Dynamics of C-reactive protein and white blood cell count in critically ill patients with nosocomial Gram positive vs. Gram negative bacteremia: a historical cohort study

Distinct patterns of vital sign and inflammatory marker responses in adults with suspected bloodstream infection

OBJECTIVES

To identify patterns in inflammatory marker and vital sign responses in adult with suspected bloodstream infection (BSI) and define expected trends in normal recovery.

METHODS

We included patients ≥16 y from Oxford University Hospitals with a blood culture taken between 1-January-2016 and 28-June-2021. We used linear and latent class mixed models to estimate trajectories in C-reactive protein (CRP), white blood count, heart rate, respiratory rate and temperature and identify CRP response subgroups. Centile charts for expected CRP responses were constructed via the lambda-mu-sigma method.

RESULTS

In 88,348 suspected BSI episodes; 6908 (7.8%) were culture-positive with a probable pathogen, 4309 (4.9%) contained potential contaminants, and 77,131(87.3%) were culture-negative. CRP levels generally peaked 1-2 days after blood culture collection, with varying responses for different pathogens and infection sources (p < 0.0001). We identified five CRP trajectory subgroups: peak on day 1 (36,091; 46.3%) or 2 (4529; 5.8%), slow recovery (10,666; 13.7%), peak on day 6 (743; 1.0%), and low response (25,928; 33.3%). Centile reference charts tracking normal responses were constructed from those peaking on day 1/2.

CONCLUSIONS

CRP and other infection response markers rise and recover differently depending on clinical syndrome and pathogen involved. However, centile reference charts, that account for these differences, can be used to track if patients are recovering line as expected and to help personalise infection.

Experience with Tissue Bank Services in 2014 and 2020 in Turku, Finland

BACKGROUND

The objective of a musculoskeletal tissue bank is to collect, test, store, and provide musculoskeletal tissue allografts required in orthopedic procedures. Strict exclusion criteria are followed when selecting suitable cadaver musculoskeletal tissue donors, and the allografts are procured under sterile conditions to avoid bacterial contamination. Tissue banking in Turku, Finland, began in 1972, and tissue bank services were last reviewed in 2003. This study aimed to review the operation of the musculoskeletal tissue bank in Turku, Finland, between 2014 and 2020 and to analyze the number, types, and contamination rate of the allografts procured from the cadaver donors. Potential donor-related factors causing bacterial contamination of the allografts and whether potential musculoskeletal tissue donors were overlooked among multiorgan donors were also studied.

METHODS

A retrospective review of all cadaver musculoskeletal tissue donors used in the Hospital District of Southwest Finland Tyks Orto Musculoskeletal Tissue Bank during the study period was conducted, and data on the procured allograft was collected and presented. The donors were selected among patients treated in the intensive care unit (ICU) of Turku University Hospital (TYKS).

RESULTS

A total of 28 cadaver donors were used, and 636 allografts were procured between 2014 and 2020. The bacterial contamination rate was 2.5%, which was lower than that in the previous international literature. The median treatment time in the ICU was significantly longer, and the median value of the highest C-reactive protein level was significantly higher in the group of donors with positive allograft bacterial cultures.

CONCLUSIONS

The bacterial contamination rate in the tissue bank was low on an international scale. Some suitable musculoskeletal tissue donors were overlooked among multiorgan donors.

Machine learning model for the prediction of gram-positive and gram-negative bacterial bloodstream infection based on routine laboratory parameters

BACKGROUND

Bacterial bloodstream infection is responsible for the majority of cases of sepsis and septic shock. Early recognition of the causative pathogen is pivotal for administration of adequate empiric antibiotic therapy and for the survival of the patients. In this study, we developed a feasible machine learning (ML) model to predict gram-positive and gram-negative bacteremia based on routine laboratory parameters.

METHODS

Data for 2118 patients with bacteremia were obtained from the Medical Information Mart for Intensive Care dataset. Patients were randomly split into the training set and test set by stratified sampling, and 374 routine laboratory blood test variables were retrieved. Variables with missing values in more than 40% of the patients were excluded. Pearson correlation test was employed to eliminate redundant features. Five ML algorithms were used to build the model based on the selected features. Additionally, 132 patients with bacteremia who were treated at Qilu Hospital of Shandong University were included in an independent test cohort to evaluate the model.

