Unrevealing culture-negative severe sepsis

The impact of antimicrobial de-escalation therapy in culture-negative pneumonia: a systematic review and meta-analysis

BACKGROUND/AIMS

Antimicrobial de-escalation (ADE) remains a challenging strategy in the treatment of pneumonia. We investigated the outcomes of ADE as measured by mortality and duration of the use of antibiotics in patients with culture- negative pneumonia.

METHODS

We performed a systematic review and meta-analysis in accordance with PRISMA guidelines. The primary outcome was inpatient mortality.

RESULTS

We examined six studies comprising 11,933 subjects, of whom 1,152 received ADE. Overall, the ADE strategy was associated with a statistically lower risk of in-hospital mortality compared with non-ADE (risk ratio [RR] = 0.60, 95% confidence interval [CI] = 0.38 to 0.93). Although substantial heterogeneity was found among the included studies (I2 = 66%), a meta-regression analysis could not reveal plausible sources of heterogeneity. And ADE was associated with a shorter duration of total and initial antibiotic therapies and total length of hospital stay compared with non-ADE.

CONCLUSION

Our findings suggest that ADE seems to be significantly associated with better clinical outcomes compared with non-ADE. Caution is demanded when interpreting data of this study because of substantial between-study heterogeneity.

Direct-from-Blood Detection of Pathogens: a Review of Technology and Challenges

Blood cultures have been the staple of clinical microbiology laboratories for well over half a century, but gaps remain in our ability to identify the causative agent in patients presenting with signs and symptoms of sepsis. Molecular technologies have revolutionized the clinical microbiology laboratory in many areas but have yet to present a viable alternative to blood cultures. There has been a recent surge of interest in utilizing novel approaches to address this challenge. In this minireview, I discuss whether molecular tools will finally give us the answers we need and the practical challenges of incorporating them into the diagnostic algorithm.

Comparison of the clinical characteristics and clinical outcomes of culture-positive septic shock and culture-negative septic shock among pediatric patients

OBJECTIVES

Among pediatric patients with septic shock, culture-negative septic shock (CNSS) is common but there have been limited data on its clinical characteristics and prognosis. We compared the clinical characteristics and clinical outcomes between culture-positive septic shock (CPSS) and CNSS in pediatric patients.

DESIGN

Retrospective single-center study.

SETTING

Pediatric intensive care unit (PICU) of a tertiary referral hospital.

PATIENTS

All pediatric patients who were admitted to the PICU due to septic shock between January 2010 and November 2021, except for those with fungal or viral infections and those who expired on the day of admittance to the PICU. The primary outcome was 30-day mortality and in-hospital mortality.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 294 patients (CPSS group, n = 185 [62.9%]; CNSS group, n = 109 [37.1%]) were included. The rates of 30-day mortality and in-hospital mortality (30-day mortality 22.7% vs 22%, in-hospital mortality 29.7% vs 25.7%) were not significantly different between the CPSS group and the CNSS group. The two groups showed comparable results in clinical outcomes such as the requirement for mechanical ventilator and renal replacement therapy, PICU stay duration, and the duration of MV and vasopressor/inotrope support. Among the CPSS group, 98 (53%) patients who were infected with multi-drug resistance (MDR) bacteria had significantly higher rates of 30-day mortality and in-hospital mortality than those infected with non-MDR bacteria.

CONCLUSIONS

Among pediatric patients, the CPSS group and CNSS group did not show significant differences in clinical features and mortality. Among the CPSS group, those with MDR bacteria had poorer prognosis.

Serum miR-34a-5p and miR-199a-3p as new biomarkers of neonatal sepsis

Background

Neonatal sepsis is a serious condition. Recent clinical studies have indicated that microRNAs (miRNAs) are key players in the pathogenesis of sepsis, which could be used as biomarkers for this condition.

Patients and methods

A total of 90 neonates with sepsis and 90 healthy neonates were enrolled in this study. qRT-PCR was performed to measure the expression levels of serum miR-34a-5p and miR-199a-3p.

Results

miR-34a-5p and miR-199a-3p serum levels were significantly reduced in neonates with sepsis compared with those in healthy neonates (P = 0.006 and P = 0.001, respectively). Significant correlations of miR-34a-5p and miR-199a-3p with each of TLC, RDW, RBS, and C-reactive protein (CRP) as well as SNAPII were observed, indicating their associations with the severity of neonatal sepsis.

Conclusion

miR-34a-5p and miR-199a-3p may be useful as novel biomarkers in neonatal sepsis and may provide a new direction for its treatment.

Clinical presentation of secondary infectious complications in COVID-19 patients in intensive care unit treated with tocilizumab or standard of care

OBJECTIVES

The hypothesis of this study is that tocilizumab should affect common signs of infection due to its immunosuppressive properties. Primary aim of the study was to investigate whether the administration of tocilizumab to critically ill patients with COVID-19, led to a different clinical presentation of infectious complications compared to patients who did not receive tocilizumab. Secondary aim was investigating differences in laboratory parameters between groups.

METHODS

Single-centre retrospective study, enrolling COVID-19 patients who developed a microbiologically confirmed infectious complication [ventilator associated pneumonia or bloodstream infection] after intensive care unit [ICU] admission and either treated with tocilizumab or not [controls].

RESULTS

A total of 58 patients were included, 25 treated with tocilizumab and 33 controls. Median time from tocilizumab administration to infection onset was 10 days [range 2-26]. Patients were 78% male, with median age 65 years [range 45-79]. At first clinical presentation of the infectious event, the frequency of hypotension [11/25, 44% vs. 11/33, 33%], fever [8/25, 32% vs. 10/33, 30%] or hypothermia [0/25,0%, vs. 2/33, 6%], and oxygen desaturation [6/25, 28% vs 4/33, 12%], as well as the frequency of SOFA score increase of ≥ 2 points [4/25, 16%,vs. 4/33, 12%] was similar in tocilizumab treated patients and controls [p>0.1 for all comparisons]. Among laboratory parameters, C-Reactive Protein elevation was reduced in tocilizumab treated patients compared to controls [8/25, 32% vs. 22/33, 67%, p=0.009].

