Transcript Slide 1

Bacterial Contamination
in Blood Products
Risks, Prevention and Detection
A summary review provided by the
American Red Cross Blood Services Regions
serving the North Atlantic Area
July, 2003
Bacterial Contamination
in Blood Products
Agenda
What is the Problem?
 What are the Risks?
 What Organisms are Associated with
Bacterial Contamination?
 What are the Sources of Contamination?
 What Corrective Actions are Planned?
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Recent Advances in
Testing Technology
1990-2003
Anti-HCV (1990)
 Multi-antigen anti-HCV (1992)
Anti-HIV1/2, replacing anti-HIV-1 (1992)
 HIV-1 p24 antigen (1996)
 HCV/HIV NAT (IND) (1999)
 Licensed NAT (2003)
 West Nile Virus (IND) (2003)
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Comparison of Residual Risks
1:100
Transmission risk,
per unit
HIV
1:1000
Bacterial
Contamination
(platelets)
Clinical
Sepsis
(platelets)
HBV
1:10 000
HCV
Septic 1:100 000
Fatalities
(platelets)
1:1 000 000
1984
1986
1988
1990
Updated from: Goodnough LT e t al. NEJM 1999;341:126-7
1992
1994
1996
1998
2000
2002
Bacterial Contamination
of Blood Products
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First recognized infectious risk of blood
transfusion
Risk greatly reduced in the 1960s by the use
of closed, sterile systems for the collection
and storage of blood
Recent dramatic improvements in safety from
viral screening and testing have reduced the
risks from Hepatitis and HIV
Bacterial sepsis is now the most common
infectious disease event following transfusion
Bacterial Contamination of
Blood Products
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Bacterial contamination occurs primarily in
room-temperature stored products
(platelets) but can occur in red blood cells
and plasma also
The blood banking community is taking
steps to improve prevention and detection
of bacterial contamination
The American Association of Blood Banks,
as well as the College of American
Pathologists have established compliance
criteria for transfusion services
Bacterial Contamination in
Blood Products
The American Association of Blood Banks has
issued two new standards (March, 2003):
 “5.1.5.1 The blood bank or transfusion service
shall have methods to limit and detect bacterial
contamination in all platelet components.”
 “5.1.5.1.1 Standard 5.1.5.1 shall be
implemented by March 1, 2004”
 “5.6.2 The venipuncture site shall be prepared
so as to minimize the risk of bacterial
contamination. Green soap shall not be used”
Bacterial Contamination
in Blood Products
College of American Pathologist’s
Accreditation Checklist (December, 2002):
“TRM.44955 Phase 1 Does the laboratory
have a system to detect the presence of
bacteria in platelet components?”
Bacterial Contamination of
Blood Products
What are the Risks?
Pooling issues
Risk of clinical sepsis
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Ness et al, Transfusion 2001;41:857-60.
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Identified clinical cases of transfusion
associated sepsis over a 12 year period, with
conversion from 51.7% random donor
platelets to 99.4% SDPs
The #donors/septic event remained constant
at 15,000 throughout the 12 year period,
despite the conversion to SDPs
Pooled random donor platelets were 5.5-times
more likely to cause sepsis than SDPs due to
pool size
Bacterial Contamination of
Blood Products
What Bacterial Organisms are associated
with Blood Product Contamination?
Bacterial species in platelets
implicated in clinical sepsis
S. epidermidis, 30.2%
S. aureus, 10.5%
E. coli, 9.3%
B. cerus, 9.3%
S. cholerae-suis, 8.1%
E. cloacae, 5.8%
B-hem. Strep, 5.8%
E. aerogenes, 2.3%
10 others, 1.3% each
Compilation of data from Clin Micro Rev
1994; 7:290-302; Transfusion 2001;41:149399; www.shot.demon.co.uk/toc
n = 86
Bacterial species in platelets
implicated in septic fatalities
reported to the FDA (1976-1998)
S. epidermidis 9.6%
S. aureus 17.3%
E. coli 5.7%
Bacillus 5.7%
Salmonella 7.7%
Enterobacter 5.7%
Streptococcus 7.7%
Klebsiella 17.3%
Serratia 15.4%
P. mirabilis 2.2%
n = 52
Differences between the species
implicated in septic morbidity and
mortality in platelet components
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S. epidermidis is less commonly observed in
septic fatalities and more commonly observed in
septic reactions
Klebsiella is commonly observed in septic
fatalities
Gram negative organisms are implicated in more
fatalities (60%) than gram positive organisms
(40%); gram positives cause a majority of septic
reactions (56%)
Organisms implicated in
sepsis from platelets
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Approximately 30% are associated with
normal skin flora
Approximately 56% are gram positive
All are aerobic or facultative anaerobes
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A rare (single case) exception: Clostridium
perfringens fatality from a pooled platelet unit
Trans Med 1998;8:19-22
Bacterial Contamination in
Blood Products
What are the Sources of Bacterial
Contamination?