RESULTS

After feature selection, 32 variables remained. All the five ML algorithms performed well in terms of discriminating between gram-positive and gram-negative bacteremia, but the performance of convolutional neural network (CNN) and random forest (RF) were better than other three algorithms. Consider of the interpretability of models, RF was chosen for further test (ROC-AUC = 0.768; 95%CI = 0.715-0.798, with a sensitivity of 75.20% and a specificity of 63.79%). To expand the application of the model, a decision tree (DT) was built utilizing the major variables, and it achieved an AUC of 0.679 (95%CI = 0.632-0.723), a sensitivity of 66%, and a specificity of 67.82% in the test cohort. When tested in the Qilu Hospital cohort, the ROC-AUC of the RF and DT models were 0.666 (95%CI = 0.579-0.746) and 0.615 (95%CI = 0.526-0.698), respectively. Finally, a software was developed to make the RF- and DT-based prediction models easily accessible.

CONCLUSION

The present ML-based models could effectively discriminate between gram-positive and gram-negative bacteremia based on routine laboratory blood test results. This simple model would be beneficial in terms of guiding timely antibiotic selection and administration in critically ill patients with bacteremia before their pathogen test results are available.

Surgical debridement of infected pubic symphysitis supports optimal outcome

INTRODUCTION

Infected pubic symphysitis (IPS) is a rare bacterial infection of the pubic symphysis that causes subpubic pain, disability and ultimately permanent immobility. Due to difficult diagnosis, patients present with long-standing complaints and consult several doctors. To date, no validated treatment protocol exists and most patients are treated conservatively with antibiotics. This study was aimed to assess the results after careful surgical debridement and pathogen-specific antibiotic treatment in IPS.

MATERIALS AND METHODS

A chart review of eight patients with proven IPS was performed. Five of eight patients filled in a specific own-developed questionnaire and could be examined clinically and radiologically at a mean of 13 months (range: 6-30 months) postoperatively.

RESULTS

There were six males and two females with an average age of 69 years (range: 55-80 years). The mean duration of symptoms before surgical treatment was 10.5 months (range: 1-30 months). There were no complications due to the surgical debridement. There was no recurrence of infection at the pubic symphysis during the follow-up period. The most common pathogen was Pseudomonas aeruginosa in three patients. Mean preoperative pain, measured on the visual analogue scale (VAS, range: 0-10) for the four analysed categories in the five follow-up patients was 7.2, 30 days postoperatively 2.7 and 13 months postoperatively 0.4. There was a steady increase in the quality of life (QoL) 30 days postoperatively and at the 13 months follow-up when compared to preoperative values.

CONCLUSIONS

Surgical debridement is the keystone for treatment of IPS and should be combined with local and systemic antibiotic therapy.

LIPID AND LIPOPROTEIN LEVELS IN HIV-INFECTED ADULTS WITH SEPSIS COMPARED TO HEALTHY HIV- INFECTED CONTROLS

Background:

In acute sepsis, reduced lipid and lipoprotein levels occur in HIV negative patients, in particular, low high-density lipoprotein cholesterol (HDL–c) levels are inversely correlated with sepsis severity and increased mortality. However, due to the limited data describing lipid and lipoprotein levels in septic HIV–infected individuals we aimed to investigate the changes in this subgroup.

Materials and Methods:

A prospective cross–sectional observational study of HIV–infected patients comparing admitted HIV – infected patients with sepsis to healthy controls from the antiretroviral therapy (ART) clinic. Non fasting - lipograms, ART use, diagnosis of tuberculosis (TB), markers of infection, renal function and mortality outcome to 3 months post discharge were reviewed.

Results:

Total cholesterol (TC), low–density lipoprotein (LDL–c) and HDL-c were all significantly lower in the sepsis group (p < 0.001). HDL–c was significantly associated with a higher white cell count (p = 0.018), higher C– reactive protein (p = 0.036) and low serum albumin (p < 0.001). In those with active TB (55%) HDL–c was reduced even further (0.55 vs. 0.72mmol/L, p = 0.013). Acute kidney injury (p = 0.560) and mortality at discharge (p = 0.097) or 3 months follow up (p = 0.953) was not associated with reduced HDL–c.

Conclusion:

Septic HIV–infected patients had significantly reduced lipid and lipoprotein levels at admission. Of note however, a low HDL–c was associated with markers of infection and reductions in HDL–c was more marked in those with active TB.

