Procalcitonin predicts real-time PCR results in blood samples from patients with suspected sepsis

The beneficial roles and mechanisms of estrogens in immune health and infection disease

Multiple epidemiologic studies have revealed that gender is considered one of the important factors in the frequency and severity of certain infectious diseases, in which estrogens may play a vital role. There is growing evidence that estrogens as female sex hormone can modulate multiple biological functions outside of the reproductive system, such as in brain and cardiovascular system. However, it is largely unknown about the roles and mechanisms of estrogens/estrogen receptors in immune health and infection disease. Thence, by reading a lot of literature, we summarized the regulatory mechanisms of estrogens/estrogen receptors in immune cells and their roles in certain infectious diseases with gender differences. Therefore, estrogens may have therapeutic potentials to prevent and treat these infectious diseases, which needs further clinical investigation.

Procalcitonin and Risk Prediction for Diagnosing Bacteremia in Hospitalized Patients: A Retrospective, National Observational Study

Bacteremia is associated with significant morbidity and mortality. Timely, appropriate therapy may improve clinical outcomes, and therefore, determining which patients benefit from more comprehensive diagnostic strategies (i.e., direct specimen testing) could be of value. We performed an assessment of procalcitonin (PCT) and clinical characteristics in the discrimination of bacteremic hospitalizations. We analyzed 71,105 encounters and 14,846 visits of patients with bacteremia alongside 56,259 without an admission. The area under the receiver-operating characteristic (AUROC) curve for the prediction of bacteremia via procalcitonin was 0.782 (95% CI 0.779-0.787). The prediction modeling of clinical factors with or without PCT resulted in a similar performance to PCT alone. However, the clinically predicted risk of bacteremia stratified by PCT thresholds allowed the targeting of high-incidence bacteremia groups (e.g., ≥50% positivity). The combined use of PCT and clinical characteristics could be useful in diagnostic stewardship by targeting further advanced diagnostic testing in patients with a high predicted probability of bacteremia.

Predictive Modeling Using Artificial Intelligence and Machine Learning Algorithms on Electronic Health Record Data: Advantages and Challenges

The rapid adoption of electronic health record (EHR) systems in US hospitals from 2008 to 2014 produced novel data elements for analysis. Concurrent innovations in computing architecture and machine learning (ML) algorithms have made rapid consumption of health data feasible and a powerful engine for clinical innovation. In critical care research, the net convergence of these trends has resulted in an exponential increase in outcome prediction research. In the following article, we explore the history of outcome prediction in the intensive care unit (ICU), the growing use of EHR data, and the rise of artificial intelligence and ML (AI) in critical care.

Sex differences in vancomycin-resistant enterococci bloodstream infections-a systematic review and meta-analysis

Background

Vancomycin-resistant enterococci (VRE) have emerged in the healthcare setting worldwide. Infections with these pathogens, i.e., bloodstream infections (BSI), are accompanied with an impaired patient outcome. Diverse factors comprising patient characteristics, therapeutic strategies, and infection control measures are positively or negatively associated with VRE BSI occurrence. However, whether sex-specific differences influence the frequency of VRE BSI is yet unknown.

The aim of this systematic review was to comprehensively summarize and analyze sex prevalence in VRE BSI patients.

Main text

A systematic search for relevant articles was conducted in PubMed and Web of Science. After screening for eligibility, data extraction from included articles and risk of bias assessment were processed. The prevalence of male/female sex in VRE BSI patients and 95% CI were calculated for each study and summarized as pooled estimated effect.

In total, nine articles met the inclusion criteria. Risk of bias assessment resulted in low (six studies) to moderate bias (three studies). The pooled prevalence of male patients suffering from VRE BSI was 59% resulting in a 1.4 male/female prevalence ratio.

Conclusions

Current literature suggests sex differences with male preference (59%) in the distribution of VRE BSI cases. Further primary studies should address the question of male-specific factors favoring the enhanced frequency of VRE BSI.

Neglected Variables in the Interpretation of Serum Procalcitonin Levels in Patients With Septic Shock

The interpretation of serum procalcitonin (PCT) levels in septic patients is facilitated by reviewing the known stimuli that activate the PCT family of genes. Herein we describe 7 pathways that, alone or in combination, can increase serum PCT levels. As a marker of activation of innate immunity, high PCT levels affect clinical diagnosis, can be trended as a measure of "source" control, and can guide duration of antibacterial therapy in septic patients. Low PCT levels reflect little to no activation of an innate immune response, influence the differential diagnosis, and support the discontinuation of empiric antibiotic therapy. Understanding the pathways that result in elevated serum PCT levels is necessary for interpretation and subsequent clinical management.

