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Etiology Acute otitis media typically follows a viral URI. The causative viruses (most commonly RSV, influenza virus, rhinovirus, and enterovirus) can themselves cause subsequent acute otitis media; more often, they predispose the patient to bacterial otitis media. Studies using tympanocentesis have consistently found S. pneumoniae to be the most important bacterial cause, isolated in up to 35% of cases. H. influenzae (nontypable strains) and M. catarrhalis are also common bacterial causes of acute otitis media, and concern is increasing about community strains of MRSA as an emerging etiologic agent. Viruses, such as those mentioned above, have been recovered either. | Chapter 031. Pharyngitis Sinusitis Otitis and Other Upper Respiratory Tract Infections Part 7 Etiology Acute otitis media typically follows a viral URI. The causative viruses most commonly RSV influenza virus rhinovirus and enterovirus can themselves cause subsequent acute otitis media more often they predispose the patient to bacterial otitis media. Studies using tympanocentesis have consistently found S. pneumoniae to be the most important bacterial cause isolated in up to 35 of cases. H. influenzae nontypable strains and M. catarrhalis are also common bacterial causes of acute otitis media and concern is increasing about community strains of MRSA as an emerging etiologic agent. Viruses such as those mentioned above have been recovered either alone or with bacteria in 1740 of cases. Clinical Manifestations Fluid in the middle ear is typically demonstrated or confirmed with pneumatic otoscopy. In the absence of fluid the tympanic membrane moves visibly with the application of positive and negative pressure but this movement is dampened when fluid is present. With bacterial infection the tympanic membrane can also be erythematous bulging or retracted and occasionally can spontaneously perforate. The signs and symptoms accompanying infection can be local or systemic including otalgia otorrhea diminished hearing fever or irritability. Erythema of the tympanic membrane is often evident but is nonspecific as it is frequently seen in association with inflammation of the upper respiratory mucosa e.g. during examination of young children . Other signs and symptoms that are occasionally reported include vertigo nystagmus and tinnitus. Acute Otitis Media Treatment There has been considerable debate on the usefulness of antibiotics for the treatment of acute otitis media. Although most cases resolve clinically 1 week after the onset of illness antibiotics appear to be of some benefit. A higher proportion of treated than of untreated patients are free of illness 3-5 days .