blood culturing in infectious diseases

1. BLOOD CULTURINGIN INFECTIOUS DISEASES Dr.T.V.Rao MD Professor of Microbiology Dr.T.V.Rao MD

2. What is a Blood Culture? • A blood culture is a laboratory test in which blood is injected into bottles with culture media to determine whether microorganisms have invaded the patient’s bloodstream. Dr.T.V.Rao MD

3. Need for Blood Culture? No microbiological test is more essential to the clinician than the blood culture. The finding of pathogenic microorganisms in a patient’s bloodstream is of great importance in terms of diagnosis, prognosis, and therapy.” - L. Barth Reller, Clin. Infect. Diseases, 1996 Dr.T.V.Rao MD

4. Blood Culture is done to Detect Infectious Diseases • Blood culture is a microbiological culture of blood. It is employed to detect infections that are spreading through the bloodstream (such as bacteremia, septicemia amongst others). This is possible because the bloodstream is usually a sterile environment Dr.T.V.Rao MD

5. Proof in Blood borne Infection • A clinically suspected infection is ultimately confirmed by isolation or detection of the infectious agent. Subsequent identification of the microorganism and antibiotic susceptibility tests further guide effective antimicrobial therapy. Bloodstream infection is the most severe form of infection and is frequently life-threatening, and blood culture to detect circulating microorganisms has been the diagnostic standard. Dr.T.V.Rao MD

6. Definitions • Bacteremia – presence of bacteria in blood stream • Some conditions have a period of bacteremia as part of the disease process (ex. Meningitis, endocarditis) • Septicemia – bacteremia plus clinical signs and symptoms of bacterial invasion and toxin production Dr.T.V.Rao MD

7. Dr.T.V.Rao MD

8. Definitions (cont’d) • Primary Bacteremia – blood stream bacterial invasion with no preceding or simultaneous site of infection with the same microorganism • Secondary Bacteremia – isolation of a microorganism from blood as well as other site(s) Dr.T.V.Rao MD

9. Bacteremia and Fungemia Episodes • Transient • Comes and goes • Usually occurs after a procedural manipulation (ex. Dental procedures) • Intermittent • Can occur from abscesses at some body site that is “seeding” the blood • Continuous Bacteremia Dr.T.V.Rao MD

10. Bacteremia Complications • Warm shock – fever, increased pulse, hyperventilation, and warm, dry flushed skin • Cold shock – decreased blood pressure, increased pulse, and rapid, shallow respirations • Septic chock • Hemodynamic changes, decreased tissue perfusion and compromised organ & tissue function • Mortality 40% to 50% Dr.T.V.Rao MD

11. Bacteremia/Septicemia Risk Factors • Immunocompromised patients • Increased use of invasive procedures • Age of patient • Administration of drug therapy Dr.T.V.Rao MD

12. Sources of Bacteremia Spread • Pericarditis and Peritonitis • Pneumonias • Pressure sores • Prosthetic medical devices • Total hip replacement • Skeletal system • Skin and soft tissue Dr.T.V.Rao MD

13. Blood culturing most important and life saving Investigation Needs optimal Methods for Diagnosis of Blood Borne Pathogens Dr.T.V.Rao MD

14. BloodCollection • Aseptic collection procedure 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 Dr.T.V.Rao MD

15. 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 Dr.T.V.Rao MD

16. Blood Culture Methods • Conventional Broth Systems • One aerobic bottle and one anaerobic bottle per blood collection • Aerobic broth contains soybean casein digest broth, Tryptic or trypticase soy broth, Brucella agar or Columbia broth base • Anaerobic broth is usually the same as aerobic with addition of 0.5% cysteine in an aerobic environment • Must be subcultured and gram stained manually Dr.T.V.Rao MD

17. Venipuncture • Venipunctureis the process of obtaining intravenous access for the purpose of intravenous therapy or obtaining a sample of venous blood. This procedure is performed by medical laboratory scientists, 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 two reasons, to obtain blood for diagnostic purposes or to monitor levels of blood components (Lavery & Ingram 2005). Dr.T.V.Rao MD

18. Phlebotomy Definition • phle·boto·my (fli) nounthe act or practice of bloodletting as a therapeutic measure • Phlebotomy from Greek words, phlebo, relates to veins, tomy, relates to cutting. • Opening a vein to collect blood Dr.T.V.Rao MD

19. LABELING THE SAMPLE • Properly labelled sample is essential so that the results of the test match the patient. The key 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. Dr.T.V.Rao MD

20. Principles for Collection • Gloves will be worn in accordance with standard precautions. • •Appropriate verification of the patient's identity, by means of an armband or area specific procedure, will occur before the specimen collection. • •Cultures should be drawn before administration of antibiotics, if possible. ??? • • blood cultures should be drawn from lines, but should be drawn viavenipuncture. Dr.T.V.Rao MD

21. What Materials We need • 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 or standard needle) • Gloves (sterile &nonsterile) • Tourniquet • Sterile gauze pad • Adhesive strip or tape • Self-sticking patient labels • Plastic zip lock specimen bags Dr.T.V.Rao MD

22. The requisitions form should be completely filled out, and the requisition must indicate the tests ordered. Dr.T.V.Rao MD

23. Self Protection A few ways to make sure your role in the collection process is carried out with efficiency, orderliness and safety Dr.T.V.Rao MD

