LightCycler SeptiFast Test Research Articles

Diagnostic Performance of a Novel Multiplex PCR Assay for Candidemia among ICU Patients

Candidemia poses a major threat to ICU patients and is routinely diagnosed by blood culture, which is known for its low sensitivity and long turnaround times. We compared the performance of a novel, Candida-specific multiplex real-time PCR assay (Fungiplex® Candida IVD Real-Time PCR Kit) with blood culture and another established diagnostic real-time PCR assay (LightCycler SeptiFast Test) with respect to Candida detection from whole blood samples. Clinical samples from 58 patients were analyzed by standard blood culture (BC) and simultaneously tested with the Fungiplex Candida PCR (FP) and the SeptiFast test (SF) for molecular detection of Candida spp. Compared to BC, the FP test showed high diagnostic power, with a sensitivity of 100% and a specificity of 94.1%. Overall diagnostic accuracy reached 94.6%. Using SF, we found a sensitivity of 60%, a specificity of 96.1%, and an overall diagnostic accuracy of 92.9%. The Fungiplex Candida PCR has shown good sensitivity and specificity on clinical samples of high-risk patients for direct detection of Candida species in whole blood samples. Together with conventional diagnostics (BC and antigen testing), this new multiplex PCR assay may contribute to a rapid and accurate diagnosis of candidiasis.

Diagnostic accuracy of the LightCycler® SeptiFast assay in the childhood febrile neutropenia

Infection is the main problem among the patients receiving cancer therapy. The mortality rate can be reduced by the appropriate treatment in the right time. Although blood culture is the gold standard for the diagnoses of sepsis, many factors influence the results of blood culture in children. For this reason, real time polymerase chain reaction (Rt-PCR) has gained importance for the diagnoses of microbiological agents as it is faster than the conventional methods. In this study, we aimed to compare the efficacy of SeptiFast (SF) test with blood culture among children with neutropenic fever. Between January 2013 and December 2014, 62 children (34 boys, 38 girls) mean age 7.56 ± 4.8 (0-18) years with cancer were included in this study during their 94 febrile attacks of neutropenia (NA). Blood samples for blood culture and Septifast test were taken before the initiation of antibiotic therapy. Blood cultures were routinely collected in aerobic and anaerobic media and incubated using the BACTEC 9120 system (Becton-Dickinson Diagnostic Systems, USA). Identification and antimicrobial susceptibility testing of the isolates were performed using the Vitek2® system (bioMérieux, France) according to the recommendations of the Clinical and Laboratory Standards Institute. The LightCycler SF test was used according to the manufacturer instructions. Of 94 attacks 34 (36.1%) were positive for blood culture and 33 (35.1%) for SF test. The positivity ratio is found as 29.7% (28/94) by blood culture when the analysis of five coagulase negative staphylococci were excluded due to contamination. Positivity was detected in 25 (26.6%) of the 94 NA both with blood culture and SF test.The difference between these two tests was statistically significant (p< 0.05). There was discordance with a rate of 28.7% between these two methods. Polymicrobial infections were detected only with SF test. The detection of fungal infection rate was higher with SF test than blood culture. When SF test was compared with blood culture the results were as follows; sensitivity 91%, specificity 98.3%, positive predictive value 97%, negative predictive value 96.7%, diagnostic performance was 96.2%, respectively. As a result, PCR based tests can be used in children with NA attacks even though blood culture is still needed to perform the antibiotic sensitivity tests. SF test seems to be a sensitive test for the early diagnosis of the pathogens and the initiation of the appropriate therapy according to the etiological agent.

