Early identification of sepsis

Analysis of pathogenic factors on the death rate of sepsis patients

BACKGROUND

The Surviving Sepsis Campaign (SSC) believed that early identification of septic shock, aggressive fluid resuscitation and maintenance of effective perfusion pressure should be carried out. However, some of the current research focused on a single death factor for sepsis patients, based on a limited sample, and the research results of the relationship between comorbidities and sepsis related death also have some controversies.

METHOD

Therefore, our study used data from a large sample of 9,544 sepsis patients aged 18-85 obtained from the MIMIC-IV database, to explore the risk factors of death in patients with sepsis. We used the general clinical information, organ dysfunction scores, and comorbidities to analyze the independent risk factors for death of these patients.

RESULTS

The death group had significantly higher organ dysfunction scores, lower BMI, lower body temperature, faster heart rate and lower urine-output. Among the comorbidities, patients suffering from congestive heart failure and liver disease had a higher mortality rate.

CONCLUSION

This study helps to identify sepsis early, based on a comprehensive evaluation of a patient's basic information, organ dysfunction scores and comorbidities, and this methodology could be used for actual clinical diagnosis in hospitals.

Extracellular proteins as potential biomarkers in Sepsis-related cerebral injury

Background

Sepsis can cause brain damage known as septic encephalopathy (SAE), which is linked to higher mortality and poorer outcomes. Objective clinical markers for SAE diagnosis and prognosis are lacking. This study aimed to identify biomarkers of SAE by investigating genes and extracellular proteins involved in sepsis-induced brain injury.

Methods

Extracellular protein differentially expressed genes (EP-DEGs) from sepsis patients' brain tissue (GSE135838) were obtained from Gene Expression Omnibus (GEO) and evaluated by protein annotation database. The function and pathways of EP-DEGs were examined using GO and KEGG. Protein-protein interaction (PPI) networks were built and crucial EP-DEGs were screened using STRING, Cytoscape, MCODE, and Cytohubba. The diagnostic and prognostic accuracy of key EP-DEGs was assessed in 31 sepsis patients' blood samples and a rat cecal ligation and puncture (CLP)-induced sepsis model. Cognitive and spatial memory impairment was evaluated 7-11 days post-CLP using behavioral tests. Blood and cerebrospinal fluid from 26 rats (SHAM n=14, CLP n=12) were collected 6 days after CLP to analyze key EP-DEGs.

Results

Thirty-one EP-DEGs from DEGs were examined. Bone marrow leukocytes, neutrophil movement, leukocyte migration, and reactions to molecules with bacterial origin were all enhanced in EP-DEGs. In comparison to the sham-operated group, sepsis rats had higher levels of MMP8 and S100A8 proteins in their venous blood (both p<0.05) and cerebrospinal fluid (p=0.0506, p<0.0001, respectively). Four important extracellular proteins, MMP8, CSF3, IL-6, and S100A8, were identified in clinical peripheral blood samples. MMP8 and S100A8 levels in the peripheral blood of sepsis patients were higher in SAE than in non-SAE. In comparison to MMP8, S100A8 had a higher area under the curve (AUC: 0.962, p<0.05) and a higher sensitivity and specificity (80% and 100%, respectively) than MMP8 (AUC: 0.790, p<0.05). High levels of S100A8 strongly correlated with 28-day mortality and the Glasgow Coma Scale (GCS) scores.

Conclusion

The extracellular proteins MMP8, CSF3, IL-6, and S100A8 may be crucial in the pathophysiology of SAE. S100A8 and MMP8 are possible biomarkers for SAE's onset and progression. This research may help to clarify the pathogenesis of SAE and improve the diagnosis and prognosis of the disease.

Long-term label-free assessments of individual bacteria using three-dimensional quantitative phase imaging and hydrogel-based immobilization

Three-dimensional (3D) quantitative phase imaging (QPI) enables long-term label-free tomographic imaging and quantitative analysis of live individual bacteria. However, the Brownian motion or motility of bacteria in a liquid medium produces motion artifacts during 3D measurements and hinders precise cell imaging and analysis. Meanwhile, existing cell immobilization methods produce noisy backgrounds and even alter cellular physiology. Here, we introduce a protocol that utilizes hydrogels for high-quality 3D QPI of live bacteria maintaining bacterial physiology. We demonstrate long-term high-resolution quantitative imaging and analysis of individual bacteria, including measuring the biophysical parameters of bacteria and responses to antibiotic treatments.

