Blood culture tv rao.pptx

7/28/2019 Blood culture tv rao.pptx

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Dr.T.V.Rao MD

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What is a Blood Culture?

A blood culture is alaboratory test in

which blood isinjected into bottleswith culture media todetermine whether

microorganisms haveinvaded the patientsbloodstream.

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Need for Blood

Culture?No microbiological test is more essential to the

clinician than the blood culture. The findingof pathogenic microorganisms in a patients

bloodstream is of great importance in terms

of diagnosis, prognosis, and therapy.

- L. Barth Reller, Clin. Infect. Diseases, 1996

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Blood Culture is done to

Detect Infectious Diseases Blood culture is a

microbiological culture of

blood. It is employed todetect infections that arespreading through thebloodstream (such asbacteremia, septicemia

amongst others). This ispossible because thebloodstream is usually asterile environment

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A clinically suspected infection is ultimatelyconfirmed by isolation or detection of theinfectious agent. Subsequent identification of the

microorganism and antibiotic susceptibility testsfurther guide effective antimicrobial therapy.Bloodstream infection is the most severe form ofinfection and is frequently life-threatening, and

blood culture to detect circulatingmicroorganisms has been the diagnosticstandard.

Proof in Blood borneInfection

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Bacteremia presence of bacteria in

blood stream

Some conditions have a period of bacteremiaas part of the disease process (ex.

Meningitis, endocarditis)

Septicemia bacteremia plus clinicalsigns and symptoms of bacterialinvasion and toxin production

Definitions

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Definitions (contd)

Primary Bacteremiablood stream bacterialinvasion with no

preceding or simultaneoussite of infection with thesame microorganism

Secondary Bacteremiaisolation of a

microorganism fromblood as well as othersite(s)

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Bacteremia and Fungemia Episodes

Transient

Comes and goes

Usually occurs after aprocedural manipulation(ex. Dental procedures)

Intermittent

Can occur fromabscesses at some bodysite that is seedingthe blood

Continuous

Bacteremia

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Warm shockfever, increased pulse,

hyperventilation, and warm, dry flushed skin

Cold shock

decreased blood pressure, increasedpulse, and rapid, shallow respirations

Septic chock

Hemodynamic changes, decreased tissue perfusionand compromised organ & tissue function

Mortality 40% to 50%

Bacteremia Complications

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Bacteremia/Septicemia RiskFactors

Immunocompromis

ed patients

Increased use of

invasive procedures

Age of patient

Administration of

drug therapy

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Sources of Bacteremia

Spread Pericarditis and

Peritonitis

Pneumonias Pressure sores

Prosthetic medicaldevices

Total hip replacement

Skeletal system

Skin and soft tissue

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Needs optimal Methods for Diagnosis ofBlood Borne Pathogens

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Blood Collection

Aseptic collectionprocedure is critical

Amount of blood 1:10 ratio of blood to

broth

Younger than 10 years

1 ml of blood for

every year of life

Over 10 years 20 ml

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Blood Collection

Frequency of Collection

Depends if bacteremia is

transient, intermediate

or continuous

Number of cultures

collected are usually

inversely related to the

type of bacteremia Usually x3 from different

body sites

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Conventional Broth Systems

One aerobic bottle and one anaerobic bottle per blood

collectionAerobic broth contains soybean casein digest broth,

Tryptic or trypticase soy broth, Brucella agar orColumbia broth base

Anaerobic broth is usually the same as aerobic withaddition of 0.5% cysteine in an aerobic environment

Must be subcultured and gram stained manually

Blood Culture Methods

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Venipuncture is the process of obtaining

intravenous access for the purpose of intravenoustherapy or obtaining a sample of venous blood. This

procedure is performed by medical laboratoryscientists, medical practitioners, some EMTs,paramedics phlebotomists and other nursing staff.Venipuncture is one of the most routinely performed

invasive procedures and is carried out for tworeasons, to obtain blood for diagnostic purposes or tomonitor levels of blood components (Lavery & Ingram2005).

Venipuncture

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Phlebotomy Definition

phlebotomy (fli)noun the act or practice

of bloodletting as atherapeutic measure

Phlebotomy fromGreek words, phlebo,relates to veins, tomy,

relates to cutting.Opening a vein to

collect blood

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Properly labelled sample is essential so that

the results of the test match the patient. Thekey elements in labelling are:

Patient's surname, first and middle.

Patient's ID number.

NOTE: Both of the above MUST match the

same on the requisition form.Date, time and initials of the phlebotomist

must be on the label of EACH tube.

LABELING THE SAMPLE

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Gloves will be worn in accordance withstandard precautions.

Appropriate verification of the patient'sidentity, by means of an armband or areaspecific procedure, will occur before thespecimen collection.

Cultures should be drawn before

administration of antibiotics, if possible.??? blood cultures should be drawn from lines,

but should be drawn viavenipuncture.

