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The C-reactive protein (CRP) test can help distinguish between a true streptococcal infection and a carrier state in children with pharyngitis. A negative CRP result at the initial visit suggests a lower likelihood of infection.
Area of Science:
- Pediatrics
- Infectious Diseases
- Clinical Chemistry
Background:
- Group A streptococcal pharyngitis is a common childhood illness.
- Differentiating between true infection and asymptomatic carriers can be challenging for clinicians.
- C-reactive protein (CRP) is an acute-phase reactant often elevated in bacterial infections.
Purpose of the Study:
- To evaluate the utility of the C-reactive protein (CRP) test in distinguishing streptococcal pharyngitis from asymptomatic carriage.
- To assess the correlation between CRP levels and serological markers of streptococcal infection.
Main Methods:
- 157 children with symptomatic pharyngitis and positive Group A Streptococcus cultures were enrolled.
- Serial blood samples were analyzed for C-reactive protein (CRP) presence.
- Patients' antibody responses to antistreptolysin O and antistreptococcal deoxyribonuclease B were measured.
Main Results:
- 78% of patients with confirmed streptococcal pharyngitis showed a positive CRP test during the acute visit.
- A negative CRP test at the initial visit was associated with only a 25% subsequent antibody response.
- The predictive value of a negative CRP was independent of culture positivity, exudate, adenitis, fever, or coryza.
Conclusions:
- The C-reactive protein (CRP) test can be a valuable tool for clinicians in diagnosing streptococcal pharyngitis.
- A negative CRP result at the time of presentation may indicate a lower probability of true streptococcal infection.
- Further investigation into CRP's role in acute pharyngitis management is warranted.
Abstract:
This study was designed to explore whether the test for C-reactive protein (CRP) is useful in differentiating bona fide streptococcal infection from the symptomatic carrier at the time of the acute visit to the physician. Serial blood samples from 157 children with symptomatic pharyngitis and a positive culture for group A streptococci were analyzed for the presence or absence of CRP. These data were compared with the patients' antibody responses to two streptococcal extracellular antigens (antistreptolysin O and antistreptococcal deoxyribonuclease B). Seventy-eight percent of patients with serologically confirmed streptococcal pharyngitis had a positive CRP test at the initial visit. Conversely, if the CRP test was negative at the acute visit, only about 25% later showed an antibody response. This latter finding held regardless of the degree of positivity of the initial culture, the presence of exudate or adenitis, or the presence of a temperature greater than 38.3 C (101 F) or coryza. These data suggest that the CRP test may be helpful to the clinician, especially if this abnormal protein is absent at the time of the acute visit.