Identifying infected patients using semi-supervised and transfer learning

Objectives

Early identification of infection improves outcomes, but developing models for early identification requires determining infection status with manual chart review, limiting sample size. Therefore, we aimed to compare semi-supervised and transfer learning algorithms with algorithms based solely on manual chart review for identifying infection in hospitalized patients.

Materials and Methods

This multicenter retrospective study of admissions to 6 hospitals included “gold-standard” labels of infection from manual chart review and “silver-standard” labels from nonchart-reviewed patients using the Sepsis-3 infection criteria based on antibiotic and culture orders. “Gold-standard” labeled admissions were randomly allocated to training (70%) and testing (30%) datasets. Using patient characteristics, vital signs, and laboratory data from the first 24 hours of admission, we derived deep learning and non-deep learning models using transfer learning and semi-supervised methods. Performance was compared in the gold-standard test set using discrimination and calibration metrics.

Results

The study comprised 432 965 admissions, of which 2724 underwent chart review. In the test set, deep learning and non-deep learning approaches had similar discrimination (area under the receiver operating characteristic curve of 0.82). Semi-supervised and transfer learning approaches did not improve discrimination over models fit using only silver- or gold-standard data. Transfer learning had the best calibration (unreliability index P value: .997, Brier score: 0.173), followed by self-learning gradient boosted machine (P value: .67, Brier score: 0.170).

Discussion

Deep learning and non-deep learning models performed similarly for identifying infection, as did models developed using Sepsis-3 and manual chart review labels.

Conclusion

In a multicenter study of almost 3000 chart-reviewed patients, semi-supervised and transfer learning models showed similar performance for model discrimination as baseline XGBoost, while transfer learning improved calibration.

A retrospective controlled study of postoperative fever after posterior lumbar interbody fusion due to degenerative lumbar disease

BACKGROUND

Postoperative fever is a common feature of spinal surgery. When fever occurs postoperatively in patients, surgeons are eager to rule out an infection. There are many reports about postoperative fever and infection; however, only a few have described the relationship between degenerative spinal disease and postoperative fever. This study aimed to investigate the causes of postoperative fever in patients with degenerative lumbar disease undergoing posterior screw fixation and interbody fusion and compare patients with non-pathologic fever and infected febrile patients.

METHODS

From March 2015 to February 2016, 263 patients with degenerative lumbar disease underwent posterior lumbar screw fixation and interbody fusion surgery in our institution. We performed risk factor analysis by categorizing patients as afebrile and febrile. Comparisons were made between afebrile patients and patients with non-pathologic fever, and an analysis was performed between patients with non-pathologic fever and patients with febrile infection. We compared each group by examining the demographic factors before surgery, surgery features, drain duration, and postoperative transfusion. The postoperative day (POD) of fever onset, postoperative fever duration, and blood sample results in patients with fever were investigated.

RESULTS

The drain duration was found to be an important factor between the afebrile febrile groups and between the non-pathologic fever and afebrile groups. POD of fever occurred earlier in the non-pathologic group than in the infection group (p = 0.04), and the duration of fever was shorter in the non-pathologic fever group than in the infection group (p = 0.01). Higher procalcitonin levels were observed at POD 5 in the infection group than in the non-pathologic fever group. (p < 0.01) The accidental dural rupture rate was higher in the infected group (p = 0.02); this was thought to be caused by the long non-ambulatory period after surgery.

CONCLUSION

This study identified risk factors and differences between infectious diseases associated with postoperative fever. A significant risk factor for postoperative non-pathological fever was a shorter catheter drainage period. Fever after 3 days, fever for more than 4 days and higher procalcitonin levels after surgery suggest infection.

Bacterial profile and antimicrobial susceptibility patterns in cancer patients

Background

Bloodstream infections have been the leading complications in cancer patients because they are at high risk for antibiotic-resistant bacterial infections. There is increasing evidence from different parts of the world of the high prevalence of antimicrobial-resistant bacterial strains in cancer patients. The burden of the infection is high in developing countries, especially in Ethiopia. Data on bacterial profile and antimicrobial susceptibility patterns among cancer patients in Ethiopia is limited. Thus, this study aimed to determine the predominant bacterial species causing bacteremia and their antibiotic resistance pattern among cancer patients at University of Gondar comprehensive specialized hospital.

