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Sepsis in the emergency department: pathogen identification by blood cultures and PCR

Introduction

Sepsis in the early stage is a common disease in emergency medicine, and rapid diagnosis is essential. The aim of our monocentric observational study (characterization of patients with sepsis in the emergency department) was to compare pathogen diagnosis by blood cultures (BC) and PCR.

Methods

Two (aerobic and anaerobic) BC and blood for PCR testing were taken from the patients immediately after admission, before initiating antibiotic therapy. For PCR testing we used the LightCycler SeptiFast (Roche Diagnostics, Basel, Switzerland), which enables rapid diagnosis of the 20 most important sepsispathogens. SeptiFast test kits were provided free of charge.

Results

We analyzed 95 patients with suspected severe infection. Thirty-four patients (35.8%) had a PCT value ≥ 2 ng/ml and were classified as septic. In septic and nonseptic patients, age (63.8 ± 17.7 vs. 62.9 ± 7.4 years, P = NS) and male sex (60.3% vs. 64.1%, P = NS) were comparable. Thirty-five patients (36.8% of total and 44.1% of septic) had positive BC, and 32 patients (33.7% of total and 52.9% of septic) had positive PCR tests. Septic patients showed significantly more positive PCR results than nonseptic patients (P < 0.01). No difference was found for BC. PCR showed an accordance of 84.4% to BC. In 11.4% of patients BC was positive and PCR was negative (agent not in PCR recognition spectrum, n = 2 (Micrococcus luteus); agent in the PCR spectrum, but not found, n = 6 (Streptococcus spp. and coagulase-negative Staphylococcus spp.); different pathogens identified by PCR and BC, n = 3). In seven patients (7.3%) with negative BC, additional, mostly Gram-negative bacteria were found by PCR. The PCR-positive in comparison with PCR-negative patients had significantly higher values for procalcitonin (17.3 ± 26.4 vs. 13.8 ± 57.2 ng/ml, P < 0.01), IL-6 (4,220 ± 14,385 vs. 626 ± 1,666 pg/ml, P < 0.01) and APACHE II score (19.1 ± 9.1 vs. 14.6 ± 8.8, P < 0.05) and Sequential Organ Failure Assessment score (4.5 ± 3.4 vs. 2.9 ± 2.6, P < 0.05). For BC-positive patients a difference was found only for Sequential Organ Failure Assessment score (4.0 ± 3.0 vs. 2.9 ± 2.6, P < 0.05).

Conclusion

In septic patients in the emergency department, PCR identifies pathogens in about 50%. A positive PCR correlates with sepsis severity as well as the inflammatory response of the host.

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Hettwer, S., Wilhelm, J., Hammer, D. et al. Sepsis in the emergency department: pathogen identification by blood cultures and PCR. Crit Care 13, P378 (2009). https://doi.org/10.1186/cc7542

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Keywords

  • Blood Culture
  • Septic Patient
  • Procalcitonin
  • Sequential Organ Failure Assessment Score
  • Micrococcus Luteus