CONCLUSION

The clinical features of infectious complications in critically ill patients with COVID-19 admitted to ICU were not affected by tocilizumab.

Factors associated with the appropriate use of ultra-broad spectrum antibiotics, meropenem, for suspected healthcare-associated pneumonia

Pneumonia is a common disease-causing hospitalization. When a healthcare-associated infection is suspected, antibiotics that provide coverage for multi-drug resistant (MDR) or extended-spectrum beta-lactamase (ESBL) bacteria are frequently prescribed. Limited data is available for guidance on using meropenem as a first-line empiric antimicrobial in hospitalized patients with risk factors for MDR/ESBL bacterial infections.This was a single-center, retrospective study designed and conducted to identify factors associated with positive cultures for MDR/ESBL pathogens in hospitalized patients with suspected healthcare-associated pneumonia.Of the 246 patients, 103 patients (41%) received meropenem. Among patients prescribed meropenem, MDR/ESBL pathogens were detected in only 20 patients (13%). Patients admitted from a skilled nursing facility/long-term acute care (SNF/LTAC) or with a history of a positive culture for MDR/ESBL pathogens were significantly associated with positive cultures of MDR/ESBL pathogens during the hospitalization (odds ratio [95% confidence intervals], 31.40 [5.20-189.6] in SNF/LTAC and 18.50 [2.98-115.1] in history of culture-positive MDR/ESBL pathogen). There was no significant difference in mortality between the 3 antibiotic groups.Admission from a SNF/LTAC or having a history of cultures positive for MDR/ESBL pathogens were significantly associated with a positive culture for MDR/ESBL pathogens during the subsequent admission. We did not detect significant association between meropenem use as a first-line drug and morbidity and mortality for patients admitted to the hospital with suspected healthcare-associated pneumonia, and further prospective studies with larger sample size are needed to confirm our findings.

Toward Rapid Detection of Viable Bacteria in Whole Blood for Early Sepsis Diagnostics and Susceptibility Testing

Sepsis is a serious bloodstream infection where the immunity of the host body is compromised, leading to organ failure and death of the patient. In early sepsis, the concentration of bacteria is very low and the time of diagnosis is very critical since mortality increases exponentially with every hour after infection. Common culture-based methods fail in fast bacteria determination, while recent rapid diagnostic methods are expensive and prone to false positives. In this work, we present a sepsis kit for fast detection of bacteria in whole blood, here achieved by combining selective cell lysis and a sensitive colorimetric approach detecting as low as 10³ CFU/mL bacteria in less than 5 h. Homemade selective cell lysis buffer (combination of saponin and sodium cholate) allows fast processing of whole blood in 5 min while maintaining bacteria alive (100% viability). After filtration, retained bacteria on filter paper are incubated under constant illumination with the electrochromic precursors, i.e., ferricyanide and ferric ammonium citrate. Viable bacteria metabolically reduce iron(III) complexes, initiating a photocatalytic cascade toward Prussian blue formation. As a proof of concept, we combine this method with antibiotic susceptibility testing to determine the minimum inhibitory concentration (MIC) using two antibiotics (ampicillin and gentamicin). Although this kit is used to demonstrate its applicability to sepsis, this approach is expected to impact other key sectors such as hygiene evaluation, microbial contaminated food/beverage, or UTI, among others.

Can acute-phase response biomarkers differentiate infection from inflammation postpediatric cardiac surgery?

Background:

Infection is a common serious complication postpediatric cardiac surgery. Diagnosis of infection after cardiopulmonary bypass (CPB) is difficult in the presence of surgical stress, hemodynamic instability, and inflammatory reaction.

Aim:

The purpose of this study is to investigate the value of available inflammatory biomarkers and its validity to differentiate infection from inflammation postpediatric cardiac surgery and to find the trend and the change in the level of these biomarkers shortly after cardiac surgery.

Methods:

We conducted a prospective study that included all children who underwent cardiac surgery in Prince Sultan Cardiac Centre-Qassim from November 2013 to October 2015. C-reactive protein, erythrocyte sedimentation rate, white blood cell count, and neutrophil count were measured for all patients presurgery, 4 consecutive days postsurgery, and predischarge. Patients were divided into two groups (the infected and the noninfected group). We compared the level of biomarkers between both groups. Then, we further analyzed the effects of CPB and preoperative steroid on postoperative inflammatory biomarker levels. Collected data were then reviewed and analyzed.

Results:

There were 134 pediatric cardiac patients included during the study period. Group 1 (bacterial negative culture group) had 125 cases and Group 2 (bacterial positive culture group) had nine cases. We found no statistically significant difference in inflammatory biomarker elevation between both groups. Only Group 2 had higher (RACHS) Risk adjustment for congenital heart surgery score, more ventilator days, and more drop in platelet count on the 2^nd and 3^rd postoperative days in comparison with the noninfected group 1. Both groups of patients who were in on and off CPB had the same level of inflammatory biomarkers with no significant differences. Giving corticosteroid preoperatively did not affect the trend of biomarker elevation and made no difference when it was compared to the group of patients who did not receive corticosteroid before surgery.

Conclusion:

Common inflammatory biomarkers cannot differentiate between infection and inflammation within the first 5 days postpediatric cardiac surgery as these reflect the inflammatory process rather than infection. Trend is more important than single reading.

Antibiotic prescribing for lower UTI in elderly patients in primary care and risk of bloodstream infection: A cohort study using electronic health records in England

BACKGROUND

Research has questioned the safety of delaying or withholding antibiotics for suspected urinary tract infection (UTI) in older patients. We evaluated the association between antibiotic treatment for lower UTI and risk of bloodstream infection (BSI) in adults aged ≥65 years in primary care.

