Bacteremic sepsis in intensive care: temporal trends in incidence, organ dysfunction, and prognosis

Prognostic Effects of Delayed Administration of Antimicrobial Therapy in Older Persons Experiencing Bacteremia With or Without Initial Sepsis Presentations

OBJECTIVES

To investigate the prognostic effects of delayed administration of appropriate antimicrobial therapy (AAT) in older persons experiencing bacteremia with and without initial sepsis syndrome, respectively.

DESIGN

A 4-year multicenter cohort study.

SETTING AND PARTICIPANTS

Older people (≥65 years of age) with community-onset bacteremia in the emergency department (ED) of 3 participating hospitals.

METHODS

Clinical data were retrospectively collected and causative microorganisms were prospectively collected for susceptibilities to determine the period of delayed AAT for each bacteremia episode. Sepsis was defined based on the Sepsis-3 criteria. A multivariable regression model was used to investigate the prognostic effects of delayed AAT, after adjusting independent determinants of 30-day mortality.

RESULTS

Of the total 2357 patients, their median (interquartile range) age was 78 (72-84) years and septic patients accounted for 48.4% (1140 patients) of the overall patients. Compared with nonseptic patients, septic individuals exhibited the shorter period of delayed AAT (median, 2.0 vs 2.5 hours; P < .001), longer hospitalization (median, 11 vs 9 days; P < .001), and higher crude mortality rates at 15 (28.9% vs 2.1%; P < .001) and 30 days (34.6% vs 4.0%; P < .001). In multivariable regression analyses, each hour of delayed AAT resulted in average increases in the 30-day crude mortality rates of 0.38% [adjusted odds ratio (AOR) 1.0038; P < .001), 0.42% (AOR 1.0042; P < .001), and 0.31% (AOR 1.0031; P = .04) among overall, septic, and nonseptic patients, respectively.

CONCLUSIONS AND IMPLICATIONS

For older persons with community-onset bacteremia, irrespective of whether or not patients experiencing initial sepsis presentations, the prognostic impacts of delayed AAT have been evidenced. Notably, because of the longer period of delayed AAT in patients without fulfilling the Sepsis-3, adopting a stricter sepsis definition and/or early bacteremia predictor to avoid delayed AAT and unfavorable prognoses in patients with bacteremia is necessary.

Afebrile Bacteremia in Adult Emergency Department Patients with Liver Cirrhosis: Clinical Characteristics and Outcomes

Cirrhotic patients with bacteremia are at an increased risk of organ failure and mortality. In addition, they can develop serious infection without fever because of their impaired immune response. Our study aimed to investigate the clinical characteristics and outcomes in afebrile bacteremic patients with liver cirrhosis. A single-center, retrospective cohort study was performed on adult patients who visited the emergency department from January 2015 to December 2018. All patients with bacteremia and diagnosis of liver cirrhosis were enrolled and classified as either afebrile or febrile. In total, 104 bacteremic patients with liver cirrhosis (afebrile: 55 patients and, febrile: 49) were included in the study. Compared with the febrile group, patients in the afebrile group showed a significantly higher rate of inappropriate antibiotics administration (43.6% vs. 20.4%, p = 0.01). They were also at an increased risk of 30-day mortality (40% vs. 18.4%, p = 0.02), intensive care unit transfer (38.2% vs. 18.4%, p = 0.03) and endotracheal intubation (27.3% vs. 10.2%, p = 0.03). The afebrile state was also an independent risk factor associated with 30-day mortality in cirrhotic patients with bacteremia. Clinicians should perform a prudent evaluation in cirrhotic patients and carefully monitor for possible signs of serious infection even in the absence of fever.