Efficient Early Diagnosis of Sepsis Using Whole-Blood PCR-Reverse Blot Hybridization Assay Depending on Serum Procalcitonin Levels

Sepsis is one of the medical emergencies, and its early detection, within the first hours of development, and proper management improve outcomes. Molecular diagnostic assays using whole blood collected from patients with suspected sepsis have been developed, but the decision making is difficult because of the possibility of false positives, due to contamination. Here, we evaluated the performance of the reverse blot hybridization assay (REBA) Sepsis-ID test for the detection of sepsis-causing microorganisms using whole-blood samples. In addition, the concentrations of C-reactive protein (CRP) and procalcitonin (PCT) were determined to evaluate whether these biomarkers can provide criteria for performing REBA Sepsis-ID in clinical settings. For this study, EDTA-anticoagulated whole blood was simultaneously collected for REBA Sepsis-ID and blood culture from 440 patients with suspected sepsis, from January to October 2015. In addition, CRP and PCT concentrations were measured in 227 patients. The overall positive rates of REBA Sepsis-ID and blood culture were 16.6% (73/440) and 13.9% (61/440), respectively. The pathogen-positive rates of REBA Sepsis-ID and blood culture were 9.8% (43/440) and 9.5% (42/440), respectively. The areas under the receiver operating characteristic (AUROC) curves of PCT and CRP for predicting pathogen-positive results of REBA Sepsis-ID were 0.72 and 0.69, respectively. The PCT concentrations in the group of patients aged ≥50 years were significantly higher than those in the group aged <50 years. After adjusting for age, the PCT AUROC value was 0.77 for predicting pathogen-positive results of REBA Sepsis-ID. The optimal cutoff values of PCT concentrations for subsequent application of REBA Sepsis-ID were 0.12 ng/mL in all patients and 0.22 ng/mL in patients aged ≥50 years. Our observations showed that REBA Sepsis-ID using whole blood was advantageous for the early detection of sepsis-causing microorganisms, and the PCT concentration could be used to determine the necessity of using REBA Sepsis-ID in clinical settings. The application of REBA Sepsis-ID using whole blood, based on the PCT concentration, may contribute to a highly efficient detection of sepsis-causing microorganisms.

Procalcitonin, C-Reactive Protein, Albumin, and Blood Cultures as Early Markers of Sepsis Diagnosis or Predictors of Outcome: A Prospective Analysis

Purpose:

Sepsis is a condition with high mortality rates and its diagnosis remains a challenge. We assessed epidemiological, clinical data, multiple biomarker profiles, and blood culture with respect to sepsis diagnosis and predictors of outcome.

Methods:

In total, 183 patients who were suspected of having sepsis and underwent blood culture collection were followed up for 7 days. Sepsis-related Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation (APACHE) II scores were calculated daily; biomarkers and blood culture test results were evaluated.

Results:

In total, 78 (43%) had sepsis, 50 (27%) had septic shock, and 55 (30%) had no sepsis. Blood culture was positive in 28% and 42% of the sepsis and septic shock groups, respectively (P < .001). Regarding clinical profiles and biomarker values, there were no differences between the sepsis and non-sepsis groups, but significant differences were observed in the septic shock group. Multivariate logistic regression models revealed that age, serum albumin level, APACHE II, and SOFA 1^st day scores were the independent variables for death.

Conclusions:

The challenge in the diagnosis of sepsis continues as clinical and laboratory differences found between the groups were due to septic shock. Older aged patients with lower albumin levels and higher APACHE II and SOFA 1^st day scores have a greater probability of mortality.

Multiplex polymerase chain reaction to diagnose bloodstream infections in patients after cardiothoracic surgery

Background

Sepsis and other infectious complications are major causes of mortality and morbidity in patients after cardiac surgery. Whereas conventional blood culture (BC) suffers from low sensitivity as well as a reporting delay of approximately 48–72 h, real-time multiplex polymerase chain reaction (PCR) based technologies like “SeptiFast” (SF) might offer a fast and reliable alternative for detection of bloodstream infections (BSI). The aim of this study was to compare the performance of SF with BC testing in patients suspected of having BSI after cardiac surgery.

Methods

Two hundred seventy-nine blood samples from 169 individuals with suspected BSI were analyzed by SF and BC. After excluding results attributable to contaminants, a comparison between the two groups were carried out. Receiver operating characteristic (ROC) curves were generated to determine the accuracy of clinical and laboratory values for the prediction of positive SF results.

Results

14.7% (n = 41) of blood samples were positive using SF and 17.2% (n = 49) using BC (n.s. [p > 0.05]). In six samples SF detected more than one pathogen. Among the 47 microorganisms identified by SF, only 11 (23.4%) could be confirmed by BC. SF identified a higher number of Gram-negative bacteria than BC did (28 vs. 12, χ² = 7.97, p = 0.005). The combination of BC and SF increased the number of detected microorganisms, including fungi, compared to BC alone (86 vs. 49, χ² = 13.51, p < 0.001). C-reactive protein (CRP) (21.7 ± 11.41 vs. 16.0 ± 16.9 mg/dl, p = 0.009), procalcitonin (28.7 ± 70.9 vs. 11.5 ± 30.4 ng/dl, p = 0.015), and interleukin 6 (IL 6) (932.3 ± 1306.7 vs. 313.3 ± 686.6 pg/ml, p = 0.010) plasma concentrations were higher in patients with a positive SF result. Using ROC analysis, IL-6 (AUC 0.836) and CRP (AUC 0.804) showed the best predictive values for positive SF results.

