Bacteriology

BacteriologyBacteriology

Used correctly, microbiologic cultures can identify a significant pathogen, or pathogens, and contribute key information towards a diagnosis. However, improperly collected microbiologic cultures can result in growth, or overgrowth, of contaminants which can lead to erroneous diagnoses and result in inappropriate antimicrobial therapy. The importance of proper transport medium, proper transport environment,  and proper preservation techniques cannot be overemphasized.

The value of microbiologic culture depends to a considerable degree on the care and skill with which cultures are taken, stored and shipped to the laboratory.Learn about how our new MALDI-TOF mass spectrometer provides results faster than ever!

Sample Collection Brochure

We offer the following guidelines to optimize these procedures:

  • Collect samples aseptically.
  • Place samples in an appropriate transport system (sterile plastic bags or containers, bacterial transport systems). Ensure transport systems are sealed tightly and are leak-proof. Do not use plastic gloves or sleeves.
  • In general, it is advised to keep specimens cold from the time they are collected until they arrive at the laboratory. Specimens should be shipped in insulated containers with a sufficient number of ice packs to last 48 hours.

Note: Specimens for anaerobic culture, dermatophyte culture, blood culture, as well as cerebral spinal fluid and joint fluid, should be maintained at room temperature to preserve sample integrity.

  • When collecting large numbers of samples (e.g. >30 milk samples for mastitis diagnosis or fecal samples for Johne's disease diagnosis), please call the laboratory for scheduling. This permits the laboratory to have personnel and media available for prompt processing.
  • Where there is any doubt as to what samples to collect and how to transport them - - CALL THE LABORATORY FIRST!

Label all samples with:

  • Client and animal information
  • Type or location of sample (feces, small intestine, uterine swab)

Completely fill out accession form including:

  • Signalment (age, breed, and sex)
  • Clinical signs and duration
  • Location of sample site, if not indicated by sample type (swabs)
  • Treatments associated with case
  • If possible, specify the test(s) you want done, and the pathogens you suspect, particularly in the case of specimens with normal bacterial flora (feces, intestinal contents, skin, or oral mucus membranes). If we don't know what you're looking for, we may not inoculate the proper media to find it.
  • Please note:  Information provided to the lab is critical for proper case set-up and interpretation as the same bacterial species may be highly significant or a meaningless contaminant, depending on the tissue and/or species from which the sample was obtained. Also, depending on the tissue/species of origin, different culture conditions may be necessary to isolate and identify specific pathogens

Necropsy Recommendations:

  • Use sterile instruments to collect samples.
  • Collect other samples before opening the gastrointestinal tract.
  • Tissue samples (lung, liver, spleen, kidney, etc.) should be 5 grams or larger to allow surface searing in the laboratory to reduce contaminants.
  • Place each sample in a separate container to prevent cross-contamination.  If the intestine is to be cultured, tie off both ends of a segment and place it in a separate container.
  • Use screw top containers for fecal samples.  Fecal samples should not be submitted in stoppered tubes, as fermentation will dislodge the stoppers.
  • Except in the case of abortions, please separate samples that are to be examined by different laboratory sections. If a specimen is to be examined by both the virology and bacteriology sections, the specimen should be divided, each piece placed in a separate container, and labeled with the source of the tissue and the desired laboratory service.

Anaerobic Pathogens:

  • Require special care as they are very susceptible to oxygen exposure. 
  • Tissue or fluid specimens are preferred.
  • If swabs are the only practical sample, the Port-a-Cul system, or similar, is preferred. 

 

 

DO NOT SUBMIT DRY SWABS OR SYRINGE CAPPED NEEDLES.  THEY WILL BE REJECTED FOR CULTURE.

 

Approximate culture times are as follows:

Aerobic (culture and sensitivity) 2-7 days
Anaerobic 7-10 days
Listeria spp. 7 days
Mycology >2 weeks
Mycoplasma 2 weeks
Mycobacteria paratuberculosis (culture)
*Note, direct PCR is recommended for this agent.
13 weeks


Transport Container Guide

Category Type Purpose/Function Sample Type Notes
Aerobic Culture
Swab Transport Systems
Amies+/- charcoal Improved recovery of fastidious organisms
-charcoal enhances maintenance of fastidious organisms by scavenging bacterial waste products
Ocular swab, respiratory swab, ear swab, wound swab, uterine swab Gel systems are not ideal for direct Gram stains
Stuart’s Transport System General bacteriostatic media designed to preserve bacterial viability and reduce overgrowth. May have gel, sponge, or liquid in tube. Ocular swab, respiratory swab, ear swab, wound swab, uterine swab  
Port-A-Cul tube Maintains anaerobic environment and is suitable for both facultative anaerobic (most bacteria) and anaerobic bacteria. Fluids, tissues, swabs If anaerobic culture is needed maintain sample at room temperature
   
Anaerobic culture Transport Systems Port-A-Cul, or similar Maintains anaerobic environment and is suitable for both facultative anaerobic (most bacteria) and anaerobic bacteria. Fluids, tissues, swabs >1 ml of fluid or >1 cm3 of tissue maintains anaerobic condition and may not require a special transport system
   
