87045

Culture, bacterial, quantitative, from respiratory tract, for bacterial colony count (e.g., for diagnosis of pneumonia)

This CPT code describes the laboratory procedure for performing a quantitative bacterial culture from a respiratory tract specimen (e.g., sputum, bronchoalveolar lavage (BAL) fluid, tracheal aspirate). The primary purpose of this test is to enumerate the number of bacterial colonies present, typically reported as colony-forming units per milliliter (CFU/mL). This quantitative count helps to differentiate between airway colonization and true infection, which is particularly crucial in the diagnosis of lower respiratory tract infections like pneumonia, especially in ventilated or critically ill patients. The process involves serial dilution of the specimen, plating on appropriate culture media, incubation, and subsequent counting of the bacterial colonies.

Clinical Indications

  • Diagnosis of suspected bacterial pneumonia (e.g., community-acquired, hospital-acquired, or ventilator-associated pneumonia (VAP)), particularly when quantitative counts are needed to distinguish infection from colonization.
  • Evaluation of lower respiratory tract infections in immunocompromised patients or those with pre-existing lung disease where the bacterial load is clinically significant.
  • Monitoring the efficacy of antimicrobial therapy by assessing changes in bacterial burden.
  • Identification of predominant pathogens and their quantity to guide targeted antibiotic selection.
  • Assessment for bacterial superinfection in patients with viral respiratory illnesses or acute respiratory distress syndrome (ARDS).

Procedure Steps

  1. Receive and accession respiratory tract specimen (e.g., sputum, BAL, tracheal aspirate) in the laboratory.
  2. Homogenize the specimen, if necessary, to ensure even distribution of microorganisms.
  3. Prepare serial dilutions of the specimen in sterile diluent.
  4. Inoculate specific volumes of diluted and undiluted specimens onto appropriate selective and non-selective bacteriologic agar media.
  5. Incubate inoculated culture plates under optimal atmospheric conditions (e.g., aerobic, microaerophilic, anaerobic) and temperature for a specified period, typically 18-48 hours.
  6. Visually count all distinct bacterial colonies growing on the quantitative culture plates.
  7. Calculate the bacterial concentration in the original specimen, expressing results in colony-forming units per milliliter (CFU/mL) or per gram (CFU/g) if applicable.
  8. Report the quantitative bacterial count; significant isolates may proceed to identification and susceptibility testing, which are coded separately.

Coding Guidelines

  • Code 87045 is specifically for quantitative bacterial cultures from respiratory tract specimens. Do not use for qualitative cultures or quantitative cultures from other body sites.
  • If bacterial identification (e.g., 87077) or antibiotic susceptibility testing (e.g., 87184, 87186) is performed on the isolated bacteria, these services should be reported separately in addition to 87045.
  • Documentation must clearly support the medical necessity for a quantitative culture, differentiating it from a routine qualitative culture, by indicating the clinical suspicion for conditions like pneumonia where bacterial load is critical.
  • This code represents a technical and professional component; typically, laboratories bill for the complete service.
  • Multiple quantitative cultures performed on the same patient within a short timeframe require strong clinical justification.

Associated ICD-10 Codes