Conclusion

The SF test represent a valuable method for rapid etiologic diagnosis of BSI in patients after cardiothoracic surgery. In particular this method applies for individuals with suspected Gram-negative blood stream. Due to the low performance in detecting Gram-positive pathogens and the inability to determine antibiotic susceptibility, it should be used in addition to BC only (Pilarczyk K, et al., Intensive Care Med Exp ,3(Suppl. 1):A884, 2015).

Ability of serum procalcitonin to distinguish focus of infection and pathogen types in patients with bloodstream infection

Background

Serum procalcitonin (PCT) is a widely recognized inflammatory marker which can distinguish systemic bacterial infection from other types of infections. The ability of PCT levels to distinguish different pathogens from different focus of infection is contradictory.

Methods

This study included 551 patients with bloodstream infection (BSI) diagnosed with positive blood culture (BC) during Jan 2013 and May 2018. The patients were divided into two groups with or without definite focus of infection. In this study, we analyzed PCT levels induced by Gram-positive bacteria, Gram-negative bacteria and fungal infection. Relationship of time between PCT peak and BC collection, and the impact of antibiotics usage on PCT peak distribution were examined.

Results

For patients without definite focus of infection, the serum PCT values of Gram-negative bacteria were higher than that of Gram-positive bacteria (P<0.05). A cut-off value of 7.54 ng/mL for PCT showed a sensitivity of 88.3%. For patients with definite focus of infection, the serum PCT values of Gram-negative bacteria were significantly higher than Gram-positive bacteria in patients with lower respiratory tract (P=0.003), abdominal (P=0.039), urinary tract infection (P=0.025), but not in patients with upper respiratory tract infection (P=0.664). The PCT values between multidrug-resistant organism (MDRO) and sensitive bacteria were not statistically significant (P>0.05) among all patients. Moreover, among patients who use antibiotics before BC collection, the longer antibiotics used, the higher trend of the proportion for PCT peak distribution after BC collection. The higher proportion of antibiotics combined before BC collection, the lower proportion of PCT peak distribution appeared before BC collection, and the higher the proportion of PCT peak distribution appeared after BC collection.

Conclusions

PCT value is determined by many factors. PCT value is related to not only Gram-positive bacteria or Gram-negative bacteria, but also related to specific pathogens, and specific of infection sites etc. The use of Antibiotics is also an important factor of PCT value.

Sexual dimorphism in bacterial infections

Background

Sex differences are important epidemiological factors that impact in the frequency and severity of infectious diseases. A clear sexual dimorphism in bacterial infections has been reported in both humans and animal models. Nevertheless, the molecular mechanisms involved in this gender bias are just starting to be elucidated. In the present article, we aim to review the available data in the literature that report bacterial infections presenting a clear sexual dimorphism, without considering behavioral and social factors.

Main body

The sexual dimorphism in bacterial infections has been mainly attributed to the differential levels of sex hormones between males and females, as well as to genetic factors. In general, males are more susceptible to gastrointestinal and respiratory bacterial diseases and sepsis, while females are more susceptible to genitourinary tract bacterial infections. However, these incidences depend on the population evaluated, animal model and the bacterial species. Female protection against bacterial infections and the associated complications is assumed to be due to the pro-inflammatory effect of estradiol, while male susceptibility to those infections is associated with the testosterone-mediated immune suppression, probably via their specific receptors. Recent studies indicate that the protective effect of estradiol depends on the estrogen receptor subtype and the specific tissue compartment involved in the bacterial insult, suggesting that tissue-specific expression of particular sex steroid receptors contributes to the susceptibility to bacterial infections. Furthermore, this gender bias also depends on the effects of sex hormones on specific bacterial species. Finally, since a large number of genes related to immune functions are located on the X chromosome, X-linked mosaicism confers a highly polymorphic gene expression program that allows women to respond with a more expanded immune repertoire as compared with men.

Conclusion

Notwithstanding there is increasing evidence that confirms the sexual dimorphism in certain bacterial infections and the molecular mechanisms associated, further studies are required to clarify conflicting data and to determine the role of specific hormone receptors involved in the gender bias of bacterial infections, as well as their potential as therapeutic targets.