Methods

A hospital-based, cross-sectional study was conducted on 200 study participants from March to July 2021. All cancer patients who developed a fever at the time of hospital visit were included in this study, and their socio-demographic and clinical data were collected using a structured questionnaire. Blood samples (10 mL for adults and 4 mL for children) were collected from each patient, and the collected blood samples were transferred into sterile tryptic soy broth, then incubated at 37°C for 7 days. Tryptic soy broth which showed signs of growth were Gram-stained and sub-cultured on blood agar, chocolate agar, MacConkey agar, and mannitol salt agar. The inoculated plates were then aerobically incubated at 37°C for 18–24 hours and the isolates obtained were identified using standard microbiological methods. Antimicrobial susceptibility tests were done using a modified Kirby-Bauer disk diffusion technique following CLSI 2021 guidelines. Data were entered using EPI data version 4.6 and analyzed with SPSS version 20.

Results

In this study, out of 200 cancer patients included and 67.5% (135/200) of them were males. The majorities of study participants, 56% (113/200) of cancer patients were pediatrics and 26.5% (53/200) of them belong under five years of age. Out of 200 patient samples that had undergone culture, 27% (54/200) samples had bacterial growth. Gram-positive bacterial isolates were predominant, 61.1%, and S. aureus was the predominant Gram-positive isolate, (51.5.6%), followed by coagulase-negative staphylococci (48.5%). Moreover, K. pneumoniae (47%) and P. aeruginosa (29.5%) were the most common Gram-negative bacterial isolates. Among patients who had BSIs, the highest prevalence of BSIs was observed among males (66.7%), and in pediatrics cancer patients (44.2%). Pediatric study participants were more venerable to bloodstream infection (P = 0.000) compared to adult participants. Meropenem (100%), amikacin (100%), piperacillin/tazobactam (72.3%), and ceftazidime (73.5%) were effective against for Gram-negative isolates while cefoxitin (81.2%) and penicillin (70.5%) were effective for Gram-positive isolates. Additionally, most Gram-negative and Gram-positive bacterial isolates were sensitive for gentamycin (75.9%). Multidrug resistance was seen among 17.1% bacterial isolates, and MDR in Gram-negative and Gram-positive bacteria were 83.3% and 16.7%, respectively. Gram-negative bacterial isolates showed a high prevalence of MDR than Gram-positive isolates.

Conclusions and recommendation

BSI’s remains an important health problem in cancer patients, and Gram-positive bacteria were more common as etiologic agents of BSIs in cancer patients. S. aureus was the dominant bacteria followed by CoNS, K. pneumoniae, and P. aeruginosa. Multidrug-resistant isolates found in cancer patients and routine bacterial surveillance and study of their resistance patterns may guide successful antimicrobial therapy and improve the quality of care. Therefore, strict regulation of antibiotic stewardship and infection control programs should be considered in the study area.

Machine learning identification of specific changes in myeloid cell phenotype during bloodstream infections

The early identification of bacteremia is critical for ensuring appropriate treatment of nosocomial infections in intensive care unit (ICU) patients. The aim of this study was to use flow cytometric data of myeloid cells as a biomarker of bloodstream infection (BSI). An eight-color antibody panel was used to identify seven monocyte and two dendritic cell subsets. In the learning cohort, immunophenotyping was applied to (1) control subjects, (2) postoperative heart surgery patients, as a model of noninfectious inflammatory responses, and (3) blood culture-positive patients. Of the complex changes in the myeloid cell phenotype, a decrease in myeloid and plasmacytoid dendritic cell numbers, increase in CD14⁺CD16⁺ inflammatory monocyte numbers, and upregulation of neutrophils CD64 and CD123 expression were prominent in BSI patients. An extreme gradient boosting (XGBoost) algorithm called the “infection detection and ranging score” (iDAR), ranging from 0 to 100, was developed to identify infection-specific changes in 101 phenotypic variables related to neutrophils, monocytes and dendritic cells. The tenfold cross-validation achieved an area under the receiver operating characteristic (AUROC) of 0.988 (95% CI 0.985–1) for the detection of bacteremic patients. In an out-of-sample, in-house validation, iDAR achieved an AUROC of 0.85 (95% CI 0.71–0.98) in differentiating localized from bloodstream infection and 0.95 (95% CI 0.89–1) in discriminating infected from noninfected ICU patients. In conclusion, a machine learning approach was used to translate the changes in myeloid cell phenotype in response to infection into a score that could identify bacteremia with high specificity in ICU patients.