C-reactive protein and albumin kinetics before community-acquired bloodstream infections - a Danish population-based cohort study

Early changes in biomarker levels probably occur before bloodstream infection (BSI) is diagnosed. However, this issue has not been fully addressed. We aimed at evaluating the kinetics of C-reactive protein (CRP) and plasma albumin (PA) in the 30 days before community-acquired (CA) BSI diagnosis. From a population-based BSI database we identified 658 patients with at least one measurement of CRP or PA from day −30 (D–30) through day −1 (D–1) before the day of CA-BSI (D0) and a measurement of the same biomarker at D0 or D1. Amongst these, 502 had both CRP and PA measurements which fitted these criteria. CRP and PA concentrations began to change inversely some days before CA-BSI diagnosis, CRP increasing by day −3.1 and PA decreasing by day −1.3. From D–30 to D–4, CRP kinetics (expressed as slopes – rate of concentration change per day) was −1.5 mg/l/day. From D–3 to D1, the CRP slope increased to 36.3 mg/l/day. For albumin, the slope between D–30 to D–2 was 0.1 g/l/day and changed to −1.8 g/l/day between D–1 and D1. We showed that biomarker levels begin to change some days before the CA-BSI diagnosis, CRP 3.1 days and PA 1.3 days before.

Diagnostic Accuracy of Procalcitonin Compared to C-Reactive Protein and Interleukin 6 in Recognizing Gram-Negative Bloodstream Infection: A Meta-Analytic Study

Objective

Gram-negative bloodstream infections (GNBSIs), especially those caused by antibiotic-resistant species, have become a public health challenge. Procalcitonin (PCT) showed promising potential in early diagnosis of GNBSI; however, little was known about its performance under different clinical settings. We here systematically assessed the diagnostic accuracy of PCT in recognizing GNBSI and made direct comparisons with C-reactive protein (CRP) and interleukin 6 (IL-6).

Methods

PubMed, Embase, ISI Web of Knowledge, and Scopus were searched from inception to March 15th, 2019. Area under the summary receiver operating characteristic curve (AUC), pooled sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated. Hierarchical summary receiver operating characteristic (HSROC) model was used for the investigation of heterogeneity and for comparisons between markers.

Results

25 studies incorporating 50933 suspected BSI episodes were included. Pooled sensitivity and specificity for PCT were 0.71 and 0.76, respectively. The overall AUC was 0.80. The lowest AUCs were found in patients with febrile neutropenia (0.69) and hematological malignancy (0.69). The highest AUC was found in groups using electrochemiluminescence immunoassay (0.87). In direct comparisons, PCT showed better overall performance than CRP with the AUC being 0.85 (95% CI 0.81–0.87) for PCT and 0.78 (95% CI 0.74–0.81) for CRP, but the relative DORs varied with thresholds between PCT and CRP (p < 0.001). No significant difference was found either in threshold (p < 0.001). No significant difference was found either in threshold (p < 0.001). No significant difference was found either in threshold (

Conclusions

PCT was helpful in recognizing GNBSI, but the test results should be interpreted carefully with knowledge of patients' medical condition and should not serve as the only criterion for GNBSI. Further prospective studies are warranted for comparisons between different clinical settings.

Predictive value of post-operative neutrophil/lymphocyte count ratio for surgical site infection in patients following posterior lumbar spinal surgery

OBJECTIVE

Surgical site infection (SSI) is a common complication in patients following posterior lumbar spinal surgery. Various laboratory data such as laboratory parameters derived neutrophil/lymphocyte count ratio (NLR), have been applied for the prediction of SSI, but more studies are necessary to evaluate the significance of these indicators. Here, our study aims to investigate the predictive value of total white blood cells (WBCs), count and percentages of neutrophils and leukocytes, NLR, and C-reactive protein (CRP) for surgical site infection (SSI) in patients after posterior lumbar spinal surgery.

METHODS

A total of 293 patients who underwent posterior lumbar spinal surgery were enrolled in this study. Each patient's medical history was retrospectively reviewed, and patients were divided into the deep SSI group (n = 13) and the non-SSI group (n = 280). Laboratory data including total WBC, count and percentages of neutrophils and leukocytes, NLR at 1 week before the operation and the 4 and 7 days post-operation, and CRP at 4 and 7 days post-operation were analysed between the SSI and non-SSI groups. Moreover, predictive power and cut-off of NLR for SSI were determined by receiver operating characteristic curve (ROC) results.

RESULTS

Data revealed that the medians of NLR were markedly increased in the SSI group as compared to that in non-SSI group at 4 days (p = 0.011) and 7 days (p = 0.047) post-operation. Moreover, the neutrophil percentage was also dramatically increased in the SSI group at both 4 and 7 days post-operation (p = 0.010 and p = 0.030) respectively compared to the non-SSI group. However, no significant difference was observed between the groups 1 week before the operation. ROC results showed that NLR at 4 days (cut-off >5.19; sensitivity: 61.5%; specificity: 77.6%; AUC = 0.708) and 7 days (cut-off >3.85; sensitivity: 69.2%; specificity: 62.7%; AUC = 0.663) post-operation could significantly discriminate the SSI and non-SSI groups. Logistic regression analysis showed that NLR at both post-operative time points (OR = 1.218; p = 0.003 and OR = 1.296; p = 0.048) could be valuable predictors for SSI.