Role of Procalcitonin in the Management of Infected Patients in the Intensive Care Unit

The combination of molecular pathogen diagnostics and the biomarker procalcitonin (PCT) are changing the use of antimicrobials in patients admitted to critical care units with severe community-acquired pneumonia, possible septic shock, or other clinical syndromes. An elevated serum PCT level is good supportive evidence of a bacterial pneumonia, whereas a low serum PCT level virtually eliminates an etiologic role for bacteria even if the culture for a potential bacterial pathogen is positive. Serum PCT levels can be increased in any shocklike state; a low PCT level eliminates invasive bacterial infection as an etiology in more than 90% of patients.

Diagnostic Accuracy of Procalcitonin for Differentiating Bacteraemic Gram-Negative Sepsis from Gram-Positive Sepsis

Objective

The identification of bacteraemia in patients with suspected sepsis is crucial for survival. A cheap, fast and reliable biomarker, which can predict the causative pathogen group, may be useful to confirm or exclude the presence of bacteraemia. This study aimed to evaluate the relationship between procalcitonin (PCT) and the causative pathogen in intensive care patients with sepsis and bacteraemia.

Methods

Patients with diagnosed sepsis, a positive blood culture and measured serum procalcitonin levels during their intensive care unit stay were included in the study. Demographic data, PCT level, leukocyte count, C-reactive protein level, creatinine level, lymphocyte count, leukocyte/lymphocyte ratio and the group of the pathogen that detected in the blood culture were retrospectively recorded.

Results

Overall, 136 sepsis patients who were diagnosed with bacteraemia were included in the study. The PCT level was 7.31 ng mL^-1 in the gram-negative group and 0.46 ng mL^-1 in the gram-positive group. For PCT, the sensitivity was 70.83% and the specificity was 84.21%, with the cut-off value being ≤1.3. The area under the receiver operating characteristics curve for PCT was 0.80.

Conclusion

Patients with gram-negative sepsis had higher PCT values than those with gram-positive sepsis. Our results suggest that PCT value may be a useful tool for distinguishing between gram-negative and gram-positive bacteraemia.

Diagnostic and prognostic performances of serum procalcitonin in patients with bloodstream infections: A parallel, case-control study comprising adults and elderly

Objective:

To examine the diagnostic and prognostic performances of serum procalcitonin (PCT) in adult and elderly patients with bloodstream infections (BSIs).

Method:

A total of 176 patients with culture-proven BSIs and 200 healthy counterparts were studied prospectively. Participants were studied in two adult (age≤65 years, n=92) and elderly (age>65 years, n=84) groups. Admission serum PCT level was measured using a standard enzyme-linked immunosorbent assay (ELISA) technique.

Results:

The mean serum PCT level (in ng/mL) was significantly higher in cases than in controls (0.18 vs. 0.07, p=0.01 in adults; 0.20 vs. 0.07, p=0.002 in elderly). At cut-off values of 0.09 ng/mL in adults and 0.08 ng/mL in the elderly, the corresponding sensitivity and specificity were 82.6 and 82.0% in adults, and 69.1 and 70.0% in elderly, respectively. At a cut-off value of 0.2 ng/mL, the sensitivity and specificity of serum PCT in predicting 28-day mortality were 81 and 81.7% in adults, and 75 and 80.4% in elderly, respectively.

Conclusion:

Although admission serum PCT is a sensitive and specific biomarker for the diagnosis of BSIs in patients younger than 65 years old, its short-term prognostic value is comparable between adults and the elderly.

Use of presepsin and procalcitonin for prediction of SeptiFast results in critically ill patients

PURPOSE

There is a need for identification of marker that could lead physicians to take the right step towards laboratory techniques for documentation of infection. The aim of this study was to investigate whether presepsin and procalcitonin (PCT) levels in patients with suspected sepsis could predict blood culture (BC) and SeptiFast (SF) results.

MATERIAL AND METHODS

100 patients were included in our study. PCT, C-reactive protein (CRP), and presepsin levels were determined. Differences between groups of patients were assessed by Mann-Whitney U test. Categorical variables were compared using chi-square test. Receiver operating characteristic (ROC) curves were plotted to determine predictive values of biomarkers for prediction of positive SF results.

RESULTS

PCT (70.9±106.36 vs. 16.35±26.79) and presepsin (4899.73±5207.81 vs. 1751.59±2830.62) were significantly higher in patients with positive SF in contrast to patients with negative SF. There was no significant difference between patients who had positive and negative BC for PCT and presepsin values. PCT and presepsin showed a similar performance in predicting positive SF results with AUC of 0.75 for PCT and 0.73 for presepsin.

CONCLUSION

Presepsin can serve as good predictor of bacteremia detected by SF and it should be included with PCT in protocols for sepsis diagnosing.

