[Validation of a rapid antigenic test in the diagnosis of pharyngitis caused by group a beta-haemolytic Streptococcus].
OBJECTIVE
To determine the validity of the rapid antigen test (RAT) OSOM StrepA Genzyme for the diagnosis of acute pharyngitis caused by group A beta-haemolytic strep (GABHS).


METHODS
Diagnostic techniques survey.


METHODS
Urban primary care centre, Spain.


METHODS
All patients over 14 years old seen in 6 surgeries with sore throat and 2 or more Centor criteria: pharyngotonsillar exudate, tender laterocervical nodes, absence of coughing, and/or history or presence of fever.


METHODS
Pharyngeal swabs were taken from all the patients, one for RAT and another to send for culture in the microbiology department.


RESULTS
A total of 182 patients were evaluable, with a mean age of 30.6 (12.1) years of which 116 were women (63.7%); 63 patients had 2 Centor criteria; 83 had 3 and 36, the 4 criteria. The culture was positive in 102 patients (56%), with GABHS showing infection in forty (22%; 95% confidence interval [CI], 21.2-22.8). Group C Streptococcus was isolated in 26 patients (14.3%). GABHS was higher among patients with four Centor criteria (38.9% vs 25.3% observed among those with 3 criteria and 7.9% with 2 criteria; P<.001). Sensitivity of RAT was 95%, with a specificity of 93%, a positive predictive value of 79.2% and a negative predictive value of 98.5%.


CONCLUSIONS
These results show the usefulness of RAT for diagnosing streptococcal pharyngitis. Its use should be spread to all primary care practices.
Llor
Carles
C
Medicina de Familia, Centro de Salud Jaume I, Tarragona, Spain. carles.llor@urv.cat
Hernández Anadón
Silvia
S
Gómez Bertomeu
Frederic Francesc
FF
Santamaria Puig
Josep Maria
JM
Calviño Domínguez
Olga
O
Fernández Pagés
Yvonne
Y
D000328:Adult; D005260:Female; D006801:Humans; D007159:Immunologic Tests; D008297:Male; D010612:Pharyngitis / Q000175:diagnosis* / Q000276:immunology / Q000382:microbiology*; D011446:Prospective Studies; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000276:immunology; D013297:Streptococcus pyogenes; D013997:Time Factors