BACTERIOLOGY AND MYCOLOGY SAMPLES - ALL SPECIES.

Correct sampling techniques and sample submission will optimise the recovery of pathogenic bacteria, yeasts and fungi. In general, swabs for bacterial isolation should be submitted in transport medium (bacteria on dry swabs dessicate rapidly). Other samples should be submitted in clearly marked, watertight, sterile containers. If submission is delayed then samples should be refrigerated at 4° C and should not be frozen. Samples should always be collected either prior to treatment or after suspension of treatment. Patient and specimen details should be included on the submission form along with a clinical history. Requests for specific antimicrobial sensitivities may also be made.

SAMPLING TECHNIQUES

The following information is not exhaustive. Please contact the laboratory if you require specific advice on any aspect of collection and submission of samples.

1. ABSCESS MATERIAL
Collect approximately 3ml of pus along with scrapings from the abscess wall if practicable and submit in a sterile universal. Pus from the centre of an abscess is often sterile. Material from recently formed abscesses is preferred.

2. ANAEROBIC CULTURES
Abscesses, deep wounds, body fluids, direct lung aspirates, tissue and blood are all suitable for anaerobic culture. Gastrointestinal specimens, faecal swabs, pharyngeal swabs, gingival swabs, vaginal swabs, cervical swabs, urethral swabs, voided urine, superficial skin swabs and tracheal washings are generally not suitable for anaerobic cultures. Preferred samples are blocks of tissue (approx. 4cm³) in a sterile container and liquid exudates collected in a sterile syringe with the air expelled and the needle bent back or plugged. Anaerobic cultures will be performed on swabs in transport medium when requested but recovery may be suboptimal. Generally, samples should not be chilled as this may reduce recovery.

3. BLOOD CULTURES
Use routine aseptic technique to prepare the skin over the venupuncture site. Withdraw between 5 and 10ml of blood (depending on the species). Change the hypodermic needle, remove the outer foil cap from a 75ml blood culture bottle and transfer the blood to the blood culture bottle. Do not remove the screw cap from the bottle.

4. DERMATOPHYTES
Collect plucked hairs for dermatophyte culture from the periphery of lesions. Similarly collect scab material from the periphery of lesions using a blunt scalpel blade. Submit samples (hair, or scrapings) in a paper envelope. Scalpel blades must be submitted in a secure strong plastic container, appropriately labeled. Clip or scrape claws as close to the base as possible. For suspected inapparant infections, submit hair and scurf brushings again in a paper envelope. Paper is preferred as saprophytic fungi will rapidly overgrow a sealed sample due to the moisture present.

5. EAR SWABS
Generally collect swabs for bacterial culture after otoscopic examination as material may be impacted into the horizontal canal making such examination difficult. In a large dog, swab the horizontal canal through the auroscope as this is the site at which most bacterial infections commence. This is also the preferred technique for collecting material for cytological examination. After collecting the material on a cotton/viscose swab, roll the swab along two clean glass slides and rapidly air dry. Submit these smears along with a swab in transport medium if cytological examination is required.

6. SKIN LESIONS
Swab intact pustules with 70% ethyl alcohol and allow to dry. Either pierce with a sterile needle and absorb the contents onto a sterile swab or aspirate the contents and express either onto a sterile swab or into a sterile vial. Use a sterile swab to sample areas of superficial pyoderma, preferably sampling from the margin of the lesion. Submit biopsies for bacterial culture in a sterile universal.

7. SYNOVIAL FLUID
A guide to sampling of synovial fluid in dogs, cats and horses is available on request. First remove the outer foil cap from a 20ml blood culture bottle. Change the needle used for athrocentesis for a sterile needle and transfer between 1ml and 2ml of synovial fluid to the blood culture bottle. Do not remove the screw cap from the bottle.

8. TISSUES AND ORGANS
Samples for bacteriology should be collected as soon as possible after death. Use a heated scalpel blade to sear the surface of the organ (e.g. lung or liver) and stab insert a sterile cotton swab. Rotate the swab, remove and place into transport medium. Alternatively submit whole tissues (approx. 4cm³) unfixed in sterile containers or open a rib and swab the marrow to limit the collection of post mortem invaders.

9. URINE
Representative samples are obtained by taking mid-stream voided urine, by catheterisation or by cystocentesis (Yam, 1994). Submit samples in boric acid to minimise bacterial overgrowth and contamination.

10. VAGINAL SWABS
To minimise contamination from the perineal/vulval area, insert the swab through a vaginal speculum. The outer plastic case of a disposable syringe may be adapted for this purpose. Alternatively a guarded swab may be used.

11. YEASTS AND FUNGI
A diversity of specimens may be collected for yeast and fungal cultures depending on the site of the lesion. Generally submit either unfixed tissue in a sterile container, fluid in a sterile container or a swab in bacterial transport medium. Where possible, tissue fixed in 10% formalin should also be submitted in order to demonstrate tissue invasion.

SAMPLING MATERIALS.

The following sampling materials are available free of charge on request:-

Please consult the Microbiology section of the price list for a comprehensive listing of available tests and services.

REFERENCES

Carter, G.R. (1990) Selection and Submission of Clinical Specimens. In: Diagnostic Procedures in Veterinary Bacteriology and Mycology. 5th Edition. Eds. Carter, G.R. and Cole, J.R.Jr. Academic Press Inc. San Diego. p 11 - 14.

Quinn, P.J. et al (1994). Clinical Veterinary Microbiology. Wolfe Publishing. London. p 13 - 16.

Yam, P.(1994). Cystocentesis in the dog and cat. In Practice. 16 (6). p 319 - 320.