Bacteriology Sample Submission Hints
General Guidelines for Sample Submission:
- Whenever possible, collect the specimen prior to administration of antimicrobial agents.
- Collect the specimen by aseptic means and transport in a sterile container.
- Collect an adequate amount of specimen. If in doubt, please call the laboratory.
- Provide a relevant, concise clinical history with the submission.
- Clearly label the specimen container with the patient's name, date and tissue site. Identification of the tissue site will allow for proper growth medium and incubation requirements to be selected.
- Select the appropriate transport system and temperature for shipment. Chilling specimens during transport will inhibit overgrowth by hardy environmental bacteria such as Proteus spp. Furthermore, transport to the laboratory in 24 hours will increase the likelihood of recovering fastidious bacteria such as Haemophilus.
- Do not send a dry fabric swab! New polyurethane sponge swabs are fine. Be sure to crush the capsule on commercial swabs.
- Anatomic sites likely to contain anaerobic bacteria contributing to the disease process would be closed cavities such as peritoneal cavity, joint space, and para-nasal sinus.
- The following specimens are generally unacceptable for culture of non-sporeforming anaerobic bacteria:
- Aerobic swabs from any site
- Gastrointestinal specimens
- Fecal or rectal swabs
- Throat or nasopharyngeal swabs (unless abscess)
- Gingival swabs (unless surgically obtained from abscessed tooth root)
- Vaginal, cervical, or urethral swabs
- Voided urine
- Tracheal washings
- Swabs from surface of ulcers, skin lesions, and fistulous tracts
- When submitting fecal or cloacal specimens, understand the laboratory's identification schemes to allow the ruling out of pathogens:
- 'Salmonella only' – media selected to recover only Salmonella
- 'Enteric pathogens' – media selected to recover Salmonella, Yersinia, Aeromonas, and Plesiomonas
- Psittacine birds – cloacal cultures are routinely set up for any Gram negative bacterium
- A specific request will be needed for Campylobacter jejuni, Vibrio cholerae or Johnes culturing.
- Fungal cultures are routinely conducted on chronic nasal discharges, aborted fetal tissues, tissue granulomas, and corneal/conjuntival specimens because of the prevalence of fungal infections at these sites.
- Do not over inoculate vials of DTM with hair/scrapings. Plant only 2-3 diseased hairs.
- Do not hold inoculated DTM cultures until the medium turns red. Bacteria and saprophytic fungi will each turn the medium red, so ship immediately.
Culture and Sensitivity:
Culture and Sensitivity are separate tests to be requested. Most bacteria recovered from submitted specimens are environmental or commensal and do not warrant antimicrobial sensitivity testing
- 'Culture only' – no antimicrobial testing will be done
- 'Call before antimicrobial testing' – laboratory will call clinician before testing an isolated strain
- 'Pathogens only' – testing on known pathogens, ex. Salmonella
- 'Culture and Sensitivity' – antibiotic testing on frank pathogens, and 'opportunistic' pathogens. The laboratory will err on the conservative side by testing bacteria like Klebsiella, Pseudomonas, Acinetobacter, and DNase (+) Staphylococci. The laboratory does not routinely conduct sensitivity testing on bacteria of low virulence, such as DNase (–) Staphylococci, non-beta hemolytic Streptococci, or Enterobacter.
Last Updated: October 9, 2008