Time series analysis of delta neutrophil index as the predictor of sepsis in patients with acute poisoning

Delta neutrophil index (DNI), which reflects the fraction of immature granulocytes, is used to detect infection and sepsis from noninfectious conditions, but few studies have evaluated in the early stage of acute poisoning. This retrospective observational study was performed on acute poisoning patients who visited to the emergency department (ED) and were consecutively admitted in intensive care units over 18-month period. The serial DNI, conventional inflammatory biomarkers, and culture results were obtained in the ED and after admission. The outcomes were the identification of sepsis, bacteremia, and 30-day mortality. Of 166 patients (mean age, 56.0 years) in this cohort, 59 (35.5%) had sepsis and 29 (17.5%) had bacteremia. Initial and peak DNI fractions 24 h after ED admission were strong independent predictors of sepsis development. Analysis of the area under the curve according to multiple receiver operating characteristics showed that DNI had a higher capability to predict sepsis than other parameters (0.815 for DNI, 0.700 for procalcitonin, 0.681 for C-reactive protein, and 0.741 for white blood cell). Using multivariable logistic regression analysis, it was found that DNI was an independent predictor of sepsis (95% confidence interval (CI) of odds: 1.03-1.18) and bacteremia (95% CI: 1.01-1.14). Therefore, initial and serial measurement of DNI may serve as useful risk predictor for development of sepsis or bacteremia in acute poisoning.

Nanosphere's Verigene® Blood Culture Assay to Detect Multidrug-Resistant Gram-Negative Bacterial Outbreak: A Prospective Study on 79 Hematological Patients in a Country with High Prevalence of Antimicrobial Resistance

Infections are a major cause of morbidity and mortality in hematological patients. We prospectively tested a new molecular assay (Verigene^®) in 79 consecutive hematological patients, with sepsis by gram-negative bacteria. A total of 82 gram-negative microorganisms were isolated by blood cultures, of which 76 cases were mono-microbial. Considering the bacteria detectable by the system, the concordance with standard blood cultures was 100%. Resistance genes were detected in 20 of the isolates and 100% were concordant with the phenotypic antibiotic resistance. Overall, this new assay correctly identified 66/82 of all the gram-negative pathogens, yielding a general sensitivity of 80.5%, and providing information on genetic antibiotic resistance in a few hours. This new molecular assay could ameliorate patient management, resulting in a more rational use of antibiotics.

Risk stratification and prognostic evaluation of endothelial cell-specific molecule1, von Willebrand factor, and a disintegrin-like and metalloprotease with thrombospondin type 1 motif for sepsis in the emergency department: An observational study

This study evaluated endothelial cell-specific molecule1 (endocan), von Willebrand factor (vWF), and A disintegrin-like and metalloprotease with thrombospondin type 1 motif (ADAMTS-13), alone or in combination, in the risk stratification and prognosis prediction of patients with sepsis. Clinical data of 301 patients were prospectively analyzed, and divided into systemic inflammatory reaction syndrome, sepsis, severe sepsis, and septic shock groups. A total of 40 healthy individuals were studied as the control group. Endocan, vWF, ADAMTS-13, vWF/ADAMTS-13, and procalcitonin levels were measured, and Acute Physiology and Chronic Health Evaluation (APACHE II) score, Mortality in Emergency Department Sepsis (MEDS) score as well as Sequential Organ Failure Assessment (SOFA) score were calculated. The all-cause death or survival of each patient was recorded during the 28-day follow-up. The endocan, vWF, and vWF/ADAMTS-13 levels significantly increased in patients and were positively correlated with disease severity. On the first day of admission, MEDS score, ADAMTS-13, and vWF/AMAMTS-13 ratio were independent predictors for 28-day mortality from sepsis. Moreover, the combination of vWF/ADAMTS-13 ratio with MEDS score improved the accuracy in predicting the 28-day mortality from sepsis. On day 5, endocan, vWF, ADAMTS-13, and vWF/ADAMTS-13 ratio were independent predictors for the 28-day mortality from sepsis, while the combined use of endocan and vWF/ADAMTS-13 ratio improved the prognostic value of individual indicators. Endocan, vWF, ADAMTS-13, and vWF/ADAMTS-13 ratio are valuable in the risk stratification and prognostic evaluation of sepsis as novel biomarkers.