METHODS AND FINDINGS

We analyzed primary care records from patients aged ≥65 years in England with community-onset UTI using the Clinical Practice Research Datalink (2007-2015) linked to Hospital Episode Statistics and census data. The primary outcome was BSI within 60 days, comparing patients treated immediately with antibiotics and those not treated immediately. Crude and adjusted associations between exposure and outcome were estimated using generalized estimating equations. A total of 147,334 patients were included representing 280,462 episodes of lower UTI. BSI occurred in 0.4% (1,025/244,963) of UTI episodes with immediate antibiotics versus 0.6% (228/35,499) of episodes without immediate antibiotics. After adjusting for patient demographics, year of consultation, comorbidities, smoking status, recent hospitalizations, recent accident and emergency (A&E) attendances, recent antibiotic prescribing, and home visits, the odds of BSI were equivalent in patients who were not treated with antibiotics immediately and those who were treated on the date of their UTI consultation (adjusted odds ratio [aOR] 1.13, 95% CI 0.97-1.32, p-value = 0.105). Delaying or withholding antibiotics was associated with increased odds of death in the subsequent 60 days (aOR 1.17, 95% CI 1.09-1.26, p-value < 0.001), but there was limited evidence that increased deaths were attributable to urinary-source BSI. Limitations include overlap between the categories of immediate and delayed antibiotic prescribing, residual confounding underlying differences between patients who were/were not treated with antibiotics, and lack of microbiological diagnosis for BSI.

CONCLUSIONS

In this study, we observed that delaying or withholding antibiotics in older adults with suspected UTI did not increase patients' risk of BSI, in contrast with a previous study that analyzed the same dataset, but mortality was increased. Our findings highlight uncertainty around the risks of delaying or withholding antibiotic treatment, which is exacerbated by systematic differences between patients who were and were not treated immediately with antibiotics. Overall, our findings emphasize the need for improved diagnostic/risk prediction strategies to guide antibiotic prescribing for suspected UTI in older adults.

Appropriateness of antibiotic prescribing in the Emergency Department

Background

Antibiotics are some of the most commonly prescribed drugs in the Emergency Department (ED) and yet data describing the overall appropriateness of antibiotic prescribing in the ED is scarce.

Objectives

To describe the appropriateness of antibiotic prescribing in the ED.

Methods

A retrospective, observational study of current practice. All patients who presented to the ED during the study period and were prescribed at least one antibiotic were included. Specialists from Infectious Disease, Microbiology and Emergency Medicine and a Senior Pharmacist assessed antibiotic appropriateness against evidence-based guidelines.

Results

A total of 1019 (13.6%) of patient presentations involved the prescription of at least one antibiotic. Of these, 640 (62.8%) antibiotic prescriptions were assessed as appropriate, 333 (32.7%) were assessed as inappropriate and 46 (4.5%) were deemed to be not assessable. Adults were more likely to receive an inappropriate antibiotic prescription than children (36.9% versus 22.9%; difference 14.1%, 95% CI 7.2%–21.0%). Patients who met quick Sepsis-related Organ Failure Assessment (qSOFA) criteria were more likely to be prescribed inappropriate antibiotics (56.7% versus 36.1%; difference 20.5%, 95% CI, 2.4%–38.7%). There was no difference in the incidence of appropriate antibiotic prescribing based on patient gender, disposition (admitted/discharged), reason for antibiotic administration (treatment/prophylaxis) or time of shift (day/night).

Conclusions

Inappropriate administration of antibiotics can lead to unnecessary adverse events, treatment failure and antimicrobial resistance. With over one in three antibiotic prescriptions in the ED being assessed as inappropriate, there is a pressing need to develop initiatives to improve antibiotic prescribing to prevent antibiotic-associated patient and community harms.

Clinical outcomes of empirical high-dose meropenem in critically ill patients with sepsis and septic shock: a randomized controlled trial

Background

Appropriate antimicrobial dosing is challenging because of changes in pharmacokinetics (PK) parameters and an increase in multidrug-resistant (MDR) organisms in critically ill patients. This study aimed to evaluate the effects of an empirical therapy of high-dose versus standard-dose meropenem in sepsis and septic shock patients.

Methods

We performed a prospective randomized open-label study to compare the changes of modified sequential organ failure assessment (mSOFA) score and other clinical outcomes of the high-dose meropenem (2-g infusion over 3 h every 8 h) versus the standard-dose meropenem (1-g infusion over 3 h every 8 h) in sepsis and septic shock patients. Patients' characteristics, clinical and microbiological outcomes, 14 and 28-day mortality, vasopressor- and ventilator-free days, intensive care unit (ICU) and hospital-free days, percent of the time of antibiotic concentrations above the minimum inhibitory concentration (%T>MIC), and safety were assessed.

Results

Seventy-eight patients were enrolled. Median delta mSOFA was comparable between two groups (- 1 in the high-dose group vs. - 1 in the standard-dose group; P value = 0.75). There was no difference between the two groups regarding clinical and microbiological cure, 14- and 28-day mortality, vasopressor- and ventilator-free days, and ICU- and hospital-free days. In patients admitted from the emergency department (ED) with a mSOFA score ≥ 7, the high-dose group demonstrated significantly better microbiological cure compared with the standard-dose group (75% (9/12 patients) vs. 20% (2/10 patients); P value = 0.03). Likewise, the high-dose group presented higher microbiological cure rate in patients admitted from ED who had either APACHE II score > 20 (83.3% (10/12) vs. 28.6% (2/7); P value = 0.045) or on mechanical ventilator (87.5% (7/8) vs. 23.1% (3/13); P value = 0.008) than the standard-dose group. Adverse events were comparable between the two groups.

Conclusions

Empirical therapy with the high-dose meropenem presented comparable clinical outcomes to the standard-dose meropenem in sepsis and septic shock patients. Besides, subgroup analysis manifested superior microbiological cure rate in sepsis or septic shock patients admitted from ED.

Trial registration

ClinicalTrials.gov, NCT03344627, registered on November 17, 2017.