Incidence of coagulase-negative staphylococcal bacteremia among ICU patients: decontamination studies as a natural experiment

The epidemiology of coagulase-negative staphylococcal (CNS) bacteremia among adult ICU patients remains unclear. Decontamination studies among ICU patients provide a unique opportunity to study the impacts of different diagnostic criteria, exposure to various decontamination interventions, and various other factors, on its incidence over three decades. Decontamination studies among ICU patients reporting CNS bacteremia incidence data were obtained mostly from recent systematic reviews. The CNS bacteremia incidence within component (control and intervention) groups of decontamination studies was benchmarked versus studies without intervention (observational groups). The impacts of antibiotic versus chlorhexidine decontamination interventions, control group concurrency, publication year, and diagnostic criteria were examined in meta-regression models. Among non-intervention (observational) studies which did versus did not specify stringent (≥ 2 positive blood cultures) diagnostic criteria, the mean CNS bacteremia incidence per 100 patients (and 95% CI; n) is 1.3 (0.9–2.0; n = 23) versus 3.6 (1.8–6.9; n = 8), respectively, giving an overall benchmark of 1.8 (1.2–2.4; n = 31). Versus the benchmark incidence, the mean incidence is high among concurrent control (5.7; 3.6–9.1%) and intervention (5.2; 3.6–6.9%), but not non-concurrent control (1.0; 0.4–3.9%) groups of 21 antibiotic studies, nor among eleven component groups of chlorhexidine studies. This high incidence remained apparent (p < 0.01) in meta-regression models adjusting for group wide factors such as diagnostic criteria and publication year. The incidence of CNS bacteremia within both intervention and concurrent (but not non-concurrent) control groups of antibiotic-based decontamination studies are unusually high even accounting for variable diagnostic criteria and other factors.

The unmet need for addressing cardiac issues in intensive care research

OBJECTIVE

Patients with primary cardiovascular disorders and comorbidities are commonly admitted to ICUs; however, little is known about the current state of cardiac research being conducted in these adult ICU patients.

DESIGN

Retrospective analysis.

PATIENTS OR SUBJECTS

None.

SETTING

In separate searches of ongoing phase II-IV clinical trials registered with ClinicalTrials.gov and funding grants available in the Canadian Institutes for Health Research funding decision database between 1999 and 2012, we identified all research initiatives focused on adult ICU patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary outcome of interest was the proportion of cardiac-specific ICU studies, defined as any involving a cardiac population with a cardiac intervention (or observation for observational analyses) and/or a cardiac outcome. A total of 192 unique studies including adult ICU patients were identified from the ClinicalTrials.gov database. These were most commonly classified as respiratory or ventilation (19%), infectious (14.1%), or neurologic (12.0%) in focus. A total of 105 grants were identified in the Canadian Institutes for Health Research database. Funded studies most commonly addressed respiratory or ventilator questions (18.1%), infectious disease issues (12.4%), or hematological/thrombosis questions (9.5%). Only 4.6% of all ICU studies in ClinicalTrials.gov and 1.9% of all Canadian Institutes for Health Research grants could be considered cardiac.

CONCLUSIONS

These findings highlight the relative paucity of cardiac-specific research in the intensive care setting relative to the high prevalence of acute cardiac diseases and comorbidities. This observed disparity warrants timely attention and should lead to meaningful research opportunities aimed at improving the outcomes of critically ill cardiac patients.

Clinical pharmacist impact on care, length of stay, and cost in pediatric cystic fibrosis (CF) patients

BACKGROUND

Cystic fibrosis (CF) patients are often treated with aminoglycoside (AG) antibiotics during infective pulmonary exacerbations. Achieving pharmacokinetic and pharmacodynamic (PK/PD) targets to improve outcomes and counteract resistance is paramount.

PURPOSE

The primary objective was to compare the number of pediatric CF patients achieving AG PK/PD targets when a clinical pharmacist (CP) managed therapeutic drug monitoring (TDM) compared with usual care (UC).

METHODS

A retrospective cohort study was conducted on the records of 40 CF patients that received AGs and ≥2 serum samples between 1/2007 and 5/2009. Chi-square and Student's t-test were used to analyze nominal and continuous variables, respectively.