CONCLUSION

NLR at 4 and 7 days post-operation are valuable laboratory predictors for SSI in patients with posterior lumbar spinal surgery.

The impact of bacteremia on lipoprotein concentrations and patient's outcome: a retrospective analysis

Bacteremia is a major clinical challenge requiring early treatment. Metabolic alterations occur during bacteremia, and accordingly plasma concentrations of lipoproteins LDL-C and HDL-C are substantially changed. We questioned whether bacteremia with Gram-negative versus Gram-positive bacteria causes contrasting changes of lipoprotein levels in order to differentiate between the 2-g stain types and if there is a relation with outcome parameters namely ICU-admission, 30-day mortality, duration of hospitalization. This is a retrospective dual-center cross-sectional study, including 258 patients with bacteremia. Plasma lipid levels were analyzed within 48 h to positive blood culture. Upon admission, HDL-C, LDL-C, and total cholesterol (p = 0.99) in plasma did not significantly differ between patients with Gram-negative and Gram-positive bacteremia, while significantly higher triglyceride concentrations were found in Gram-negative bacteremia (p < 0.05). 30-day mortality and ICU admission were associated with lower LDL-C and HDL-C concentrations as compared to survivors and non-ICU patients, and patients with HDL-C < 20 mg dl^-1 and LDL-C < 55 mg dl^-1 had a relative risk (RR) of 2.85 for ICU therapy requirement and RR = 2 of death within 30 days. Reduced HDL-C and LDL-C concentrations were associated with adverse patient's outcome in bacteremia. Discrimination between Gram-negative and Gram-positive pathogens upon lipoprotein patterns is unlikely.

Trends in Antimicrobial Resistance against Enterobacteriaceae Strains Isolated from Blood: A 10-year Epidemiological Study in Mainland China (2004-2014)

Background:

Antimicrobial resistance is a serious problem that compromises the empirical treatment of infections, resulting in a lack of effective antibiotics and high medical expenses. Here, we aimed to monitor the trends in antimicrobial resistance among Enterobacteriaceae isolated from blood samples in mainland China.

Methods:

A total of 2240 Enterobacteriaceae isolates from blood were collected from hospitalized patients at 19 tertiary hospitals between October 2004 and June 2014. The minimum inhibitory concentrations of all isolates were determined using the agar dilution method according to the Clinical and Laboratory Standards Institute 2016 guidelines.

Results:

The most commonly isolated bacteria were Escherichia coli, compromising 47.0% (1053/2240) of the total isolates, followed by Klebsiella spp. (26.3%), Salmonella spp. (10.4%), and Enterobacter spp. (9.2%). The detection rates of extended-spectrum β-lactamases (ESBLs) among E. coli were 68.9% (2004–2005), 73.2% (2007–2008), 67.9% (2009–2010), 72.6% (2011–2012), and 58.4% (2013–2014), whereas those in ESBL-producing Klebsiella pneumoniae were slightly decreased (75.9%, 50.0%, 41.4%, 40.2%, and 43.0%, respectively). Carbapenems were the most potent agents against the Enterobacteriaceae isolates, followed by moxalactam, tigecycline, and amikacin. However, there was a decrease in the susceptibility rates for carbapenems in all species, particularly K. pneumoniae (decreased by 10.6% for imipenem) and Enterobacter aerogenes (decreased by 21.1% for imipenem). Reviving antibiotics (tigecycline and polymyxins) showed good in vitro activity against Enterobacteriaceae.

Conclusions:

The activity of antibiotics against Enterobacteriaceae isolated from blood was decreased overall. Large proportions of ESBL-producing isolates were identified among E. coli and Klebsiella spp. Carbapenem-resistant isolates have become a major challenge in the treatment of infections.

Predictive value of C-reactive protein in critically ill patients after abdominal surgery

OBJECTIVES:

The development of sepsis after abdominal surgery is associated with high morbidity and mortality. Due to inflammation, it may be difficult to diagnose infection when it occurs, but measurement of C-reactive protein could facilitate this diagnosis. In the present study, we evaluated the predictive value and time course of C-reactive protein in relation to outcome in patients admitted to the intensive care unit (ICU) after abdominal surgery.