Culture-Negative and Culture-Positive Sepsis: A Comparison of Characteristics and Outcomes

BACKGROUND

The primary objective of this study was to compare the characteristics of culture-positive and culture-negative status in septic patients. We also determined whether culture status is associated with mortality and whether unique variables are associated with mortality in culture-positive and culture-negative patients separately.

METHODS

Utilizing patient records from intensive care units, emergency department, and general care wards in a large academic medical center, we identified adult patients with suspected infection and ≥2 systemic inflammatory response syndrome criteria between January 1, 2007, and May 31, 2014. We compared the characteristics between culture-positive and culture-negative patients and used binary logistic regression to identify variables independently associated with culture status and mortality. We also did sensitivity analyses using patients with Sequential Organ Failure Assessment and quick Sequential Organ Failure Assessment criteria for sepsis.

RESULTS

The study population included 9288 culture-negative patients (89%) and 1105 culture-positive patients (11%). Culture-negative patients received more antibiotics during the 48 hours preceding diagnosis but otherwise demonstrated similar characteristics as culture-positive patients. After adjusting for illness severity, a positive culture was not independently associated with mortality (odds ratio = 1.01 [95% CI, 0.81-1.26]; P = .945). The models predicting mortality separately in culture-negative and culture-positive patients demonstrated very good and excellent discrimination (C-statistic ± SD, 0.87 ± 0.01 and 0.92 ± 0.01), respectively. In the sensitivity analyses using patients with sepsis by Sequential Organ Failure Assessment and quick Sequential Organ Failure Assessment criteria, after adjustments for illness severity, positive cultures were still not associated with mortality (odds ratio = 1.13 [95% CI, 0.86-1.43]; P = .303; and odds ratio = 1.05 [95% CI, 0.83-1.33]; P = .665), respectively. In all models, physiological derangements were associated with mortality.

CONCLUSIONS

While culture status is important for tailoring antibiotics, culture-negative and culture-positive patients with sepsis demonstrate similar characteristics and, after adjusting for severity of illness, similar mortality. The most important factor associated with negative cultures is receipt of antibiotics during the preceding 48 hours. The risk of death in patients suspected of having an infection is most associated with severity of illness. This is aligned with the Sepsis-3 definition using Sequential Organ Failure Assessment score to better identify those suspected of infection at highest risk of a poor outcome.

Analysis Of Blood Culture Results Of Burn Septicaemia Patients Over A Period Of Nine Years In The Baghdad Burn Medical Centre

Burn is one of the most devastating traumas that someone can encounter in their life. Burn wound sepsis is still the leading cause of death in burned patients. Appropriate knowledge of the causative pathogen in burn sepsis is important for successful patient management and for the reduction of the incidence of antibiotic resistance. A retrospective study was conducted between 2010 and 2018 at the Burn Specialty Hospital in Baghdad. A total of 320 blood culture samples were obtained from patients with sepsis or suspected of having sepsis. Patient age ranged between 9 months to 70 years old, with a mean total burn surface area of 45.26%. The most common microorganisms isolated from those patients who had sepsis or suspicion of sepsis were Klebsiella (48 cases) followed by Pseudomonas (36 cases), Staphylococcus species (26 cases), Enterococcus (8 cases), Acinetobacter (11 cases), E-Coli (11 cases), Candida (4 cases), Proteus (2 cases), and Salmonella, Streptococcus pneumonia, Monilia, and Seriata one case for each. The most commonly isolated organism was Klebsiella: it was sensitive to Imipenem followed by Amikacin, Nitrofurantoin, Piperacillin, Ciprofloxacin, Co-trimoxazole, Chloramphenicol, Tetracycline, Azithromycin and Cefotaxime. Microbiological surveillance of burn patients with sepsis or suspicion of having sepsis over a period of 9 years in our hospital has shown that the most common microorganism isolated from blood cultures was Klebsiella. Klebsiella was sensitive to Imipenem mainly according to sensitivity testing using the disk diffusion method.

New markers for sepsis caused by Pseudomonas aeruginosa during burn infection

INTRODUCTION

Sepsis is a leading cause of mortality in burn patients. One of the major causes of sepsis in burn patients is Pseudomonas aeruginosa. We hypothesized that during dissemination from infected burn wounds and subsequent sepsis, P. aeruginosa affects the metabolome of the blood resulting in changes to specific metabolites that would serve as biomarkers for early diagnosis of sepsis caused by P. aeruginosa.

OBJECTIVES

To identify specific biomarkers in the blood after sepsis caused by P. aeruginosa infection of burns.

METHODS

Gas chromatography with time-of-flight mass spectrometry was used to compare the serum metabolome of mice that were thermally injured and infected with P. aeruginosa (B-I) to that of mice that were neither injured nor infected, mice that were injured but not infected, and mice that were infected but not injured.

RESULTS

Serum levels of 19 metabolites were significantly increased in the B-I group compared to controls while levels of eight metabolites were significantly decreased. Thymidine, thymine, uridine, and uracil (related to pyrimidine metabolism), malate and succinate (a possible sign of imbalance in the tricarboxylic acid cycle), 5-oxoproline (related to glutamine and glutathione metabolism), and trans-4-hydroxyproline (a major component of the protein collagen) were increased. Products of amino acid metabolism were significantly decreased in the B-I group, including methionine, tyrosine, indole-3-acetate, and indole-3-propionate.

CONCLUSION

In all, 26 metabolites were identified, including a unique combination of five metabolites (trans-4-hydroxyproline, 5-oxoproline, glycerol-3-galactoside, indole-3-acetate, and indole-3-propionate) that could serve as a set of biomarkers for early diagnosis of sepsis caused by P. aeruginosa in burn patients.

