The UMMC Microbiology Laboratory utilizes a variety of methods for identification of bacteria, mycobacteria and fungi. Methods include, but are not limited to, traditional biochemical and enzyme-based methods, serotyping, and microscopy. It is our goal to utilize the most current methods available to provide our patients with accurate and rapid results.
Valid interpretation of results can be achieved only if the specimen obtained is appropriate for processing. As a result, care must be taken to collect only those specimens that may yield pathogens, rather than colonizing flora or contaminants. Specific rules for the collection of material vary, depending upon the source of the specimen, but several general principles apply:
Use of the aerobic culture swab is recommended for most sites for which a swab of such size is a suitable method to collect the specimen.
Anaerobic bacteria form a major part of the body's normal flora so extreme caution must be taken to avoid contamination by anaerobic normal flora and overgrowth by coexisting aerobic bacteria.
The collection procedures offered below are guidelines only to provide for the optimum specimen possible.
Chlorhexidine Blood Culture Prep kits must be used according to package insert. If kits are not available, the following procedure must be used: Swab skin over the site of venipuncture with 70% alcohol. Allow alcohol to dry completely. Swab the site in concentric circles with an iodophor solution (2% iodine or a povidone-iodine preparation). If the patient is known to be hypersensitive to iodine, the skin may be prepared exclusively with 70% alcohol. Do not touch venipuncture area after preparation. Gloves should be worn when performing the venipuncture. Do not recap needles. Decontaminate the diaphragm on the tops of the Bactec bottles with a 70% alcohol solution before injecting the blood into the bottle. Inoculate a Bactec Plus aerobic bottle with 8 - 10 mL and an anaerobic bottle with 5 - 7 mL. Inoculate Peds Plus with 1 - 3 mL. Three sets of cultures per twenty-four hours should pick up 97-99% of positive results. Blood cultures should not be drawn from indwelling intravenous or intra-arterial catheters because of the risk of contamination unless venipuncture cannot be obtained. In cases where cultures are drawn from indwelling catheters discard the first 5 mL.
Use sterile scissors to cut off tip and/or 5-7 cm of intra-cutaneous segment. Submit in sterile container. Foley catheters are not acceptable specimens. Do Not Refrigerate. Must be received in lab within 24 hours.
Collect CSF aseptically from a lumbar puncture into sterile tubes. Send tube #2 or #3 for Microbiology testing. A minimum of 1.0 mL is required for each culture needed; i.e., bacterial, fungal, etc. Do Not Refrigerate. Must be received in lab within 2 hours.
Collect outflow fluid aseptically in a sterile container.
Place 5-10 mL (0.5 mL minimum) in sterile container, or anaerobic transport system if anaerobes are suspected for each culture needed; i.e., bacterial, fungal, etc. Can add sterile heparin if specimen may clot. Do Not Refrigerate. Must be received in lab within 2 hours.
Examine with Wood's light. If Wood's light positive (green fluorescence) pluck fluorescing hairs with sterile forceps. If Wood's light negative, pluck dull gray hairs. Can also scrape the scalp with a scalpel. Hair stubs, contents of plugged follicles, and skin scales are also acceptable. For fungus detection only.
Clean skin around nail with 70% alcohol. Take deep scrapings of involved areas or clip generous amounts of nails. Remove surface nail and discard. Send clippings from inner nail. Store at room temperature and deliver to lab within 24 hours.
Cleanse infected area with 70% alcohol. Using a sterile scalpel, scrape skin from the borders of the active lesion. Skin from the periphery of the lesion, as well as adjoining healthy areas is preferable. Separate swab needed for each type of culture needed; i.e., 1 for bacterial, 1 for fungal, etc. If stain is requested, submit additional swab. Do Not Refrigerate.
Collect surgically or through needle biopsy. Place a 4 mm2 portion into a sterile container for each culture needed; i.e., bacterial, fungal, etc. Indicate which culture is most critical in case of insufficient quantity to perform all. If anaerobes are suspected, place specimen in the inner tube of anaerobic transport system. Do Not place in formalin. Do Not Refrigerate. Must be received in lab within 24 hours.
1 - 2 mL required for routine culture; 25 - 50 mL of urine is required for AFB or fungus testing. If unable to deliver to lab immediately, refrigerate specimen.
Collect 2 swabs for each culture needed; i.e., 2 for bacterial, 2 for fungal, etc. Must collect with anaerobic swab if anaerobes are suspected. Do Not Refrigerate. Deliver to lab within 24 hours.