Utility of routine surveillance blood cultures in asymptomatic allogeneic hematopoietic stem cell transplant recipients with indwelling central venous catheters at a comprehensive cancer center

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Journal ClubJournal Club
Ahmed Abdelhakeem , 26 February 2015Ahmed Abdelhakeem , 26 February 2015

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Background
Many transplant centers obtain surveillance blood cultures (SBCs) from
asymptomatic allogeneic hematopoietic stem cell transplant (allo-HCT)
recipients with central venous catheters for early detection of potential
blood stream infections.
2 published studies, both in pediatric patients, that examined the utility of
obtaining SBCs in asymptomatic HCT patients

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Background (cont’d)

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Introduction
Surveillance cultures:
• Detect colonization of pathogenic organism prior to symptom onset
• Provide basis for early antimicrobial therapy
Small proportion of patients CVC colonization develop subsequent BSI.
No reliable methods to identify colonized patients who could develop subsequent
infection

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Introduction (cont’d)
BSIs causes significant morbidity and mortality in patients undergoing allo-HCT.
Long term CVCs increase risk of BSI.
Incidence of post-transplant BSI varies between 12.5% - 41%
Gram-positive organisms more frequent than gram-negative organisms.
 Substantial proportion of BSIs are CVC related.
Many HCT centers obtain weekly SBCs.
Prior knowledge of organisms colonizing CVCs may facilitate therapy.

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Introduction (cont’d)
Many allo-HCT patients have a blunted inflammatory response .
may remain asymptomatic despite having occult or overt bacteremia.
SBCs may be useful :
During the initial preengraftment period of profound neutropenia
In patients receiving corticosteroids.
SBCs are not recommended in the absence of clinical signs and symptoms in
immunocompetent individuals.
• Currently, No guidelines exist for the management of asymptomatic patients
with positive SBCs.

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Methods
The medical records of study patients were reviewed retrospectively.
Data retrieved included:
Demographic data (eg, age, sex, underlying malignancy).
Type of allo-HCT.
Antimicrobial prophylaxis.
Usage of corticosteroids or other immunosuppressive agents.
Number of SBCs.
Presence of neutropenia on the day of the positive culture.
Time in days from CVC insertion to positive SBC.

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Methods (cont’d)
In patients with a positive SBC:
 microbiologic data, clinical course, management and outcome of the episode
were retrieved.
All patients had a nontunneled, non antibiotic-coated CVC prior to
transplantation.
Routine weekly SBCs were obtained :
 starting 1 day prior to transplantation.
 lasting until 100 days posttransplant, or as long as the CVC was in place.
• SBCs obtained Only from asymptomatic patients with a normative temperature
(<38C).

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Methods (cont’d)
All patients received prophylactic antibiotics while they were neutropenic
 ( fluoroquinolones ) most often.
SBCs were drawn from the CVC.
All reported positive cultures were included in this study regardless of the
type of pathogens recovered.
They were divided into 1 of 3 predefined groups based on current
recommendations for catheter-related infections.

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Methods (cont’d)
Group 1 Group 2 Group 3
< 10 colony –forming units
(cfu)/ml
>10 cfu/ml positive SBCs not included in
the previous 2 groups
regardless of colony count or
organism isolated.
common skin inhabitants
low virulence pathogens
coagulase negative Staphylococci
Corynebacterium spp.
Bacillus spp.
Micrococcus spp.
Low risk for development of
bactremia .
Some risk for development
of bacteremia
Higher risk for development
of bacteremia.

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Results
During the study period, a total of
794 patients underwent allo-HCT.
18 were excluded because of fever
or an active infection prior to the
first scheduled SBC
leaving 776 study patients.

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Results (cont’d)
Of the 776 patients

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Results (cont’d)

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Results (cont’d)
A total of 6,801 SBCs were drawn from the 776 patients

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Results (cont’d)
211 positive SBCs.
All patients with >1 positive SBC
belonged to group 1.
Number Of PatientsNumber Of Patients

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Results (cont’d)
Group 3 was composed of only 25 (0.37%) of all 6,801 SBCs performed, or 3.2% of all patients .

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Results (cont’d)
Of the 211 positive SBCs:
171 (81%) had minimal clinical
significance. ( Group 1)
40 positive cultures (19%) potentially
significant. (Group 2 & 3)
The frequency of potentially
significant SBCs was 5.1% for the
entire cohort and 0.59% of all SBCs
drawn

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Results (cont’d)

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Results (cont’d)

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Results (cont’d)
Removal of the CVC was performed in 19 (9%) of the patients with a positive SBC:
• 6 of 171 in group 1 .
• 3 of 15 of group 2 .
• 10 of24 (42%) in group 3.
The positive SBC triggered administration of antibiotics in 44 (21%) of the patients:
• 9 of 171 in group 1.
• 11 of 15 (73%) in group 2.
• 24 of 25 (96%) in group 3.
Thirteen patients (6%) with a positive SBC were admitted to the hospital:
• 1 of 171 from group 1.
• None from group 2.
• 12 of 25 (48%) from group 3.

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Cost analysis
The cost of a single SBC, was $201.
During the 2-year study period, $1.367 million was spent on SBCs in
asymptomatic patients.
There were 211 positive cultures; hence, the cost of a positive culture was
$6,478.7.
Only 40 SBCs were considered to be clinically significant (groups 2 and 3).
Hence, the cost of recovering 1 potential pathogen from SBCs from
asymptomatic patients was $34,174.

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Conclusion
All potentially significant cultures and some that were deemed to have minimal
significance led to medical intervention, some of which were probably
unnecessary.
No adverse outcomes occurred in patients with positive SBCs for the first 30 days
following the positive result, regardless of the pathogen isolated or the
quantitative colony count.
The frequency of clinically significant positive SBCs in asymptomatic adult allo-HCT
recipients is very low.
Routine use of this practice leads to some unnecessary medical interventions and
added costs.

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Thanks For ListeningThanks For Listening
Ahmed Abdelhakeem , 26 February 2015Ahmed Abdelhakeem , 26 February 2015