CPT® Code 87650

The CPT® Code 87650 refers to a laboratory test designed for the detection of the infectious agent known as Streptococcus, group A (GAS) through the use of nucleic acid techniques, specifically targeting DNA or RNA. This test is crucial in identifying the presence of GAS, which is primarily transmitted via respiratory droplets and direct contact with infected skin lesions, such as those seen in impetigo. Additionally, there have been instances of transmission through contaminated food and water. The clinical manifestations of GAS infections are diverse, commonly presenting as respiratory and skin infections, but can also lead to more severe conditions such as meningitis, osteomyelitis, toxic shock syndrome, and necrotizing fasciitis. The direct probe technique utilized in this test focuses on identifying a unique nucleic acid sequence, referred to as the target sequence, specific to the GAS bacterium. This is achieved by using a probe that is labeled with either fluorescent or chemiluminescent markers. During the testing process, the sample is treated to release nucleic acids from the target organism, if present. The labeled probe then selectively binds to the matching target sequence, forming a stable hybrid. Ribosomal RNA is often the target of this detection method due to its abundance in microorganisms, as it is typically present in thousands of copies compared to the limited 1-2 copies found in genomic DNA. For enhanced sensitivity, an amplified probe technique (CPT® Code 87651) may be employed, which involves exponentially multiplying the target sequence of GAS DNA or RNA into millions of copies. The polymerase chain reaction (PCR) or reverse transcriptase polymerase chain reaction (RT-PCR) are the most commonly used amplification methods. Furthermore, nucleic acid detection with quantification (CPT® Code 87652) allows for an assessment of the quantity of microorganisms present by utilizing quantitative or real-time PCR to amplify the isolated nucleic acid segment and generate reports documenting the absolute or relative amounts of the known nucleic acid sequence at each stage of the process.