Sources of Bacterial
Contamination
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Skin Surface Contamination
Phlebotomy Core
Donor Bacteremia
Containers and Disposables
Environment
Skin source
Avoiding Skin Contamination
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Diversion of the initial blood flow
Improvement in pre-phlebotomy skin
cleansing
Diversion of initial blood flow
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Diversion of initial blood flow into
sampling tubes
Reduces the load of skin-associated
bacteria entering blood container
Phlebotomy “core” directed into
sampling pouch instead of blood
container
Clinical data supporting
diversion of initial blood flow
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de Korte et al. Vox
Sang 2002;83:13-16
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Collected blood
normally or diverted
the first 10mL of
whole blood into a
satellite bag
Performed bacterial
testing by automated
blood culture
(BacT/Alert) in a
laminar flow hood
Total
bacterial
prevalence
S.
epidermidis
Standard
Collection
0.35%
0.14%
Collection
with
diversion
0.21%
P-value
<0.05
prevalence
(0.270.44)
0.03%
(0.120.35)
<0.02
Skin disinfection methods
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Some agents may reduce the number of
surface bacteria more than others
Method of application and applicator may
have some impact on the extent of
reduction of surface bacteria
Minimum scrub of 30 seconds required to
be effective
Impact of Skin Disinfection on surface bacteria
CFU per
plate
PVPI
Isopropyl
ChlorGreen
Alcohol + hexidine
soap +
Tincture Gluconate Isopropyl
of
alcohol
Iodine
60%
0%
63%
0
34-40%
1-10
35-43%
34%
25%
17%
11-100
10-14%
2%
12%
47%
>100
0-13%
1%
3%
36%
Goldman et al, Transfusion 1997;37:309-12
Recurrent contamination from the dimpled
skin of one plateletpheresis donor
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Anderson et al., Am J Med 1986;405-11.
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One donor gave 17 plateletpheresis donations from a
scarred dimpled site in the right antecubital fossa
Two units were implicated in septic events traced to
this donor
Four units, including the two units linked to the septic
event, were culture positive with coagulase negative
Staphylococcus
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Follow up blood samples obtained from the nonscarred left antecubital fossa were routinely culture
negative
Donor bacteremia
Recurrent contamination from an
asymptomatic bacteremic donor
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Rhame et al., Ann Intern Med 1973;78:633-41.
 One plateletpheresis donor was linked to 7
cases of Salmonella cholerae-suis transfusion
associated bacterial sepsis; 2 cases were fatal
 Three of the cases were linked to positive
culture of the platelet units
 The donor had a low-grade bacteremia and
unknowingly had Salmonella osteomyelitis of
the tibia
Container source
Multiple cases of sepsis from
contaminated blood containers
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Heltberg et al. Transfusion 1993;33:221-7
Högman et al. Transfusion 1993;33:189-91.
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Serratia marcescens was cultured from three septic
patients and their implicated units in Denmark
All units were collected using the same lot of blood
containers
11 of 1,515 blood products collected using the
implicated lot were positive for Serratia marcescens
An organism of the same ribotype was isolated from
the manufacturing plant
The same containers were implicated in Sweden
Environmental source
A fatal case of Clostridium perfringens
sepsis from a platelet pool
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McDonald et al., Transfusion Medicine
1998;8:19-22.
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C. Perfringens is a spore forming facultative
anaerobe, found in soil and human intestinal tract
Organism recovered from platelet pool; septic
recipient was on antibiotics; no organism recovered
Patients death was considered a septic event
The same serotype of Clostridium was isolated from
the arm of 1 of the 4 donors; a subsequent culture of
the same arm 6 months later yielded fecal flora
The donor was a mother who carried her two
toddlers in the crook of her arm
Bacterial Contamination
in Blood Products
What Options exist to Prevent and Detect
Bacterial Contamination?
Bacterial Contamination of Platelets
Prevention and Detection Options
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Donor screening – not feasible except for arm
screening. Can’t detect asymptomatic
bacteremic donors
Arm Preparation-Limited effectiveness of arm
scrub
Pathogen reduction – not yet available. May not
inactivate spore forming organisms
Better phlebotomy methods and initial blood
diversion
Bacterial detection offers best confirmatory
option
Bacterial Detection Options in
Platelet Products
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Visual examination for discoloration, clumping or
abnormal morphology
Microscopy
 Gram stain
 Acridine orange
Measuring Biochemical changes
 Lowered pH
 Reduced Glucose
Bacterial culture
 Detection through oxygen consumption
 Detection through CO2 production
Bacterial Detection Options in
Platelet Products
Visual Examination
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Inspect product prior to transfusion for discoloration or
abnormal clumping
Perform “swirl” procedure to detect morphologic changes
in platelets
 Normal shaped platelets will align with fluid flow and
“shimmer” when swirled
 Contaminated platelets, among others, lose discoid
shape and do not “shimmer” when swirled– Not a
specific marker for contamination
Swirling
Alignment with flow
SENSITIVITY: 75%
SPECIFICITY: 95%
No alignment with flow
Low pH
Metabolic disturbance
Leach MF et al. Vox Sang 1998;74(suppl 1):1180.
