Investigate & Document Culture Failures

Biological Failures (Specimen-Related)

These failures are inherent to the sample quality or the patient’s pathology. The laboratory could not have prevented them

Low Viability
- Cause: Specimen exposed to extreme heat/cold during transport, delay in transit (>4 days), or collected in the wrong additive (EDTA/Formalin)
- Evidence: Upon receipt, the media was yellow/acidic or the blood was hemolyzed/clotted. In culture, cells never attached or remained small and dark (necrotic)
Low Cellularity / Acellularity
- Cause: “Dry tap” bone marrow (mostly blood), hypocellular amniotic fluid (early gestation), or necrotic tumor biopsy
- Evidence: In culture, very few cells are visible. For amnio, only 1–2 colonies formed despite weeks of incubation
Pathology
- Cause: Some tumors have low mitotic indices or undergo massive apoptosis in vitro. In constitutional bloods, patients on immunosuppressive therapy may have T-cells that fail to respond to PHA
Documentation: The report states “Culture Failure” or “Unsuccessful Study.” The comment must explicitly describe the condition: “Specimen received clotted and >72 hours old. No dividing cells were obtained.” This places the failure in context for the physician

These are errors within the laboratory’s control. A pattern of these failures triggers a Quality Assurance (QA) audit

Incubator Malfunction
- Scenario: A thermostat breaks, cooking the cells at \(50^\circ\text{C}\), or a CO2 tank runs empty, raising the pH to lethal levels
- Investigation: Check the daily temperature/gas logs. Did multiple patients fail in the same incubator on the same day?
Media/Reagent Failure
- Scenario: A bad lot of Fetal Bovine Serum (FBS) lacks growth factors, or a batch of PHA is inactive
- Investigation: “Cluster Failure.” Did all blood cultures set up on Tuesday fail? Check the lot numbers of the media used that day. Run a QC test on the current reagents using a healthy donor control
Contamination
- Scenario: Microbial overgrowth destroys the sample
- Investigation: Was it a single tube (technique error) or the whole batch (media contamination)? Identify the organism (fungal vs. bacterial) to find the source
Labeling/Processing Error
- Scenario: The laboratory scientist forgot to add PHA to a blood culture, or harvested the wrong tube
- Investigation: Review the worksheet. Interview the staff involved

When a failure is identified in progress, attempts are made to rescue it

Rescue Strategies
- Subculture: If cells are crowded or stunned, splitting them into fresh media can jumpstart growth
- Enrichment: Adding “Chang” media (hormone-rich) or increasing serum concentration to 20%
- Co-Culture: For bone marrow, using “feeder layers” or conditioned media
The “Call Back”: If failure is inevitable, the ordering physician must be notified immediately (not weeks later). This allows for a repeat collection (e.g., a second blood draw) while the clinical need is still relevant

Every failure is logged in the QA database

Metrics: Labs track their “Culture Success Rate” monthly (e.g., Target \(>98\%\) for blood, \(>95\%\) for amnio). A drop in this rate triggers a “Root Cause Analysis”
Records
- Accession Number
- Specimen Type
- Date of Setup / Harvest
- Reagent Lot Numbers
- Laboratory Scientist ID
- Reason for Failure: (e.g., “Gross Fungal Contamination”)
Sign-Off: The Laboratory Director (MD/PhD) usually reviews all culture failures before the final report is released to ensure all salvage options were exhausted and the explanation is clinically sound