Diagnosis The primary goal of diagnostic testing is to separate acute streptococcal pharyngitis from pharyngitis of other etiologies (particularly viral) so that antibiotics can be prescribed more efficiently for patients to whom they may be beneficial. The most appropriate standard for the diagnosis of streptococcal pharyngitis, however, has not been definitively established. Throat swab culture is generally regarded as such. However, this method cannot distinguish between infection and colonization, and it takes 24–48 h to yield results that vary according to technique and culture conditions. Rapid antigen-detection tests offer good specificity (90%) but lower sensitivity when implemented in routine. | Chapter 031. Pharyngitis Sinusitis Otitis and Other Upper Respiratory Tract Infections Part 10 Diagnosis The primary goal of diagnostic testing is to separate acute streptococcal pharyngitis from pharyngitis of other etiologies particularly viral so that antibiotics can be prescribed more efficiently for patients to whom they may be beneficial. The most appropriate standard for the diagnosis of streptococcal pharyngitis however has not been definitively established. Throat swab culture is generally regarded as such. However this method cannot distinguish between infection and colonization and it takes 24-48 h to yield results that vary according to technique and culture conditions. Rapid antigen-detection tests offer good specificity 90 but lower sensitivity when implemented in routine practice. The sensitivity has also been shown to vary across the clinical spectrum of disease 65-90 . Several clinical prediction systems Table 31-3 can increase the sensitivity of rapid antigen-detection tests to 90 in controlled settings. Since the sensitivities achieved in routine clinical practice are often lower several medical and professional societies continue to recommend that all negative rapid antigendetection tests in children be confirmed by a throat culture to limit transmission and complications of illness caused by group A streptococci. The Centers for Disease Control and Prevention the Infectious Diseases Society of America the American College of Physicians and the American Academy of Family Physicians do not recommend backup culture when adults have negative results in a high-sensitivity rapid antigen-detection test however given the lower prevalence and smaller benefit in this age group. Table 31-3 Guidelines for the Diagnosis and Treatment of Acute Pharyngitis Age Group Diagnostic Criteria Treatment Recommendations Adults Clinical suspicion of streptococcal pharyngitis . fever tonsillar swelling exudate enlarged tender anterior cervical lymph nodes absence of