24. Steps 1 – 3, Check, Explain, Wash • 1.Identify the patient • 2.Explain the procedure to the patient. • 3.Wash hands with soap and water withfriction for 15 seconds or use alcohol based hand rub Dr.T.V.Rao MD

25. 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 or standard needle) • Gloves (sterile &nonsterile) • Tourniquet • Sterile gauze pad • Adhesive strip or tape • Self-sticking patient labels • Plastic zip lock specimen bags Dr.T.V.Rao MD

26. . Barrier protection for the phlebotomist consists of the latex gloves. Dr.T.V.Rao MD

27. Obtaining Blood • 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 in anaerobic and 10 in aerobic bottle • Dispose of syringe in sharps container • Label bottles and send to lab Dr.T.V.Rao MD

28. Method of Blood Collection • A minimum of 10 ml of blood is taken through venipuncture and injected into two or more "blood bottles" with specific media for aerobic and anaerobic organisms. • The blood is collected using clean technique. This requires that both the tops of the culture bottles and the venipuncture site of the patient are cleaned prior to collection with alcohol swabs containing 2% Chlorhexidine and 70% isopropyl alcohol. Dr.T.V.Rao MD

29. The area of skin is cleaned with a disinfectant, or an alcohol swab. • Using sterile gloves, do not wipe away the surgical solution, touch the puncture site, or in any way compromise the sterile process. It is vital that the procedure is performed in as sterile a manner as possible as the persistent presence of skin commensals in blood cultures could indicate endocarditis but they are most often found as contaminants Dr.T.V.Rao MD

30. The vein is anchored and the needle is inserted. Dr.T.V.Rao MD

31. The vacutainer tube is depressed into the needle to begin drawing blood Dr.T.V.Rao MD

32. Additional vacutainer tubes can be utilized. Determine what tests are ordered and what tubes will be necessary BEFORE you begin to draw blood, and determine the order of draw for the tubes.. Dr.T.V.Rao MD

33. When the final tube is being drawn, release the tourniquet. Then remove the tube, and remove the needle. Dr.T.V.Rao MD

34. After the needle is removed from the vein, apply firm pressure over the site to achieve haemostasis. Dr.T.V.Rao MD

35. Apply a bandage to the area. Dr.T.V.Rao MD

36. Preparation of Cap before Injecting Blood • Prep the rubber cap of the blood culture bottles with an alcohol pad in a circular motion. Allow the alcohol to dry. Dr.T.V.Rao MD

37. Inject the Blood ….. • Inject the blood into the Selected Media • Gently rotate the bottles to mix the blood & the broth (do not shake vigorously). Dr.T.V.Rao MD

38. Follow the universal precautions when disposing Needle • Dispose of needle in sharps container and dispose of other waste in proper container Dr.T.V.Rao MD

39. Label the tubes, checking the requisition for the proper identification. Dr.T.V.Rao MD

40. Give the all possible Medical Information • Patient’s name • • Hospital number (Patient ID) • • Patient’s location (room and bed #) • • Date and time of collection • • Collector’s initials • • Site of venipuncture • • Or other information as per facility • Include you Mobile Contact No – A vital information can be delivered any time Dr.T.V.Rao MD

41. Document the Medical Records • Document the following in the medical record: • –Date & time specimen obtained • –Site of specimen collection Dr.T.V.Rao MD

42. Frequency of 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 Dr.T.V.Rao MD

43. Second Set • If 2 or more sets of blood cultures have been ordered, obtain the second set in the same manner as the first, making a new venipuncture at a different site. Dr.T.V.Rao MD

44. Traditional Methods in Blood cultures • Most microbiological culture procedures require the use of solid media, like blood agar and Mac Conkeys agar plates that need to be visually monitored by trained personnel at intervals of 24 hours. These conventional cultures using normal media take at least a minimum of 72 hours to isolate the pathogen and carry out susceptibility test to know the efficacy of antibiotics on simple aerobic bacteria. Dr.T.V.Rao MD

45. Bacteria and Fungi Are Identified by Phenotypic Characters Dr.T.V.Rao MD

46. Biochemical Tests gives Better Clues in Identification Dr.T.V.Rao MD

47. 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 • BacTec – measures 14CO2 • BacTec 9000 Series – measures CO2 • ESP – measures consumption of gases • BacT-Alert – measures change in pH Dr.T.V.Rao MD

48. Automation reduces the time requirement • But this can be completed within 30 hours by using automated techniques. This is especially useful when large number of specimens needs to be cultured, as the instrument, which has been programmed for the same, automatically screens these. Dr.T.V.Rao MD

49. BacT/AlerT 3D culture system • BacT/AlerT 3D culture system. This is the first automated non-radiometric and non-invasive culture system that continuously monitors system for culture of bacteria (both aerobic and anaerobic), fungi and mycobacteria. All these bacteria can be cultured using different media as prescribed.. Dr.T.V.Rao MD

50. bioMérieux BacT/ALERT® 3D • The bioMérieux BacT/ALERT® 3D provides an optimal environment for the recovery of a wide range of pathological organisms, including bacteria, yeasts and mycobacteria; utilizing proprietary plastic culture bottles ensuring added safety to the user. Dr.T.V.Rao MD