Use of the LightCycler SeptiFast test for rapid etiologic diagnosis of nosocomial infection in gynecological sepsis

SeptiFast versus blood culture in clinical routine - A report on 3 years experience

BACKGROUND

In recent years a multiplex real-time PCR (SeptiFast) has been introduced, allowing detection of 25 common blood pathogens considerably faster than conventional blood culture.

METHODS

SeptiFast was applied routinely in addition to blood culture in cases of critically ill patients with fever and other signs of severe systemic infections. In this study data of 470 episodes were retrospectively analysed to assess the impact of various parameters, such as clinical indications, assigning ward and antimicrobial treatment on test outcome using a multivariate logistic model.

RESULTS

After exclusion of microorganisms classified as contaminants, the concordance between SeptiFast and blood culture was 85.5%. SeptiFast detected 98 out of 120, while blood culture merely found 63 out of 120 potential pathogens. In comparison to blood culture, SeptiFast showed considerably higher positivity rates in sepsis, pneumonia and febrile immunosuppression and a lower rate in endocarditis. The highest positivity and concordance between tests was shown in patients from the emergency room (P = 0.007).

CONCLUSIONS

The results obtained in this study are similar to those from prospective settings confirming the robustness of the SeptiFast assay in routine use. Our data suggest that SeptiFast is a valuable add-on to blood culture and may increase the diagnostic efficiency of a microbiological laboratory.

Direct molecular detection of pathogens in blood as specific rule-in diagnostic biomarker in patients with presumed sepsis: our experience on a heterogeneous cohort of patients with signs of infective systemic inflammatory response syndrome

The practical value of blood cultures in the diagnosis of sepsis is impaired by a delay in the turnaround time to result and by the fact that blood culture positive can be found for only about 30% of these patients. Conventional laboratory signs of sepsis and acute phase protein biomarkers are sensitive and easy to use, but often also very nonspecific. Molecular diagnostic reflects currently the most promising avenue to decrease time to result and to influence decision making for antibiotic therapy in the septic host. In this study, we wish to highlight the impact of the LightCycler SeptiFast, a multipathogen probe-based real-time polymerase chain reaction, in the rapid etiological diagnosis of sepsis in patients with clinical and laboratory signs of bloodstream infections. We have evaluated prospectively 830 adult patients with suspected bloodstream infection and at least two criteria of systemic inflammatory response syndrome. In more than 50% of critically ill patients strongly suspected of having sepsis, we arrived to an etiological diagnosis only by the molecular method in a median time of 15 h, with specificity and predictive positive values of 96% and 94%, respectively. We highlight the role of DNAemia as time-critical, high-specificity, etiological, non-culture-based rule-in diagnostic biomarker in patients with presumed sepsis.

Evaluation of the Light-Cycler® SeptiFast Test in Newborns With Suspicion of Nosocomial Sepsis

Background:

Nosocomial sepsis (NS) in newborns (NBs) is associated with high mortality rates and low microbial recovery rates. To overcome the latter problem, new techniques in molecular biology are being used.

Objectives:

To evaluate the diagnostic efficacy of SeptiFast test for the diagnosis of nosocomial sepsis in the newborn.

Materials and Methods:

86 blood specimens of NBs with suspected NS (NOSEP-1 Test > 8 points) were analyzed using Light Cycler SeptiFast (LC-SF) a real-time multiplex PCR instrument. The results were analyzed with the Roche SeptiFast Identification Software. Another blood sample was collected to carry out a blood culture (BC).

Results:

Sensitivity (Sn) and specificity (Sp) of 0.69 and 0.65 respectively, compared with blood culture (BC) were obtained for LC-SF. Kappa index concordance between LC-SF and BC was 0.21. Thirteen (15.11%) samples were BC positive and 34 (31.39%) were positive with LC-SF tests.

Conclusions:

Compared with BC, LC-SF allows the detection of a greater number of pathogenic species in a small blood sample (1 mL) with a shorter response time.

Molecular diagnosis of sepsis: New aspects and recent developments

By shortening the time to pathogen identification and allowing for detection of organisms missed by blood culture, new molecular methods may provide clinical benefits for the management of patients with sepsis. While a number of reviews on the diagnosis of sepsis have recently been published we here present up-to-date new developments including multiplex PCR, mass spectrometry and array techniques. We focus on those techniques that are commercially available and for which clinical studies have been performed and published.

Early aetiological agent identification of osteomyelitis with the Light Cycler SeptiFast test from peripheral blood

The commercial real-time PCR SeptiFast test allows identification of 25 bacterial and fungal species directly from peripheral blood in patients with bloodstream infections. A 22-year-old Caucasian woman reported an open femur fracture requiring a two step surgical procedure. After the second procedure the patient manifested sepsis and Enterobacter cloacae/aerogenes DNA was detected in the peripheral blood with the SeptiFast. Thereafter, femur osteomyelitis was diagnosed and E cloacae was cultured from intraoperative bone samples. The patient completed a 3-month course of antimicrobial therapy. Five months after therapy was discontinued, the patient remained symptom free, but delayed bone consolidation occurs. Molecular methods to identify aetiological agents in blood, in addition to conventional cultures, could represent an advantageous tool in clinical practice also in patients with post-traumatic bone infections.

Commercial multiplex technologies for the microbiological diagnosis of sepsis

In patients with suspected sepsis, rapid and accurate diagnosis of the causative infectious agent is critical. Although clinicians often use empiric antimicrobial therapy until the blood cultures are available to potentially adjust treatment, this approach is often not optimum for patient care. Recently, several commercial molecular multiplex technologies have shown promise for fast and comprehensive diagnosis of microorganisms and their antimicrobial resistance signatures. While one class of multiplex technologies is directed at improving the speed and diagnostic information obtained from positive blood cultures, the other identifies the causative microorganisms directly from clinical blood samples. This review provides an overview of these molecular technologies and describes their performance capabilities compared to standard blood cultures and in some cases to each other. We discuss the current clinical impact, limitations, and likely futures advances these multiplex technologies may have in guiding the management of patients with sepsis.

Bench-to-bedside review: Rapid molecular diagnostics for bloodstream infection--a new frontier?

Among critically ill patients, the diagnosis of bloodstream infection poses a major challenge. Current standard bacterial identification based on blood culture platforms is intrinsically time-consuming and slow. The continuous evolvement of molecular techniques has the potential of providing a faster, more sensitive and direct identification of causative pathogens without prior need for cultivation. This may ultimately impact clinical decision-making and antimicrobial treatment. This review summarises the currently available technologies, their strengths and limitations and the obstacles that have to be overcome in order to develop a satisfactory bedside point-of-care diagnostic tool for detection of bloodstream infection.