Bacteriology and Mycology

Submission Guidelines and General Considerations: 

Samples intended for bacterial or fungal culture should be collected and transported in a manner to decrease contamination and ensure viability of any pathogens in the sample.

Samples should be transported to the lab quickly (same day or overnight, if possible) and cold (keep refrigerated and ship on ice packs). This approach decreases the overgrowth of contaminants and maintains any microbial populations in the same relative quantities as the time of collection.

To prevent sample processing delays, please ensure the submission form and transport containers are labeled consistently and legibly. Clearly and specifically indicate what the sample is (ex: peritoneal swab, lung tissue, intestinal biopsy, urine collected by cystocentesis, etc.). Indicate the top differentials so that pathogens requiring special culture conditions will not be missed.

Specific Guidelines:

  • Liquids and tissues should be placed in a sterile container with no additives. Commonly used transport containers include red top tubes and sterile plastic bags.
    • If a tissue sample is smaller than 0.5cm³, please ensure the sample does not desiccate by adding 0.5mL of sterile saline to the container.
  • If liquids or tissues are not available, then a swab sample may be appropriate. Commercial culturettes are designed to prevent desiccation. If using a sterile cotton swab, place it in a red top tube with 0.5mL of sterile saline.
  • Because the laboratory performs a semi-quantitative urine culture, a minimum of 0.5mL urine is required. The report will indicate the quantity considered significant based on collection method: cystocentesis, clean catheterization, clean mid-stream free catch. Collection through indwelling catheters is not recommended as growth may represent a biofilm on the catheter and not bacteria present in the urinary bladder.
  • Blood culture requires special collection tubes. Yellow top tubes are recommended. Skin must be sterilely prepped prior to blood draw. Collection and culture of three blood samples is recommended to aid final interpretation.
  • If anaerobes are on the differential list, the request for anaerobic culture must be indicated on the submission form. Samples greater than 2mL or 2cm³ are adequate to preserve viability of anaerobic organisms. For smaller samples, use a commercial anaerobic transport device. If using an anaerobic transport tube containing gel, don’t push the sample all the way to the bottom; a depth of approximately 2cm is adequate.
  • If multiple samples are contained in the same transport device, they must be treated as one sample. Once samples have touched, they cannot be tested separately.

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