An alternate pathophysiologic paradigm of sepsis and septic shock: implications for optimizing antimicrobial therapy

Plague: Clinics, Diagnosis and Treatment

Plague still poses a significant threat to human health and as a reemerging infection is unfamiliar to the majority of the modern medical doctors. In this chapter, the plague is described according to Dr. Nikiforov's experiences in the diagnosis and treatment of patients, and also a review of the relevant literature on this subject is provided. The main modern methods and criteria for laboratory diagnosis of plague are briefly described. The clinical presentations include the bubonic and pneumonic form, septicemia, rarely pharyngitis, and meningitis. Early diagnosis and the prompt initiation of treatment reduce the mortality rate associated with bubonic plague and septicemic plague to 5-50 %; although a delay of more than 24 h in the administration of antibiotics and antishock treatment can be fatal for plague patients. Most human cases can successfully be treated with antibiotics.

Colistin Population Pharmacokinetics after Application of a Loading Dose of 9 MU Colistin Methanesulfonate in Critically Ill Patients

Colistin has been revived, in the era of extensively drug-resistant (XDR) Gram-negative infections, as the last-resort treatment in critically ill patients. Recent studies focusing on the optimal dosing strategy of colistin have demonstrated the necessity of a loading dose at treatment initiation (D. Plachouras, M. Karvanen, L. E. Friberg, E. Papadomichelakis, A. Antoniadou, I. Tsangaris, I. Karaiskos, G. Poulakou, F. Kontopidou, A. Armaganidis, O. Cars, and H. Giamarellou, Antimicrob Agents Chemother 53:3430-3436, 2009, http://dx.doi.org/10.1128/AAC.01361-08; A. F. Mohamed, I. Karaiskos, D. Plachouras, M. Karvanen, K. Pontikis, B. Jansson, E. Papadomichelakis, A. Antoniadou, H. Giamarellou, A. Armaganidis, O. Cars, and L. E. Friberg, Antimicrob Agents Chemother 56:4241- 4249, 2012, http://dx.doi.org/10.1128/AAC.06426-11; S. M. Garonzik, J. Li, V. Thamlikitkul, D. L. Paterson, S. Shoham, J. Jacob, F. P. Silveira, A. Forrest, and R. L. Nation, Antimicrob Agents Chemother 55:3284-3294, 2011, http://dx.doi.org/10.1128/AAC.01733-10). In 19 critically ill patients with suspected or microbiologically documented infections caused by XDR Gram-negative strains, a loading dose of 9 MU colistin methanesulfonate (CMS) (∼ 270 mg colistin base activity) was administered with a maintenance dose of 4.5 MU every 12 h, commenced after 24 h. Patients on renal replacement were excluded. CMS infusion was given over 30 min or 1 h. Repeated blood sampling was performed after the loading dose and after the 5th or 6th dose. Colistin concentrations and measured CMS, determined after hydrolization to colistin and including the partially sulfomethylated derivatives, were determined with a liquid chromatography-tandem mass spectrometry assay. Population pharmacokinetic analysis was conducted in NONMEM with the new data combined with data from previous studies. Measured colistimethate concentrations were described by 4 compartments for distribution and removal of sulfomethyl groups, while colistin disposition followed a 1-compartment model. The average observed maximum colistin A plus B concentration was 2.65 mg/liter after the loading dose (maximum time was 8 h). A significantly higher availability of the measured A and B forms of colistimethate and colistin explained the higher-than-expected concentrations in the present study compared to those in previous studies. Creatinine clearance was a time-varying covariate of colistimethate clearance. The incidence of acute renal injury was 20%.

Timing of antibiotics, volume, and vasoactive infusions in children with sepsis admitted to intensive care

INTRODUCTION

Early administration of antibiotics for sepsis, and of fluid boluses and vasoactive agents for septic shock, is recommended. Evidence for this in children is limited.

METHODS

The Alberta Sepsis Network prospectively enrolled eligible children admitted to the Pediatric Intensive Care Unit (PICU) with sepsis from 04/2012-10/2014. Demographics, severity of illness, and outcomes variables were prospectively entered into the ASN database after deferred consent. Timing of interventions were determined by retrospective chart review using a study manual and case-report-form. We aimed to determine the association of intervention timing and outcome in children with sepsis. Univariate (t-test and Fisher's Exact) and multiple linear regression statistics evaluated predictors of outcomes of PICU length of stay (LOS) and ventilation days.

RESULTS

Seventy-nine children, age median 60 (IQR 22-133) months, 40 (51%) female, 39 (49%) with severe underlying co-morbidity, 44 (56%) with septic shock, and median PRISM-III 10.5 [IQR 6.0-17.0] were enrolled. Most patients presented in an ED: 36 (46%) at an outlying hospital ED, and 21 (27%) at the Children's Hospital ED. Most infections were pneumonia with/without empyema (42, 53%), meningitis (11, 14%), or bacteremia (10, 13%). The time from presentation to acceptable antibiotic administration was a median of 115.0 [IQR 59.0-323.0] minutes; 20 (25%) of patients received their antibiotics in the first hour from presentation. Independent predictors of PICU LOS were PRISM-III, and severe underlying co-morbidity, but not time to antibiotics. In the septic shock subgroup, the volume of fluid boluses given in the first 2 hours was independently associated with longer PICU LOS (effect size 0.22 days; 95% CI 0.5, 0.38; per ml/kg). Independent predictors of ventilator days were PRISM-III score and severe underlying co-morbidity. In the septic shock subgroup, volume of fluid boluses in the first 2 hours was independently associated with more ventilator days (effect size 0.09 days; 95% CI 0.02, 0.15; per ml/kg).