Sepsis: the LightCycler SeptiFast Test MGRADE®, SepsiTest™ and IRIDICA BAC BSI assay for rapidly identifying bloodstream bacteria and fungi – a systematic review and economic evaluation

Sepsis can lead to multiple organ failure and death. Timely and appropriate treatment can reduce in-hospital mortality and morbidity. To determine the clinical effectiveness and cost-effectiveness of three tests [LightCycler SeptiFast Test MGRADE(®) (Roche Diagnostics, Risch-Rotkreuz, Switzerland); SepsiTest(TM) (Molzym Molecular Diagnostics, Bremen, Germany); and the IRIDICA BAC BSI assay (Abbott Diagnostics, Lake Forest, IL, USA)] for the rapid identification of bloodstream bacteria and fungi in patients with suspected sepsis compared with standard practice (blood culture with or without matrix-absorbed laser desorption/ionisation time-of-flight mass spectrometry). Thirteen electronic databases (including MEDLINE, EMBASE and The Cochrane Library) were searched from January 2006 to May 2015 and supplemented by hand-searching relevant articles. A systematic review and meta-analysis of effectiveness studies were conducted. A review of published economic analyses was undertaken and a de novo health economic model was constructed. A decision tree was used to estimate the costs and quality-adjusted life-years (QALYs) associated with each test; all other parameters were estimated from published sources. The model was populated with evidence from the systematic review or individual studies, if this was considered more appropriate (base case 1). In a secondary analysis, estimates (based on experience and opinion) from seven clinicians regarding the benefits of earlier test results were sought (base case 2). A NHS and Personal Social Services perspective was taken, and costs and benefits were discounted at 3.5% per annum. Scenario analyses were used to assess uncertainty. For the review of diagnostic test accuracy, 62 studies of varying methodological quality were included. A meta-analysis of 54 studies comparing SeptiFast with blood culture found that SeptiFast had an estimated summary specificity of 0.86 [95% credible interval (CrI) 0.84 to 0.89] and sensitivity of 0.65 (95% CrI 0.60 to 0.71). Four studies comparing SepsiTest with blood culture found that SepsiTest had an estimated summary specificity of 0.86 (95% CrI 0.78 to 0.92) and sensitivity of 0.48 (95% CrI 0.21 to 0.74), and four studies comparing IRIDICA with blood culture found that IRIDICA had an estimated summary specificity of 0.84 (95% CrI 0.71 to 0.92) and sensitivity of 0.81 (95% CrI 0.69 to 0.90). Owing to the deficiencies in study quality for all interventions, diagnostic accuracy data should be treated with caution. No randomised clinical trial evidence was identified that indicated that any of the tests significantly improved key patient outcomes, such as mortality or duration in an intensive care unit or hospital. Base case 1 estimated that none of the three tests provided a benefit to patients compared with standard practice and thus all tests were dominated. In contrast, in base case 2 it was estimated that all cost per QALY-gained values were below £20,000; the IRIDICA BAC BSI assay had the highest estimated incremental net benefit, but results from base case 2 should be treated with caution as these are not evidence based. Robust data to accurately assess the clinical effectiveness and cost-effectiveness of the interventions are currently unavailable. The clinical effectiveness and cost-effectiveness of the interventions cannot be reliably determined with the current evidence base. Appropriate studies, which allow information from the tests to be implemented in clinical practice, are required. This study is registered as PROSPERO CRD42015016724. The National Institute for Health Research Health Technology Assessment programme.

Rapid Molecular Detection of Pathogens in 516 Consecutive Haematological Patients with Febrile Neutropenia