Clinical significance of miR-181a in patients with neonatal sepsis and its regulatory role in the lipopolysaccharide-induced inflammatory response

Neonatal sepsis (NS) poses a serious threat to the health of neonates worldwide. The present study aimed to investigate the diagnostic value of microRNA (miR)-181a in patients with NS and the regulatory role of miR-181a in lipopolysaccharide (LPS)-induced inflammation. A total of 102 neonates with NS and 50 neonates without sepsis were enrolled in the present study. The serum levels of miR-181a were estimated using reverse transcription-quantitative PCR. Receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic value of miR-181a for NS. The effect of miR-181a on the expression of Toll-like receptor (TLR)4 was assessed after modification of the expression of miR-181a in monocytes isolated from the blood of neonates in vitro. An ELISA was used to measure the concentration of inflammatory cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-8 in the supernatant of monocytes. The serum levels of miR-181a were decreased in patients with NS compared with those in the controls. The area under the ROC curve of miR-181a was 0.893 with a sensitivity of 83.3% and a specificity of 84.0%. LPS stimulation in monocytes also led to a decrease in the expression of miR-181a. TLR4 was proven to be a direct target gene of miR-181a, according to the results of a luciferase reporter assay, and overexpression of miR-181a suppressed TLR4 expression in monocytes. Regarding LPS-induced inflammation, it was revealed that the upregulated levels of TNF-α and IL-8 induced by LPS were reduced by overexpression of miR-181a in monocytes. In conclusion, decreased serum levels of miR-181a may serve as a diagnostic biomarker in patients with NS and overexpression of miR-181a inhibits the LPS-induced inflammatory response at least partially by targeting TLR4. Aberrant miR-181a may be a non-invasive biomarker for NS patients, and provide a novel insight into the pathologic mechanisms of action behind the development of NS.

The value of procalcitonin in systemic inflammatory response syndrome after open-heart surgery for CHD

BAKGROUND

Systemic inflammatory response syndrome, which is marked by fever, is a possible complication after open-heart surgery for CHD. The inflammatory response following the use of cardiopulmonary bypass shows similar clinical signs with sepsis. Therefore serial measurements of procalcitonin, an early infection marker, can be helpful to differentiate between sepsis and systemic inflammatory response syndrome.

OBJECTIVES

To evaluate serial levels of procalcitonin in children who underwent open-heart surgery for cyanotic and acyanotic CHD, and identify factors associated with elevated level of procalcitonin.

METHODS

Children and infants who had open-heart surgery and showed fever within 6 hours after surgery were recruited. Procalcitonin levels were serially measured along with leukocyte and platelet count. Other data were also recorded, including diagnosis, age, body weight, axillary temperature, aortic clamp time, bypass time, duration of mechanical ventilation, risk adjustment for congenital heart surgery score-1, and length of stay in Cardiac ICU. The patients were categorised into cyanotic and acyanotic CHD groups.

RESULTS

High mean of procalcitonin level suggested the presence of bacterial infection. Cyanotic CHD group had significantly higher mean of procalcitonin level compared to acyanotic CHD group in the first two measurements. Both groups had no leukocytosis, though platelet count results were significantly different between the two groups. There was no significant difference of procalcitonin level observed in culture results and adverse outcomes.

CONCLUSION

Serial procalcitonin measurement can be helpful to determine the cause of fever. Meanwhile other conventional markers such as leukocyte and platelet should be assessed thoroughly.

Procalcitonin: Where Are We Now?

Procalcitonin is a biomarker that is generally elevated in bacterial infections. This review describes a conceptual framework for biomarkers using lessons from the history of troponin, applies this framework to procalcitonin with a review of observational studies and randomized trials in and out of the intensive care unit, and concludes with clinical recommendations and thoughts on how to test a test.

Epidemiology of Community-Acquired Sepsis in Adult Patients: A Six Year Observational Study

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to an infection and it is a major cause of morbidity and mortality worldwide. The aim of this study is to describe epidemiology of community-acquired sepsis in the Intensive care unit (ICU) of the Macedonian tertiary care University Clinic for Infectious Diseases. A prospective observational study was conducted over a 6-year period from January, 2011 to December, 2016. All consecutive adults with community-acquired sepsis or septic shock were included in the study. Variables measured were incidence of sepsis, age, gender, comorbidities, season, source of infection, complications, interventions, severity indexes, length of stay, laboratory findings, blood cultures, 28-day and in hospital mortality. Of 1348 admissions, 277 (20.5%) had sepsis and septic shock. The most common chronic condition was heart failure (26.4%), and the most frequent site of infection was the respiratory tract (57.4%). Median Simplified Acute Physiology Score (SAPS II) was 50.0, and median Sequential Organ Failure Assessment (SOFA) score was 8.0. Blood cultures were positive in 22% of the cases. Gram-positive bacteria were isolated in 13% and Gram-negatives in 9.7% of patients with sepsis. The overall 28-day and in hospital mortality was 50.5% and 56.3% respectively. The presence of chronic heart failure, occurrence of ARDS, septic shock and the winter period may influence an unfavorable outcome. Mortality compared to previous years is unchanged but patients that we have been treating these last 6 years have had more severe illnesses. Better adherence to the Surviving Sepsis guidelines will reduce mortality in this group of severely ill patients.

Mesenchymal stromal cell-derived nanovesicles ameliorate bacterial outer membrane vesicle-induced sepsis via IL-10

Background

Sepsis remains a source of high mortality in hospitalized patients despite proper antibiotic approaches. Encouragingly, mesenchymal stromal cells (MSCs) and their produced extracellular vesicles (EVs) have been shown to elicit anti-inflammatory effects in multiple inflammatory conditions including sepsis. However, EVs are generally released from mammalian cells in relatively low amounts, and high-yield isolation of EVs is still challenging due to a complicated procedure. To get over these limitations, vesicles very similar to EVs can be produced by serial extrusions of cells, after which they are called nanovesicles (NVs). We hypothesized that MSC-derived NVs can attenuate the cytokine storm induced by bacterial outer membrane vesicles (OMVs) in mice, and we aimed to elucidate the mechanism involved.