A preliminary study: the role of preoperative procalcitonin in predicting postoperative fever after mini-percutaneous nephrolithotomy in patients with a negative baseline urine culture

To evaluate the role of preoperative procalcitonin (PCT) levels in predicting postoperative fever after mini-percutaneous nephrolithotomy (mini-PCNL) in patients with a negative baseline urine culture. Between January 2014 and October 2017, 329 patients with a negative baseline urine culture and who underwent mini-PCNL were enrolled in this study. Patients were stratified into the control or febrile group based on a body temperature either less than or greater than 38 °C, respectively. Demographic and perioperative data were compared between the groups, and variables found to be statistically significant were included in a binary logistic regression analysis. A total of 68 (20.6%) patients experienced postoperative fever. The univariate analysis revealed a statistically significant difference between groups in preoperative fever (p = 0.032), stone burden (p < 0.001), C-reactive protein (p = 0.011), PCT (p < 0.001) and interleukin-6 (p = 0.035) levels. Binary logistic regression analysis indicated that stone burden > 353 mm³ (p = 0.003) and PCT > 0.05 ng/mL (p < 0.001) are independent risk factors for postoperative fever in mini-PCNL-treated patients with a negative baseline urine culture. We concluded that patients with stone burden > 353 mm³ or PCT > 0.05 ng/mL were more likely to develop postoperative fever after mini-PCNL, though with a negative baseline urine culture.

Adjuvant role of SeptiFast to improve the diagnosis of sepsis in a large cohort of hematological patients

Febrile neutropenia and sepsis are common and life-threatening complications in hematological diseases. This study was performed retrospectively in 514 patients treated for febrile neutropenia at our institute, to investigate the clinical usefulness of a molecular tool, LightCycler® SeptiFast test (SF), to promptly recognize pathogens causing sepsis in hematological patients. We collected 1837 blood samples of 514 consecutive hematological patients. The time of processing is short. Overall, 757 microorganisms in 663 episodes were detected by molecular test and standard blood cultures (BC): 73.6% Gram-positive bacteria, 23.9% Gram-negative bacteria, and 2.5% fungal species. This large analysis demonstrated a significant episode-to episode agreement (71.9%) between the two methods, higher in negative samples (89.14%), and a specificity of 75.89%. Clinical variables that gave a statistically significant contribution to their concordance were absolute neutrophil count, ongoing antimicrobial therapy, timing of test execution, and organ localization of infection. The large analysis highlights the potential of molecular-based assays directly performed on blood samples, especially if implementing the detection of antibiotic resistance genes, which was lacking in the used study.

Curcumin suppresses inflammatory cytokines and heat shock protein 70 release and improves metabolic parameters during experimental sepsis

CONTEXT

Curcumin has been reported to have anti-inflammatory, antioxidant and hypoglycaemic properties, besides reducing mortality in sepsis.

OBJECTIVE

This study evaluates the biological activities of a curcumin dispersion formulated by spray-drying in experimental sepsis.

MATERIALS AND METHODS

Male Wistar rats were subjected to sepsis by caecal ligation and puncture (CLP), controls were sham operated. The animals were treated with curcumin dispersion (100 mg/kg, p.o.) or water for 7 days prior to CLP and at 2 h after surgery. One group was used to analyze curcumin absorption through HPLC; another had the survival rate assessed during 48 h; and from a third group, blood was collected by decapitation to analyze metabolic and inflammatory parameters.

RESULTS

The plasma curcumin levels reached 2.5 ng/mL at 4 h, dropped significantly (p < 0.001) at 6 h (1.2 ng/mL), and were undetectable at 24 h in both groups. Curcumin temporarily increased the survival rate of the septic rats by 20%. Moreover, it attenuated glycaemia (p < 0.05) and volemia (p < 0.05) alterations typically observed during sepsis, and decreased the levels of the proinflammatory cytokines IL-1β and IL-6 in plasma (p < 0.001) and peritoneal lavage fluid (p < 0.05) of septic rats. Serum HSP70 levels were decreased (p < 0.01) at 24 h after CLP.

DISCUSSION AND CONCLUSION

Our results show that the curcumin dispersion dose employed was not detrimental to the septic rats. In fact, it temporarily increased their survival rate, improved important metabolic parameters, reduced proinflammatory cytokines and HSP70 production.

Effects of Target Temperature Management on the Outcome of Septic Patients with Fever

Objectives

To investigate the effects of target temperature management on hemodynamic changes, inflammatory and immune factors, and clinical outcomes of sepsis patients with fever.