▪ BACKGROUNDFebrile neutropenia and sepsis are frequent and life-threatening complications in patients with haematological malignancies. Although the proportion of infectious deaths in haematological patients has decreased over the last two decades, much remains to be done to further reduce these events. More effective preventive and prophylactic strategies for high-risk patients are necessary. Blood cultures (BC) identify a pathogen in only 20 to 30% of febrile episodes, the culturing and pathogen identification process is lengthy, postponing the start of a pathogen-targeted treatment. Thereby, a sensitive tool to promptly recognize pathogens causing sepsis is of high clinical relevance. METHODSWe assessed the diagnostic usefulness of the LightCycler SeptiFast test (SF; Roche Molecular Systems), a PCR-based multiplex assay performed on peripheral blood and capable of detecting 25 among the most common species isolated in sepsis. The assay uses dual fluorescent resonance energy transfer (FRET) probes against the species-specific internal transcribed spacer (ITS) regions, a non-coding sequence interspaced among highly conserved bacterial and fungal RNA. Time from processing to result is remarkably short (less than 6 hours). In this study, blood samples from febrile haematological patients were concomitantly tested by traditional blood culture (BacT/Alert 3D; bioMerieux). RESULTSA total of 1941 blood samples were collected from 516 consecutive haematological patients treated for febrile neutropenia at the San Raffaele Haematology and Bone Marrow Transplantation Unit, from 2009 to 2013. Out of the total 1941 episodes examined, positive results were detected in 537 samples by SF (28%), and in 263 by BC (14%). Together, the two methods identified a total of 586 microorganisms in 509 (26%) episodes: Gram-positive bacterial species (80%), Gram-negative bacterial species (17%), and fungal species (3%). Concordance between the two methods was 77%, with most of the discordant samples that tested negative by culture but positive using the molecular approach (50% of the total positive samples). The cases positive by SF alone were mostly samples from patients already receiving antimicrobial therapy, or, importantly, sample positive for fungal pathogens such as Aspergillus fumigatus, which is hard to detect by the traditional approaches. CONCLUSIONThis analysis demonstrates a significant correlation between the molecular test and the standard BC in haematological patients with febrile neutropenia. A molecular test such as SF, in combination with traditional assays, can play an important role in the diagnosis of sepsis, particularly in persistent fever despite antibacterial therapy, when a non-responding bacterial infection or an invasive fungal infection is suspected, therefore leading to a rapid diagnosis and an earlier targeted antimicrobial therapy. DisclosuresNo relevant conflicts of interest to declare.

Etiological diagnosis of bloodstream infections through a multiplex real-time polymerase chain reaction test in pediatric patients: a case series from a tertiary Italian hospital

Background: The outcome of bloodstream infections (BSIs) is strongly related to microbiological diagnosis. Several factors may reduce blood culture (BC) diagnostic yield in pediatric BSIs, making the application of molecular methods quite promising. Methods: Multiplex real-time polymerase chain reaction (PCR) tests (the LightCycler Septifast Test MGRADE by Roche Diagnostics - LC-SF) performed in the tertiary centre of Regina Margherita Children's Hospital (Turin, Italy) over a 3-year period were retrospectively evaluated. Results of the LC-SF test were compared with those of BC (Automated Bact/Alert 3D, Biomerieux) collected at a close time point. Results: 545 LC-SF tests were collected from 289 patients (183 males, median age 6.8 years, interquartile range (IQR) = 2.7–13.1); 163 had congenital or acquired immunodeficiency. In 515 cases (94.5%) the LC-SF test was performed with ongoing empirical antimicrobial therapy. Etiological definition was achieved in 111 BSI cases (20.4%). Both LC-SF and BC identified the responsible pathogen in 39 episodes. The LC-SF test alone gave a positive result in 29 septic episodes; BC alone permitted the etiological diagnosis in 43 episodes, but isolates were not included in the LC-SF master list in 10 cases. A 26% increase in bacterial identification chances due to the LC-SF test was documented. Cohen's kappa test indicated a moderate strength of agreement (0.49) between LC-SF tests and BCs closely collected. Conclusions: BC remains the gold standard for the etiological diagnosis of BSIs, but PCR methods proved to be a valuable adjunctive diagnostic tool in pediatric BSIs, especially in children receiving empirical chemotherapy.

Real-time PCR-based identification of bacterial and fungal pathogens from blood samples.

Latest major contributions in the field of sepsis diagnostics result from advances in PCR technologies permitting new standards in speed and quality, given the fact that a timely diagnosis is the decisive factor to the survival of patients with bloodstream infections.Multiplex real-time PCR is a quantitative method for simultaneous amplification and detection of different targeted DNA molecules within hours. Nevertheless, various studies have shown a number of technical shortcomings as well as a high heterogeneity in sensitivity.The present method allows the standardized and rapid detection and identification of 25 common bacteria and fungi responsible for bloodstream infections from whole blood samples by using LightCycler(®) SeptiFast (LC-SF) test, based on real-time PCR.

