Chapter 131. Diphtheria and Other Infections Caused by Corynebacteria and Related Species (Part 3)

Clinical ManifestationsRespiratory Diphtheria The clinical diagnosis of diphtheria is based on the constellation of sore throat; adherent tonsillar, pharyngeal, or nasal pseudomembranous lesions; and low-grade fever. In addition, diagnosis requires the isolation of C. diphtheriae or the histopathologic isolation of compatible gram-positive organisms. The Centers for Disease Control and Prevention (CDC) recognizes confirmed respiratory diphtheria (laboratory proven or epidemiologically linked to a culture-confirmed case) and probable respiratory diphtheria (clinically compatible but not laboratory proven or epidemiologically linked). Carriers are defined as individuals who have positive cultures for C. diphtheriae and either are asymptomatic or have symptoms but lack pseudomembranes....
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Chapter 131. Diphtheria and Other Infections Caused by Corynebacteria and Related Species (Part 3) Chapter 131. Diphtheria and Other Infections Caused by Corynebacteria and Related Species (Part 3) Clinical Manifestations Respiratory Diphtheria The clinical diagnosis of diphtheria is based on the constellation of sorethroat; adherent tonsillar, pharyngeal, or nasal pseudomembranous lesions; andlow-grade fever. In addition, diagnosis requires the isolation of C. diphtheriae orthe histopathologic isolation of compatible gram-positive organisms. The Centersfor Disease Control and Prevention (CDC) recognizes confirmed respiratorydiphtheria (laboratory proven or epidemiologically linked to a culture-confirmedcase) and probable respiratory diphtheria (clinically compatible but not laboratoryproven or epidemiologically linked). Carriers are defined as individuals who havepositive cultures for C. diphtheriae and either are asymptomatic or have symptomsbut lack pseudomembranes. Most patients seek medical care for initialmanifestations of sore throat and fever. Occasionally, weakness, dysphagia,headache, and voice change are the initial manifestations. Neck edema anddifficulty breathing are seen in more advanced cases and carry a poor prognosis. The systemic manifestations of diphtheria stem from the effects ofdiphtheria toxin and include weakness as a result of neurotoxicity and cardiacarrhythmias or congestive heart failure due to myocarditis. Thepseudomembranous lesion is most often located in the tonsillopharyngeal region.Less commonly, the lesions are detected in the larynx, nares, and trachea orbronchial passages. Large pseudomembranes are associated with severe diseaseand a poor prognosis. A few patients develop massive swelling of the tonsils andpresent with bull-neck diphtheria, which results from massive edema of thesubmandibular and paratracheal region and is further characterized by foul breath,thick speech, and stridorous breathing. The diphtheritic pseudomembrane is grayor whitish and sharply demarcated. Unlike the exudative lesion associated withstreptococcal pharyngitis, the pseudomembrane in diphtheria is tightly adherent tothe underlying tissues. Attempts to dislodge the membrane may cause bleeding.Hoarseness suggests laryngeal diphtheria, in which laryngoscopy may bediagnostically helpful. Cutaneous Diphtheria This is a variable dermatosis most often characterized by punched-outulcerative lesions with necrotic sloughing or pseudomembrane formation (Fig.131-2). The diagnosis requires cultivation of C. diphtheriae from lesions, whichmost commonly occur on the extremities. Patients usually seek medical attentionbecause of nonhealing or enlarging skin ulcers, which may be associated with apreexisting wound or dermatoses such as eczema, psoriasis, and venous stasisdisease. The lesions rarely exceed 5 cm. Figure 131-2 Cutaneous diphtheria due to nontoxigenic C. diphtheriae on the lowerextremity. (From the Centers for Disease Control and Prevention.) Other Clinical Manifestations C. diphtheriae causes rare cases of endocarditis and septic arthritis, mostoften in patients with preexisting risk factors such as cardiac valvular disease,injection drug use, or cirrhosis. Complications Airway obstruction poses a significant early risk in patients presenting withadvanced diphtheria. Pseudomembranes may slough and obstruct the airway ormay advance to the larynx or into the tracheobronchial tree. Children areparticularly prone to obstruction because of their small airways. Polyneuropathy and myocarditis are late toxic manifestations of diphtheria.During the outbreak in the Kyrgyz Republic in 1995, myocarditis was seen in 22%and neuropathy in 5% of hospitalized patients. The mortality rate was 7% amongpatients with myocarditis as opposed to 2% among those without myocardialmanifestations. The median time to death in hospitalized patients was 4.5 days.Myocarditis is typically associated with dysrhythmia of the conduction tract anddilated cardiomyopathy. Neurologic manifestations may appear during the first or second week ofillness, typically beginning with dysphagia and nasal dysarthria and progressing toother signs of cranial nerve involvement, including weakness of the tongue andfacial numbness. Ciliary paralysis, which is typical, manifests as blurred visiondue to paralysis of pupillary accommodation, with a preserved light reflex. Cranialneuropathy may be followed by respiratory and abdominal muscle weaknessrequiring artificial ventilation. Several weeks later—sometimes as cranialneuropathy is improving—a generalized sensorimotor polyneuropathy mayappear, with prominen ...