Procalcitonin-guided diagnosis and antibiotic stewardship revisited

Several controlled clinical studies have evaluated the potential of the infection biomarker procalcitonin (PCT) to improve the diagnostic work-up of patients with bacterial infections and its influence on decisions regarding antibiotic therapy. Most research has focused on lower respiratory tract infections and critically ill sepsis patients. A clinical utility for PCT has also been found for patients with urinary tract infections, postoperative infections, meningitis, and patients with acute heart failure with possible superinfection (i.e., pneumonia). In these indications, PCT levels measured on hospital admission were found to substantially reduce the initiation of antibiotic treatment in low-risk situations (i.e., bronchitis, chronic obstructive pulmonary disease exacerbation). For more severe infections (i.e., pneumonia, sepsis), antibiotic stewardship by monitoring of PCT kinetics resulted in shorter antibiotic treatment durations with early cessation of therapy. Importantly, these strategies appear to be safe without increasing the risk for mortality, recurrent infections, or treatment failures. PCT kinetics also proved to have prognostic value correlating with disease severity (i.e., pancreatitis, abdominal infection) and resolution of illness (i.e., sepsis). Although promising findings have been published in these different types of infections, there are a number of limitations regarding PCT, including suboptimal sensitivity and/or specificity, which makes a careful interpretation of PCT in the clinical context mandatory. This narrative review aims to update clinicians on the strengths and limitations of PCT for patient management, focusing on research conducted within the last 4 years.

Prospective evaluation of SeptiFast Multiplex PCR in children with systemic inflammatory response syndrome under antibiotic treatment

Background

Antimicrobially pre-treated children with systemic inflammation often pose a diagnostic challenge to the physician. We aimed to evaluate the additional use of SeptiFast multiplex polymerase chain reaction (PCR) to identify causative pathogens in children with suspected systemic bacterial or fungal infection.

Methods

Prospective observational study in 39 children with systemic inflammatory response syndrome (SIRS) under empiric antibiotic treatment. Primary outcome was the rate of positive blood cultures (BC), compared to the rate of positive SeptiFast (SF) results.

Results

In total, 14 SF-samples yielded positive results, compared to 4 positive BC (p < 0.05). All blood cultures and 13 of 14 positive SF-tests were considered infection. Median time for positive BC was 2 days, and time to definite result was 6 days, compared to 12 h for SF. Antimicrobial therapy was adapted in 7 of the 14 patients with positive SeptiFast, and in 3 of the 4 patients with positive BC.

Best predictive power for positive SF shown by receiver-operating characteristic was demonstrated for procalcitonin PCT (Area under the curve AUC: 0.79), compared to C-reactive protein CRP (AUC: 0.51) and leukocyte count (AUC: 0.46). A procalcitonin threshold of 0.89 ng/ml yielded a sensitivity of 0.82 and a specifity of 0.7. Children with a positive SeptiFast result on day 0 had a significantly higher risk to require treatment on the Pediatric Intensive Care Unit or to be deceased on day 30 (Odds-Ratio 8.62 (CI 1.44-51.72).

Conclusions

The additional testing with SeptiFast in antimicrobially pre-treated children with systemic inflammation enhances the rate of pathogen detection. The influence of multiplex PCR on clinically relevant outcome parameters has to be further evaluated. (Trial registration: DRKS00004694)

Diagnostic accuracy of presepsin (sCD14-ST) and procalcitonin for prediction of bacteraemia and bacterial DNAaemia in patients with suspected sepsis

Early diagnosis and prompt targeted therapy are essential for septic patients' outcome. Procalcitonin (PCT) has been shown to predict bacteraemia and bacterial DNAaemia. Presepsin, the circulating soluble form of CD14 subtype, increases in response to bacterial infections, and is considered a new, emerging, early marker for sepsis. We evaluated the diagnostic accuracy of presepsin in predicting bacteraemia and bacterial DNAaemia in 92 patients with suspected sepsis, and we compared it with that of PCT and C-reactive protein (CRP). Presepsin median values were significantly higher in bacteraemic vs non-bacteraemic patients [1290 pg ml-1, interquartile range (IQR) 1005-2041 vs 659 pg ml-1, IQR 381-979; P<0.001] and in patients with vs patients without bacterial DNAaemia (1297 pg ml-1, IQR 1001-2046 vs 665 pg ml-1, IQR 381-940; P<0.001). Receiver operating characteristics analysis showed an area under the curve (AUC) for presepsin of 0.788 [95 % confidence interval (CI): 0.687-0.889; P<0.001] in predicting bacteraemia and of 0.777 (95 % CI: 0.676-0.878; P<0.001) in predicting bacterial DNAaemia, lower, but not significantly different, than those of PCT (0.876, P=0.12 and 0.880, P=0.07, respectively). Both biomarkers performed significantly better than CRP, which had an AUC for bacteraemia of 0.602 and for DNAaemia of 0.632 (all P values <0.05). In conclusion, in patients with suspected sepsis, presepsin and PCT showed a good diagnostic accuracy in predicting both bacteraemia and bacterial DNAaemia, superior to CRP.

