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LightCycler SeptiFast technology in patients with solid malignancies: clinical utility for rapid etiologic diagnosis of sepsis
Critical Care volume 16, Article number: 404 (2012)
Recent development of molecular tools for pathogen detection introduced the possibility of early targeted antimicrobial treatment that, in turn, may improve the outcome of patients with sepsis .
We retrospectively evaluated 54 results of the SeptiFast test from patients with solid malignancy admitted to the ICU between June 2009 and August 2011. Specimens from suspected bloodstream infection were analyzed using LightCycler SeptiFast (Roche Molecular Diagnostics, Prague, Czech Republic) according to the manufacturer's instructions and evaluated in comparison with blood culture results obtained from blood sampled no longer than 24 hours before or after sampling for SeptiFast. Blood culturing and identification were performed according to the routine diagnostic procedures. The total number of complementary blood cultures analyzed was 85. Consistently, negative results from SeptiFast and blood culture were obtained in 21 (39%) cases.
To assess the true positivity of both microbiological methods, discrepant cases were evaluated in the context of clinical and laboratory findings by two independent physicians experienced in critical care (Figure 1). The clinically relevant presence of a pathogen detected by blood culture but not by SeptiFast was recorded for Klebsiella pneumoniae/oxytoca, and in both cases the presence of another member of Enterobacteriaceae was reported by SeptiFast, Escherichia coli and Enterobacter cloacae/aerogenes - thus misidentification of strains with atypical phenotype cannot be excluded . Our results also show that SeptiFast is more efficient in detection of clinically relevant infection by E. coli and Pseudomonas aeruginosa.
The turnaround time for blood culture analysis is 24 to 48 hours. The workflow in our laboratory allows SeptiFast analysis every working day during a day shift. In such conditions, the turnaround time of SeptiFast results for samples delivered to the laboratory on a workday between 7 am and 2 pm was as follows: 100% of samples, 10 hours; 97% of samples, 8 hours; 59% of samples, 6 hours. The average turnaround time for tests performed with manual DNA isolation was 6 hours 11 minutes; by implementation of automated isolation of DNA using the MagNA Pure Compact System , the mean turnaround time was shortened to 5 hours 17 minutes.
In conclusion, detection of pathogen by the LightCycler SeptiFast system is generally not inferior to the results from blood culture. The added value of multiplex DNA amplification-based pathogen detection is the shorter test turnaround time and probably the increased true sensitivity of detection of certain pathogens. Moreover, in clinical settings pathogen detection may be required after an antibiotic administration; in such conditions, cultivation independent methods are of clear benefit .
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The authors received a contribution for the reagents, equipment from Roche Diagnostics for this project, and were supported by the European Regional Development Fund and the State budget of the Czech Republic for RECAMO (CZ.1.05/2.1.00/03.0101).
Reimbursement from Roche Diagnostics unrelated to the present work: in 2008, DV and LD for a lecture on a pharmacogenomic and predictive oncology topic, respectively, and in 2010, MV and LD for an expertise work on a protocol for automated DNA isolation from formalin-fixed paraffin-embedded tissues.
LD, MV, RT and DV participated in the design of the study. LD and MV carried out the molecular genetics part of the study. DM and PJ evaluated the microbiological findings in the context of clinical status. All authors participated in writing the report.
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Dubská, L., Vyskočilová, M., Minaříková, D. et al. LightCycler SeptiFast technology in patients with solid malignancies: clinical utility for rapid etiologic diagnosis of sepsis. Crit Care 16, 404 (2012) doi:10.1186/cc10595
- Blood Culture
- Turnaround Time
- Solid Malignancy
- Pathogen Detection
- Blood Culture Result