RESULTS

Twenty-nine patients with 52 courses of AGs were included the CP group, and 22 patients with 42 courses were included the UC group. Ninety-eight percent of patients in the CP group reached AG PK/PD targets compared with 71% in the UC group, P < 0.001. Patients in the CP group reached the AG PK/PD target in a mean of 1.9 ± 0.8 days compared with 4.8 ± 3.4 days in the UC group, P < 0.0001. The average LOS in the CP group was 9 ± 5 days compared with 12 ± 7.5 days in the UC group, P = 0.033. The mean number of levels per patient was 2.7 in the CP group compared with 5.2 (range of 2-20) in the UC group, P < 0.001. Resource utilization associated with drug levels, dosing adjustments and LOS were $26,549, $14,069, and $1,680,000 in the CP group as compared with $40,683, $27,812, and $1,940,000, respectively, in the UC group.

CONCLUSION

CP managed TDM resulted in a significantly higher percentage of pediatric CF patients achieving AG PK/PD targets 3 days sooner with an average LOS that was 3 days shorter. CP managed TDM resulted in significantly fewer dosage adjustments, drug levels, and cost associated with serum sampling, drug wastage, and LOS.

Diabetes mellitus and community-acquired bloodstream infections in the critically ill

INTRODUCTION

Community-acquired bloodstream infections have not been studied related to diabetes mellitus in the critically ill.

HYPOTHESIS

We hypothesized that the diagnosis of diabetes mellitus and poor chronic glycemic control would increase the risk of community-acquired bloodstream infections (CA-BSIs) in the critically ill.

METHODS

We performed an observational cohort study between 1998 and 2007 in 2 teaching hospitals in Boston, Massachusetts. We studied 2551 patients 18 years or older, who received critical care within 48 hours of admission and had blood cultures obtained within 48 hours of admission. The exposure of interest was diabetes mellitus defined by International Classification of Diseases, Ninth Revision, Clinical Modification, code 250.xx in outpatient or inpatient records. The primary end point was CA-BSI (<48 hours of hospital admission). Patients with a single coagulase-negative Staphylococcus positive blood culture were not considered to have bloodstream infection. Associations between diabetes groups and bloodstream infection were estimated by bivariable and multivariable logistic regression models. Subanalyses included evaluation of the association between hemoglobin A1c (HbA1c) and bloodstream infection, diabetes and risk of sepsis, and the proportion of the association between diabetes and CA-BSI that was mediated by acute glycemic control.

RESULTS

Diabetes is a predictor of CA-BSI. After adjustment for age, sex, race, patient type (medical vs surgical), and acute organ failure, the risk of bloodstream infection was significantly higher in patients with diabetes (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.10-1.82; P = .006) relative to patients without diabetes. The adjusted risk of bloodstream infection was increased in patients with HbA1c of 6.5% or higher (OR, 1.31; 95% CI, 1.04-1.65; P = .02) relative to patients with HbA1c less than 6.5%. Furthermore, the adjusted risk of sepsis was significantly higher in patients with diabetes (OR, 1.26; 95% CI, 1.04-1.54; P = .02) relative to patients without diabetes. Maximum glucose did not significantly mediate the relationship between diabetes mellitus diagnosis and CA-BSI.

CONCLUSIONS

A diagnosis of diabetes mellitus and HbA1c of 6.5% or higher is associated with the risk of CA-BSI in the critically ill.

Characteristics and outcomes of culture-negative versus culture-positive severe sepsis

Introduction

Culture-negative sepsis is a common but relatively understudied condition. The aim of this study was to compare the characteristics and outcomes of culture-negative versus culture-positive severe sepsis.

Methods

This was a prospective observational cohort study of 1001 patients who were admitted to the medical intensive care unit (ICU) of a university hospital from 2004 to 2009 with severe sepsis. Patients with documented fungal, viral, and parasitic infections were excluded.

