An Assessment of Rapid Streptococcal Tests in Community Clinics in Israel

Pharyngitis is a clinical diagnosis which requires antibiotic treatment only if caused by group A Streptococcus (GAS).

However, it is impossible to identify by clinical signs alone those patients whose symptoms are caused by this pathogen.

Diagnosis demands a throat culture, which requires at least 24 hours to rule in infection and 48 hours to rule it out.

Rapid Streptococcal tests (RST) based on antigen identification have been in use for over 10 years. These allow determination of the presence of GAS within 10 minutes using tests designed for point of care use.

While the specificity of these tests is generally reported as high (90-95%), the sensitivity is quoted at between 60% and 90% , depending on author affiliation, place of testing and type of test.

Various protocols have been put forward, these combine clinical signs (Centor criteria) with RST or throat cultures in order to lower antibiotic over-use.

These protocols are often under-used by primary physicians, even when RSTs are available.

Clalit health services, the largest HMO in Israel, has decided to evaluate all the RSTs available in the country in community clinic settings in order to determine the feasibility of adopting these tests to improve clinical care.

The sensitivity, specificity and ease-of-use will be assessed in 25 clinics in various settings (urban and rural). Gold standard will be a standard throat culture processed in the district laboratory.

The effect of point-of-care testing will be estimated by requiring physicians to decide on antibiotic use before receiving the result of the RST. (They will be free to change this decision after the test).

Clinics were selected by number of throat cultures sent in previous years. The number of patients was determined using the positivity rates of 2005. The results of this study will enable us to estimate the benefit and cost of adopting RSTs, and to determine in which situations they will be most efficacious.

Inclusion criteria

• sore throat
• at least two Centor criteria:
• fever > 38 deg C or history of fever
• enlarged cervical lymph nodes
• tonsillar exudate
• lack of cough
• age 3-14 years

Exclusion criteria

• antibiotic treatment in preceding 7 days
• no informed consent