METHODS:

We included patients admitted to the ICU after abdominal surgery over a period of two years. The patients were divided into two groups according to their outcome: favorable (F; left the ICU alive, without modification of the antibiotic regimen) and unfavorable (D; death in the ICU, surgical revision with or without modification of the antibiotic regimen or just modification of the regimen). We then compared the highest C-reactive protein level on the first day of admission between the two groups.

RESULTS:

A total of 308 patients were included: 86 patients had an unfavorable outcome (group D) and 222 had a favorable outcome (group F). The groups were similar in terms of leukocytosis, neutrophilia, and platelet count. C-reactive protein was significantly higher at admission in group D and was the best predictor of an unfavorable outcome, with a sensitivity of 74% and a specificity of 72% for a threshold of 41 mg/L. No changes in C-reactive protein, as assessed based on the delta C-reactive protein, especially at days 4 and 5, were associated with a poor prognosis.

CONCLUSIONS:

A C-reactive protein cut-off of 41 mg/L during the first day of ICU admission after abdominal surgery was a predictor of an adverse outcome. However, no changes in the C-reactive protein concentration, especially by day 4 or 5, could identify patients at risk of death.

Search of Unknown Fever Focus Using PET in Critically Ill Children With Complicated Underlying Diseases

OBJECTIVES

PET/CT with F-fluorodeoxyglucose can be used to image cellular metabolism and has been used for evaluating fever of unknown origin in adults. However, there are limited studies about the role of F-fluorodeoxyglucose PET/CT in evaluation of fever of unknown origin in critically ill children, especially those presenting with complicated underlying diseases under treatment. Here, we report our preliminary experience using F-fluorodeoxyglucose PET/CT in this specific group of patients.

DESIGN

Retrospective observational study.

SETTING

PICUs of a university hospital.

PATIENTS

Nineteen critically ill children (mean age, 5.7 yr old) with complicated underlying diseases requiring intensive care support underwent F-fluorodeoxyglucose PET/CT to evaluate fever of unknown origin. The median hospitalized stay was 34 days (range, 15-235 d) and fever of at least 7 days (mean, 21.6 d; range, 7-52 d). The PET scan was advocated after all routine microbiology, and conventional imaging showed negative or inconclusive results.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The F-fluorodeoxyglucose PET/CT findings (blinded to the final clinical diagnosis) were compared with final histopathology, culture, serology results, or follow-up imaging. A final diagnosis was made in 16 patients (84.2%). F-fluorodeoxyglucose PET/CT accurately localized the source of fever in 14 patients, confers to a sensitivity of 87.5% (14 of 16; 95% CI, 0.604-0.978). A false-positive scan in a patient led to subsequent unnecessary investigations. Two false-negative F-fluorodeoxyglucose PET/CT images were later attributed to relapse of underlying disease in the bone marrow and renal abscesses, respectively. In the other two patients where F-fluorodeoxyglucose PET/CT also showed negative findings, fever subsided shortly thereafter without treatment.

CONCLUSIONS

Our preliminary experience suggests that F-fluorodeoxyglucose PET/CT may be clinically beneficial in evaluating fever of unknown origin in children with complicated underlying diseases mandating intensive support in ICUs if usual investigative methods are unsuccessful. Further large prospective studies are needed to validate these findings.

Neither Single nor a Combination of Routine Laboratory Parameters can Discriminate between Gram-positive and Gram-negative Bacteremia

Adequate early empiric antibiotic therapy is pivotal for the outcome of patients with bloodstream infections. In clinical practice the use of surrogate laboratory parameters is frequently proposed to predict underlying bacterial pathogens; however there is no clear evidence for this assumption. In this study, we investigated the discriminatory capacity of predictive models consisting of routinely available laboratory parameters to predict the presence of Gram-positive or Gram-negative bacteremia. Major machine learning algorithms were screened for their capacity to maximize the area under the receiver operating characteristic curve (ROC-AUC) for discriminating between Gram-positive and Gram-negative cases. Data from 23,765 patients with clinically suspected bacteremia were screened and 1,180 bacteremic patients were included in the study. A relative predominance of Gram-negative bacteremia (54.0%), which was more pronounced in females (59.1%), was observed. The final model achieved 0.675 ROC-AUC resulting in 44.57% sensitivity and 79.75% specificity. Various parameters presented a significant difference between both genders. In gender-specific models, the discriminatory potency was slightly improved. The results of this study do not support the use of surrogate laboratory parameters for predicting classes of causative pathogens. In this patient cohort, gender-specific differences in various laboratory parameters were observed, indicating differences in the host response between genders.