Multiplex PCR System for Rapid Detection of Pathogens in Patients with Presumed Sepsis – A Systemic Review and Meta-Analysis

BackgroundBlood culture is viewed as the golden standard for the diagnosis of sepsis but suffers from low sensitivity and long turnaround time. LightCycler SeptiFast (LC-SF) is a real-time multiplex polymerase chain reaction test able to detect 25 common pathogens responsible for bloodstream infections within hours. We aim to assess the accuracy of LC-SF by systematically reviewing the published studies.MethodRelated literature on Medline, Embase, and Cochrane databases was searched up to October 2012 for studies utilizing LC-SF to diagnose suspected sepsis and that provided sufficient data to construct two-by-two tables.ResultsA total of 34 studies enrolling 6012 patients of suspected sepsis were included. The overall sensitivity and specificity for LC-SF to detect bacteremia or fungemia was 0·75 (95% CI: 0·65–0·83) and 0·92 (95%CI:0·90–0·95), respectively. LC-SF had a high positive likelihood ratio (10·10) and a moderate negative likelihood ratio (0·27). Specifically, LC-SF had a sensitivity of 0·80 (95%CI: 0·70–0·88) and a specificity of 0·95(95%CI: 0·93–0·97) for the bacteremia outcome, and a sensitivity of 0·61 (95%CI: 0·48–0·72) and a specificity of 0·99 (95%CI: 0·99–0·99) for the fungemia outcome. High heterogeneity was found in the bacteremia outcome subgroup but not in the fungemia outcome subgroup.ConclusionLC-SF is of high rule-in value for early detection of septic patients. In a population with low pretest probability, LC-SF test can still provide valuable information for ruling out bacteremia or fungemia.

Rapid Detection of Pathogens Causing Sepsis in Neutropenic Hematologic Patients by a Multiplex PCR-Based Assay

Abstract 4921 BACKGROUND:Febrile neutropenia and sepsis are frequent and life-threatening complications in patients with hematological malignancies. Prompt administration of appropriate antimicrobials is crucial to decrease the high morbidity and mortality rates of these conditions. Blood cultures (BC) identify a pathogen in only 20 to 30% of febrile episodes, with even lower sensitivity in patients already receiving antibiotics at time of sampling. Moreover the culturing and pathogen identification process is lengthy, postponing the start of a pathogen-targeted treatment, a particularly relevant issue when highly aggressive or rare agents are involved. Thereby the setup of molecular tools able to promptly recognize pathogens causing sepsis even despite ongoing antimicrobial therapy is of potential clinical relevance. METHODS:We assessed the diagnostic usefulness of the LightCycler SeptiFast test (SF), a PCR-based multiplex assay which can be performed on peripheral blood in hematological patients. In this study, blood samples from febrile oncohaematological patients were tested by traditional blood culture (BacT/Alert 3D; bioMerieux) and by a novel commercial real-time PCR assay (LightCycler SeptiFast; Roche Molecular Systems) performed concomitantly at the onset of febrile neutropenia. RESULTS:A total of 869 blood samples were collected from 273 consecutive patients treated for febrile neutropenia at the San Raffaele Hematology Unit over the last three years (July 2009–July 2011). Out of the total 869 episodes examined, positive results were detected in 246 samples by SF (28.3%), and in 143 by BC (16.4%). Together, the two methods identified a total of 345 microorganisms in 312 (36%) episodes: Gram-positive bacterial species (74%), Gram-negative bacterial species (23%), and fungal species (3%). Concordance between the two methods was 73%, mainly due to samples that tested negative by culture but positive using the molecular approach (54% of the total positive samples). The cases positive by SF alone were mostly samples from patients with initial concordant results on samples harvested before the administration of a specific antimicrobial therapy, or, importantly, sample positive for a clinically relevant agent such as Aspergillus fumigatus, which is hard to detect by the traditional approaches. CONCLUSION:The LightCycler SeptiFast test gives new insights into the natural history of infection and in the development of new algorithms for the diagnosis of sepsis in critical patients. Using SF combined with BC improves microbiological documentation in febrile neutropenia particularly in persistent fever despite antibacterial therapy, when a nonresponding bacterial infection or an invasive fungal infection is suspected; results of SF may lead to a more targeted antibiotic therapy early after the onset of fever. Disclosures:No relevant conflicts of interest to declare.

