Is rapid strept besting better than emperic therapy for group A beta- hemolytic streptococcus (GAS)?
V. K Knight
Novanber 15, 1996
32 y.o. WM without significant PMHx, presents with 3 days worsening sore throat and subjective fevers. PE is only notable for Temp 38.1, erythematous posterior pharynx without exudate, and mildly tender shotty anterior cervical nodes. Should this patient be treated emperically for strept or should I obtain a rapid strep test?
CLINICAL BOTTOM LINES:
1. Most cases of adult pharyngitis, even secondary to GAS, are self-limiting and pose no threat of serious sequelae. (~40,000 untreated GAS infections -> 1 case rheumatic fever)
2. Rapid strept testing is becoming a more increasingly
reliable tool to quickly assess for most GAS
pharyngitis, significantly decreasing unnecessary antibiotic usage.
3. There are certain clinical criteria that correlate more strongly with GAS pharyingitis, such as fever, pain duration, enlarged/exudative tonsils and cervical adenopathy. However, more clinical trials are needed to better formulate guidelines that will help physicians gain more efficient use of rapid strept testing.
Three phased prospective study of 338 consecutive, ages 4 to 43 (mean 17.9 years) patients presenting with sore throat, sampled from 3424 patterns seen over a year in a New Zealand general practice.
Clinical Features in sore throat patients with positive and negative beta-hemolytic streptococcal growth
|Positive Growth||Negative Growth||p value|
|pain for less than 3 days||79||39||p<0.001|
|large cervical glands||36||17||p<0.01|
|pus on tonsils||44||17||p<0.01|
Head-to-Head blinded comparison of an optical immunoassay (Strep A OIA), an enzyme-linked immunosorbant assay (TP-ST) and a group A selective agar (culture) in assessing for group A beta-hemolytic streptococcal pharygitis in 801 patients presenting to ER's or clinics
|Sensitivity (%)||Specificity (%)||+ Predictive Value||- Predictive Value||Sensitivity (95%CI)|
|Strep A OIA||92.3||95.4||91.5||95.8||89-96|
I. Annual incidence of sore throat 100 per 1000 people (~25 million cases)
2. Rapid strept test available at UNC - Biostar
Strep A Optical Immunoassay (Strep A OIA)
*cost - S21
*test turn-around time - 7 minutes
*specimen collection on ration swab only
*must send two swabs so that negative rapid strept can be confirmed with culture.
3. UNC laboratory procedure - confirmation of negative Strep A OIA with 5% sheep blood agar plate. Prior studies have shown its sensitivity for GAS to be less than that of Strep A OIA.
4. Penicillin V 500mg QID X 10 days - mainstay
therapy for GAS pharyngitis
*cost - $4.40 (10 day supply)
*anaphalaxis - 2-5 cases per 10,000
*death - 2-5 cases per 100,000
1. Heiter BJ and Bourbeau PP. Comparison of two rapid streptococcal antigen detection assays with culture for diagnosis of streptococcal pharyngitis. J of Clinical Microbiology, May 1995;33(5):1408-1410.
2. Kljakovic M. Sore throat presentation and
management in general practice. New Zealand Med J. 8 Sept