Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (602 page)

   Specific diagnosis of viral pharyngitis or upper respiratory tract infection is rarely needed; most patients can be managed symptomatically on the basis of clinical presentation. When indicated, specific diagnosis may be pursued by virus culture, or more commonly, by molecular diagnostic testing using a respiratory virus panel. Serologic diagnostic testing is not useful.

   The common viral causes of primary pharyngitis include adenovirus, Enterovirus, rhinoviruses, HSV, EBV, CMV, influenza,, and parainfluenza viruses.

Bacterial Disease

   Group A beta-hemolytic streptococcus (GAS): GAS causes infection in a significant minority (10–30%) of patients seeking medical attention for acute pharyngitis. Most infections have an acute onset of sore throat with erythema of the tonsillar and posterior pharyngeal mucosa and exudate. Fever, headache, and abdominal pain are commonly reported. Physical examination often shows enlarged, tender anterior cervical lymph nodes, petechiae of the palate, and uvular inflammation. Conjunctivitis, rhinorrhea, cough, and sneezing are uncommon symptoms and suggest another pathogen.

   Scarlet fever may complicate “strep throat” and is characterized by formation of a typical “scarlatiniforme” rash in the first or second day of fever. The rash is characterized as fine, rough-textured (sandpaper), blanching and worse in the armpits and skinfolds. The rash resolves after several days, followed by desquamation. A bright red, “strawberry” tongue may be obvious.

   Who Should Be Suspected?

   Various criteria have been recommended for predicting the probability of GAS infection and need for antibiotic treatment. They have generally shown better negative than positive predictive value. For children, the following criteria have been recommended. With six criteria, the probability of a culture positive for GAS = 75%; the probability falls to 59% if only five criteria are met:

   Age: 5–15 years

   Season: late fall, winter, or early spring

   Pharyngeal erythema, edema, and/or exudates

   Anterior lymph nodes: tender, enlarged

   Temperature: 101–103°F

   No typical viral upper respiratory signs and symptoms