Evaluation of the Septifast MGrade Test on Standard Care Wards--A Cohort Study

Background

The immediate need for appropriate antimicrobial therapy in septic patients requires the detection of the causative pathogen in a timely and reliable manner. In this study, the real-time PCR Septifast M^Grade test was evaluated in adult patients meeting the systemic inflammatory response syndrome (SIRS) criteria that were treated at standard care wards.

Methods

Patients with clinical suspected infection, drawn blood cultures (BC), the Septifast M^Grade test (SF) and sepsis biomarkers were prospectively screened for fulfillment of SIRS criteria and evaluated using the criteria of the European Centre of Disease Control (ECDC) for infection point prevalence studies.

Results

In total, 220 patients with SIRS were prospectively enrolled, including 56 patients with detection of bacteria in the blood (incidence: 25.5%). BC analysis resulted in 75.0% sensitivity (95% confidence interval, CI: 61.6%– 85.6%) with 97.6% specificity (CI: 93.9%– 99.3%) for detecting bacteria in the blood. In comparison to BC, SF presented with 80.4% sensitivity (CI: 67.6%– 89.8%) and with 97.6% specificity (CI: 93.9%– 99.3%). BC and SF analysis yielded comparable ROC-AUCs (0.86, 0.89), which did not differ significantly (p = 0.558). A trend of a shorter time-to-positivity of BC analysis was not seen in bacteremic patients with a positive SF test than those with a negative test result. Sepsis biomarkers, including PCT, IL-6 or CRP, did not help to explain discordant test results for BC and SF.

Conclusion

Since negative results do not exclude bacteremia, the Septifast M^Grade test is not suited to replacing BC, but it is a valuable tool with which to complement BC for faster detection of pathogens.

Diagnostic Accuracy of Procalcitonin for Predicting Blood Culture Results in Patients With Suspected Bloodstream Infection: An Observational Study of 35,343 Consecutive Patients (A STROBE-Compliant Article)

Previous studies have suggested that procalcitonin is a reliable marker for predicting bacteremia. However, these studies have had relatively small sample sizes or focused on a single clinical entity. The primary endpoint of this study was to investigate the diagnostic accuracy of procalcitonin for predicting or excluding clinically relevant pathogen categories in patients with suspected bloodstream infections. The secondary endpoint was to look for organisms significantly associated with internationally validated procalcitonin intervals. We performed a cross-sectional study that included 35,343 consecutive patients who underwent concomitant procalcitonin assays and blood cultures for suspected bloodstream infections. Biochemical and microbiological data were systematically collected in an electronic database and extracted for purposes of this study. Depending on blood culture results, patients were classified into 1 of the 5 following groups: negative blood culture, Gram-positive bacteremia, Gram-negative bacteremia, fungi, and potential contaminants found in blood cultures (PCBCs). The highest procalcitonin concentration was observed in patients with blood cultures growing Gram-negative bacteria (median 2.2 ng/mL [IQR 0.6-12.2]), and the lowest procalcitonin concentration was observed in patients with negative blood cultures (median 0.3 ng/mL [IQR 0.1-1.1]). With optimal thresholds ranging from ≤0.4 to ≤0.75 ng/mL, procalcitonin had a high diagnostic accuracy for excluding all pathogen categories with the following negative predictive values: Gram-negative bacteria (98.9%) (including enterobacteria [99.2%], nonfermenting Gram-negative bacilli [99.7%], and anaerobic bacteria [99.9%]), Gram-positive bacteria (98.4%), and fungi (99.6%). A procalcitonin concentration ≥10 ng/mL was associated with a high risk of Gram-negative (odds ratio 5.98; 95% CI, 5.20-6.88) or Gram-positive (odds ratio 3.64; 95% CI, 3.11-4.26) bacteremia but dramatically reduced the risk of PCBCs or fungemia. In this large real-life setting experience with more than 35,000 patients, procalcitonin was highly effective at excluding bloodstream infections regardless of pathogen categories. The results from our study are limited by its cross-sectional design and deserve to be validated in prospective longitudinal studies.

Antimicrobial Stewardship in the Emergency Department: Challenges, Opportunities, and a Call to Action for Pharmacists

Antimicrobial resistance is a national public health concern. Misuse of antimicrobials for conditions such as upper respiratory infection, urinary tract infections, and cellulitis has led to increased resistance to antimicrobials commonly utilized to treat those infections, such as sulfamethoxazole/trimethoprim and flouroquinolones. The emergency department (ED) is a site where these infections are commonly encountered both in ambulatory patients and in patients requiring admission to a hospital. The ED is uniquely positioned to affect the antimicrobial use and resistance patterns in both ambulatory settings and inpatient settings. However, implementing antimicrobial stewardship programs in the ED is fraught with challenges including diagnostic uncertainty, distractions secondary to patient or clinician turnover, and concerns with patient satisfaction to name just a few. However, this review article highlights successful interventions that have stemmed inappropriate antimicrobial use in the ED setting and warrant further study. This article also proposes other, yet to be validated proposals. Finally, this article serves as a call to action for pharmacists working in antimicrobial stewardship programs and in emergency medicine settings. There needs to be further research on the implementation of these and other interventions to reduce inappropriate antimicrobial use to prevent patient harm and curb the development of antimicrobial resistance.

