Blood Culture Sample Collection
Special Instructions (when applies):
For good laboratory test results you must have proper collection and handling of the specimen. It is best to collect blood cultures when the animal has an elevated temperature, prior to placing it on antibiotics or after it has been off antibiotics for at least two to three days. In the latter instance, if sulfonamide drugs or penicillin was the antibiotic used for treatment, please use culture broth which has an antibiotic inhibitor present. Please state clinical diagnosis and time of collection. List current antibiotic therapy, clinical diagnosis, and any special organisms suspected to be present or to be ruled out. Indicate if culture is for BrucelIa or Francisella testing. Do not use expired blood culture media.
Collection
- Properly label one aerobic and one anaerobic
- 1-3 ml of blood should be drawn prior to initiation of antimicrobial therapy and placed in pediatric bottles. If more than one culture is ordered, the specimens should be drawn separately no less than 30 minutes apart. This is to rule out the possibility of transient bacteremia.
- An animal in the advanced stages of disease is most desirable
- Specimens should be collected from more than one diseased animal
- Specimens should be collected from animals in various stages of illness
- It is desirable to have duplicate samples from one animal, but this may not be practical, especially in small laboratory animals
- Strict aseptic technique is essential. If present remove the plastic cap from the blood culture bottles, swab the stoppers with tincture of iodine or povidone iodine and allow to stoppers to dry.
- For any laboratory animal, blood may be collected via cardiac stick if the animal is first anesthetized. This technique also provides a large sample.
- Pre-incubate or maintain specimen at room temperature. Do not refrigerate.
- First shave the skin, cleanse the venipuncture site with isopropanol.
- Then use tincture of iodine or povidone iodine to disinfect the site using progressively larger concentric circles. Iodine should remain in contact with skin for about 1 minute or until dry to ensure disinfection.
- The venipuncture site must not be palpated after preparation.
- Blood is then drawn. Following venipuncture, alcohol is used to remove the iodine from the site.
Bottle Preparation
- Cleanse the bottle with disinfectant
- Remove over caps from bottles (1 aerobic MH07591 and I anaerobic MH07592) and cleanse each rubber septum with separate 70% alcohol swabs. Allow septum to dry for I mm before inoculating.
- Draw as much blood as possible and inoculate each bottle with 1-3 ml of blood. Do not vent or overfill bottles.
- Collect two blood culture sets sequentially from separate collect sites. A third blood culture set can be made 4-6 hours later. Transport time
Three negative sets of blood cultures in the absence of antimicrobial therapy are usually sufficient to exclude the presence of bacteremia. Yeast often are isolated from routine blood cultures. However, if yeast or other fungi are specifically suspected, a separate fungal blood culture should be drawn along with each of the routine blood culture specimens.
Additional Information
- Volume of blood cultured seems to be more important than the specific culture technique being employed by the laboratory.
- The isolation of coagulase-negative Staphylococcus poses a critical and difficult clinical dilemma. Although coagulase-negative Staphylococcus is the most commonly isolated organism from blood cultures, only a few (6.3%) of the isolates represent true clinically significant bacteremia.
- Conversely, coagulase-negative Staphylococcus is well recognized as a cause of infections involving prosthetic devices, cardiac valves, CSF shunts, dialysis catheters, and indwelling vascular catheters. Ultimately, the scientist is responsible for determining whether an organism is a contaminant or a pathogen. The decision is based on both laboratory and clinical data.
- Virtually any organism, including normal flora, can cause bacteremia.
- A negative culture result does not necessarily rule out bacteremia; false-negative results occur when pathogens fail to grow.
- A positive culture result does not necessarily indicate & bacteremia; false-positive results occur when contaminants grow.
- Gram-negative bacilli, anaerobes, and fungi should be considered pathogens until proven otherwise.
- The most difficult interpretation problem is to determine whether an organism that is usually considered normal skin flora is a true pathogen.