Specimen Collection and Transport for Recovery of Anaerobic Bacteria

SPECIMEN COLLECTION GUIDELINES

Specimens that should never be cultured for anaerobes

The following sites will be rejected as being inappropriate for anaerobic culture because it would be impossible to distinguish pathogenic anaerobes from those that are normal commensals at that particular site.

• Gingival swabs, throat, nasal wash or nasopharyngeal swabs
• Sputum, tracheal aspirates, or bronchoscopic specimens
• Voided urine, vaginal or cervical swabs
• Gastric contents, small-bowel contents, feces, rectal swabs
• Decubitus ulcers, perineum, rectal abscess
• IV catheters and cannulas
• Skin or mucosal surface swabs where anaerobes are likely to be part of the normal flora 

Anaerobic Culture Policy

Specific types of specimens submitted to the laboratory fall into one of the following two groups:
 
Group A
Specimen is processed for anaerobic culture regardless of the request and even if the specimen was not properly collected or transported. If not properly collected and transported a comment will be appended to the report which states “Anaerobic transport system not sent or oxygenated. Recovery of anaerobes may be compromised.” 

 
Group B
Specimen is only processed for anaerobic culture upon request if the specimen has been properly collected and transported. Note:  If Group B specimens are received in the proper transport but an anaerobic culture is NOT ordered, a call is made to verify if the doctor does or does not want an anaerobic culture. 

 
The following outlines how each individual specimen type is handled by the laboratory. This means that the laboratory will not perform anaerobic cultures on Group B specimens (i.e. not properly collected and transported) because the results may be falsely negative and possibly clinically misleading.

Specimen Types

Group A (Automatically Cultured)

• Tissues including liver, spleen, lung, brain, fascia, heart, pericardial, bone, muscle, endometrial
• Sterile fluids such as blood, vitreous/aqueous, synovial fluid, bile, amniocentesis fluid, culdocentesis fluid, pleural, tympanocentesis fluid, peritoneal, pericardial, urine (suprapubic aspirate ONLY)
• Sterile aspirates from deep-seated abscesses (brain, subdural, epidural, eye/orbital, lung, liver, spleen, mediastinum, tubo-ovarian abscess)

Group B (Cultured by Request)

• Any specimen submitted on a swab (poor specimen for isolating anaerobes)
• Intra-abdominal abscess or drainages
• Dental infections to include dental points
• Surgical wound infections
• Superficial wounds
• Diabetic foot swabs
• Abscess fluid (aspirates) or tissue (collected in OR) when contamination by normal anaerobic commensals is very high (peritonsillar, sinus, perirectal, perineal, pilonidal, prostatic, intra-peritoneal, intra-abdominal, tubo-vaginal, placenta-C Section only, IUD)

Containers

Ideally, pus, fluid and/or tissue (not swabs) should be collected to optimize the recovery of the anaerobic bacteria present. An anaerobic transport tube ^(a) or jar ^(b) should be used – pus or fluid can be directly injected into this container using a needle and syringe. Never send a needle and syringe to the laboratory – this is unsafe and unacceptable practice. Needles should be removed or capped with a point-lok device. Tissues can be placed into the anaerobic tube or jar (preferred) by momentarily unscrewing the cap, holding the tube or jar upright at all times and inserting the sample into the agar (approximately 5 mm from the bottom of the jar). The cap should be immediately replaced and screwed down tight for transport of the tube. 
 
Anaerobic transport tubes (^a = Anaerobic Transport Medium Surgery Pack, Cat # AS-914, Lawson # 11231) and jars (^b = BBL Port-A-Cul Sterile Pack Transport Jar, Cat # 221602, Lawson # 78556) are stocked in the hospital on all nursing stations, the Emergency Department and in the Operating Rooms. In the community, physicians can order anaerobic collection kits using the standard forms for other collection materials and supplies. Use Lawson numbers stated above. Always ensure that the correct collection kits are available before performing a procedure that may require specimens to be sent for anaerobic culture.

Turn Around Time

Anaerobes grow slowly, so that the isolation and identification of an organism from an anaerobic culture may not be finalized for up to 7 days. If susceptibility testing is requested, results may take 7-14 days since this testing is performed by an outside reference laboratory.

Order and Specimen Handling

Label the tube and order the test. If using Orders Management, follow protocol to order the test and generate a computerized specimen label. If not using Orders Management, label the tube and complete a Microbiology request form. The requisition for culture should be fully completed and placed in the outer pouch of a Biohazard transport bag. Place the anaerobic tube or jar in the inner compartment of the bag. Make sure the specimen is immediately transported to the lab. 
  
A sufficient volume or amount of patient specimen must be submitted in an oxygen-free transport system to the microbiology laboratory to permit recovery of anaerobic pathogens. Swab specimens are unacceptable for recovery of anaerobes unless they are embedded in a special anaerobic transport medium. For optimal recovery of potentially pathogenic bacteria, the laboratory recommends the following collection methods:

PROCEDURES FOR COLLECTING/TRANSPORTING ANAEROBIC SPECIMENS

MOST ACCEPTABLE METHODS

Sterile Anaerobic Transport Medium Method (Anaerobe Systems #AS914). Use this method for tissue or bone specimens.

