COLLECTING BLOOD FOR CULTURINGprinciples and practice

COLLECTING BLOOD FOR CULTURING

principles and practice Dr.T.V.Rao MD

4/8/2017 Dr.T.V.Rao MD @ Blood culture 1

Why we culture the BloodPhysicians and clinical

microbiologists have long appreciated that blood cultures are perhaps the most important laboratory tests to diagnose serious infections.

• Saves the lives and reducing the infectious process if done with precision and accuracy


THE GREAT PROBLEM WITH CONTAMINATION

• It has also become apparent that contaminated i.e., the presence of a pathogen from outside the blood stream blood cultures are common, leading to falsely positive test results.


Contamination is the major issue in collection

• Contaminated blood cultures constitute as many as half or more of all positive blood cultures in some centres, are very costly to patients and the health care system, and are confusing for clinicians


Need to think on our failures

• Today much Microbiology failed in our country incoordination of laboratory with clinicians, and even much worse with upcoming teaching hospitals leave the virtual technique of blood collection to most inexperience student nurses , most important factor is the failure of the health care worker (HCW) to use strict aseptic technique when obtaining the blood specimen.


Need for phlebotomists • Studies have shown that

trained phlebotomists or blood culture teams have fewer contaminated blood cultures than other HCWs. A second factor is the antiseptic agent itself; tincture of iodine and chlorhexidine gluconate are more effective at skin sterilization than iodophor (povidone iodine) preparations.


Select equipment, prepare area•Prepare a clean, designated and if

possible, dedicated area for

collecting blood samples.


Type of phlebotomy equipment• Single-use, vacuum-based

phlebotomy equipment is available to reduce the risk of environmental contamination.

• Safer injection devices are increasingly available to prevent reuse of injection equipment and needle-stick injuries.


Prepare Your Hands• Proper hygiene is essential to

safely performing venipuncture.

• Be sure to wash hands with soap and water and dry with a clean, single-use towel.

• Depending on workplace procedure, you may be able to clean hands with alcohol rub if they are not visibly contaminated

• After cleaning your hands you may now put on -sterile gloves.


Select equipment, prepare area

• Wear a new pair of gloves for each patient

• Use a sterile single-use lancet or phlebotomy set for each patient

• Inspect packaging for breaches in integrity

• Do not use equipment that may not be sterile (punctured, torn or damaged).


Locate The Vein

• With the patient's arm extended, inspect the antecubital fossa.

• Look for a visible, good-sized vein, which will typically be the median cubital vein. This vein should be clearly visible before applying the tourniquet

• Finally, apply the tourniquet 3 to 4 inches above the venipuncture site.

• Tip: Keep in mind that opting for the basilic vein increases the risk of damaging a nerve or artery and is typically more painful.


Disinfect Site• It's important to disinfect the site before drawing

blood to reduce the chances of contamination.

• Cleanse the site with a 70% alcohol swab by starting from the center of the venipuncture site and working outwards, covering roughly 2-4cms

• Be sure to allow the area to dry to reduce the risk of contamination.

• Be sure to NOT touch the disinfected site. If site has been touched or contaminated, repeat the cleaning process.


Draw Blood

Withdraw Slowly withdraw the needle and gently apply pressure to the puncture site with a clean gauze or cotton ball. Have the patient hold the gauze or cotton on the site with their arm extended.

Release Once the blood has been collected, first release the tourniquet. Be sure to do this before removing the needle from the vein.

Puncture Puncture the vein quickly and at a 30 degree angle or less.

Have Have the patient ball up their hand (form a fist).

Place Place your thumb BELOW the venipuncture site to anchor the vein. Be sure not to touch the venipuncture site or you will need to repeat the cleaning process.

Perform Perform venipuncture using the following steps:


Use of Iodophors • One step is to use more efficacious antiseptic preparations. Povidone iodine preparations (iodophors) require 1.5 to 2 minutes of contact time to produce maximum antiseptic effect


Chlorhexidine gluconate is

faster • Iodine tincture and chlorhexidine gluconate only require 30 seconds


Prepacked skin Antiseptic Kits

• A possible benefit related to the use of commercially marketed pre packaged skin antiseptic kits. However, available data are limited, and I believe that no firm recommendations regarding these prepackaged kits can be made at this time.

4/8/2017Dr.T.V.Rao MD @ Blood culture 19

Caution on Interpretation of Blood culture reports

• if only a single blood culture grows a coagulase-negative staphylococcus, Bacillus spp., Corynebacterium spp., Propionibacterium spp., viridans group streptococcus, Micrococcus spp., or Aerococcus spp., the likelihood of contamination is high, and full identification of the microorganism as well as susceptibility testing should not be done unless there is direct communication between the physician caring for the patient and the laboratory director.


What is recommended for disinfection

The Clinical and Laboratory Standards Institute, a consensus organization that publishes guidelines based on best available data, recommends tincture of iodine, chlorine peroxide, and chlorhexidine gluconate over povidone-iodine and further states that iodine tincture and chlorhexidine gluconate are probably equivalent


Health care workers in Hurry • Many HCWs who obtain

blood cultures are in a hurry, do not understand the importance of antiseptic contact time, and are unlikely to wait up to 2 minutes before obtaining blood for culture. Although the evidence-base has limitations


Complete the Procedure •After sampling, minimize bleeding by applying gentle pressure on the sampling site with a dry, clean cotton ball or other similar material.•Apply clean dressing to the wound after bleeding has stopped.


Abandon collection from Indwelling

catheters • A third factor is the means

by which blood is obtained for culture. In recent years, there has been a trend toward obtaining blood cultures from existing indwelling intravenous catheters or other access devices (e.g., ports).


MODERN CULTURE METHODS

Modern blood culture systems and media that incorporate antibiotic-binding resins or activated charcoal, while detecting more true pathogens, also have been shown to greatly enhance the detection of coagulase-negative staphylococci, the most common blood culture contaminants.


Reducing Contamination


Try with Best efforts to reduce Contamination

•We cannot eliminate blood culture contamination entirely, but it is possible for institutions to reduce contamination rates


Safety measures are Increased with

HIV • Finally, blood culture

techniques changed after recognition that HIV is a blood-borne pathogen. In the pre-HIV era, the needle used to obtain the blood culture was removed and a second sterile needle was placed on the syringe for inoculation of the blood culture bottles.


•Program created by Dr.T.V.Rao MD for the Benefit of Medical and Health care workers

in the developing world on matters of Hygiene •Email

• [email protected]


mailto:[email protected]

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