Interpretation of C-reactive protein concentrations in critically ill patients

Infection is often difficult to recognize in critically ill patients because of the marked coexisting inflammatory process. Lack of early recognition prevents timely resuscitation and effective antimicrobial therapy, resulting in increased morbidity and mortality. Measurement of a biomarker, such as C-reactive protein (CRP) concentration, in addition to history and physical signs, could facilitate diagnosis. Although frequently measured in clinical practice, few studies have reported on the pathophysiological role of this biomarker and its predictive value in critically ill patients. In this review, we discuss the pathophysiological role of CRP and its potential interpretation in the inflammatory processes observed in critically ill patients.

Discriminative value of inflammatory biomarkers for suspected sepsis

BACKGROUND

Circulating biomarkers can facilitate sepsis diagnosis, enabling early management and improved outcomes. Procalcitonin (PCT) has been suggested to have superior diagnostic utility compared to other biomarkers.

STUDY OBJECTIVES

To define the discriminative value of PCT, interleukin-6 (IL-6), and C-reactive protein (CRP) for suspected sepsis.

METHODS

PCT, CRP, and IL-6 were correlated with infection likelihood, sepsis severity, and septicemia. Multivariable models were constructed for length-of-stay and discharge to a higher level of care.

RESULTS

Of 336 enrolled subjects, 60% had definite infection, 13% possible infection, and 27% no infection. Of those with infection, 202 presented with sepsis, 28 with severe sepsis, and 17 with septic shock. Overall, 21% of subjects were septicemic. PCT, IL6, and CRP levels were higher in septicemia (median PCT 2.3 vs. 0.2 ng/mL; IL-6 178 vs. 72 pg/mL; CRP 106 vs. 62 mg/dL; p < 0.001). Biomarker concentrations increased with likelihood of infection and sepsis severity. Using receiver operating characteristic analysis, PCT best predicted septicemia (0.78 vs. IL-6 0.70 and CRP 0.67), but CRP better identified clinical infection (0.75 vs. PCT 0.71 and IL-6 0.69). A PCT cutoff of 0.5 ng/mL had 72.6% sensitivity and 69.5% specificity for bacteremia, as well as 40.7% sensitivity and 87.2% specificity for diagnosing infection. A combined clinical-biomarker model revealed that CRP was marginally associated with length of stay (p = 0.015), but no biomarker independently predicted discharge to a higher level of care.

CONCLUSIONS

In adult emergency department patients with suspected sepsis, PCT, IL-6, and CRP highly correlate with several infection parameters, but are inadequately discriminating to be used independently as diagnostic tools.

Impact of molecular mimicry on the clinical course and outcome of sepsis syndrome

We investigated the impact of molecular mimicry between pathogenic microbes and their antigenic surrounding on the clinical course and outcome of pneumonia induced sepsis. Using mathematical prediction, we estimated the mimicry tendency of the identified pathogenic flora of patients with the human proteome as well as intestinal microbes. Since gut bacteria become invasive and hostile in critical illness, mimicry between these organisms and the infectious flora is expected to be rather hyperinflammatory type, in contrast to the expectedly tolerogenic self versus pathogen cross-reactions. Differential effects of these two kinds of cross-reactions were studied. The predicted similarity of the identified pathogenic flora and intestinal microbes was higher in non-survivor patients compared to survivors (P=0.019). Higher values of "pathogen versus intestinal flora/pathogen versus human proteome" mimicry ratios (inflammatory quotients) were associated with mortality at a higher extent of significance (P<0.01), and correlated with admission APACHE II disease severity scores (R=0.311; P=0.017). We also found a correlation between the previously reported sepsis mortality rates by causative agent and the corresponding inflammatory quotients of these pathogens (R=0.738; P<0.05). Gram negative species showed higher similarity to intestinal bacteria and reached higher inflammatory quotients compared to Gram positives (P=0.01 and P<0.01, respectively). The disadvantageous effect of "pathogen versus intestinal flora" mimicry - presumably due to the extension of inflammation from the infectious focus to the already injured gut - is in accordance with the gut-lymph hypothesis, assessing that the destruction of the intestinal symbiosis culminates in the formation of damageous gut origin lymph. Our results raise the idea that molecular mimicry between pathogenic microbes and their antigenic surrounding might be a contributing factor behind the clinically and experimentally observed differences in microbiologically distinct forms of sepsis syndrome.