• Medium
  • Must be stored at room temperature.
  • Contains both thioglycollate and cysteine in an agar base to reduce the oxygen tension of the specimen.
• Equipment needed
  • Anaerobic Transport Medium tube
  • Gloves (sterile or non-sterile depending upon procedure)
  • Completed lab requisition (if not using Orders Mnagement)
• Procedure
  • Check patient identiband.
  • Explain procedure to patient; screen as necessary.
  • Wash hands.
  • Apply gloves.
  • If applicable, remove dressing and place in plastic bag (see procedure for dressings).
  • Obtain the specimen (cut tissue or bone) that is small enough to fit within the Anaerobic Transport tube. Note: A small area representing the focal point of infection is sufficient for culture.
  • Holding the transport tube upright, open the capped tube carefully and quickly.
  • Quickly embed thetissue orbone down into the agar.
  • Quickly recap the tube.
  • Remove gloves, wash hands.
  • Redress wound if applicable.
  • Label the tube and order the test:
    • If using Orders Management, follow protocol to order the test and generate a computerized specimen label;
    • If not using Orders Management, label the tube and complete a Microbiology requestion.
  • Transport the specimen to the laboratory.
    • If using the pneumatic tube system, follow the packaging instructions for transporting items via the system.
    • If transporting via courier:
      • Place the Anaerobic Transport Medium tube in a specimen transport bag.
      • Place the transport bag in a transport cooler.

Note: An alternative transport system for tissue or bone specimens is the larger BBL™Port-A-Cul™ Sterile Pack Transport Jar:

• Store Port-A-Cul at room temperature prior to use.
• Do not open the envelope until ready to use.
• Do not use if medium in unopened jar is oxidized (pink to lavender color) to a depth greater than 3 mm.
• Open package by peeling apart.
• Obtain specimen.
• Using aseptic technique, remove jar cap and immediately insert specimen approximately 5 mm from the bottom of the jar.
• Replace screw cap and tighten.
• Transport to the laboratory.

Syringe/Needle Method Use for abscesses, sinus tracts, draining wounds.

• Equipment needed:  You may use EITHER one.
  • Sterile 10 mL syringe.
  • Syringe Collection Pack (obtain from storeroom) which contains:
    • 3cc syringe with a 22 gauge needle attached.
    • Point-Lok™ needle device.
  • Procedure
    • Check patient identiband.
    • Explain procedure to patient; screen as necessary.
    • Wash hands.
    • Apply gloves.
    • If applicable, remove dressing and place in plastic bag (see procedure for dressings).
    • Aspirate the specimen fluid into either the 10 mL or 3 mL syringe avoiding the introduction of room air.
    • With the 10 mL syringe, merely expel any air, remove needle, and recap with the syringe’s plastic cap.
    • With the 3 mL syringe only, quickly place the uncapped tip of the needle into the Point-Lok^TM device.
    • Remove gloves, wash hands.
    • Redress wound if applicable.
    • Label the syringe and order the test.
      • If using Orders Management, follow protocol to order the test and generate a computerized specimen label and apply it to the syringe.
      • If not using Orders Management, complete a label and attach it to the syringe. Complete a Microbiology request form.
    • Transport the specimen to the laboratory
      • If using the pneumatic tube system, follow the packaging instructions for transporting items via the system.
      • If transporting via courier:
        • Place the labeled syringe with the Point-Lok^TM attached in a specimen transport bag.
        • Place the transport bag in a transport cooler.
        • Give the completed Microbiology request form (if using one) to the courier.

LEAST ACCEPTABLE METHOD

Swab Method (Note: Swabs expose anaerobic bacteria to oxygen and must ONLY be used for recovery of anaerobes if the two methods described above cannot be used.)

• Equipment
  • Aerobic culturette
    • Anaerobic Transport Medium Tube
• Procedure
  • Check patient identiband.
  • Explain procedure to patient; screen as necessary.
  • Wash hands.
  • Apply gloves.
  • If applicable, remove dressing and place in plastic bag (see procedure for dressings).
  • Open the aerobic culturette and carefully remove the swab (discard the aerobic culture tube).
  • Swab the area.
  • Holding the anaerobic transport medium tube upright, carefully remove the cap.
  • Quickly embed the swab just below the surface of the agar in the tube. Do not push the swab to the bottom of the tube.
  • Quickly break the shaft of the swab off at the lip level of the transport tube using a sharp, snapping motion.
  • Quickly replace the cap.
  • Remove gloves, wash hands.
  • Reapply dressing, if applicable.
  • Label the Anaerobic transport tube and order the test.
    • If using Orders Management, follow protocol to order the test and generate a computerized specimen label and apply it to the syringe.
    • If not using Orders Management, complete a label and attach it to the syringe. Complete a Microbiology request form.
  • Transport the specimen to the laboratory
  • If using the pneumatic tube system, follow the packaging instructions for transporting items via the system.
  • If transporting via courier:
    • Place the labeled tube in a specimen transport bag.
    • Place the transport bag in a transport cooler.
    • Give the completed Microbiology request form (if using one) to the courier.

Note:  Additional swabs under aerobic conditions must be sent for stains and recovery of
           aerobic bacteria.

UNACCEPTABLE METHODS

• The following types of respiratory specimens are unsuitable for anaerobic culturing because they easily become contaminated with “normal anaerobic flora” of the upper respiratory tract:
• Coughed sputum
• Bronchoscopic specimens
• Nasotracheal tube suctioning
• CSF
• Genital specimens
• Cervical
• Vaginal
• Decubitus ulcers
• Peri-rectal abscess, rectal

COLLECTION METHODS OF SPECIFIC TYPES OF SPECIMENS

*Transport tube must be held upright while the cap is off because it contains an oxygen-free gas which will escape if the tube is tilted while open.

**Collection of swab specimens for the recovery of anaerobes is NOT recommended. If a swab must be submitted, both aerobic and anaerobic transport collection media should be collected.  NOTE: an additional aerobic swab should be sent for stains/recovery of aerobic bacteria.