Bacterial Detection Options in
Platelet Products
Microscopic Methods
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Gram Stain or Acridine Orange preferred
methods
Limitations:
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Must be performed by the Transfusion Service
prior to product issue for transfusion
Lack sensitivity with low bacterial load
Bacterial Detection Options
in Platelet Products
Measuring Biochemical Changes
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Measure changes in glucose consumption
against a control. Variances of >2 S.D. may
indicate bacterial contamination
“Dipstick” testing
Limitations:
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Both this method and staining methods are
subjective, require high levels of contamination, and
must be performed prior to issue by the Transfusion
Service
Detecting Bacteria in Platelets:
Biochemical Changes
100
90 Glucose, % Day 0
80
70
60
50
40
30
20
10
0
0
1
2
-2 SD
3
4
Storage Time, d
after Burstain JM et al. Transfusion 1997;37:255-8.
5
Control
Bacillus
Klebsiella
Chemical Tests - Dipsticks
Must be performed immediately before issue because of its
relative insensitivity and the need for high bacterial counts
Bacterial Detection Options in
Platelet Products
Blood Culture Methods
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Two methodologies presently approved by
FDA for Quality Control use
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bioMeriuex BacT/Alert System
Pall Biomedical BDS System
Bacterial Detection Options
in Platelet Products
bioMeriuex BacT/Alert System
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Detects bacterial growth in culture bottles by measuring
CO2 production
Automated reader continuously monitors samples
Sampling interval of >24 hours post phlebotomy
Culturing interval of >24 hours post sampling (aerobic
and anaerobic cultures)
Cultures incubate for 5-7 days; may identify positive
cultures post-transfusion
FDA-Approved for Q.C. purposes only on Leukoreduced
Apheresis Platelets
Practical Application of Culturing
in a Transfusion Service Laboratory
Aubuchon, Dartmouth
Experience in first 3 years:
3,927 apheresis units cultured
(5 mL into aerobic bottle, BacT/Alert automated system)
23 initial positives (0.5%) in 28 h (10-69)
14 not confirmed on repeat culture
5 not able to be recultured
4 confirmed positives
RATE = 1/1,000 units (95% CI: to 1/600)
Detecting Bacteria in Platelets:
Detection of Growth by O2 Consumption
Pall BDS system
Measure %O2
in headspace
24 h
Filter: Stops
WBCs+Plts
Passes: Bacteria
Gas impermeable bag
Limit: 19.5%
24 h at 35C
Bacterial Detection Options in
Platelet Products
Pall Biomedical BDS System
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Detects bacterial contamination by measuring O2
consumption
Automated reader measures O2 levels in headspace of
culture pouch
Sampling interval of >24-48 hours
Culture performed for >24-30 hours
FDA-Approved for Q.C. on leukoreduced platelet
concentrates and leukoreduced apheresis platelets
Bacterial Detection Options in
Platelet Products
Limitations of Blood Culture Methods
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Early sampling/testing may not detect small
# bacteria per bag. Approved methods
require 24-30 hour wait before sampling
Two FDA-Approved methods require bacteria
to grow up after sampling to detectable
levels, so culture must be done well before
planned transfusion (Blood Center)
The two time intervals (collection to sampling
and sampling to release/transfusion)
dominate the logistic considerations
Bacterial Detection Options in
Platelet Products
Limitations of Blood Culture Methods
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Both options require leukoreduced platelets
BacT/Alert requires continued culture after
product release
Release and recall (BacT/ALERT) or hold to end
of culture to release (PALL BDS)
Bacterial Detection Options in
Platelet Products
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Limitations of Blood Culture Methods
Need to balance the risk of platelet shortages
versus the risk of platelet contamination
The two available devices are FDA-Approved for
Q.C, and not approved as pre-release tests
Cost
Probable negative impact on outdates
Possible extension of platelet storage to seven
days or pooling/storing whole blood derived
platelets
Bacterial Contamination in
Transfusable Blood Products
AABB Guidance
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Association Bulletin #03-07 issued May
16, 2003
Provides guidance for methods to limit
contamination and to detect
contamination
AABB Association Bulletin #03-07
May 16, 2003
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Methods to Limit Contamination:
Careful phlebotomy – No green soap prep
Iodine based scrub recommended
Consider phlebotomy diversion – “sample
first” technologies
Consider increased use of apheresis
platelets
AABB Association Bulletin #03-07
May 16, 2003
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Methods to Detect Contamination:
Culture methods optimal. Two approved
products cited. Other culture methods can be
validated. No label claims allowed
Due to insensitivity, staining and dipstick
methods should be used as close in time to issue
as possible
Validation of all methods is required
“Swirl” procedure useful for inspection but does
not by itself meet AABB Standard 5.1.5.1
Bacterial Contamination in
Blood Products
American Red Cross Bacterial Prevention and
Detection Strategy
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Implement prevention and detection strategies to
meet the requirements and timelines of the AABB
and CAP
Solicit customer feedback to develop efficient and
cost-effective implementation strategies
Keep customers well-informed during the preimplementation period