Otitis Externa External Ear Infections

Otitis externa is similar to skin and soft tissue infections elsewhere. Two major types of external otitis exist: acute or chronic. Acute external otitis may be localized or diffuse. Acute localized disease occurs in the form of a pustule or furunde and typically results from Staphylococcus aureus. Erysipelas caused by group A strepto-cocd may involve the external ear canal and the soft tissue of the ear itself. Acute diffuse otitis externa (swimmer's ear) is related to maceration (softening of tissue) of the ear from swimming and/or hot, humid weather. Gram-negative bacilli, particularly Pseudomonas aeruginosa, play an important role. A severe, hemorrhagic external otitis caused by P. aeruginosa is difficult to treat and has occasionally been related to hot tub use.

Chronic otitis externa results from the irritation of drainage from the middle ear in patients with chronic, suppurative otitis media and a perforated eardrum. Ma-

Pinna

External auditory

Tympanic „ . . membrane Semicircular canals

Temporal

Sexual Organs

Vestibule

Cochlea

Auditory

(eustaclan)

tube

Vestibular nerve

Cochlear nerve

Figure 56-2 The ear. (Modified from Thibodeau GA, Patton KT: Anatomy and physiology, ed 2, St Louis, 1993, Mosby.)

Vestibule

Cochlea

Auditory

(eustaclan)

tube

Vestibular nerve

Cochlear nerve

Acoustic "nerve (VIII)

Pinna

External auditory

Middle ear inner ear

Tympanic „ . . membrane Semicircular canals

External ear _I,

Temporal

Figure 56-2 The ear. (Modified from Thibodeau GA, Patton KT: Anatomy and physiology, ed 2, St Louis, 1993, Mosby.)

lignant otitis externa is a necrotizing infection that spreads to adjacent areas of soft tissue, cartilage, and bone. If allowed to progress and spread into the central nervous system or vascular channel, a life-threatening situation may develop. P. aeruginosa, in particular, and anaerobes are frequendy associated with this process. Malignant otitis media is seen in patients with diabetes who have blood vessel disease of the tissues overlying the temporal bone in which the poor local perfusion of tissues results in a milieu for invasion by bacteria. On occasion, external otitis can extend into the cartilage of the ear, usually requiring surgical intervention. Certain viruses may infect the external auditory canal, the soft tissue of the ear, or the tympanic membrane; influenza A virus is a suspected, but not an established, cause. VZV may cause painful vesicles within the soft tissue of the ear and the ear canal. Mycoplasma pneumoniae is a cause of bullous myringitis (a painful infection of the eardrum with hemorrhagic bullae); the ear canal itself may be involved as well.

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Bacterial Vaginosis Facts

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