C-reactive protein, an early marker of community-acquired sepsis resolution: a multi-center prospective observational study

Introduction

C-reactive protein (CRP) has been shown to be a valuable marker in the diagnosis of infection and in monitoring its response to antibiotics. Our objective was to evaluate serial CRP measurements after prescription of antibiotics to describe the clinical course of Community-Acquired Sepsis admitted to intensive care units (ICU).

Methods

During a 12-month period a multi-center, prospective, observational study was conducted, segregating adults with Community-Acquired Sepsis. Patients were followed-up during the first five ICU days, day of ICU discharge or death and hospital outcome. CRP-ratio was calculated in relation to Day 1 CRP concentration. Patients were classified according to the pattern of CRP-ratio response to antibiotics: fast response if Day 5 CRP-ratio was < 0.4, slow response if Day 5 CRP-ratio was between 0.4 and 0.8, and no response if Day 5 CRP-ratio was > 0.8. Comparison between survivors and non-survivors was performed.

Results

A total of 891 patients (age 60 ± 17 yrs, hospital mortality 38%) were studied. There were no significant differences between the CRP of survivors and non-survivors until Day 2 of antibiotic therapy. On the following three days, CRP of survivors was significantly lower (P < 0.001). After adjusting for the Simplified Acute Physiology Score II and severity of sepsis, the CRP course was significantly associated with mortality (OR_CRP-ratio = 1.03, confidence interval _95%= (1.02, 1.04), P < 0.001). The hospital mortality of patients with fast response, slow response and no response patterns was 23%, 30% and 41%, respectively (P = 0.001). No responders had a significant increase on the odds of death (OR = 2.5, CI_95% = (1.6, 4.0), P < 0.001) when compared with fast responders.

Conclusions

Daily CRP measurements after antibiotic prescription were useful as early as Day 3 in identification of Community-Acquired Sepsis patients with poor outcome. The rate of CRP decline during the first five ICU days was markedly associated with prognosis. The identification of the pattern of CRP-ratio response was useful in the recognition of the individual clinical course.

PTX3 predicts severe disease in febrile patients at the emergency department

OBJECTIVES

The long pentraxin PTX3 is a promising marker of disease severity in severely ill patients. In order to identify patients warranting critical care as quickly as possible, we investigated the value of PTX3 as a biomarker for disease severity in patients presenting with fever at the emergency department.

METHODS

Levels of PTX3 were measured in 211 febrile patients at the emergency and the levels were linked to markers of disease severity including admittance to a special care unit, bloodstream infection and congestive heart failure.

RESULTS

In comparison to median baseline levels of 2.30 ng/ml (interquartile range 1.66-3.67 ng/ml), levels of PTX3 were significantly elevated in patients admitted to the intensive-/medium care unit (median value 44.4 ng/ml, interquartile range 13.6-105.9 ng/ml) and in patients referred to the ward (median value 14.2 ng/ml, interquartile range 7.01-25.1 ng/ml). In addition, PTX3 was associated with duration of hospital stay and acute congestive heart failure. The levels were predictive for bloodstream infection (AUC=0.71; 95% CI 0.62-0.81).

CONCLUSIONS

PTX3 may be a useful marker for differentiation of patients with severe disease in patients presenting with fever to the emergency department.

A retrospective analysis of changes in inflammatory markers in patients treated with bacterial viruses

Bacteriophages are increasingly considered an alternative to antibiotics for the treatment of bacterial infections. Clinical improvement may be associated with a lowering of inflammatory markers during the antibiotic treatment of bacterial infections. Some experimental data suggest that phage treatment may have anti-inflammatory properties. We present a retrospective analysis of C-reactive protein (CRP) serum concentration, erythrocyte sedimentation rate (ESR), and white blood cell count (WBC) measured in patients with chronic, symptomatic, antibiotic therapy-resistant bacterial infections who qualified for phage treatment within the protocol "Experimental Phage Therapy of Antibiotic Therapy-Resistant Infections, Including MRSA Infections". Data collected from 37 patients with osteomyelitis (with or without metal implants or joint endoprosthesis) or skin and soft tissue or lower respiratory tract infection induced by, in the majority of cases, S. aureus were analyzed. Phage preparations (natural phage lysates) were administered orally (one 10-ml ampoule three times daily after neutralization of gastric juice with 10 ml of dihydroxyaluminium sodium carbonate) and/or locally (one ampoule two times daily for wet compresses or irrigation of a fistula). No significant changes in mean serum levels of CRP measured after 5-8 days of phage administration were observed compared with the baseline CRP levels measured before therapy (35.7 vs. baseline 38.6 mg/l, n = 11). However, a significant decrease in mean CRP values measured later, between days 9 and 32, was noted (16.1 vs. baseline 23.3 mg/l, n = 26, P < 0.05). Similar tendencies were observed in the changes in mean WBC values, but mean ESR in the patients before, in the early phase, and later during therapy did not change significantly. This is the first report suggesting that the application of phage preparations may probably influence and diminish the inflammatory reaction that accompanies bacterial infection.

