Which of the following is the most common bacterial pathogen in acute suppurative otitis media in children?

Question

Accepted Answer

B. Streptococcus pneumoniae. ## Microbiology of Acute Suppurative Otitis Media

**Key Point:** Streptococcus pneumoniae remains the most common bacterial pathogen in acute suppurative otitis media (ASOM) in children, despite the introduction of pneumococcal conjugate vaccines (PCV7 and later PCV13).

### Common Bacterial Pathogens in ASOM

| Pathogen | Frequency | Notes |
|----------|-----------|-------|
| *Streptococcus pneumoniae* | 25–35% | Most common; encapsulated gram-positive diplococcus |
| *Haemophilus influenzae* (non-typeable) | 20–30% | Second most common; gram-negative coccobacillus |
| *Moraxella catarrhalis* | 10–15% | Gram-negative diplococcus; more common in younger children |
| *Group A Streptococcus* | <5% | Rare in ASOM; more common in acute mastoiditis |
| Viruses (RSV, rhinovirus, influenza) | 50–70% | Often precedes bacterial infection |

**High-Yield:** The "big three" bacterial pathogens in ASOM are *S. pneumoniae*, non-typeable *H. influenzae*, and *M. catarrhalis*. These account for >90% of culture-positive cases.

**Clinical Pearl:** Although PCV vaccines have reduced invasive pneumococcal disease, *S. pneumoniae* remains the leading cause of ASOM because the vaccine does not prevent mucosal colonization or otitis media.

### Pathogenesis Context
These pathogens typically ascend from the nasopharynx via the Eustachian tube, especially during upper respiratory infections when mucociliary clearance is impaired.

![Acute Suppurative Otitis Media diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/3219.webp)

Answer

A. Group A Streptococcus

Answer

C. Haemophilus influenzae type b

Answer

D. Moraxella catarrhalis

Which of the following is the most common bacterial pathogen in acute suppurative otitis media in children?

Explanation

Microbiology of Acute Suppurative Otitis Media

Common Bacterial Pathogens in ASOM

Pathogenesis Context

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Pathogen	Frequency	Notes
Streptococcus pneumoniae	25–35%	Most common; encapsulated gram-positive diplococcus
Haemophilus influenzae (non-typeable)	20–30%	Second most common; gram-negative coccobacillus
Moraxella catarrhalis	10–15%	Gram-negative diplococcus; more common in younger children
Group A Streptococcus	<5%	Rare in ASOM; more common in acute mastoiditis
Viruses (RSV, rhinovirus, influenza)	50–70%	Often precedes bacterial infection