most cases of sinusitis are viral in origin 1.
- Symptoms in acute VRS typically peak within 3 days then gradually decline and resolve within 10 to 14 days, which helps in differentiating viral from bacterial infections 1.
- Nasal purulence alone does not indicate a bacterial infection; discolored nasal discharge is a sign of inflammation and is not specific for infection, as the coloration is related to the presence of neutrophils, not bacteria 1.
Management of VRS is primarily directed toward relief of symptoms, with antibiotics not recommended for treating VRS since they are ineffective for viral illness and do not provide direct symptom relief 1. Palliative medications such as analgesics, anti-inflammatory agents, nasal saline, decongestants, antihistamines, mucolytics, cough suppressants, and topical or oral corticosteroids may be used alone or in varying combinations for symptom relief. Understanding the progression from viral to bacterial sinusitis helps explain why antibiotics are not recommended for early sinusitis symptoms and should be reserved for cases showing clear signs of bacterial involvement.
From the Research
Bacterial Sinusitis as a Sequelae to Viral Sinusitis
- Most cases of acute rhinosinusitis are caused by viruses, with bacterial infection developing as a secondary complication 2, 3, 4.
- The most common bacteria isolated from patients with community-acquired acute purulent sinusitis are Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pyogenes 3, 4.
- Staphylococcus aureus and anaerobic bacteria are commonly isolated from patients with chronic sinusitis 3, 4.
Infection Onset
- The infection typically begins with a viral cause, such as rhinoviruses, influenza viruses, and parainfluenza viruses, with a small proportion developing a secondary bacterial infection 3, 4.
- The microbiology of sinusitis is influenced by previous antimicrobial therapy, vaccinations, and the presence of normal flora capable of interfering with the growth of pathogens 3, 4.
Diagnosis and Treatment
- Acute rhinosinusitis is a clinical diagnosis, with cardinal features including unilateral facial pain or pressure, fever, and purulent nasal discharge 5.
- Antibiotics should be considered for patients with severe symptoms, significant worsening after 3 to 5 days of symptoms, or 7 or more days of symptoms 2, 5.
- Amoxicillin is as effective as amoxicillin-clavulanate as a first-line treatment for acute bacterial rhinosinusitis for those without a beta-lactam allergy 5.