Methods

Patients diagnosed with sepsis with a core temperature of ≥39°C were randomly divided into two groups: a low-temperature group (LT group: 36.5°C–38°C) and a high-temperature group (HT group: 38.5°C–39.5°C). A target core temperature was achieved within 6 hrs posttreatment and maintained for 24 hrs. Then, the hemodynamic changes, inflammatory and immune factors, and clinical outcomes were evaluated.

Results

Compared with the HT group, C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) showed a significant decrease in the LT group (P < 0.05). In contrast, IL-4 and IL-10 were higher in the LT group than in the HT group (P < 0.05). The CD4-T lymphocyte (CD4+), CD8-T lymphocyte (CD8+), and monocytic human leukocyte antigen-DR (mHLA-DR) in the LT group were higher than in the HT group (P < 0.05). The ICU stay and the anti-infection treatment costs were higher in the LT group (P < 0.05).

Conclusion

Low-temperature management of patients resulted in a low level of proinflammatory cytokines. Excessive temperature control in sepsis patients with fever may be harmful.

A novel method for the rapid detection of microbes in blood using pleurocidin antimicrobial peptide functionalized piezoelectric sensor

The rapid detection of microbes is critical in clinical diagnosis and food safety. Culture-dependent assays are the most widely used microbial detection methods, but these assays are time-consuming. In this study, a rapid microbial detection method was proposed using a pleurocidin/single-walled carbon nanotubes/interdigital electrode-multichannel series piezoelectric quartz crystal (pleurocidin/SWCNT/IDE-MSPQC) sensor. The selected pleurocidin antimicrobial peptide served as a recognition probe that exhibits broad-spectrum antimicrobial activity and the SWCNT acted as the electronic transducer and cross-linker for the immobilization of pleurocidin on the IDE. The response mechanism of the sensor was based on the specific interaction between pleurocidin and the microbe causing pleurocidin to detach from the SWCNT modified IDE, resulting in a sensitive frequency shift response of the MSPQC. Microbes that may be clinically present in the bloodstream during an infection were successfully detected by the proposed method within 15min. The developed strategy provides a new universal platform for the rapid detection of microbes.

Rapid antimicrobial susceptibility testing of clinical isolates by digital time-lapse microscopy

Rapid antimicrobial susceptibility testing (AST) is essential for early and appropriate therapy. Methods with short detection time enabling same-day treatment optimisation are highly favourable. In this study, we evaluated the potential of a digital time-lapse microscope system, the oCelloScope system, to perform rapid AST. The oCelloScope system demonstrated a very high accuracy (96 % overall agreement) when determining the resistance profiles of four reference strains, nine clinical isolates, including multi-drug-resistant isolates, and three positive blood cultures. AST of clinical isolates (168 antimicrobial agent–organism combinations) demonstrated 3.6 % minor, no major and 1.2 % very major errors of the oCelloScope system compared to conventional susceptibility testing, as well as a rapid and correct phenotypic detection of strains with methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase (ESBL) profiles. The net average time-to-result was 108 min, with 95 % of the results being available within 180 min. In conclusion, this study strongly indicates that the oCelloScope system holds considerable potential as an accurate and sensitive AST method with short time-to-result, enabling same-day targeted antimicrobial therapy, facilitating antibiotic stewardship and better patient management. A full-scale validation of the oCelloScope system including more isolates is necessary to assess the impact of using it for AST.

The efficacy of procalcitonin as a biomarker in the management of sepsis: slaying dragons or tilting at windmills?

BACKGROUND

Sepsis is defined as systemic inflammatory response syndrome (SIRS) in the context of an underlying infectious process, and is associated with high rates of morbidity and mortality, particularly when initial therapy is delayed. Numerous biomarkers, including but not limited to cytokines (interleukins-2 and -6 [IL-2, IL-6] and tumor necrosis factor-α [TNF-α]), leukotrienes, acute-phase proteins (C-reactive protein [CRP]), and adhesion molecules, have been evaluated and rejected as unsuitable for the diagnosis of sepsis, predicting its severity, and guiding its treatment. Most recently, procalcitonin (PCT) has been suggested as a novel biomarker that may be useful in guiding therapeutic decision making in the management of sepsis. This article assesses critically the published literature on the clinical utility of PCT concentrations for guiding the treatment of sepsis in adult patients.

