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