Rapid detection of group A beta-hemolytic streptococcus (GAS) is used routinely to help diagnose and treat pharyngitis. However, available rapid antigen detection tests for GAS have relatively low sensitivity, and backup testing is recommended in children. Newer assays are more sensitive yet require excessive time for practical point-of-care use as well as laboratory personnel. The Alere i strep A test is an isothermal nucleic acid amplification test designed to offer highly sensitive results at the point of care within 8 min when performed by nonlaboratory personnel. The performance of the Alere i strep A test was evaluated in a multicenter prospective trial in a Clinical Laboratory Improvement Amendments (CLIA)-waived setting in comparison to bacterial culture in 481 children and adults. Compared to culture, the Aleri i strep A test had 96.0% sensitivity and 94.6% specificity. Discrepant results were adjudicated by PCR and found the Alere i strep A test to have 98.7% sensitivity and 98.5% specificity. Overall, the Alere i strep A test could provide a one-step, rapid, point-of-care testing method for GAS pharyngitis and obviate backup testing on negative results.
In developed countries, 15% of school-age children and 4% to 10% of adults will have an episode of group A streptococcus (GAS) pharyngitis each year (1). The accurate diagnosis and treatment of GAS pharyngitis is necessary to reduce symptoms, prevent suppurative and nonsuppurative sequelae, reduce transmission, and avoid unnecessary antibiotic use (1). Yet, clinical features and prediction rules alone are not adequate to make a diagnosis (2). Given that current point-of-care rapid antigen detection tests (RADT) for GAS have a limited sensitivity of approximately 85% (3), current guidelines recommend confirming negative results in children with a backup method, most commonly by culture (1). However, this two-step process adds additional time and costs, and it risks that some patients will be lost to follow-up (4). The Alere i strep A test is a new isothermal nucleic acid amplification test using a nicking enzyme amplification reaction (NEAR) that can provide results in under 8 min in a point-of-care (POC) setting. We performed a prospective, multicenter trial to evaluate the performance of the Alere i strep A test in comparison to bacterial culture, as the reference standard, with PCR adjudication for discrepant results.
MATERIALS AND METHODSWe prospectively enrolled subjects at 10 clinical sites within the United States (in Florida, Georgia, Nebraska, New Jersey, New York, and Ohio) from 21 January to 14 March 2014. The sites included emergency departments (general and pediatric), an urgent care center, and private practices (clinical and research focused). Subjects were eligible if they presented with complaints of a sore throat and signs of suspected pharyngitis: pharyngeal erythema, tender cervical lymphadenopathy, swollen tonsils, palatal petechiae, or scarlatiniform rash. Subjects were excluded if they had systemic antibiotic use in the past 2 wee...