Usefulness of Real-Time PCR for the Diagnosis of Sepsis in ICU-Acquired Infections

Real-time PCR methods are able to rapidly detect a wide panel of microorganisms. These methods are of interest in critically ill patients to determine the presence of bacteria in the blood and other biological samples, especially in those patients with prior antimicrobial treatment. In intensive care unit (ICU), the LightCycler SeptiFast (LC-SF) Test provides 1.5 to 2 fold higher positivity rate compared with conventional blood cultures. Although identification of the bacterium by LC-SF is rapid and sensitive, susceptibility test could not be performed using this technique, except the methicillin- resistance for Staphylococci. The conventional cultures remain necessary for samples in ICU because of the high incidence of multidrug-resistant bacteria and the need for antimicrobial susceptibility of the bacterium to treat the patient correctly. A negative result for a Gram positive or negative bacterium allows deescalating the initial antimicrobial treatment, and decreasing the pressure of selection. Moreover, it is necessary to understand and interpret a DNA signal knowing that a dead bacterial material may be detected in a patient without any infection. What is the clinical relevance of bacterial DNA present in the blood and does the DNAemia found reflect true infection? Cost-effectiveness of the real-time PCR should be determined. Meanwhile, this test should be restricted to severe clinical situations, especially ICU patients with severe sepsis. In the future, real-time PCR tests should include more pathogens and antimicrobial resistant targets.

Performance of the LightCycler SeptiFast Test M grade in Detecting Microbial Pathogens in Purulent Fluids

The performance of the LightCycler SeptiFast (SF) assay was compared to that of culture methods in the detection of microorganisms in 43 purulent fluids from patients with pyogenic infections. The SF assay was more sensitive than the culture methods (86% versus 61%, respectively), irrespective of whether the infections were mono- or polymicrobial.

Multiplex PCR Allows Rapid and Accurate Diagnosis of Bloodstream Infections in Newborns and Children with Suspected Sepsis

Sepsis is a major health problem in newborns and children. Early detection of pathogens allows initiation of appropriate antimicrobial therapy that strongly correlates with positive outcomes. Multiplex PCR has the potential to rapidly identify bloodstream infections, compensating for the loss of blood culture sensitivity. In an Italian pediatric hospital, multiplex PCR (the LightCycler SeptiFast test) was compared to routine blood culture with 1,673 samples obtained from 803 children with suspected sepsis; clinical and laboratory information was used to determine the patient infection status. Excluding results attributable to contaminants, SeptiFast showed a sensitivity of 85.0% (95% confidence interval [CI] = 78.7 to 89.7%) and a specificity of 93.5% (95% CI = 92.1 to 94.7%) compared to blood culture. The rate of positive results was significantly higher with SeptiFast (14.6%) than blood culture (10.3%) (P < 0.0001), and the overall positivity rate was 16.1% when the results of both tests were combined. Staphylococcus aureus (11.6%), coagulase-negative staphylococci (CoNS) (29.6%), Pseudomonas aeruginosa (16.5%), and Klebsiella spp. (10.1%) were the most frequently detected. SeptiFast identified 97 additional isolates that blood culture failed to detect (24.7% P. aeruginosa, 23.7% CoNS, 14.4% Klebsiella spp., 14.4% Candida spp.). Among specimens taken from patients receiving antibiotic therapy, we also observed a significantly higher rate of positivity of SeptiFast than blood culture (14.1% versus 6.5%, respectively; P < 0.0001). On the contrary, contaminants were significantly more frequent among blood cultures than SeptiFast (n = 97 [5.8%] versus n = 26 [1.6%]), respectively; P < 0.0001). SeptiFast served as a highly valuable adjunct to conventional blood culture in children, adding diagnostic value and shortening the time to result (TTR) to 6 h.