Principles for Collection

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Chlorhexidine swabs (1-2 packages) Alcohol swabs Blood culture bottles (2 bottles per set) 2 syringes (adult: 20 cc, paediatric: 5 cc) 2 needles (adult: 22 gauge or preferably larger butterfly

or standard needle; pediatric: 25 or 23 gauge butterfly orstandard needle)

Gloves (sterile &nonsterile) Tourniquet

Sterile gauze pad Adhesive strip or tape Self-sticking patient labels Plastic zip lock specimen bags

What Materials We need

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The requisitions form should be completelyfilled out, and the requisition must indicate

the tests ordered.

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Self Protection

A few ways to make sure yourrole in the collection process is

carried out with efficiency,orderliness and safety

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Steps 1 3, Check, Explain, Wash

1.Identify the patient

2.Explain theprocedure to thepatient.

3.Wash hands withsoap and water withfriction for 15 seconds

or use alcohol basedhand rub

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Materials Chlorhexidine swabs (1-2 packages) Alcohol swabs Blood culture bottles (2 bottles per set)

2 syringes (adult: 20 cc, paediatric: 5 cc) 2 needles (adult: 22 gauge or preferably larger butterfly

or standard needle; pediatric: 25 or 23 gauge butterfly orstandard needle)

Gloves (sterile &nonsterile)

Tourniquet Sterile gauze pad Adhesive strip or tape Self-sticking patient labels Plastic zip lock specimen bagsDr.T.V.Rao MD 25


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. Barrier protection for the phlebotomist

consists of the latex gloves.

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Locate the vein

Prep kit Alcohol 5 sec. Dry 30-60 sec ( resource poor conditions )

Ideal to collect with alcohol swabs containing 2%Chlorhexidine and 70% isopropyl alcohol

Remove caps, clean with alcohol

Put on gloves

Without palpating, draw 20 ml and put 10 inanaerobic and 10 in aerobic bottle

Dispose of syringe in sharps container

Label bottles and send to lab

Obtaining Blood

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Method of Blood Collection

A minimum of 10 ml of blood istaken through venipunctureand injected into two or more"blood bottles" with specific

media for aerobic andanaerobic organisms.

The blood is collected usingclean technique. This requiresthat both the tops of the culturebottles and the venipuncturesite of the patient are cleanedprior to collection with alcoholswabs containing 2%Chlorhexidine and 70%isopropyl alcohol.

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The area of skin is cleaned with adisinfectant, or an alcohol swab.

Using sterile gloves, do notwipe away the surgicalsolution, touch the puncture

site, or in any waycompromise the sterileprocess. It is vital that theprocedure is performed in assterile a manner as possibleas the persistent presence ofskin commensals in bloodcultures could indicateendocarditis but they aremost often found ascontaminants

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The vein is anchored and the

needle is inserted.

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The vacutainer tube is depressed into

the needle to begin drawing blood

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Additional vacutainer tubes can be utilized. Determine what tests areordered and what tubes will be necessary BEFORE you begin to draw

blood, and determine the order of draw for the tubes..

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When the final tube is being drawn, release thetourniquet. Then remove the tube, and remove the

needle.

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After the needle is removed from the vein, apply firm

pressure over the site to achieve haemostasis.

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Apply a bandage to the area.

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Preparation of Cap before

Injecting BloodPrep the rubber

cap of the bloodculture bottleswith an alcoholpad in a circular

motion. Allowthe alcohol todry.

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Inject the Blood ..

Inject the bloodinto the Selected

MediaGently rotate the

bottles to mix the

blood & the broth(do not shakevigorously).

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Follow the universal precautions

when disposing NeedleDispose of

needle in

sharpscontainer anddispose of otherwaste in propercontainer

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Label the tubes, checking the requisition for the

proper identification.

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Patients name

Hospital number (Patient ID)

Patients location (room and bed #)

Date and time of collection

Collectors initials

Site of venipuncture

Or other information as per facility Include you Mobile Contact No A vital

information can be delivered any time

Give the all possible Medical

Information

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Document the Medical

Records

Document the

following in themedical record:

Date & timespecimen obtained

Site of specimencollection

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Depends if bacteremia is

transient, intermediate or

continuousNumber of cultures

collected are usually

inversely related to the

type of bacteremia

Usually x3 from

different body sites

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Second Set

If 2 or more sets ofblood cultures have

been ordered,obtain the secondset in the samemanner as the first,making a newvenipuncture at adifferent site.

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Most microbiological culture procedures

require the use of solid media, like blood

agar and Mac Conkeys agar plates that needto be visually monitored by trainedpersonnel at intervals of 24 hours. Theseconventional cultures using normal media

take at least a minimum of 72 hours to isolatethe pathogen and carry out susceptibility testto know the efficacy of antibiotics on simpleaerobic bacteria.