Methods

NVs were produced from MSCs by the breakdown of cells through serial extrusions and were subsequently floated in a density gradient. Morphology and the number of NVs were analyzed by transmission electron microscopy and nanoparticle tracking analysis. Mice were intraperitoneally injected with Escherichia coli-derived OMVs to establish sepsis, and then injected with 2 × 10⁹ NVs. Innate inflammation was assessed in peritoneal fluid and blood through investigation of infiltration of cells and cytokine production. The biodistribution of NVs labeled with Cy7 dye was analyzed using near-infrared imaging.

Results

Electron microscopy showed that NVs have a nanometer-size spherical shape and harbor classical EV marker proteins. In mice, NVs inhibited eye exudates and hypothermia, signs of a systemic cytokine storm, induced by intraperitoneal injection of OMVs. Moreover, NVs significantly suppressed cytokine release into the systemic circulation, as well as neutrophil and monocyte infiltration in the peritoneum. The protective effect of NVs was significantly reduced by prior treatment with anti-interleukin (IL)-10 monoclonal antibody. In biodistribution study, NVs spread to the whole mouse body and localized in the lung, liver, and kidney at 6 h.

Conclusions

Taken together, these data indicate that MSC-derived NVs have beneficial effects in a mouse model of sepsis by upregulating the IL-10 production, suggesting that artificial NVs may be novel EV-mimetics clinically applicable to septic patients.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1352-4) contains supplementary material, which is available to authorized users.

Mice Fed an Obesogenic Western Diet, Administered Antibiotics, and Subjected to a Sterile Surgical Procedure Develop Lethal Septicemia with Multidrug-Resistant Pathobionts

Despite antibiotics and sterile technique, postoperative infections remain a real and present danger to patients. Recent estimates suggest that 50% of the pathogens associated with postoperative infections have become resistant to the standard antibiotics used for prophylaxis. Risk factors identified in such cases include obesity and antibiotic exposure. To study the combined effect of obesity and antibiotic exposure on postoperative infection, mice were allowed to gain weight on an obesogenic Western-type diet (WD), administered antibiotics and then subjected to an otherwise recoverable sterile surgical injury (30% hepatectomy). The feeding of a WD alone resulted in a major imbalance of the cecal microbiota characterized by a decrease in diversity, loss of Bacteroidetes, a bloom in Proteobacteria, and the emergence of antibiotic-resistant organisms among the cecal microbiota. When WD-fed mice were administered antibiotics and subjected to 30% liver resection, lethal sepsis, characterized by multiple-organ damage, developed. Notable was the emergence and systemic dissemination of multidrug-resistant (MDR) pathobionts, including carbapenem-resistant, extended-spectrum β-lactamase-producing Serratia marcescens, which expressed a virulent and immunosuppressive phenotype. Analysis of the distribution of exact sequence variants belonging to the genus Serratia suggested that these strains originated from the cecal mucosa. No mortality or MDR pathogens were observed in identically treated mice fed a standard chow diet. Taken together, these results suggest that consumption of a Western diet and exposure to certain antibiotics may predispose to life-threating postoperative infection associated with MDR organisms present among the gut microbiota.IMPORTANCE Obesity remains a prevalent and independent risk factor for life-threatening infection following major surgery. Here, we demonstrate that when mice are fed an obesogenic Western diet (WD), they become susceptible to lethal sepsis with multiple organ damage after exposure to antibiotics and an otherwise-recoverable surgical injury. Analysis of the gut microbiota in this model demonstrates that WD alone leads to loss of Bacteroidetes, a bloom of Proteobacteria, and evidence of antibiotic resistance development even before antibiotics are administered. After antibiotics and surgery, lethal sepsis with organ damage developed in in mice fed a WD with the appearance of multidrug-resistant pathogens in the liver, spleen, and blood. The importance of these findings lies in exposing how the selective pressures of diet, antibiotic exposure, and surgical injury can converge on the microbiome, resulting in lethal sepsis and organ damage without the introduction of an exogenous pathogen.

Safety of antimicrobial de-escalation for culture-negative severe pneumonia

Purpose

This study investigated the outcomes of antimicrobial de-escalation (ADE) based on mortality and the incidence of multi-drug resistant (MDR) pathogen occurrence in patients with culture-negative pneumonia presenting with sepsis and septic shock.

Materials and Methods

We retrospectively analyzed patients diagnosed with severe pneumonia requiring intensive care unit (ICU) admission and possessing negative microbiological culture results at a tertiary referral hospital in South Korea from March 2008 to July 2018.

Results

We identified 107 patients with culture-negative pneumonia. The Acute Physiologic and Chronic Health Evaluation (APACHE) II and Sepsis-related Organ Failure Assessment (SOFA) mean scores were 20.3 ± 8.6 and 9.6 ± 3.3, respectively. Among the patients, 40 (37.4%) underwent ADE. The APACHE II, SOFA, and follow-up SOFA scores did not differ significantly between the groups, and no differences were found in ICU mortality and MDR pathogen occurrence (27.5% vs 41.8%, P = .137 and 15.0% vs 16.9% P = .794, respectively).

Conclusions

We observed similar ICU mortality and MDR pathogen occurrence in patients with culture-negative pneumonia presenting with sepsis/shock regardless of whether they received ADE. Additionally, ADE lowered the antimicrobial burden.

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MDR pathogen occurrence was not reduced in patients who underwent ADE.

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ADE was not significantly associated with increased ICU mortality.

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Antimicrobial burden was significantly lower in ADE group.

Focus of infection and microbiological etiology in community-acquired infections in hospitalized adult patients in the Faroe Islands

BACKGROUND

The aim of the present study was to gain national data on the clinical and microbiological characteristics of community-acquired infections in the Faroe Islands and to compare these data with data from other geographical areas.

METHODS

A prospective, observational study involving all patients > = 16 years admitted at the Department of Medicine at the National Hospital, Torshavn, Faroe Islands from October 2013 until April 2015.