Diagnostic accuracy and potential clinical value of the LightCycler SeptiFast assay in the management of bloodstream infections occurring in neutropenic and critically ill patients

The objectives of this study were to compare the performance of the LightCycler SeptiFast Test MGRADE and conventional blood culture in the etiological diagnosis of febrile episodes occurring in neutropenic and critically ill patients (in the intensive care unit; ICU), and to assess the potential clinical value of the SeptiFast test in patient management. A total of 86 febrile episodes occurring in 33 neutropenic patients and 53 ICU patients were analyzed. Blood samples for blood culture and SeptiFast testing were obtained at the onset of fever, before the implementation of empirical antimicrobial therapy. The overall microorganism-to-isolate agreement between the SeptiFast test and blood culture was 69% (κ=0.37) in neutropenic patients and 75% (κ=0.56) in ICU patients. The sensitivity of the SeptiFast assay for clinically relevant episodes of bacteremia and fungemia was 62% in neutropenic patients and 70% in ICU patients. Based on SeptiFast results, empirical treatments were deemed adequate in all but one of the febrile episodes. Nevertheless, early antibiotic treatment readjustment was judged feasible in most of clinically significant episodes overall. The SeptiFast assay is a valuable ancillary method for the diagnosis of bloodstream infections in neutropenic and ICU patients. In these clinical settings, results of the SeptiFast assay may lead to a more targeted antibiotic therapy early after the onset of fever.

Automated Extraction Improves Multiplex Molecular Detection of Infection in Septic Patients

Sepsis is one of the leading causes of morbidity and mortality in hospitalized patients worldwide. Molecular technologies for rapid detection of microorganisms in patients with sepsis have only recently become available. LightCycler SeptiFast test Mgrade (Roche Diagnostics GmbH) is a multiplex PCR analysis able to detect DNA of the 25 most frequent pathogens in bloodstream infections. The time and labor saved while avoiding excessive laboratory manipulation is the rationale for selecting the automated MagNA Pure compact nucleic acid isolation kit-I (Roche Applied Science, GmbH) as an alternative to conventional SeptiFast extraction. For the purposes of this study, we evaluate extraction in order to demonstrate the feasibility of automation. Finally, a prospective observational study was done using 106 clinical samples obtained from 76 patients in our ICU. Both extraction methods were used in parallel to test the samples. When molecular detection test results using both manual and automated extraction were compared with the data from blood cultures obtained at the same time, the results show that SeptiFast with the alternative MagNA Pure compact extraction not only shortens the complete workflow to 3.57 hrs., but also increases sensitivity of the molecular assay for detecting infection as defined by positive blood culture confirmation.

Multiplex Blood PCR in Combination with Blood Cultures for Improvement of Microbiological Documentation of Infection in Febrile Neutropenia

The frequent lack of microbiological documentation of infection by blood cultures (BC) has a major impact on clinical management of febrile neutropenic patients, especially in cases of unexplained persistent fever. We assessed the diagnostic utility of the LightCycler SeptiFast test (SF), a multiplex blood PCR, in febrile neutropenia. Blood for BC and SF was drawn at the onset of fever and every 3 days of persistent fever. SF results were compared with those of BC, clinical documentation of infection, and standard clinical, radiological, and microbiological criteria for invasive fungal infections (IFI). A total of 141 febrile neutropenic episodes in 86 hematological patients were studied: 44 (31%) microbiologically and 49 (35%) clinically documented infections and 48 (34%) unexplained fevers. At the onset of fever, BC detected 44 microorganisms in 35/141 (25%) episodes. Together, BC and SF identified 78 microorganisms in 61/141 (43%) episodes (P = 0.002 versus BC or SF alone): 12 were detected by BC and SF, 32 by BC only, and 34 by SF only. In 19/52 (37%) episodes of persistent fever, SF detected 28 new microorganisms (7 Gram-positive bacterial species, 15 Gram-negative bacterial species, and 6 fungal species [89% with a clinically documented site of infection]) whereas BC detected only 4 pathogens (8%) (P = 0.001). While BC did not detect fungi, SF identified 5 Candida spp. and 1 Aspergillus sp. in 5/7 probable or possible cases of IFI. Using SeptiFast PCR combined with blood cultures improves microbiological documentation in febrile neutropenia, especially when fever persists and invasive fungal infection is suspected. Technical adjustments may enhance the efficiency of this new molecular tool in this specific setting.

