The cost of contamination of blood cultures
Contaminated blood cultures (defined as the isolation of a microorganism introduced into the culture during the sampling and/or processing of the specimen and which is not present in the patient's blood at the time of sampling, or otherwise not implicated in the ongoing infection³) can lead to suboptimal patient care and potentially cause a significant increase in costs for hospitals. An article published in 2019 analysed the results of studies that have focused on this topic¹.
Blood cultures are a very important part of the diagnostic pathway because they provide critical information about the presence of bacterial or fungal infections in a patient’s bloodstream. However, contaminated blood cultures can lead to misdiagnosis, inadequate treatment, and additional costs¹. In this article, we will review the results of recent studies on the cost of blood culture contamination and possible interventions to reduce this risk.
Microbial identification process
If a blood culture is found to be positive, microbial identification of the pathogen and susceptibility testing must be performed to determine the appropriate antimicrobial treatment. However, in the event of contamination, the actual pathogen may be misidentified or even unidentified, leading to misdiagnosis and inadequate treatment.
Unnecessary antimicrobial treatment
If a blood culture is classified as contaminated, the patient may continue to receive unnecessary antimicrobial treatment, increasing the risk of antimicrobial resistance and adverse reactions to drugs.
Length of the patient's hospital stay
The length of time that patients with contaminated blood cultures remain in hospital has been found to be up to 5 days longer than that of patients with truly negative blood cultures¹. Another study reported an increase of 2.35 days²in the time spent in hospital due to contaminated blood cultures. This increases the cost of health care and reduces the patient's quality of life.
Additional total hospital cost
Analysis of all the factors considered in the studies led to the conclusion that the total additional cost to hospitals attributable to contaminated blood culture is between $2,923 and $5,812¹. Taking into consideration direct costs only, those attributable to the additional pharmaceutical and microbiological requirements associated with a false positive blood culture range from $305 to $1,389¹.
Conclusions
In conclusion, the contamination of blood cultures can lead to additional costs and inadequate care for patients. According to international recommendations⁴, the frequency of contamination of blood cultures should be no higher than 3%. The execution of correct skin antisepsis and sample inoculation procedures are indicated to reduce the risk of introducing the most common contaminants into the culture³.
The results of the studies noted in this article highlight the importance of reducing the risk of contamination by adopting interventions to improve the quality of patient care and blood culture management. These interventions might include:
- greater attention to hand hygiene
- training for health care personnel on the sampling of blood cultures, for example, on:
- the timing of the sampling
- the volume of blood collected
- the transport of vials to the Microbiology laboratory³
- the implementation of infection prevention protocols
- the use of advanced technologies for the sampling and analysis of blood cultures¹.
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References
1. Dempsey C, Skoglund E, Muldrew KL, Garey KW. Economic health care costs of blood culture contamination: A systematic review. Am J Infect Control. 2019;47(8):963-967.2.
2. Lalezari A, Cohen MJ, Svinik O, et al. A simplified blood culture sampling protocol for reducing contamination and costs: a randomized controlled trial. Clin Microbiol Infect. 2020;26(4):470-474.
3. CLSI. Principles and procedures for blood cultures; Approved Guidelines. CLSI document M47-A. Wayne, PA: Clinical and Laboratory Standards Institute, 2007.
4. Baron Ej, Miller JM, Weinstein MP et al. A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2013 recommendations by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM)(a). Clin Infect Dis 2013;57:e22-2121
