Study type: Body fluid, throat swab [two swabs should be submitted for the 2–step algorithm so that a culture can be performed if the screen is negative; specific liquid-based collection systems may be required for NAAT methods, the testing facility should be consulted prior to specimen collection]; related body system: Immune and Respiratory systems.

The onset of strep throat is sudden and includes symptoms such as chills, headache, sore throat, malaise, and exudative gray-white patches on the tonsils or pharynx. Early diagnosis and treatment appear to lessen the seriousness of symptoms during the acute phase and overall duration of the infection and sequelae. A two-step algorithm using a rapid screening test followed by a confirmatory culture is widely used. A negative result does not mean absence of infection; studies have indicated a high percentage of false negative findings in the presence of GAS infection. Administration of antibiotics is often initiated before confirmatory culture results are reported. Evidence of GAS by conventional methods disappears rapidly after the initiation of antibiotic therapy.

Concerns regarding emergence of antibiotic-resistant microorganisms have led to the implementation of mandatory antibiotic stewardship programs in most facilities in order to curb unnecessary use of antibiotics. Within the past 5 yr, a number of nucleic acid amplification tests (NAATs) that employ molecular methods (e.g., PCR) have gained FDA approval for use in clinical laboratories and point-of-care (office) settings. The sensitivity and specificity of PCR assays is reported to be on par with culture methods, but with a much faster time to results reporting (i.e., less than 60 min for NAAT vs several days for bacterial culture). Increased awareness and availability of NAAT for GAS may eventually eliminate the need for a two-step process and help prevent unnecessary administration of antibiotics. Rheumatic fever is a possible sequelae to an untreated streptococcal infection; for additional information refer to the studies titled, “Antistreptococcal Deoxyribonuclease-B Antibody” and “Antistreptolysin O Antibody.”