Specimen Collection Guidelines

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Samples from Skin Lesions

For most dermatological conditions, diagnosis may be established on the basis of physical examination and clinical history without the collection of diagnostic specimens. Important characteristics to be noted on physical examination include the nature of the skin lesions (erythematous, macular, papular, maculopapular, vesicular, bullous, petechial, purpuric, etc.) and the anatomic distribution of spread (central, peripheral, diffuse, etc.) In cases of indeterminate diagnoses, unusual presentations, and some rare conditions, collection of specimens from rashes and/or skin lesions may be necessary. In the case of vesicular rashes, specimens for microscopy and culture are taken directly from vesicles. In other exanthemata (macular and/or papular), the diagnosis may be more readily established from alternative specimens (e.g. blood cultures, serology). In suspected cutaneous anthrax or bubonic plague, specimens from the skin lesions (scars and buboes, respectively) and blood cultures may be taken.

Vesicular or Vesiculo-pustular Rash and Slide Preparation (for diagnosis of viral infections)


Materials

Supplies
  • Sterile swabs and appropriate transport media
  • Sterile screw cap vials
  • Sterile lancets or needles (for piercing of vesicles).
  • Syringe with wide-bore needle (for aspiration of abscesses/buboes)
  • Wide mouth screw-cap containers (for biopsy specimens)
  • Glass slides and slide boxes
Reagents
  • Sterile saline

Procedure

Step Action
1. HSV-infected cells are present in greatest numbers in the base of the vesicles or ulcers that are useful for direct HSV-1 and HSV-2 antigen detection.
2. Clean the fresh mature vesicle or ulcer with 70% ethanol.
3. Using a tuberculin syringe fitted with 26-27 gauge needle, insert the needle, bevel edge up, into the base of the vesicle.
4. Aspirate fluid and immediately, carefully inject the fluid into a vial containing 1- 2ml viral transport media; rinse once.
5. Lift the membrane of the vesicle and using a sterile Dacron swab, firmly rub at the base of the ulcer (Calcium alginate swabs cannot be used).
6. Immediately place the swab in the vial containing viral transport media.
7. Carefully scrape cells from base of the ulcer with scalpel or curette.
8. Rinse the lesion with two to three drops of viral transport media to make a cell suspension.
9. Aspirate the suspension and prepare three spots on a clean glass microscope slide
10. The slide should be left to dry in air.
11. Fix in cold acetone
12. Place in a slide box for transport to the laboratory

Handling

Specimens for bacteriological analysis should be transported in Stuart’s or Amies medium. Swabs for suspected viral pathogens should be transported in virus transport medium. Other specimens should be handled as described in the relevant section.

If processing takes longer than 2 hours, bacteriology specimens can be maintained at ambient temperature for 24 hours. Specimens for virus isolation may be refrigerated at 4-8oC, and transported to the laboratory as rapidly as possible. In some instances, the outbreak investigation team may bring liquid nitrogen for specimen preservation. If this is the case, follow the instructions of the experienced laboratorian as to appropriate use. If there are any questions regarding handling and transport, check with the laboratory which will be receiving the specimens. In any outbreak investigation, it should be considered essential to consult the receiving laboratory about the handling of most specimen types before setting out into the field.