87481

Infectious agent detection by nucleic acid (DNA or RNA); Candida species, amplified probe technique

CPT code 87481 describes a laboratory procedure for the detection of infectious agent antigen by nucleic acid (DNA or RNA) for Candida species using an amplified probe technique. This molecular diagnostic test is designed to identify the presence of fungal organisms from the Candida genus in various clinical specimens, such as vaginal swabs, blood, urine, or tissue samples. Unlike direct probe techniques (represented by code 87480), the amplified probe technique involves an enzymatic process, such as Polymerase Chain Reaction (PCR) or Transcription Mediated Amplification (TMA), to significantly increase the number of target nucleic acid sequences. This amplification step allows for much higher sensitivity and specificity, enabling the detection of very low concentrations of the fungal pathogen that might be missed by direct methods or traditional culture techniques. In the clinical setting, this test is often utilized to diagnose vulvovaginal candidiasis (VVC), especially in recurrent or complicated cases, and to detect systemic candidemia in immunocompromised patients. Rapid identification via molecular methods is critical because Candida species vary in their susceptibility to antifungal agents; for example, Candida glabrata and Candida auris often demonstrate higher resistance to fluconazole compared to Candida albicans. The laboratory process includes specimen preparation, nucleic acid extraction, the amplification of specific DNA or RNA sequences unique to the Candida genus, and the subsequent detection of these sequences using fluorescent or chemiluminescent probes. The results are typically reported as detected or not detected.

Clinical Indications

  • Suspected vulvovaginal candidiasis with inconclusive microscopy or culture results
  • Evaluation of recurrent or chronic vaginitis symptoms such as itching, burning, and abnormal discharge
  • Rapid screening for systemic candidemia in immunocompromised or critically ill patients
  • Identification of Candida species in sterile body fluids or tissue biopsies
  • Monitoring of patients at high risk for fungal infections, such as those undergoing chemotherapy or organ transplantation
  • Differentiating fungal infection from bacterial vaginosis or trichomoniasis in a symptomatic patient

Procedure Steps

  1. Collection of the clinical specimen (e.g., vaginal swab, blood in EDTA tube, or sterile fluid) using appropriate transport media.
  2. Accessioning and preparation of the specimen in the laboratory following CLIA-certified molecular diagnostic protocols.
  3. Lysis of the fungal cells to release the genetic material (DNA or RNA).
  4. Extraction and purification of the nucleic acids from the clinical matrix to remove inhibitory substances.
  5. Addition of primers and enzymes specifically designed to target conserved regions of the Candida genome.
  6. Thermal cycling or isothermal incubation to achieve enzymatic amplification of the target nucleic acid sequences.
  7. Hybridization of amplified sequences with labeled molecular probes for detection.
  8. Signal detection and interpretation of results using specialized instrumentation.
  9. Validation of internal controls to ensure the absence of PCR inhibitors and the integrity of the assay.

Coding Guidelines

  • Use 87481 specifically for amplified probe techniques; do not use for direct probe (87480) or quantification (87482).
  • If the test is performed as part of a larger multiplex panel for multiple organisms (e.g., a comprehensive vaginitis panel), check for more specific panel codes like 87801 or 87660-87661, though 87481 is often billed individually if performed as a stand-alone test.
  • Modifier 59 may be required if 87481 is performed on the same day as other infectious agent molecular tests, depending on Payer-specific NCCI edits.
  • Do not report 87481 in conjunction with 87800 (Infectious agent antigen detection by nucleic acid, multiple organisms, direct probe technique) for the same organism.
  • Ensure the medical record supports the necessity of an amplified nucleic acid test over traditional culture or direct microscopy.

Associated ICD-10 Codes