Preliminary clinical study using a multiplex real-time PCR test for the detection of bacterial and fungal DNA directly in blood

Early diagnosis of sepsis, rapid identification of the causative pathogen(s) and prompt initiation of appropriate antibiotic treatment have a combined impact on mortality due to sepsis. In this observational study, a new DNA-based system (LightCycler SeptiFast (LC-SF) test; Roche Diagnostics) allowing detection of 16 pathogens at the species level and four groups of pathogens at the genus level has been evaluated and compared with conventional blood cultures (BCs). One hundred BC and LC-SF results were obtained for 72 patients admitted to the intensive-care unit over a 6-month period for suspected sepsis. Microbiological data were compared with other biological parameters and with clinical data. The positivity rate of BCs for bacteraemia/fungaemia was 10%, whereas the LC-SF test allowed detection of DNA in 15% of cases. The LC-SF performance, based on its clinical relevance, was as follows: sensitivity, 78%; specificity, 99%; -positive predictive value, 93%; and negative predictive value, 95%. Management was changed for four of eight (50%) of the patients because organisms were detected by the LC-SF test but not by BC. LC-SF results were obtained in 7–15 h, in contrast to the 24–72 h required for BC. According to the LC-SF results, initial therapy was inadequate in eight patients, and antibiotic treatment was changed. Our results suggest that the LC-SF test may be a valuable complementary tool in the management of patients with clinically suspected sepsis.

Clinical impact of a commercially available multiplex PCR system for rapid detection of pathogens in patients with presumed sepsis

BackgroundTimely identification of pathogens is crucial to minimize mortality in patients with severe infections. Detection of bacterial and fungal pathogens in blood by nucleic acid amplification promises to yield results faster than blood cultures (BC). We analyzed the clinical impact of a commercially available multiplex PCR system in patients with suspected sepsis.MethodsBlood samples from patients with presumed sepsis were cultured with the Bactec 9240™ system (Becton Dickinson, Heidelberg, Germany) and aliquots subjected to analysis with the LightCycler® SeptiFast® (SF) Test (Roche Diagnostics, Mannheim, Germany) at a tertiary care centre. For samples with PCR-detected pathogens, the actual impact on clinical management was determined by chart review. Furthermore a comparison between the time to a positive blood culture result and the SF result, based on a fictive assumption that it was done either on a once or twice daily basis, was made.ResultsOf 101 blood samples from 77 patients, 63 (62%) yielded concordant negative results, 14 (13%) concordant positive and 9 (9%) were BC positive only. In 14 (13%) samples pathogens were detected by SF only, resulting in adjustment of antibiotic therapy in 5 patients (7,7% of patients). In 3 samples a treatment adjustment would have been made earlier resulting in a total of 8 adjustments in all 101 samples (8%).ConclusionThe addition of multiplex PCR to conventional blood cultures had a relevant impact on clinical management for a subset of patients with presumed sepsis.

Mikrobiologisches Sepsis-Screening chirurgischer Intensivpatienten mit dem „Lightcycler“ Septifast®-Test – eine Pilotstudie

