Chapter 031. Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections (Part 6)

Chronic otitis externa is caused primarily by repeated local irritation, most commonly arising from persistent drainage from a chronic middle-ear infection. Other causes of repeated irritation, such as insertion of cotton swabs or other foreign objects into the ear canal, can lead to this condition, as can rare chronic infections such as syphilis, tuberculosis, or leprosy. Chronic otitis externa typically presents as erythematous, scaling dermatitis in which the predominant symptom is pruritus rather than pain; this condition must be differentiated from several others that produce a similar clinical picture, such as atopic dermatitis, seborrheic dermatitis, psoriasis, and dermatomycosis. Therapy...
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Chapter 031. Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections (Part 6) Chapter 031. Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections (Part 6) Chronic otitis externa is caused primarily by repeated local irritation, mostcommonly arising from persistent drainage from a chronic middle-ear infection.Other causes of repeated irritation, such as insertion of cotton swabs or otherforeign objects into the ear canal, can lead to this condition, as can rare chronicinfections such as syphilis, tuberculosis, or leprosy. Chronic otitis externatypically presents as erythematous, scaling dermatitis in which the predominantsymptom is pruritus rather than pain; this condition must be differentiated fromseveral others that produce a similar clinical picture, such as atopic dermatitis,seborrheic dermatitis, psoriasis, and dermatomycosis. Therapy consists ofidentifying and treating or removing the offending process, although successfulresolution is frequently difficult. Invasive otitis externa, also known as malignant or necrotizing otitisexterna, is an aggressive and potentially life-threatening disease that occurspredominantly in elderly diabetic patients and other immunocompromisedpatients. The disease begins in the external canal, progresses slowly over weeks tomonths, and often is difficult to distinguish from a severe case of chronic otitisexterna because of the presence of purulent otorrhea and an erythematous swollenear and external canal. Severe, deep-seated otalgia is often noted and can helpdifferentiate invasive from chronic otitis externa. The characteristic finding onexamination is granulation tissue in the posteroinferior wall of the external canal,near the junction of bone and cartilage. If left unchecked, the infection can migrateto the base of the skull (resulting in skull-base osteomyelitis) and on to themeninges and brain, with a high associated mortality rate. Cranial nerveinvolvement is occasionally seen, with the facial nerve usually affected first andmost often. Thrombosis of the sigmoid sinus can occur if the infection extends tothat area. CT, which can reveal osseous erosion of the temporal bone and skullbase, can be used to help determine the extent of disease, as can gallium andtechnetium-99 scintigraphy studies. P. aeruginosa is by far the most commonpathogen, although S. aureus, Staphylococcus epidermidis, Aspergillus,Actinomyces, and some gram-negative bacteria have also been associated with thisdisease. In all cases, the external ear canal should be cleansed and a biopsyspecimen of the granulation tissue within the canal (or of deeper tissues) should beobtained for culture of the offending organism. IV antibiotic therapy is directedspecifically toward the recovered pathogen. For P. aeruginosa, the regimentypically includes an antipseudomonal penicillin or cephalosporin (e.g.,piperacillin or ceftazidime) with an aminoglycoside. A fluoroquinolone antibioticis frequently used in place of the aminoglycoside and can even be administeredorally, given the excellent bioavailability of this drug class. In addition, antibioticdrops containing an agent active against Pseudomonas (e.g., ciprofloxacin) areusually prescribed and are combined with glucocorticoids to reduce inflammation.Cases of invasive Pseudomonas otitis externa recognized in the early stages cansometimes be treated with oral and otic fluoroquinolones alone, albeit with closefollow-up. Extensive surgical debridement, once an important component of thetreatment approach, is now rarely indicated. Infections of Middle-Ear Structures Otitis media is an inflammatory condition of the middle ear that resultsfrom dysfunction of the eustachian tube in association with a number of illnesses,including URIs and chronic rhinosinusitis. The inflammatory response to theseconditions leads to the development of a sterile transudate within the middle-earand mastoid cavities. Infection may occur if bacteria or viruses from thenasopharynx contaminate this fluid, producing an acute (or sometimes chronic)illness. Acute Otitis Media Acute otitis media results when pathogens from the nasopharynx areintroduced into the inflammatory fluid collected in the middle ear (e.g., by noseblowing during a URI). The proliferation of these pathogens in this space leads tothe development of the typical signs and symptoms of acute middle-ear infection.The diagnosis of acute otitis media requires the demonstration of fluid in themiddle ear (with tympanic membrane immobility) and the accompanying signs orsymptoms of local or systemic illness (Table 31-2). Table 31-2 Guidelines for the Diagnosis and Treatment of Acute OtitisMedia Illness Diagnostic Criteria TreatmentSeverity Recommendations Mild to Fluid in the middle ear, Initial therapyamoderate evidenced by decreased tympanic Observation alone membrane mobility, air/fluid (symptom relief only)b level behind tympanic membrane, bulging tympanic or membrane, purulent otorrhea Amoxicillin, 80–90 and mg/kg qd (up to 2 g) PO in divided doses (bid or tid), A ...