Results

There were 415 culture-negative patients (41.5%) and 586 culture-positive patients (58.5%). Gram-positive bacteria were isolated in 257 patients, and gram-negative bacteria in 390 patients. Culture-negative patients were more often women and had fewer comorbidities, less tachycardia, higher blood pressure, lower procalcitonin levels, lower Acute Physiology and Chronic Health Evaluation II (median 25.0 (interquartile range 19.0 to 32.0) versus 27.0 (21.0 to 33.0), P = 0.001) and Sequential Organ Failure Assessment scores, less cardiovascular, central nervous system, and coagulation failures, and less need for vasoactive agents than culture-positive patients. The lungs were a more common site of infection, while urinary tract, soft tissue and skin infections, infective endocarditis and primary bacteremia were less common in culture-negative than in culture-positive patients. Culture-negative patients had a shorter duration of hospital stay (12 days (7.0 to 21.0) versus 15.0 (7.0 to27.0), P = 0.02) and lower ICU mortality than culture-positive patients. Hospital mortality was lower in the culture-negative group (35.9%) than in the culture-positive group (44.0%, P = 0.01), the culture-positive subgroup, which received early appropriate antibiotics (41.9%, P = 0.11), and the culture-positive subgroup, which did not (55.5%, P < 0.001). After adjusting for covariates, culture positivity was not independently associated with mortality on multivariable analysis.

Conclusions

Significant differences between culture-negative and culture-positive sepsis are identified, with the former group having fewer comorbidities, milder severity of illness, shorter hospitalizations, and lower mortality.

Epidemiology and prognostic determinants of bacteraemic catheter-acquired urinary tract infection in a single institution from 1991 to 2010

OBJECTIVES

To determine the epidemiology of bacteraemic Catheter-Acquired Urinary Tract Infection (CA-UTI) and to identify independent predictors of mortality.

METHODS

This study was part of a bloodstream infection surveillance study that prospectively collected data on consecutive patients with bacteraemia in our institution from 1991 to 2010. Factors associated with 30-day mortality were determined.

RESULTS

CA-UTI was the confirmed source of 1007 bacteraemias. The most common microorganisms isolated were Escherichiacoli (42%), Klebsiella spp (15%), Enterococcus faecalis (12%) and Pseudomonas aeruginosa (12%). Along the 2006-2010 periods, antibiotic-resistant E. coli and Klebsiella spp isolates accounted for 49% of the bacteraemia due to CA-UTI. Shock and mortality accounted for 125 and 92 cases, respectively (12% and 9%). Factors associated with mortality were: inappropriate empirical treatment (OR: 1.86, 95% CI: 1.48-2.44), ultimately or rapidly fatal prognosis of underlying disease (OR: 2.56, 95% CI: 1.48-4.44) and shock on presentation (OR: 12.62, 95% CI: 7.61-20.95). Inappropriate empirical treatment was most frequent in cases of bacteraemia produced by antibiotic-resistant E. coli or Klebsiella spp, Enterococcus spp. and P. aeruginosa. Factors associated with the isolation of a microorganism of this type were previous antibiotic therapy and healthcare-associated bacteraemia (OR: 1.50, 95% CI: 1.16-2.14 and OR: 3.03, 95% CI: 2.22-4.01, respectively).

CONCLUSIONS

In cases of previous antibiotic therapy or healthcare-associated bacteraemic CA-UTI may indicate the need to initiate empirical therapy activity against antibiotic-resistant Enterobacteriaceae, E. faecalis and P. aeruginosa.

Evolution over a 15-year period of clinical characteristics and outcomes of critically ill patients with community-acquired bacteremia

OBJECTIVE

In recent years, outcomes for critically ill patients with severe sepsis have improved; however, no data have been reported about the outcome of patients admitted for community-acquired bacteremia. We aimed to analyze the changes in the prevalence, characteristics, and outcome of critically ill patients with community-acquired bacteremia over the past 15 yrs.

DESIGN

A secondary analysis of prospective cohort studies in critically ill patients in three annual periods (1993, 1998, and 2007).

SETTING

Forty-seven ICUs at secondary and tertiary care hospitals.

