Skip to main content
Figure 1 | Critical Care

Figure 1

From: LightCycler SeptiFast technology in patients with solid malignancies: clinical utility for rapid etiologic diagnosis of sepsis

Figure 1

Scheme summarizing detection of pathogens together with clinical evaluation of discrepant findings. Totally 47 pathogens were detected in 29 SeptiFast (SF) and/or 43 blood culture (BC) samples. From 20 pathogens listed on the SF menu [2], nine were detected in the present study and all pathogens detected by blood culture were on the SF menu, 18 microorganisms were detected by both BC and SF, 12 by BC only, and 18 by SF only. The clinical evaluation is as follows: each pathogen detected by either method was classified as possible infection (based on clinical data; for example, benefit from antimicrobial therapy), as probable infection (based on clinical data and cultivation of the pathogen from other site), as highly probable infection (based on clinical data and presence of the pathogen in blood within the relevant time window), as unlike infection (for example, contamination) or as undetermined. To obtain orientation in false positive and false negative results in pathogen detection by SF and cultivation, we assigned a score value to each positive classification as follows: possible infection (score 2), probable infection (score 3), and highly probable infection (score 4). Black boxes represent summary of cases when pathogen was detected by both methods, SF and BC. Red boxes left of concordant events show detection by BC only, and blue objects right of black squares represent events of pathogen detection by SF only. Empty boxes, cases evaluated by both ICU experts as unlike infection; unclear, cases evaluated by ICU experts discrepantly (for example, unlike vs. possible or probable infection). The size of filled objects together with abbreviated classification describe the evaluation of ICU experts for each case: h.pr., highly probable infection; pr., probable infection; po., possible infection. Coagulase-negative staphylococci (CoNS) were detected far more often by BC than SF, probably as a result of contamination of blood culture sample by staphylococci from normal skin flora. Regarding CoNS, SF is able to reflect the amount of CoNS DNA template; if its level is below the discrimination threshold (crossing point (CP) value of amplification growth curve >20), the result is reported as negative. In this context, we retrospectively evaluated all SF raw data files for the CoNS amplification curve and its CP. The CoNS curve with CP >20 was present in 15 out of 44 (34%) SF staphylococci-negative with a lowest CP of 21.4, supporting the necessity for the discrimination threshold in the SF evaluation algorithm for commensal bacteria.

Back to article page