Procalcitonin better than C-reactive protein, erythrocyte sedimentation rate, and white blood cell count in predicting DNAemia in patients with sepsis

BACKGROUND

Procalcitonin (PCT) levels can be used to predict bacteremia and DNAemia in patients with sepsis. In this study, the diagnostic accuracy of PCT in predicting blood culture (BC) results and DNAemia, as detected by real-time PCR (RT-PCR), was compared with that of other markers of inflammation commonly evaluated in patients with suspected sepsis, such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and white blood cell (WBC) count.

METHODS

A total of 571 patients for whom BC, blood RT-PCR, PCT, CRP, ESR, and WBC count were requested for laboratory diagnosis of sepsis were included in the study. Receiver operating characteristic curve analysis was performed to compare the ability of the above biomarkers to predict BC and blood RT-PCR results.

RESULTS

A total of 108 pathogens were identified by BC (79 pathogens, 14.5% positive rate) and/or RT-PCR (90 pathogens, 16.5% positive rate), after exclusion of 26 contaminated samples. The PCT areas under the curve (AUCs) in predicting BC (0.843; 95% CI 0.796-0.890; p < 0.0001) and RT-PCR (0.916; 95% CI 0.888-0.945; p < 0.0001) results were significantly greater than AUCs found for CRP, ESR, and WBC count.

CONCLUSIONS

PCT showed a better diagnostic accuracy than CRP, ESR, and WBC count in predicting DNAemia and bacteremia in patients with suspected sepsis.

Developments for improved diagnosis of bacterial bloodstream infections

Bloodstream infections (BSIs) are associated with high mortality and increased healthcare costs. Optimal management of BSI depends on several factors including recognition of the disease, laboratory tests and treatment. Rapid and accurate identification of the etiologic agent is crucial to be able to initiate pathogen specific antibiotic therapy and decrease mortality rates. Furthermore, appropriate treatment might slow down the emergence of antibiotic resistant strains. Culture-based methods are still considered to be the "gold standard" for the detection and identification of pathogens causing BSI. Positive blood cultures are used for Gram-staining. Subsequently, positive blood culture material is subcultured on solid media, and (semi-automated) biochemical testing is performed for species identification. Finally, a complete antibiotic susceptibility profile can be provided based on cultured colonies, which allows the start of pathogen-tailored antibiotic therapy. This conventional workflow is extremely time-consuming and can take up to several days. Furthermore, fastidious and slow-growing microorganisms, as well as antibiotic pre-treated samples can lead to false-negative results. The main aim of this review is to present different strategies to improve the conventional laboratory diagnostic steps for BSI. These approaches include protein-based (MALDI-TOF mass spectrometry) and nucleic acid-based (polymerase chain reaction [PCR]) identification from subculture, blood cultures, and whole blood to decrease time to results. Pathogen enrichment and DNA isolation methods, to enable optimal pathogen DNA recovery from whole blood, are described. In addition, the use of biomarkers as patient pre-selection tools for molecular assays are discussed.

Better tests, better care: improved diagnostics for infectious diseases

In this IDSA policy paper, we review the current diagnostic landscape, including unmet needs and emerging technologies, and assess the challenges to the development and clinical integration of improved tests. To fulfill the promise of emerging diagnostics, IDSA presents recommendations that address a host of identified barriers. Achieving these goals will require the engagement and coordination of a number of stakeholders, including Congress, funding and regulatory bodies, public health agencies, the diagnostics industry, healthcare systems, professional societies, and individual clinicians.

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.

A prediction model for real-time PCR results in blood samples from febrile patients with suspected sepsis

Sepsis, a systemic, deleterious host response to infection that leads to organ dysfunction, is a potentially deadly condition needing prompt identification of the causative organisms and early appropriate antimicrobial therapy. Among non-culture-based diagnostic methods, SeptiFast (SF) can be employed to speed bacterial and fungal DNA detection, but it suffers from poor sensitivity and high cost. The aim of the present study, performed in 285 febrile patients, was to develop a prediction model to restrict the SF assay to clinical cases with a high probability of positive SF results. The prevalence of SF results positive for a pathogen was 17.2 %. Independent predictors of positive results were: blood sampling within 12 h after the onset of fever [odds ratio (OR) 20.03; 95 % confidence interval (CI) 6.87-58.38; P<0.0001]; ≥0.5 ng serum procalcitonin (PCT) ml(-1) (OR 18.52; 95 % CI 5.12-67.02; P<0.0001); body temperature ≥38 °C (OR 3.78; 95 % CI 1.39-10.25; P = 0.009); ≤3 g serum albumin dl(-1) (OR 3.40; 95 % CI 1.27-9.08; P = 0.014); and ≥13 000 white blood cells mm(-3) (OR 2.75; 95 % CI 1.09-7.69; P = 0.05). The model showed good calibration (Hosmer-Lemeshow chi-squared 1.61; P = 0.978). Area under the receiving operating characteristic curve was 0.944 (95 % CI 0.914-0.973; P<0.0001). These results suggest that a prediction model based on PCT and a few other routinely available laboratory and clinical variables could be of help in selecting patients with a high probability of SF-positive results.

