What is the role of S pyogenes in the pathogenesis of acute otitis media (AOM)?

Updated: Sep 25, 2019
  • Author: John D Donaldson, MD, FRCSC, FACS; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Although S pyogenes (a gram-positive coccus that constitutes the group A streptococci [GAS] in the Lancefield classification), is still the fourth most commonly isolated bacterial pathogen from ears with AOM, it has shown a steady decline in frequency of recovery from the ear and in virulence over the past half-century. Similarly, a substantial decline in the major complications of streptococcal infection, rheumatic fever, glomerulonephritis, and scarlet fever has occurred.

S pyogenes may be associated with streptococcal toxic shock syndrome, which may include coagulopathy, soft tissue necrosis or fasciitis, desquamating rash, and liver or renal involvement. [15] It is primarily a pathogen of the pharynx, with more than 80 distinct M-protein strains identified. Currently, with the improvement in primary care and the availability of rapid identification tests, early aggressive treatment is normally instituted against this bacterium, which has shown minimal ability to develop resistance to antimicrobial agents.

Acute necrotic otitis media was associated with scarlet fever in the early 1900s; however, the condition was also associated with measles, pneumonia, and influenza. Generally, the patient was extremely ill with the systemic component of the disease and presented with a spontaneous perforation shortly after the onset of otalgia.

Early inspection of the ear would show the perforation to be moderate to large; within days, significant evidence of tissue necrosis would be observed, perhaps including the entire tympanic membrane, ossicles, the tympanic mucoperiosteum, or the bone of the mastoid air cells. The patient would demonstrate a marked conductive hearing loss, although sensorineural loss was not uncommon.

Pathologically, the ear showed a marked paucity of the normal vascular proliferation associated with an inflammatory reaction. Instead, a complete loss of the vascularity normally associated with vasculitis or toxin exposure occurred. Healing was never normal; tissue was replaced by epithelial invasion or scar tissue formation.

In industrialized societies, acute necrotic otitis media is now primarily of historic interest. The disease is still reported in aboriginal populations living in areas where modern medicine has not yet penetrated.

In the preantibiotic era, S pyogenes also appeared to be the organism most commonly recovered from patients with acute coalescent mastoiditis. In the 1990s, S pyogenes relinquished this distinction to S pneumoniae, but it remains a prominent pathogen when this disease is encountered in very young persons.


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