CONCLUSION

Higher volume of early fluid boluses in children with sepsis and septic shock was independently associated with longer PICU LOS and ventilator days. More study on the benefits and harms of fluid bolus therapy in children are needed.

Therapeutical Administration of Peptide Pep19-2.5 and Ibuprofen Reduces Inflammation and Prevents Lethal Sepsis

Sepsis is still a major cause of death and many efforts have been made to improve the physical condition of sepsis patients and to reduce the high mortality rate associated with this disease. While achievements were implemented in the intensive care treatment, all attempts within the field of novel therapeutics have failed. As a consequence new medications and improved patient stratification as well as a thoughtful management of the support therapies are urgently needed. In this study, we investigated the simultaneous administration of ibuprofen as a commonly used nonsteroidal anti-inflammatory drug (NSAID) and Pep19-2.5 (Aspidasept), a newly developed antimicrobial peptide. Here, we show a synergistic therapeutic effect of combined Pep19-2.5-ibuprofen treatment in an endotoxemia mouse model of sepsis. In vivo protection correlates with a reduction in plasma levels of both tumor necrosis factor α and prostaglandin E, as a likely consequence of Pep19-2.5 and ibuprofen-dependent blockade of TLR4 and COX pro-inflammatory cascades, respectively. This finding is further characterised and confirmed in a transcriptome analysis of LPS-stimulated human monocytes. The transcriptome analyses showed that Pep19-2.5 and ibuprofen exerted a synergistic global effect both on the number of regulated genes as well as on associated gene ontology and pathway expression. Overall, ibuprofen potentiated the anti-inflammatory activity of Pep19-2.5 both in vivo and in vitro, suggesting that NSAIDs could be useful to supplement future anti-sepsis therapies.

Empiric antimicrobial therapy in severe sepsis and septic shock: optimizing pathogen clearance

Mortality and morbidity in severe sepsis and septic shock remain high despite significant advances in critical care. Efforts to improve outcome in septic conditions have focused on targeted, quantitative resuscitation strategies utilizing intravenous fluids, vasopressors, inotropes, and blood transfusions to correct disease-associated circulatory dysfunction driven by immune-mediated systemic inflammation. This review explores an alternate paradigm of septic shock in which microbial burden is identified as the key driver of mortality and progression to irreversible shock. We propose that clinical outcomes in severe sepsis and septic shock hinge upon the optimized selection, dosing, and delivery of highly potent antimicrobial therapy.

The role of antimicrobials in the treatment of sepsis and critical illness-related bacterial infections: examination of the evidence

OBJECTIVE

To appraise the evidence behind the Surviving Sepsis Campaign Guidelines on antimicrobial therapy in sepsis and evaluate relevant literature in small animal veterinary critical care.

DATA SOURCE

Electronic searches using MEDLINE and EMBASE databases.

HUMAN DATA SYNTHESIS

Current recommendations are to administer appropriate antimicrobials within 1 hour of a diagnosis of severe sepsis or septic shock. Evidence is supportive of this recommendation in septic shock but the evidence is less compelling in milder forms of critical illness-related infections. It is unclear when the administration of appropriate antimicrobials is most beneficial and when it should be considered essential. Evidence supports shorter courses of antimicrobial therapy for many infections seen in the critical care unit with the biomarkers procalcitonin and C-reactive protein helpful in guiding the duration of therapy.

VETERINARY DATA SYNTHESIS

Current evidence is lacking to support the use of early and aggressive use of antimicrobials in all patients with critical illness-related bacterial infections. Two studies failed to demonstrate improved survival in patients with pulmonary or abdominal infections administered appropriate vs inappropriate empirical antimicrobials. One study failed to show an improved survival when dogs with abdominal infections were administered antimicrobials within 1 hour vs 6 hours of diagnosis of infection. Information regarding ideal duration of antimicrobial therapy and use of biomarkers to guide therapy is currently lacking.

CONCLUSION

Clinicians should aim to administer early and appropriate antimicrobials; however, the impact this will have on patient outcome remains uncertain. The ability to administer early and appropriate antimicrobials may be considered a measure of the quality of medical practice rather than a prognostic indicator.

Association between source of infection and hospital mortality in patients who have septic shock

RATIONALE

Mortality caused by septic shock may be determined by a systemic inflammatory response, independent of the inciting infection, but it may also be influenced by the anatomic source of infection.

OBJECTIVES

To determine the association between the anatomic source of infection and hospital mortality in critically ill patients who have septic shock.

