Lab Test Details
General Considerations
Result quality is largely a product of specimen source, collection method, and the manner in which it is transported to the laboratory.
The following should be considered for sample collection and transport:
1. Collect culture specimens before antibiotic therapy whenever possible.
2. The specimen must be representative of the infection with as little contamination from normal flora as possible.
3. Utilize appropriate collection devices, use sterile equipment and aseptic technique to collect specimens. Collect specimens in sturdy, sterile, leak proof containers
4. Collect an adequate amount of specimen. Inadequate amounts of specimen may yield false-negative results.
5. Clear and specific instructions on proper collection techniques must be given to patients when they must collect their own specimens (for example: a clean catch urine or a sputum for AFB culture).
6. The specimen must be transported promptly and maintained in a manner that allows survival of fastidious organisms and prevents overgrowth by more hardy organisms.
7. Specimens collected in syringes are best maintained by removing needle and dead-capping the syringe, expelling excess air, and transporting to the lab in the syringe.
8. A fluid, tissue or aspirate specimen is a more desirable specimen than a swab.
Specimens Unsuitable for Microbiological Testing
Specimens that will not be processed include the following:
- Saliva
- 24 hour urine, stool, or sputum specimens
- Foley catheter tips
- Urine specimens >1 hour since collection without refrigeration or preservative
- Most duplicate specimens received on the same date; exceptions include: blood cultures, CSF, tissues, and sterile body fluids excluding urine
- Specimens contaminated with another type of specimen. For example: a urine specimen should not contain stool and vice versa
- Certain clinical specimens are unsuitable for anaerobic culture
- Swabs are not recommended for cultures, especially AFB and Fungus cultures.
- Dry swabs or dried tissue
- Gram stain for GC on specimens from cervical, vaginal, or anal crypts
- Specimens received in formalin
- Urine specimens for GC/CT/TV in excess of 60 ml
Reviewed: 02/02/23 Amanda Blackwell