What bacteria are commonly associated with rhinosinusitis?

From the Guidelines

The bacteria most commonly associated with rhinosinusitis include Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus. In acute bacterial rhinosinusitis, Streptococcus pneumoniae accounts for approximately 30-35% of cases, followed by Haemophilus influenzae (20-25%) and Moraxella catarrhalis (10-15%) 1. Staphylococcus aureus is more frequently isolated in chronic rhinosinusitis cases, along with anaerobic bacteria such as Peptostreptococcus, Bacteroides, and Fusobacterium species. Pseudomonas aeruginosa and other gram-negative bacteria may be found in patients with underlying conditions like cystic fibrosis or immunodeficiency. The microbiology differs somewhat between acute and chronic cases, with viral pathogens often preceding bacterial infection in acute cases. Understanding the bacterial profile is important for appropriate antibiotic selection, with amoxicillin or amoxicillin-clavulanate typically used as first-line treatment for uncomplicated acute bacterial rhinosinusitis, while chronic cases may require culture-directed therapy and longer treatment courses 1. Some key points to consider when managing rhinosinusitis include:

• The use of symptomatic treatment and reassurance as the preferred initial treatment strategy for patients with mild symptoms 1
• The consideration of factors that predispose patients to antibiotic-resistant organisms when selecting antibiotics 1
• The importance of patient education about the chosen treatment strategy and worsening signs and symptoms that should prompt them to contact a physician 1

From the FDA Drug Label

Azithromycin Tablets, USP are indicated for the treatment of patients with mild to moderate infections ... Acute bacterial sinusitis due to Haemophilus influenzae, Moraxella catarrhalis or Streptococcus pneumoniae. Amoxicillin and clavulanate potassium tablets USP is a combination penicillin-class antibacterial and beta-lactamase inhibitor indicated in the treatment of infections due to susceptible isolates of the designated bacteria in the conditions listed below*: ... 1.3 Sinusitis – caused by beta-lactamase–producing isolates of H. influenzae and M. catarrhalis.

The bacteria commonly associated with rhinosinusitis are:

• Haemophilus influenzae
• Moraxella catarrhalis
• Streptococcus pneumoniae 2 3

From the Research

Bacteria Associated with Rhinosinusitis

The bacteria commonly associated with rhinosinusitis include:

• Streptococcus pneumoniae 4, 5, 6, 7, 8
• Haemophilus influenzae 4, 5, 6, 7, 8
• Moraxella catarrhalis 4, 5, 6, 8
• Streptococcus pyogenes 5
• Staphylococcus aureus 5
• Anaerobic organisms (Prevotella and Porphyromonas, Fusobacterium, and Peptostreptococcus spp.) 5
• Pseudomonas aeruginosa 5

Specific Bacteria in Different Types of Rhinosinusitis

• Acute bacterial rhinosinusitis: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis 4, 6, 7, 8
• Chronic rhinosinusitis: Staphylococcus aureus, anaerobic organisms (Prevotella and Porphyromonas, Fusobacterium, and Peptostreptococcus spp.) 5
• Nosocomial sinusitis: Pseudomonas aeruginosa and other aerobic and facultative Gram-negative rods 5