Traditional Methods in

Blood cultures

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Bacteria and Fungi Are Identifiedby Phenotypic Characters

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Biochemical Tests gives BetterClues in Identification

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Newer Blood Culture Methods

Newer Blood Culture Systems

Biphasic Broth-Slide System

Agar paddles attached to top of bottle

Closed system

Continuous Monitoring Blood Culture Systems

BacTecmeasures 14CO2

BacTec 9000 Seriesmeasures CO2

ESPmeasures consumption of gases

BacT-Alertmeasures change in pH

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Automation reduces the

time requirement But this can be completed

within 30 hours by

using automatedtechniques. This isespecially useful whenlarge number ofspecimens needs to becultured, as theinstrument, which hasbeen programmed for thesame, automaticallyscreens these.

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BacT/AlerT 3D culture

system BacT/AlerT 3D culture

system. This is the firstautomated non-

radiometric and non-invasive culture systemthat continuouslymonitors system forculture of bacteria (bothaerobic and anaerobic),

fungi and mycobacteria.All these bacteria can becultured using differentmedia as prescribed..

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bioMrieux

BacT/ALERT 3D The bioMrieux

BacT/ALERT 3Dprovides an optimal

environment for therecovery of a wide rangeof pathologicalorganisms, includingbacteria, yeasts and

mycobacteria; utilizingproprietary plastic culturebottles ensuring addedsafety to the user.

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BacT/ALERT 3D Microbial

Detection System This newest generation ofthe time-testedBacT/ALERT system offersadvantages in every

dimension of testing. Fromits space-saving modulardesign to its easy touch-screen operation andflexible data management

options, every laboratorywill find something to loveabout the BacT/ALERT 3D!

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P i i l f f ti i f B T


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Principles of functioning of BacTalert Monitors

Microorganisms multiply in themedia, generating CO2. As CO2increases, the sensor in thebottle turns a lighter colour.

Measuring reflected light, the

BacT/ALERT 3D monitors anddetects color changes in thesensor.

Algorithms analyze the data todetermine positivity, and thelaboratory is notified

immediately with visual andaudible alarms.

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Principles in BacT/AlerT 3Dculture system

This is a closed systemand works on thecolorimetric principle of

detection of CO2produced by theorganisms. The CO2causes a lowering of thepH of the medium, whichin turn produces a colour

change in a sensorattached to the CO2-sensitive base of eachbottle.

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Automation improves


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Automation improvesquality of services

Overall, laboratoriestransitioning fromconventional to

automated processesfind thattechnologists andmicrobiologists aremore open toinnovation andimproved quality.

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After inoculating the culture vials, they are

sent to the clinical pathology microbiologydepartment. Here the bottles are entered intoa blood culture machine, which incubate thespecimens at body temperature. The bloodculture instrument reports positive blood

cultures (cultures with bacteria present, thusindicating the patient is "bacteremia"). Mostcultures are monitored for 5 days after whichnegative vials are removed.

Automation Signals

Bacteremia cases

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A vial is positive, a microbiologist will perform a

Gram Stain on the blood for a rapid, general ID ofthe bacteria, which they will report to the attending

physician of the bacteremic patient. The blood is alsosubcultured onto agar plates to isolate thepathogenic organism for culture and susceptibilitytesting, which takes up to 3 days. This culture &

sensitivity (C&S) process identifies the species ofbacteria. Antibiotic sensitivities are then assessed onthe bacterial isolate to inform clinicians onappropriate antibiotics for treatment.

The positives cases to be

proceeded without delay

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Culturing Mycobacterium

from Blood Mycobacterial growth is

generally observed within aweek in case of smear (1+)

positive. Speciation into

mycobacterium tuberculosiscomplex and mycobacteriaother than tuberculosis takesan additional three days.

An important Investigationin AIDS and otherImmunosuppressed patients


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Testing drug resistance in

Tuberculosis a priority Susceptibility testing to

primary line of anti-tuberculosis drugs viz

streptomycin, isoniazid,rifampicin, ethambutoland pyrizinamide andsecondary line of drugsviz kanamycin, para-

amino salicylic acid,cycloserine, ethionamide,capreomycin etc requires5-10 days.


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Rapid Susceptibility Testing

Rapid susceptibility willbe carried out for gramnegative and

staphylococcal isolatesand other isolates onrequest. These will bereported within 12 hoursusing API systems.

Automation has made iteasier to arrive at aprecise laboratorydiagnosis of infection

Th C t i t d


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If the skin is not adequately cleansed before

drawing blood for culture, bacteria on the skinwill be injected into the bottle, producing a falsepositive blood culture

It is difficult for the physician to determinewhether the bacteria growing in the blood cultureis a real pathogen causing bloodstream infection

or whether bacteria on the skin have contaminatedthe culture. This can lead to excess use ofantibiotics and prolongation of hospital stay.

The Contaminated

Blood Culture

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The programme created by

Dr.T.V.Rao MD as TechnicalSeries for Microbiologists in theDeveloping World

[email protected]

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Blood culture tv rao.pptx

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