RESULTS

Of 5279 admissions, 1054 cases were with community-acquired infection and were included in the study. Out of these 1054 cases, 471 did not meet the criteria for SIRS (Systemic Inflammatory Response Syndrome), while the remaining 583 cases had sepsis. Mean age was 68 years. At least one comorbidity was found in 80% of all cases. Documented infections were present in 75%, and a plausible pathogen was identified in 29% of all cases. The most common gram-positive pathogen was Staphylococcus aureus, and the most frequent gram-negative pathogen was Escherichia coli. The most common focus of infection was lower respiratory tract, followed by urinary tract, and skin-soft tissue/bone-joint. Bacteremia was found in 10% of the cases.

CONCLUSION

In community-acquired infections in hospitalized patients in the Faroe Islands the lower respiratory tract and the urinary tract were the most frequent foci of infection. Gram-negative pathogens and Escherichia coli were the most frequent pathogens in infection without Systemic Inflammatory Response Syndrome, in sepsis and in bacteremia. Our data on clinical characteristics and microbiological etiology provide new information which may be used to develop local guidelines for the managing of patients admitted with community-acquired infections.

Expression Levels of Candidate Circulating microRNAs in Early-Onset Neonatal Sepsis Compared With Healthy Newborns

The high mortality rate of neonatal sepsis is directly connected with time-consuming diagnostic methods that have low sensitivity and specificity. The need of the hour is to develop novel diagnostic techniques that are rapid and more specific. In this study, we estimated the expression levels of circulating microRNAs (miRNAs) that are involved in regulating immune response genes and underlying inflammatory responses, which may be used for sepsis diagnosis. The total circulating miRNA was isolated and the candidate miRNAs (miR-132, miR-146a, miR-155, and miR-223) were quantified by real-time polymerase chain reaction technique. Statistical analysis revealed that miR-132 (P < .01) and miR-223 (P < .05) were downregulated in septic newborns compared with healthy babies. The decrease in expression of miR-132 and miR-223 may be associated with increased expression of immune-related genes involved in TLR (Toll-like receptor) signaling pathway. Further case-control studies with large sample size are required to identify the potential of miRNAs in neonatal sepsis diagnosis.

Detection of sepsis in patient blood samples using CD64 expression in a microfluidic cell separation device

A microfluidic affinity separation device was developed for the detection of sepsis in critical care patients.

Application of the 2016 EULAR/ACR/PRINTO Classification Criteria for Macrophage Activation Syndrome in Patients with Adult-onset Still Disease

OBJECTIVE

To evaluate the clinical significance of the 2016 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR)/Pediatric Rheumatology International Trials Organization (PRINTO) classification criteria for macrophage activation syndrome (MAS) in patients with adult-onset Still disease (AOSD).

METHODS

We performed a retrospective analysis of patients with AOSD with fever who were admitted to Severance Hospital between 2005 and 2016. The patients with AOSD were evaluated for MAS using the 2016 classification criteria for MAS. Clinical features, laboratory findings, and overall survival were analyzed. Logistic regression analysis was used to evaluate the factors associated with in-hospital mortality.

RESULTS

Among 64 patients with AOSD, 36 (56.3%) were classified as having MAS. The overall survival rate was significantly lower in patients with MAS than in those without (67% vs 100%, p < 0.001). Multivariate analysis showed that a low erythrocyte sedimentation rate, a low albumin level, an increase in ferritin of over 2 folds, and the development of MAS on admission were significantly associated with mortality in patients with AOSD.

CONCLUSION

The 2016 EULAR/ACR/PRINTO classification criteria for MAS are potentially useful for the identification of patients with AOSD at high risk for a poor outcome. Febrile patients with AOSD should be monitored with the 2016 classification criteria for MAS in the early diagnosis and proper treatment of MAS.

Urine metabolomics in neonates with late-onset sepsis in a case-control study

Although late-onset sepsis (LOS) is a major cause of neonatal morbidity and mortality, biomarkers evaluated in LOS lack high diagnostic accuracy. In this prospective, case-control, pilot study, we aimed to determine the metabolic profile of neonates with LOS. Urine samples were collected at the day of initial LOS evaluation, the 3^rd and 10^th day, thereafter, from 16 septic neonates (9 confirmed and 7 possible LOS cases) and 16 non-septic ones (controls) at respective time points. Urine metabolic profiles were assessed using non-targeted nuclear magnetic resonance spectroscopy and targeted liquid chromatography-tandem mass spectrometry analysis. Multivariate statistical models with data from either analytical approach showed clear separation between the metabolic profiles of septic neonates (both possible and confirmed) and the controls. Metabolic changes appeared to be related to disease progression. Overall, neonates with confirmed or possible LOS exhibited comparable metabolic profiles indicating similar metabolic alternations upon the onset of clinical manifestations. This methodology therefore enabled the discrimination of neonates with LOS from non-septic individuals, providing potential for further research toward the discovery of LOS-related biomarkers.

Source Identification and Source Control

Identifying sources of infection and establishing source control is an essential component of the workup and treatment of sepsis. Investigation with history, physical examination, laboratory tests, and imaging can in identifying sources of infection. All organ systems have the potential to develop sources of infection. However, there are inherent difficulties presented by some that require additional diligence, namely, urinalysis, chest radiographs, and intraabdominal infections. Interventions include administration of antibiotics and may require surgical or other specialist intervention. This is highlighted by the Surviving Sepsis Campaign with specific recommendations for time to antibiotics and expeditious time to surgical source control.

The detection of microbial DNA but not cultured bacteria is associated with increased mortality in patients with suspected sepsis-a prospective multi-centre European observational study

OBJECTIVES

Blood culture results inadequately stratify the mortality risk in critically ill patients with sepsis. We sought to establish the prognostic significance of the presence of microbial DNA in the bloodstream of patients hospitalized with suspected sepsis.