PATIENTS

All adults admitted to the participating ICUs with at least one true-positive blood culture finding within the first 48 hrs of admission.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 829 patients was diagnosed with community-acquired bacteremia during the study periods (148, 196, and 485 in the three periods). The prevalence density rate of community-acquired bacteremia increased from nine per 1000 ICU admissions in 1993 to 24.4 episodes per 1,000 ICU admissions in 2007 (p < 0.001). The prevalence of septic shock also increased from 4.6 episodes/1,000 admissions in 1993 to 14.6 episodes/1,000 admissions in 2007 (p < 0.001). Patients with community-acquired bacteremia were significantly older and had more comorbidities. No significant differences were observed in the presence of Gram-positive and Gram-negative micro-organisms among the three study periods. Mortality related to community-acquired bacteremia decreased over the three study periods: 42%, 32.2%, and 22.9% in 1993, 1998, and 2007, respectively (p < 0.01). The occurrence of septic shock and the number of comorbidities were independently associated with worse outcome. Appropriate antibiotic therapy and development of community-acquired bacteremia in 1998 and 2007 were independently associated with better survival.

CONCLUSIONS

The prevalence of community-acquired bacteremia in ICU patients has increased. Despite a higher percentage of more severe and older patients, the mortality associated with community-acquired bacteremia decreased. Improved management of severe sepsis might explain the improvements in outcomes.

Anti-peptidoglycan antibodies and Fcγ receptors are the key mediators of inflammation in Gram-positive sepsis

Gram-positive bacteria are an important public health problem, but it is unclear how they cause systemic inflammation in sepsis. Our previous work showed that peptidoglycan (PGN) induced proinflammatory cytokines in human cells by binding to an unknown extracellular receptor, followed by phagocytosis leading to the generation of NOD ligands. In this study, we used flow cytometry to identify host factors that supported PGN binding to immune cells. PGN binding required plasma, and plasma from all tested healthy donors contained IgG recognizing PGN. Plasma depleted of IgG or of anti-PGN Abs did not support PGN binding or PGN-triggered cytokine production. Adding back intact but not F(ab')₂ IgG restored binding and cytokine production. Transfection of HEK293 cells with FcγRIIA enabled PGN binding and phagocytosis. These data establish a key role for anti-PGN IgG and FcγRs in supporting inflammation to a major structural element of Gram-positive bacteria and suggest that anti-PGN IgG contributes to human pathology in Gram-positive sepsis.

Multicellularity and antibiotic resistance in Klebsiella pneumoniae grown under bloodstream-mimicking fluid dynamic conditions

BACKGROUND

While the importance of fluid dynamical conditions is well recognized in the growth of biofilms, their role during bacteremia is unknown. We examined the impact of physiological fluid shear forces on the development of multicellular aggregates of Klebsiella pneumoniae.

METHODS

Wild-type and O-antigen or capsular mutants of K. pneumoniae were grown as broth culture in a Taylor-Couette flow cell configured to provide continuous shear forces comparable to those encountered in the human arterial circulation (ie, on the order of 1.0 Pa). The size distribution and antibiotic resistance of aggregates formed in this apparatus were determined, as was their ability to persist in the bloodstream of mice following intravenous injection.

RESULTS

Unlike growth in shaking flasks, bacteria grown in the test apparatus readily formed aggregates, a phenotype largely absent in capsular mutants and to a lesser degree in O-antigen mutants. Aggregates were found to persist in the bloodstream of mice. Importantly, organisms grown under physiological shear were found to have an antibiotic resistance phenotype intermediate between that of fully planktonic and biofilm states.

CONCLUSIONS

When grown under intravascular-magnitude fluid dynamic conditions, K. pneumoniae spontaneously develops into multicellular aggregates that are capable of persisting in the circulation and exhibit increased antibiotic resistance.

Epidemiology and prognostic determinants of bacteraemic biliary tract infection

OBJECTIVES

To determine the epidemiology of bacteraemia due to biliary tract infection (BTI) and to identify independent predictors of mortality.