METHODS

A comprehensive search of all published studies of the use of serum concentrations of PCT to guide the treatment of sepsis in adult patients (1996 to 2011) was conducted with PubMed and Google Scholar. The search focused on the value of PCT concentrations to guide the diagnosis, prognosis, monitoring, and escalation and de-escalation of antbiotic therapy in these patients. Keywords searched included "procalcitonin," "sepsis," "sepsis biomarker," "sepsis diagnosis," "sepsis prognosis," "sepsis mortality," "antibiotic escalation," "antibiotic de-escalation," "antibiotic duration," and "antimicrobial stewardship."

RESULTS

Forty-six trials evaluating the efficacy of PCT concentrations in diagnosing sepsis have been published, with 39 of these trials yielding positive results and 7 yielding negative results. Wanner et al. published the largest study (n=405) demonstrating that peak PCT concentrations occur early after injury in both patients with sepsis and those with multiple organ dysfunction syndrome (MODS). Among 17 trials assessing the prognostic value of PCT concentrations with regard to clinical outcome and morbidity, 12 trials yielded positive results and five showed negative or equivocal results. Reith et al. published the largest study of the prognostic use of PCT concentrations (n=246), demonstrating that median PCT values on post-operative days (POD) one, four, and 10 were predictive of mortality in patients with abdominal sepsis (p<0.01). Among 14 trials of the utility of PCT concentrations for establishing an infectious cause of sepsis, 13 yielded positive results and only one yielded negative results. The largest study of this use of PCT concentrations, conducted by Baykut et al. (n=400), evaluated these concentrations in post-operative patients with infection, and demonstrated that concentrations of PCT remained elevated until POD 4, with a second increase observed between POD 4 and POD 6. In uninfected patients, PCT concentrations began to decrease on POD 2. Only a single study has assessed the utility of PCT concentrations in guiding the escalation of antibiotic therapy, and its results were negative. Specifically, Jensen et al. (n=1,200) compared a PCT-guided antibiotic escalation strategy with the standard of care for sepsis and found no difference in outcomes. They also found that the PCT group had a longer average stay in the intensive care unit (ICU), greater rates of mechanical ventilation, and a decreased estimated glomerular filtration rate (eGFR). Among four trials focusing on PCT concentrations and antibiotic de-escalation, all showed positive results with the measurement of PCT concentrations. The largest such study, by Bouadma et al. (n=621), demonstrated a four-day decrease in antibiotic duration when PCT concentrations were used to guide therapy relative to the study arm given the standard of care, with no increase in mortality (p=0.003).

CONCLUSIONS

The diagnostic value of serum PCT concentrations for discriminating among SIRS, sepsis, severe sepsis, and septic shock remains to be established. Although higher PCT concentrations suggest a systemic bacterial infection as opposed to a viral, fungal, or inflammatory etiology of sepsis, serum PCT concentrations do not correlate with the severity of sepsis or with mortality. At present, PCT concentrations are solely investigational with regard to determining the timing and appropriateness of escalation of antimicrobial therapy in sepsis. Nevertheless, serum PCT concentrations have established utility in monitoring the clinical response to medical and surgical therapy for sepsis, and in surveillance for the development of sepsis in burn and ICU patients, and may have a role in guiding the de-escalation of antibiotic therapy.

Correlation between inflammatory factors and post-stroke pneumonia in diabetic patients

Pneumonia is the most common cause of mortality in stroke patients and it has been demonstrated to contribute to mortality and poor functional outcome following stroke in the majority of clinical studies. The risk of infection may be attributed to stroke-induced immunodepression syndrome (SIDS). Cytokine production is increased in SIDS. However, the correlation between biomarkers and the risk of post-stroke pneumonia in patients with diabetes mellitus is not clear. The aim of this study was to determine the correlation between pneumonia and the levels of C-reactive protein (CRP) and interleukin-6 (IL-6), as well as to identify early predictors of pneumonia in acute ischemic stroke patients with diabetes mellitus. Additionally, we investigated the impact of pneumonia on functional outcome after 1 month. A total of 106 ischemic stroke patients with diabetes mellitus who were admitted after the onset of symptoms were included in the study. They were divided into two groups, the pneumonia and non-pneumonia groups. CRP, IL-6, white blood cells (WBCs), mean body temperature and National Institutes of Health Stroke Scale (NIHSS) score were measured at the time of admission. The modified Rankin Scale score was assessed at 30 days. The levels of IL-6, CRP and WBCs, as well as mean body temperature were significantly higher in the patients with pneumonia than in the patients without pneumonia. There were also significant differences between the pneumonia and non-pneumonia groups in age, admission NIHSS score, length of hospital stay and dysphagia. Pneumonia patients had worse outcomes compared with patients without pneumonia at 1 month. Age, NIHSS score and dysphagia were significantly associated with pneumonia. WBCs and mean body temperature were not significant predictors of pneumonia. Older patients with more severe ischemic stroke are more susceptible to the development of pneumonia during the stay in hospital. Pneumonia contributes to poor functional outcome. IL-6, CRP, age, NIHSS score and dysphagia may predict the occurrence of pneumonia on the day of stroke symptom onset.