Biomarkers and molecular analysis to improve bloodstream infection diagnostics in an emergency care unit

Molecular pathogen detection from blood is still expensive and the exact clinical value remains to be determined. The use of biomarkers may assist in preselecting patients for immediate molecular testing besides blood culture. In this study, 140 patients with ≥ 2 SIRS criteria and clinical signs of infection presenting at the emergency department of our hospital were included. C-reactive protein (CRP), neutrophil-lymphocyte count ratio (NLCR), procalcitonin (PCT) and soluble urokinase plasminogen activator receptor (suPAR) levels were determined. One ml EDTA blood was obtained and selective pathogen DNA isolation was performed with MolYsis (Molzym). DNA samples were analysed for the presence of pathogens, using both the MagicPlex Sepsis Test (Seegene) and SepsiTest (Molzym), and results were compared to blood cultures. Fifteen patients had to be excluded from the study, leaving 125 patients for further analysis. Of the 125 patient samples analysed, 27 presented with positive blood cultures of which 7 were considered to be contaminants. suPAR, PCT, and NLCR values were significantly higher in patients with positive blood cultures compared to patients without (p < 0.001). Receiver operating characteristic curves of the 4 biomarkers for differentiating bacteremia from non-bacteremia showed the highest area under the curve (AUC) for PCT (0.806 (95% confidence interval 0.699–0.913)). NLCR, suPAR and CRP resulted in an AUC of 0.770, 0.793, and 0.485, respectively. When compared to blood cultures, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for SepsiTest and MagicPlex Sepsis Test were 11%, 96%, 43%, 80%, and 37%, 77%, 30%, 82%, respectively. In conclusion, both molecular assays perform poorly when one ml whole blood is used from emergency care unit patients. NLCR is a cheap, fast, easy to determine, and rapidly available biomarker, and therefore seems most promising in differentiating BSI from non-BSI patients for subsequent pathogen identification using molecular diagnostics.

Live genomics for pathogen monitoring in public health

Whole genome analysis based on next generation sequencing (NGS) now represents an affordable framework in public health systems. Robust analytical pipelines of genomic data provides in short laps of time (hours) information about taxonomy, comparative genomics (pan-genome) and single polymorphisms profiles. Pathogenic organisms of interest can be tracked at the genomic level, allowing monitoring at one-time several variables including: epidemiology, pathogenicity, resistance to antibiotics, virulence, persistence factors, mobile elements and adaptation features. Such information can be obtained not only at large spectra, but also at the "local" level, such as in the event of a recurrent or emergency outbreak. This paper reviews the state of the art in infection diagnostics in the context of modern NGS methodologies. We describe how actuation protocols in a public health environment will benefit from a "streaming approach" (pipeline). Such pipeline would NGS data quality assessment, data mining for comparative analysis, searching differential genetic features, such as virulence, resistance persistence factors and mutation profiles (SNPs and InDels) and formatted "comprehensible" results. Such analytical protocols will enable a quick response to the needs of locally circumscribed outbreaks, providing information on the causes of resistance and genetic tracking elements for rapid detection, and monitoring actuations for present and future occurrences.

The potential for PCR based testing to improve diagnosis and treatment of sepsis

Early and appropriate antibiotic use is critical for the treatment of sepsis. In practice, however, early antibiotic administration is hampered by diagnostic uncertainty with regard to both early diagnosis of disease and delayed or absent microbiological results. The diagnostic uncertainty often persists into the later stages of sepsis when clinical response to antibiotic treatment is assessed. Blood culture, the current "gold standard" test for diagnosis of sepsis, is inadequate due to low sensitivity and delayed results. However, despite this, the technology remains entrenched in microbiology laboratories due to decades of accumulated experience with the technique. However, in recent years there has been increasing experience with testing based on polymerase chain reaction (PCR). As the technology continues to improve, PCR testing is becoming faster and more sensitive. Moreover, PCR technologies that quantify bacterial load may enable monitoring of response to treatment and susceptibility testing.

Non-culture-based methods to diagnose bloodstream infection: Does it work?

Bloodstream infections are a major cause of morbidity and mortality worldwide. Molecular methods for the detection of pathogens in blood have been developed. The clinical utility of these methods and their integration into the clinical workflow is discussed.