Blood culture Transport Systems Blood culture bottle Nutritive support of microorganisms; contains additive to neutralize bacteriocidal tendencies of blood and prevent coagulation. Blood -Prep top of bottle with 70% alcohol prior to inoculation.
-Critical for a successful blood culture
Isolator Tube Designed for isolation and concentration of microorganisms; lyses leukocytes and erythrocytes in the blood and helps prevent coagulation. Blood -Prep top of bottle with 70% alcohol prior to inoculation.
-Critical for a successful blood culture
-Needs to be processed within 18 hours
  
Other Sterile Red Top Tube Sterile tube without preservatives Blood, fluids, ear notches, swabs (with sterile saline added), preputial washings, urine -Do not use for submission of fecal samples.
-Prep top of bottle with 70% alcohol prior to inoculation with needle.
-May need to add sterile saline to maintain sample moisture
Modified Cary-Blair Transport Media Maintains enteric pathogens and helps prevent overgrowth of normal flora. Media is buffered to prevent pH changes. Only add fecal material to the fill line. feces Only acceptable for bacterial culture. A second specimen in clean container is needed for fecal floats and molecular assays.
Urine Transport tube Maintains samples up to 24 hours without refrigeration. Urine Not acceptable for urinalysis or PCR testing.
Universal Transport Media Maintains viruses, Ureaplasma, Mycoplasma, and Chlamydia sp. for up to 48 hours. Ocular swabs, respiratory swabs, reproductive tract swabs, tissue  
Weybridge MediaAids in isolation of Campylobacter sp. from reproductive tract Reproductive tract  
Whirl-pak (or similar) bag Sterile bag Tissue, milk, feces  


 

Commonly Submitted Specimen Guide

Source Collection Method Container Temperature Requirements
Abscess -Percutaneous aspiration of pus from intact abscess
-Exudate
-Section of abscess wall
-Swab
Red top tube
Bacterial Transport System (aerobe or anaerobic)
Whirl-pak bag
Refrigeration
 
Samples for anaerobic culture are best kept at room temperature
Blood -Surgical prep with percutaneous blood collection
-2-3 samples over 24 hours ideal
-Sample when febrile, if possible
-Blood culture bottle
-Yellow-top Isolator tube
Room temperature
CSF -Surgical prep with percutaneous collection
 
->1 ml preferred due to low numbers of bacteria expected
-Sterile Container
-Port-A-Cul fluid transport
-Blood culture bottle
-Fluid in EDTA tube for cytology or send slides; NOT FOR CULTURE
Room temperature
Dermatophyte -Clean lesion with 70% alcohol; pluck hair from edge of lesion
-Toothbrush over coat
Sealed envelope or bag Room temperature
Eye -Corneal scrapings, swab of conjunctiva or edge of corneal ulcer.
-Remove crusts/contaminants before sampling.
-Topical dyes and anesthetics can interfere-rinse eye prior to sampling.
-Sample from unaffected eye can help interpret growth in affected eye if unilateral
-Aerobic transport system
-Universal or viral transport media for mycoplasma, chlamydia, and viruses if suspected.
Refrigeration
Feces Per rectum or immediately collected from the ground-Send 5-10 grams in sealed, leak-proof container or bag.
-Cary-Blair Transport Medium acceptable for Bacteriology ONLY
Refrigeration
Joint -Surgical prep with percutaneous fluid collection
-Synovium (surgical sampling/maintain moisture)
-Sterile Container
-Port-A-Cul fluid transport
-Blood culture bottle
-Fluid in EDTA tube for cytology or send slides; NOT FOR CULTURE
Room temperature
Lower Respiratory -Transtracheal wash
-Bronchioalveolar lavage
-Tissue (5 grams ideal)
-Aspirate
Note: Do not culture nasal passage to determine pathogen of lower respiratory tract
-Sterile container or bag
-Port-A-Cul fluid transport container
-Fluid in EDTA tube for cytology or send slides; NOT FOR CULTURE
Refrigeration
Milk -Cleaning and disinfection of teat.
-Forestrip teat
-3-5 mls
Sterile, screw-top containeer Refrigeration or frozen (if there will be delay in submission)
Outer Ear Clear debris from canal with saline, then swab ear canal. Two swabs recommended, one for culture and one for Gram stain (same tube) -Aerobic bacterial transport system.
Note: Gel systems are not ideal for direct Gram stains
Refrigeration
Skin -Surgical prep with biopsy of active inflammation
-Aspiration of pustules.
-Cleanse surface of skin with saline; swab the affected area, do not touch unaffected areas.
-Sterile container
-Aerobic bacterial transport system. Submit two swabs, can be in same tube
Note: Gel systems are not ideal for direct Gram stain.
Refrigeration
Upper Respiratory -Remove crusts and/or debris from nares
-Swab nasal cavity or nasopharynx
-Biopsy
 
-Aerobic transport system
-Universal or viral transport media for mycoplasma, chlamydia, and viruses if suspected.
-Sterile container
Refrigeration
Urine -Sterile prep of skin with cystocentesis
-Clean catherization
-Mid-stream free catch after cleansing of genital region
-Samples from indwelling catheter not recommended unless patient displays clinical signs
-Send 3-5 mL in:
-Sterile urine cup
-Red top tube
-Urine transport system
Refrigeration
Uterine -Biopsy with culture and histopathology is recommended to aid in culture interpretation.
-Alternatively, clean external genitalia and sample uterus with double guarded swab. 
-Aerobic transport system for swab or tissue
- 10% Formalin for biopsy
Refrigeration