An adequate approach to surgically induced sepsis needs an early and targeted antibiotic therapy in addition to focus sanitation. The PCR-based LightCycler Septifast test can detect 90 % of the sepsis-associated microoganisms (e. g., Gram-positive, Gram-negative bacteria, fungi) within only a few hours. A systematic microbiological screening was performed using conventional cultures from blood, urine, drain material and tracheal secretions as well as with the culture-independent Septifast test (blood supplemented with EDTA) as a comparison in consecutive surgical patients on the intensive care unit within a defined time period. Overall, 52 patients were enrolled in the investigation during the study period of 4 months. Out of overall 258 Septifast tests, 33 (12.8 %) were positive. Additional information on the microbial spectrum was achieved in 24 cases (72.2 %) when compared with the simultaneously performed conventional blood cultures; 32 (12.4 %) of 258 blood cultures were positive. If the frequent occurrence of coagulase-negative STAPHYLOCOCCUS (CNS) is classified as contamination, blood cultures resulted 10 times (31.3 %) in additional information compared with the Septifast test including the CNS in 20 cases (62.5 %). Except for Proteus mirabilis, this refers to microorganisms which are not in the analytical spectrum of the Septifast(R) test. A positive Septifast test showed a high coincidence with SIRS (75.8 %). This first systematic use of the time-saving LightCycler Septifast test shows that it can detect bacteremia in surgical patients at the ICU, with, in part, negative blood cultures. Positive Septifast test results which cannot be explained by clinical symptoms, occur rarely. The detection of pathological microbes with the Septifast test provides additional findings (72.2 %) for therapeutic decision-making, which can be obtained considerably more rapidly in comparison with conventional microbiological cultures (a few hours versus 2 days). For surgical patients with SIRS and subsequent need of intensive care, a Septifast test should be considered. In conclusion, it is recommended that the test should be further and systematically investigated.

Diagnosis of bloodstream infections in immunocompromised patients by real-time PCR

The diagnosis of bloodstream infections (BSIs) in immunocompromised patients, such as patients with cancer, is challenging. Although blood culture (BC) is considered the standard diagnostic tool for BSIs, it takes several days to yield results and has low sensitivity in these patients. Here, we tested a novel method for diagnosing BSIs in a large cohort of immunodepressed patients. Real-time PCR (LightCycler SeptiFast Test M(GRADE), Roche Diagnostics) was compared with BC for its ability to detect bacteria and fungi in blood samples from 100 immunocompromised patients (98 with cancer) in whom sepsis was suspected. In concordant samples (79.2% of total cases), real-time PCR identified the presence or absence of microbes significantly faster than BC (p=3.7x10(-49), t-test). Furthermore, in 6 cases, SeptiFast distinguished contamination of BCs by coagulase-negative staphylococci. SeptiFast, however, failed to detect 5 cases of clinically relevant BSI that tested positive by BC. SeptiFast rapidly diagnosed BSIs in our cohort of immunosuppressed patients. The results of this study suggest that SeptiFast can be used in conjunction with, but cannot replace, BC to better identify the etiology of fever in immunocompromised patients.

Detección automática de bacterias y hongos en sangre

La sepsis es una de las principales causas de mortalidad y morbilidad en los hospitales. La detección temprana de los patógenos mediante técnicas basadas en ácidos nucleicos puede facilitar el diagnóstico rápido de la bacteriemia y/o fungemia, la rápida adecuación del tratamiento antibiótico, reducir el uso de antibióticos innecesarios y disminuir la mortalidad. Se describen 2 técnicas disponibles comercialmente que ayudan, en un tiempo reducido, a identificar distintas bacterias y hongos productores de sepsis: LightCycler® SeptiFast Test Mgrade (Roche Diagnostic SL) y GenoType Blood Culture (Hain Lifescience). De estas 2 técnicas, mostramos los resultados de un estudio inicial propio con el LightCycler® SeptiFast Test Mgrade. El estudio se realizó con 50 muestras correspondientes a 28 pacientes (1-3 muestras por paciente) con síndrome séptico ingresados en la unidad de cuidados intensivos, comparando la nueva técnica con el hemocultivo convencional. La concordancia entre los resultados del hemocultivo y el SeptiFast fue buena, 79% en el primer ensayo, y 89% en el segundo, después de corregir defectos técnicos. Inicialmente se observó inhibición importante de los controles internos para los bacilos gramnegativos, por la presencia de heparina en la sangre empleada y un exceso de ácido desoxirribonucleico (ADN) debido al número de leucocitos. Con la finalidad de disminuir las inhibiciones, en otro estudio posterior se trabajó con 24 muestras a la mitad de volumen original, llevando el ácido nucleico extraído a dilución 1:4. Con estas modificaciones, se apreciaron reducciones importantes de las inhibiciones. En comparación con el hemocultivo, el SeptiFast diferencia mejor las contaminaciones por estafilococos coagulasa-negativa y especies de estreptococos.