Etiology

General considerations

• Coinfection with both bacterial and viral pathogens is common (∼ 66% of cases).

• Less commonly (27% of cases): solely a bacterial infection

• Purely viral AOM is rare (< 5%); cases are usually mild and self-limiting.

Bacterial pathogens

• S. pneumoniae

• Haemophilus influenzae

• Moraxella catarrhalis

• Group A ß-hemolytic streptococci (in older children)

Viral pathogens

• Respiratory syncytial virus

• Parainfluenza virus

• Influenza virus

• Rhinovirus

• Adenovirus

Passive cigarette smoke

Children who attend daycare centers

Formula feeding/bottle-feeding

Pacifier use

Children who have more than one sibling or live in a crowded space

Male sex

Family or personal history of AOM

Anatomic abnormalities

Feeding in a supine position