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Make the Diagnosis: Streptococcal Pharyngitis

No matter what the patient's age, most cases of pharyngitis will not be attributable to streptococcus. During the general physical examination, clinicians should consider performing a throat culture or rapid antigen test, but only in tandem with the Centor score. None of the univariate signs or symptoms associated with pharyngitis has high enough sensitivity and specificity for diagnosis according to clinical grounds alone. The greatest utility for the Centor score is in identifying patients for whom a throat culture or rapid streptococcal test should be performed because the score itself is not sufficient for confirming a diagnosis of streptococcal pharyngitis.

Prior Probability

The prevalence of streptococcal pharyngitis is higher in children than among infants and adults: group A β-hemolytic streptococcal bacteria can be isolated by throat culture in 24% to 36% of children and in 5% to 24% of adults with sore throat. Streptococcal pharyngitis is also more common in autumn and winter; thus, it may be appropriate to adjust the pretest probability upward during those seasons.

Population for Whom Streptococcal Pharyngitis Should Be Considered

  • Children and adults with sore throat.

Detecting the Likelihood of Streptococcal Pharyngitis

The Centor score and modified Centor score perform differently for younger vs older patients (Table 47-7). The Centor score improves greatly when combined with rapid strep test results (Table 47-8).

Table 47-7Likelihood Ratios for Centor Scores as a Function of Age
Table 47-8Centor Score Combined With Rapid Strep Point-of-Care Test Results, Adults

Reference Standard Tests

Streptococcal throat culture, rapid streptococcal antigen tests.

Original Article: Does This Patient Have Strep Throat?

Clinical Scenarios

In each of the following cases, the physician must decide whether the patient has group A β-hemolytic streptococcal pharyngitis (strep throat). In case 1, a 7-year-old boy presents in March without a cough but with 1 day of sore throat accompanied by fever, headache, moderate cervical adenopathy, and a markedly exudative and erythematous pharynx. His brother was recently ...

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