Clinical application of sepsis biomarkers

Sepsis is one of the leading causes of death in the critically ill. Early diagnosis is important to avoid delay in instituting appropriate treatment. However, diagnosis can be delayed because of difficulty in interpreting clinical features. Sepsis biomarkers can aid early diagnosis. This article reviews the application of readily available biomarkers for diagnosis of sepsis, for predicting prognosis, and for antibiotic stewardship. 178 biomarkers are described in the literature--ranging from specimen cultures, which lack sensitivity and specificity for early diagnosis of sepsis, to biomarkers such as C-reactive protein, procalcitonin, and genetic biomarkers, which have their own limitations. Future research will mainly focus on use of more than one biomarker, but the main problem in sepsis biomarker research seems to be a lack of a recommended biomarker.

Delta neutrophil index as an early marker of disease severity in critically ill patients with sepsis

BACKGROUND

The immature granulocyte count has been reported to be a marker of infection and sepsis. The difference in leukocyte subfractions (delta neutrophil index, DNI) in ADVIA 2120 reflects the fraction of circulating immature granulocytes in the blood. This study evaluated the clinical utility of DNI as a severity and prediction marker in critically ill patients with sepsis.

METHODS

One hundred and three patients admitted to the medical intensive care unit with sepsis were studied. DNI (the difference in leukocyte subfractions identified by myeloperoxidase and nuclear lobularity channels) was determined using a specific blood cell analyzer.

RESULTS

Forty four patients (42.7%) were diagnosed with severe sepsis/septic shock. Overt disseminated intravascular coagulation (DIC) occurred in 40 (38.8%). DNI was significantly higher in patients with severe sepsis/septic shock and overt DIC than in patients without (p < 0.05). DNI correlated with DIC score (r = 0.54, p < 0.001). We observed a monotonic increase in the proportion of overt DIC and severe sepsis/septic shock associated with increasing quartiles of DNI (p < 0.001). A DNI value > 6.5% was a better indicator of severe sepsis/septic shock than C-reactive protein, lactate, white blood cell count, and absolute neutrophil count (sensitivity, 81.3%; specificity, 91.0%; positive predictive value, 88.6%; and negative predictive value, 84.7%). In 36 (82%) of the 44 patients with severe sepsis/septic shock, DNI values were already elevated up to 12 hours before the onset of organ/circulatory failure.

CONCLUSIONS

DNI may be used as a marker of disease severity in critically ill patients with sepsis. High levels of DNI may help to identify patients with an impending risk of developing severe sepsis/septic shock.

Infection after acute ischemic stroke: risk factors, biomarkers, and outcome

Background. The activation of inflammatory cascades triggered by ischemic stroke may play a key role in the development of infections. Methods. Patients admitted with ischemic stroke within 24 hours were prospectively enrolled. Biomarkers of infection were measured on days 1, 3, and 5. The patients were continuously monitored for predefined infections. Results. Patients with infection were older (OR 1.06 per year, 95% CI 1.01–1.11) and had a higher National Institute of Health Stroke Scale Score (NIHSS, OR 1.21, 95% CI 1.10–1.34), localization in the insula, and higher stroke volumes on diffusion-weighted imaging. The maximum temperature on days 1 and 3, leukocytes, interleukin-6, lipopolysaccharide-binding protein on days 1, 3, and 5, C-reactive protein on days 3 and 5, and procalcitonin on day 5 were higher and HLA-DR-expression on monocytes on days 1, 3, and 5 lower in patients with infection. Age and NIHSS predicted the development of infections. Infection was an independent predictor of poor functional outcome. Conclusions. Severe stroke and increasing age were shown to be early predictors for infections after stroke.