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FRECUENTLY ASKED QUESTIONS
Does the transport of patient’s specimen from the clinic to the laboratory have any effect on the final culture results?
Yes! A patient’s specimen is a valuable sample that must be handled with care from the moment it is collected. Immediately after collection, the specimen should be placed in a properly conditioned cool box with enough ice packs to maintain a temperature between 2°C and 8°C during transport to the laboratory.
Failure to maintain the correct temperature range can compromise the integrity of the specimen and negatively affect the quality of the laboratory results.
How many patient specimens should be processed in one batch?
No more than eight specimens, including both negative and positive controls, should be processed in a single batch.
The positive control, which should be included at the end of the batch once per week, is essential for assessing the performance of the NALC-NaOH solution and phosphate-buffered saline (PBS).
The negative control, placed in the middle of the batch, is important for verifying the sterility of the decontamination process. However, it does not rule out false results in microscopy smears or culture.
How many laboratory technologists should be able and available to perform a lab test?
At least two (2) laboratory technologists must be trained, proficient, and competent to perform the same laboratory test. This ensures continuous service delivery and quality control. For example, if the laboratory receives between 8 and 14 patient specimens in a day, the samples should be divided into two batches and processed separately by each technologist in different Biosafety Cabinets (BSCs).
If only one technologist and/or one BSC is available to process more than seven specimens, the second batch should be stored in a refrigerator at 2°C to 8°C and processed after completing the first batch.
When processing multiple batches in the same BSC, disinfect the cabinet and allow 20 minutes of air circulation between batches to maintain biosafety and prevent cross-contamination.
Is the Lab technician-contaminated culture a key performance indicator?
Yes! The culture contamination rate, M. tuberculosis isolation rate, false-positive liquid culture results, and other related outcomes can serve as performance indicators for laboratory technologists involved in specimen processing.
These indicators should be monitored regularly — on a weekly, bi-weekly, or monthly basis — to identify and address any quality issues promptly. For example, high contamination rates may indicate the need for refresher training or corrective actions to improve laboratory practices and ensure reliable results.
Does TB-LOG recommend using decontaminant reagents prepared in house?
Yes, in-house preparation of decontaminant reagents is acceptable, provided they are prepared correctly and in accordance with the relevant Standard Operating Procedures (SOPs).
If the reagents—such as NaOH, Sodium Citrate, and Phosphate Buffer (PB)—are not prepared properly (e.g., using a non-calibrated scale, incorrect volumes of distilled water, or poor-quality chemicals), this can negatively impact the quality of laboratory results.
Therefore, strict adherence to SOPs and proper quality control measures during reagent preparation are essential to ensure reliable and valid TB culture outcomes.