What is the next step for a patient with a sore throat and a negative rapid strep (streptococcal) test, particularly in those with a history of recurrent streptococcal infections or rheumatic fever?

Management of Negative Rapid Strep Test

Yes, send a throat culture for confirmation in children and adolescents; in adults, a negative rapid test alone is sufficient and no culture is needed. 1

Age-Based Diagnostic Algorithm

For Children and Adolescents (Ages 3-18 years)

• A backup throat culture is mandatory after a negative RADT because rapid tests have only 80-90% sensitivity, meaning they miss 10-20% of true streptococcal infections 1, 2
• The high specificity (≥95%) of RADTs means positive results do not require culture confirmation, but negative results must be verified 1
• Treatment can be safely delayed up to 9 days after symptom onset while awaiting culture results and still effectively prevent acute rheumatic fever 2
• This represents a critical change from older practice—the 2012 IDSA guidelines explicitly require culture backup for negative RADTs in this age group 1

For Adults

• A negative RADT alone is sufficient to rule out group A streptococcal pharyngitis—do not send a culture 1, 2
• The rationale is twofold: group A streptococcal pharyngitis prevalence is only 5-10% in adults, and the risk of acute rheumatic fever is exceptionally low in this population 2
• Physicians who wish to achieve maximal diagnostic sensitivity may optionally continue using backup cultures, but this is not the standard recommendation 1

Special Populations Requiring Culture Confirmation

Patients with History of Rheumatic Fever

• These high-risk patients warrant culture confirmation regardless of age, as they face substantially elevated risk of recurrent rheumatic fever with subsequent streptococcal infections 3
• The consequences of missing a true infection in this population are severe enough to justify the additional testing 3

Patients with Recurrent Streptococcal Infections

• Consider culture confirmation when "ping-pong" spread of group A streptococci has been occurring within a family, as this increases pretest probability 1
• Recurrent infections may warrant more aggressive diagnostic approaches to break the transmission cycle 1

Timeline and Treatment Considerations

• Culture results typically add 18-24 hours to the diagnostic timeline 4
• If culture returns positive, initiate treatment immediately—the 9-day window for preventing rheumatic fever provides flexibility but earlier treatment reduces symptom duration by 1-2 days 2
• Antimicrobial therapy can be initiated empirically while awaiting culture results if clinical suspicion is high, but must be discontinued if the culture is negative 2

Common Pitfalls to Avoid

• Do not treat based on exposure history alone when testing is negative and symptoms are minimal—this leads to unnecessary antibiotic use and resistance 5
• Do not assume false-negative results are due to timing—if proper swabbing technique was used (both tonsillar surfaces and posterior pharyngeal wall) and no recent antibiotics were given, the test accuracy is not affected by early testing 4
• Do not order anti-streptococcal antibody titers for acute diagnosis—these reflect past infections, not current ones, and have no role in acute pharyngitis management 1
• Do not retest asymptomatic patients after treatment unless special circumstances exist, as follow-up cultures are not routinely indicated 1