An Update on C-reactive Protein for Intensivists

This review aims to summarise the physiology of C-reactive protein (CRP), its possible roles and limitations as an inflammatory and infective marker in intensive care medicine, and also the emerging roles of CRP in the pathogenesis of cardiovascular and autoimmune diseases. Observational and animal studies on uses of CRP were retrieved from the PubMed database without any language restrictions. Quantitative data were not pooled because of the heterogeneity of patient characteristics and disparate ways in which CRP was studied. Serum CRP concentrations are determined by the synthetic rate of its production in the liver regulated predominantly by interleukin-6. It has a half-life of 19 hours and is relatively slow in its onset and offset in response to an acute inflammatory process when compared to procalcitonin. It has some favourable properties and limitations as an inflammatory marker. An elevated CRP concentration is not specific to infections and the absolute CRP concentrations cannot be used to differentiate between bacterial, fungal and severe viral infections. The dynamic response of CRP to therapy that aims to modify the underlying inflammatory process and the clinical context of a patient are of pivotal importance when CRP concentrations are interpreted. CRP is found to be a significant partaker and prognostic factor in a wide range of cardiovascular and chronic diseases. In summary, CRP concentration is an important prognostic factor of many acute and chronic diseases. Serial CRP measurements may be useful to reflect a patient's response to therapy that aims to modify the underlying inflammatory process.

Using innate immunity to characterize the host response to microbial invasion in severe sepsis

Severe sepsis is a life-threatening systemic inflammatory response to microbial infection. Although mortality from severe sepsis has decreased modestly over the past three decades, its incidence is increasing dramatically. Current treatment of severe sepsis relies primarily on identification and appropriate antibiotic coverage of the invading pathogen, with supportive therapies aimed primarily at reducing the risk of associated organ injury. Current efforts to identify the invading pathogens are successful in approximately only 50% of patients with severe sepsis. In this review, we examine host-pathogen interactions through the Toll-like receptors and Nod signaling systems as principal mechanisms of the innate immune response, and explore the application of high-throughput genomic technologies that have permitted a more complete dissection of the innate immune response during severe sepsis. Early controlled studies suggest that these genome-wide tools can readily identify pathogen-specific host responses in macrophages and dendritic cells. However, despite considerable progress, clinical application of these approaches to pathogen recognition in hospitalized patients with severe sepsis is still years away.

Hyperglycaemia upon onset of ICU-acquired bloodstream infection is associated with adverse outcome in a mixed ICU population

This study aimed to assess whether a relationship exists between hyperglycaemia and outcome in a mixed cohort of critically ill patients with nosocomial bloodstream infection (BSI), and to evaluate patterns of blood glucose levels between survivors and non-survivors. A historical observational cohort study was conducted in the intensive care unit (ICU) of a tertiary care referral centre. One-hundred-and-thirty patients with a microbiologically documented ICU-acquired BSI (period 2003 to 2004) were included. For the study, morning blood glucose levels were evaluated from one day prior until five days after onset of BSI. The contribution of hyperglycaemia, divided in three subgroups (> or = 150 mg/dl, > or = 175 mg/dl and > or = 200 mg/dl), to in-hospital mortality was estimated by logistic regression. In-hospital mortality was 36.2%. Over the seven study days, no differences were found in daily morning blood glucose levels between survivors (n = 83) and non-survivors (n = 47). Nevertheless, the trend of blood glucose levels upon onset of BSI showed a remarkable increase in the non-survivors, whereas it decreased in the survivors. Hyperglycaemia (> or = 175 mg/dl and > or = 200 mg/dl) was observed more often among the non-survivors. Multivariate logistic regression showed that APACHE II (P = 0.002), antibiotic resistance (P = 0.004) and hyperglycaemia (> or = 175 mg/dl) upon onset of BSI (P = 0.017) were independently associated with in-hospital mortality, whereas a history of diabetes (P = 0.041) was associated with better outcome. Hyperglycaemia (> or = 175 mg/dl) upon onset of ICU-acquired BSI is associated with worse outcome in a heterogeneous ICU population. Patterns of morning blood glucose levels have only limited value in the prediction of the individual course.