METHODS

We analysed the data collected during the Rapid Diagnosis of Infections in the Critically Ill (RADICAL) study, which compared a novel culture-independent PCR/electrospray ionization-mass spectrometry (ESI-MS) assay with standard microbiological testing. Patients were eligible for the study if they had suspected sepsis and were either hospitalized or were referred to one of nine intensive care units from six European countries. The blood specimen for PCR/ESI-MS assay was taken along with initial blood culture taken for clinical indications.

RESULTS

Of the 616 patients recruited to the RADICAL study, 439 patients had data on outcome, results of the blood culture and PCR/ESI-MS assay available for analysis. Positive blood culture and PCR/ESI-MSI result was found in 13% (56/439) and 40% (177/439) of patients, respectively. Either a positive blood culture (p 0.01) or a positive PCR/ESI-MS (p 0.005) was associated with higher SOFA scores on enrolment to the study. There was no difference in 28-day mortality observed in patients who had either positive or negative blood cultures (35% versus 32%, p 0.74). However, in patients with a positive PCR/ESI-MS assay, mortality was significantly higher in comparison to those with a negative result (42% versus 26%, p 0.001).

CONCLUSIONS

Presence of microbial DNA in patients with suspected sepsis might define a patient group at higher risk of death.

Septic shock with no diagnosis at 24 hours: a pragmatic multicenter prospective cohort study

Background

The lack of a patent source of infection after 24 hours of management of shock considered septic is a common and disturbing scenario. We aimed to determine the prevalence and the causes of shock with no diagnosis 24 hours after its onset, and to compare the outcomes of patients with early-confirmed septic shock to those of others.

Methods

We conducted a pragmatic, prospective, multicenter observational cohort study in ten intensive care units (ICU) in France. We included all consecutive patients admitted to the ICU with suspected septic shock defined by clinical suspicion of infection leading to antibiotic prescription plus acute circulatory failure requiring vasopressor support.

Results

A total of 508 patients were admitted with suspected septic shock. Among them, 374 (74 %) had early-confirmed septic shock, while the 134 others (26 %) had no source of infection identified nor microbiological documentation retrieved 24 hours after shock onset. Among these, 37/134 (28 %) had late-confirmed septic shock diagnosed after 24 hours, 59/134 (44 %) had a condition mimicking septic (septic shock mimicker, mainly related to adverse drug reactions, acute mesenteric ischemia and malignancies) and 38/134 (28 %) had shock of unknown origin by the end of the ICU stay. There were no differences between patients with early-confirmed septic shock and the remainder in ICU mortality and the median duration of ICU stay, of tracheal intubation and of vasopressor support. The multivariable Cox model showed that the risk of day-60 mortality did not differ between patients with or without early-confirmed septic shock. A sensitivity analysis was performed in the subgroup (n = 369/508) of patients meeting the Sepsis-3 definition criteria and displayed consistent results.

Conclusions

One quarter of the patients admitted in the ICU with suspected septic shock had no infection identified 24 hours after its onset and almost half of them were eventually diagnosed with a septic shock mimicker. Outcome did not differ between patients with early-confirmed septic shock and other patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1537-5) contains supplementary material, which is available to authorized users.

Escherichia coli Braun Lipoprotein (BLP) exhibits endotoxemia - like pathology in Swiss albino mice

The endotoxin lipopolysaccharide (LPS) promotes sepsis, but bacterial peptides also promote inflammation leading to sepsis. We found, intraperitoneal administration of live or heat inactivated E. coli JE5505 lacking the abundant outer membrane protein, Braun lipoprotein (BLP), was less toxic than E. coli DH5α possessing BLP in Swiss albino mice. Injection of BLP free of LPS purified from E. coli DH5α induced massive infiltration of leukocytes in lungs and liver. BLP activated human polymorphonuclear cells (PMNs) ex vivo to adhere to denatured collagen in serum and polymyxin B independent fashion, a property distinct from LPS. Both LPS and BLP stimulated the synthesis of platelet activating factor (PAF), a potent lipid mediator, in human PMNs. In mouse macrophage cell line, RAW264.7, while both BLP and LPS similarly upregulated TNF-α and IL-1β mRNA; BLP was more potent in inducing cyclooxygenase-2 (COX-2) mRNA and protein expression. Peritoneal macrophages from TLR2^−/− mice significantly reduced the production of TNF-α in response to BLP in contrast to macrophages from wild type mice. We conclude, BLP acting through TLR2, is a potent inducer of inflammation with a response profile both common and distinct from LPS. Hence, BLP mediated pathway may also be considered as an effective target against sepsis.

Rapid Isolation of Staphylococcus aureus Pathogens from Infected Clinical Samples Using Magnetic Beads Coated with Fc-Mannose Binding Lectin

Here we describe how Staphylococcus aureus bacteria can be rapidly isolated from clinical samples of articular fluid and synovial tissue using magnetic beads coated with the engineered chimeric human opsonin protein, Fc-mannose-binding lectin (FcMBL). The FcMBL-beads were used to capture and magnetically remove bacteria from purified cultures of 12 S. aureus strains, and from 8 articular fluid samples and 4 synovial tissue samples collected from patients with osteoarthritis or periprosthetic infections previously documented by positive S. aureus cultures. While the capture efficiency was high (85%) with purified S. aureus strains grown in vitro, direct FcMBL-bead capture from the clinical samples was initially disappointing (< 5% efficiency). Further analysis revealed that inhibition of FcMBL binding was due to coating of the bacteria by immunoglobulins and immune cells that masked FcMBL binding sites, and to the high viscosity of these complex biological samples. Importantly, capture of pathogens using the FcMBL-beads was increased to 76% efficiency by pretreating clinical specimens with hypotonic washes, hyaluronidase and a protease cocktail. Using this approach, S. aureus bacteria could be isolated from infected osteoarthritic tissues within 2 hours after sample collection. This FcMBL-enabled magnetic method for rapid capture and concentration of pathogens from clinical samples could be integrated upstream of current processes used in clinical microbiology laboratories to identify pathogens and perform antibiotic sensitivity testing when bacterial culture is not possible or before colonies can be detected.