METHODS

This was a retrospective, multicenter cohort study of 7,974 patients who had septic shock in 29 academic and community intensive care units in Canada, the United States, and Saudi Arabia from January 1989 to May 2008.

MEASUREMENTS AND MAIN RESULTS

Subjects were assigned 1 of 20 anatomic sources of infection based on clinical diagnosis and/or isolation of pathogens. The primary outcome was hospital mortality. Overall crude hospital mortality was 52% (21-85% across sources of infection). Variation in mortality remained after adjusting for year of admission, geographic source of admission, age, sex, comorbidities, community- versus hospital-acquired infection, and organism type. The source of infection with the highest standardized hospital mortality was ischemic bowel (75%); the lowest was obstructive uropathy-associated urinary tract infection (26%). Residual variation in adjusted hospital mortality was not explained by Acute Physiology and Chronic Health Evaluation II score, number of Day 1 organ failures, bacteremia, appropriateness of empiric antimicrobials, or adjunct therapies. In patients who received appropriate antimicrobials after onset of hypotension, source of infection was associated with death after adjustment for both predisposing and downstream factors.

CONCLUSIONS

Anatomic source of infection should be considered in future trial designs and analyses, and in development of prognostic scoring systems.

Variability of linezolid concentrations after standard dosing in critically ill patients: a prospective observational study

Introduction

Severe infections in intensive care patients show high morbidity and mortality rates. Linezolid is an antimicrobial drug frequently used in critically ill patients. Recent data indicates that there might be high variability of linezolid serum concentrations in intensive care patients receiving standard doses. This study was aimed to evaluate whether standard dosing of linezolid leads to therapeutic serum concentrations in critically ill patients.

Methods

In this prospective observational study, 30 critically ill adult patients with suspected infections received standard dosing of 600 mg linezolid intravenously twice a day. Over 4 days, multiple serum samples were obtained from each patient, in order to determine the linezolid concentrations by liquid chromatography tandem mass spectrometry.

Results

A high variability of serum linezolid concentrations was observed (range of area under the linezolid concentration time curve over 24 hours (AUC₂₄) 50.1 to 453.9 mg/L, median 143.3 mg*h/L; range of trough concentrations (C_min) < 0.13 to 14.49 mg/L, median 2.06 mg/L). Furthermore, potentially subtherapeutic linezolid concentrations over 24 hours and at single time points (defined according to the literature as AUC₂₄ < 200 mg*h/L and C_min < 2 mg/L) were observed for 63% and 50% of the patients, respectively. Finally, potentially toxic levels (defined as AUC₂₄ > 400 mg*h/L and C_min > 10 mg/L) were observed for 7 of the patients.

Conclusions

A high variability of linezolid serum concentrations with a substantial percentage of potentially subtherapeutic levels was observed in intensive care patients. The findings suggest that therapeutic drug monitoring of linezolid might be helpful for adequate dosing of linezolid in critically ill patients.

Trial registration

Clinicaltrials.gov NCT01793012. Registered 24 January 2013.

Non-pulmonary infections but not specific pathogens are associated with increased risk of AKI in septic shock

INTRODUCTION

Little is known regarding the relationship between the anatomic infection site and etiologic pathogen with the occurrence of acute kidney injury (AKI) in severe infections. We set out to determine the association between the site of infection, type of pathogen in septic shock and occurrence of AKI.

METHODS

Using a large, international multicenter database that included data from 28 academic and community hospitals, we retrospectively analyzed adult (age >18 years) cases of septic shock occurring between January 1996 and December 2008. Early acute kidney injury (AKI) was classified by the RIFLE criteria at or within 24 h of shock diagnosis. Multivariate logistic regression was used to determine the association between the infection site/microbial pathogen and occurrence of AKI. Analyses were adjusted for demographics, illness severity, comorbidities and intensive care unit interventions (partial adjustment) ± site of infection and microbial pathogen (full adjustment).

RESULTS

After exclusions, 4,493 cases from potentially eligible patients in the database were included in the analytic cohort of whom 3,298 (73.4 %) experienced AKI. Patients with AKI were older (p < 0.0001), had a higher mean Acute Physiology and Chronic Health Evaluation score (p < 0.0001), and had greater laboratory and hemodynamic abnormalities. The most common site of infection among septic shock patients with AKI was the lung (34.5 %), followed by gastrointestinal (GI) (26.2 %) and urinary (15.3 %) sources. Likewise, the most common infecting organism among septic shock patients with AKI was E. coli (23.9 %) followed by S. aureus (GI) (16.1 %) and other enterobacteriaceae (15.7 %). There was a large degree of variability in the occurrence of AKI based on the site of infection and the pathogen in unadjusted analysis (p < 0.0001), which persisted with partial (excluding infection site and microbial pathogen grouping) adjustment (p < 0.0001). Fully adjusted multivariate analysis showed significant variations in AKI only in relation to the anatomic source of infection, with non-pulmonary infections having higher risk than pulmonary infections. The pathogen group/pathogen had no significant independent impact on AKI.

CONCLUSION

This study demonstrates that the presence of septic AKI varies significantly based on the site of infection but not the type of causative organism.