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WELCOME. Dr Anand Deshpande P D Hinduja National Hospital & MRC Mumbai. Bacterial contamination of blood products. - PowerPoint PPT Presentation
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WELCOME
BACTERIAL CONTAMINATION OF BLOOD PRODUCTS
Dr Anand DeshpandeP D Hinduja National Hospital & MRC
Mumbai
While the blood bank community has successfully implemented the high standards of blood screening for viral markers including NAT screening, transmission of donor bacteria has clearly emerged as the greatest infectious risk to transfusion safety
Bacterial contamination of blood products is a persistent but often overlooked problem in Transfusion Medicine
The dramatic decrease in risk of transfusion-transmitted viral disease was accomplished by conversion from Paid to volunteer whole blood donors in the 1970s. Increased direct questioning of donors regarding risks for the Viruses and increased testing of collected donor blood for antibodies, antigens and nucleic acid of these viruses starting in the 1970s. Risk of hepatitis B may decrease further with universal childhood vaccination. Not shown in the graph are the rare risks of other transmissible diseases. The dashed line indicates the unknown risks, if any, of new viruses and other potentially emerging pathogens, such as prions that cause new variant Creutzfeldt-Jakob Disease.(J of Am Med Ass, Feb 2001, Volume 285, No 5; 579
“SHOT” DATA
CAP CHECKLIST – TRM.44955 PHASE II
Does the laboratory have a validated system to detect the presence of bacteria in platelet concentrates ?For random donor platelets, any of the following testing methods satisfy this checklist question: detection of decreased pH or glucose by analytic instrument or dipstick; gram stain; acridine orange stain. Though of low sensitivity, these methods may detect units that are heavily contaminated by bacteria. Culture or FDA-approved commercial detection systems have greater sensitivity. The swirling technique is not recommended because of its very low sensitivity.
CAP CHECKLIST – TRM.44955 – Revised (Nov 2011) PHASE II
Bacterial Contamination in Platelets
The enhanced sensitivity requirement reflects the availability of multiple FDA-cleared quality control strategies; insensitive methods including pH, glucose and microscopy are no longer acceptable. Equivalent system is defined as a system that has been validated to demonstrate comparable or improved sensitivity in CFU/mL. If this testing is performed by the supplier of platelet components, the laboratory can satisfy this checklist requirement by having an agreement with the supplier to be notified of supply units suspected of containing bacteria.
Origin of bacteria From donor –
Unsuspected bacterimia Venipuncture site
Rarely during processing and storage At the time of transfusion
Risk estimates HIV / HCV / HAV – 1 in a few million
HBV – 1 in 0.3 million
Bacteria (RBCs) – 1 in 30,000
Bacteria (Platelets) – 1 in 3000
Organisms in RBC component Yersinia entercolotica, Serratia &
Pseudomonas Y. enterocolitis – fever, diarrhea –
Endotoxins Initial lag phase – rapidly proliferative
after 20 – 25 days of storage 25 fatalities reported in USA (1995 –
2004) Risk of death – 0.13 / million Autologous
Transfusion fatalities by organisms in Red cell transfusions (25)
Summary of Organisms from RBC Transfusions identified in the BACON, SHOT and BACTHEM studies
Organisms in Platelet component 50 -250 times higher risk than viral infection
Room temperature storage Organisms are varied – coagulase
negative staphylococcus commonest, Bacillus
Contamination risk is 1:3000 approx, whereas Septic reactions occur in 1/4th to 1/6th of the contaminated platelets
Fatalities – gram negative organisms Clinically, Fever-Hypertension-Sepsis-
Death Sometimes difficult to diagnose
Plasma / Cryo
Frozen state
Rarely associated with contamination
Strategies to reduce risk of post transfusion sepsis Bacterial Avoidance
Growth inhibition
Detection
Elimination
I. Bacterial AvoidanceA] Donor screening
Careful selection of healthy blood donors Recent dental procedures Recent use of antibiotics/Medical & surgical
interventions Problems – e.g. Yersinia sepsis – retrospective
analysis – 50 % donors had GI symptoms Special considerations – Autologous blood
units
Bacterial avoidance
B] Skin preparations
Not possible to have sterile venipuncture Sebaceous glands / Hair follicles Scarring or dimpling
Isopropyl alcohol + Iodine + Isopropyl alcohol
Chlorhexidine
Percentage of Donors with Bacteria growth after skin disinfection
Bacterial avoidance
C] Diversion
Significant reduction in blood contamination if first 10 -20 ml of blood is diverted to the pouch
Study from Netherlands – 0.35 % - 0.21 %
Expected to reduce gram positive organisms
Apheresis vs WBD platelets Significant reduction in sepsis (John
Hopkins study) 1:4818 1: 15098
Cultures with apheresis platelets
II. Growth inhibitors… Optimising storage temperature
Red cells (10 – 60 C) – Yersinia / Serratia Frozen - ? Practicality Platelets – (200 – 240 C)
40 C – Temperature induced activation
Growth inhibition…Optimising storage timeA. Red Cells Yersinia sepsis in units > 25 days old Proposed to reduce shelf life for 25
days Rejected – 20 % units > 25 days
- Recruiting new donor - Units < 25 days also
causes sepsis
B. Platelets Ideal would be 1 – 2 days Diagnostic disease markers –
impossible (NAT/Culture)
III. Bacterial detection No ideal procedure for detection of
bacteria Limitations Short shelf life of 5 days The amount of bacterimia changes with
time Contamination may occur during
sampling processes Innoculation may be very small
Bacterial genome detection – NAT Bacterial culture – most reliable
method – 24 hrs
IV. Bacterial eliminationLeucodepletion by filtration Prestorage leucocyte filters Related to leucocyte phagocytosis Related to direct filter binding
mechanism No evidence that prestorage leucocyte
reduction by filtration contributed to bacterial proliferation
V. Pathogen inactivation Final common pathway
Photodynamic and photochemical methods
UK experience - Poster at Cancun – ISBT - 2012 1996 – 2010 – 40 cases – SHOT 33/40 – platelet transfusion 9/33 – fatalities NHS – BacT / ALERT for culture 0.03% confirmed positive No report of transmission of bacteria by
transfusion of platelets in 2011
Factors affecting outcome of Transfusion of Bacterially contaminated blood components
Under reporting Septic or fatal reaction – elderly,
neonates or patients immunocompromised by illness or chemo
If patients on antimicrobial therapy - severity
Low levels of bacterial contamination causes mild symptoms like fever and chills – resembling FNHTRs
Conclusion ……. Significant progress in understanding Source reduction by good skin preparation
and diversion pouch Better and specific method like Bact
culture Towards safer blood and better patient
care
……………
Conclusion
There is always another pathogen waiting its turn
A zero-risk blood supply is not achievable
The safest transfusion is still the one not infused……………….
THANK YOU