CPT® Code 87557

The CPT® Code 87557 refers to a laboratory test designed for the detection of the infectious agent Mycobacteria tuberculosis through the analysis of nucleic acids, specifically DNA or RNA. Mycobacteria tuberculosis is a gram-positive, acid-fast bacterium that is the causative agent of both latent tuberculosis infection and active tuberculosis disease. This bacterium can affect the lungs as well as other areas of the body. Common symptoms associated with pulmonary tuberculosis include a persistent cough and chest pain, while systemic symptoms may encompass fatigue, weight loss, anorexia, fever, chills, and night sweats. Tuberculosis is transmitted from person to person primarily through respiratory secretions, making it highly contagious and potentially fatal if not treated appropriately. The testing process involves a direct probe test, which identifies a unique nucleic acid sequence known as the target sequence of the M. tuberculosis organism, provided it is present in the sample. This probe is labeled with either fluorescent or chemiluminescent markers. The sample undergoes treatment to release nucleic acids from the target organism, allowing the labeled probe to specifically bind to the matching target sequence, forming a stable hybrid. Ribosomal RNA is often the focus of these tests due to its abundance in microorganisms, as it is typically found in thousands of copies compared to the 1-2 copies of genomic DNA. In the amplified probe technique, which is represented by CPT® Code 87556, the sensitivity of the assay is significantly enhanced by exponentially multiplying the target sequence of M. tuberculosis DNA or RNA into millions of copies. The polymerase chain reaction (PCR) or reverse transcriptase polymerase chain reaction (RT-PCR) is the most commonly employed amplification technique. Following amplification, the replicated sequences are identified using labeled DNA probes. The CPT® Code 87557 specifically pertains to the quantification of these amplified nucleic acid sequences, providing an assessment of the number of microorganisms present in the sample. Quantitative or real-time PCR is frequently utilized to amplify the isolated nucleic acid segment and generate a report documenting the absolute or relative amounts of the known nucleic acid sequence at each stage of the process.