METHODS

This study was part of a bloodstream infection surveillance study that prospectively collected data on consecutive patients with bacteraemia in our institution from 1991 to 2010. BTI was the confirmed source of 1373 patients with bacteraemia, and the independent prognostic factors of 30 day mortality were determined.

RESULTS

The mean age of patients with biliary sepsis was 71 years (± 14 years). The most frequent comorbidities were biliary lithiasis and solid-organ cancer [484 cases (35%) and 362 cases (26%), respectively]. The BTI was healthcare-associated in 33% of patients. Shock and mortality accounted for 209 and 126 cases, respectively (15% and 9%). The most frequent microorganisms isolated were Escherichia coli (749, 55%), Klebsiella spp. (240, 17%), Enterococcus spp. (171, 12%), Pseudomonas aeruginosa (86, 6%) and Enterobacter spp. (63, 5%). There were 47 (3%) cefotaxime-resistant (CTX-R) E. coli or Klebsiella spp. Inappropriate empirical antibiotic treatment was an independent factor associated with mortality (OR 1.4, 95% CI 1.1-1.7). Inappropriate empirical treatment was more frequent in P. aeruginosa and CTX-R Enterobacteriaceae bacteraemia. These microorganisms were significantly more common in patients with previous antibiotic therapy, solid-organ cancer or transplantation and in healthcare-associated bacteraemia.

CONCLUSIONS

In patients with bacteraemic BTI, inappropriate empirical therapy was more frequent in P. aeruginosa and CTX-R Enterobacteriaceae infection and was associated with a higher mortality rate. In patients with bacteraemia due to BTI and solid-organ cancer or transplantation, healthcare-associated infection or previous antibiotic treatment, initial therapy with piperacillin/tazobactam or a carbapenem would be advisable.

Incidence of bacteremia at the time of ICU admission and its impact on outcome

CONTEXT

Blood culture is routinely taken at the time of admission to the intensive care unit (ICU) for patients suspected to have infection. We undertook this study to determine the incidence of bacteremia at the time of ICU admission and to assess its impact on the outcome.

METHODS

Retrospective cohort study from all the admissions in ICU, in whom blood cultures sent at the time of admission were analyzed. Data regarding patient demographics, probable source of infection, previous antibiotic use and ICU course was recorded. Severity of illness on admission was assessed by acute physiology and chronic health evaluation II score.

STATISTICAL ANALYSIS

Qualitative data were analyzed using Chi-square or Fisher Exact test and quantitative data were analyzed using Student's t-test. Primary outcome measure was ICU mortality.

RESULTS

Of 567 patients, 42% patients were on antibiotics. Sixty-four percent of the patients were direct ICU admission from casualty, 10.76% were from wards and 6.17% from other ICUs, and 19.05% were transfers from other hospitals. Blood cultures were positive in 10.6% patients. Mortality was significantly higher in patients with positive blood cultures (45% vs. 13.6%; P=0.000). On univariate analysis, only previous antibiotic use was statistically associated with higher mortality (P=0.011). Bacteremic patients who were already on antibiotics had a significantly higher mortality (OR 12.9, 95% CI: 1.6-100).

CONCLUSIONS

Blood cultures may be positive in only minority of the patients with suspected infection admitted to ICU. Nevertheless, the prognosis of those patients with positive blood culture is worse, especially if culture is positive in spite of the patient being on antibiotics.

Incidence of bacteremia at the time of ICU admission and its impact on outcome

CONTEXT

Blood culture is routinely taken at the time of admission to the intensive care unit (ICU) for patients suspected to have infection. We undertook this study to determine the incidence of bacteremia at the time of ICU admission and to assess its impact on the outcome.

METHODS

Retrospective cohort study from all the admissions in ICU, in whom blood cultures sent at the time of admission were analyzed. Data regarding patient demographics, probable source of infection, previous antibiotic use and ICU course was recorded. Severity of illness on admission was assessed by acute physiology and chronic health evaluation II score.

STATISTICAL ANALYSIS

Qualitative data were analyzed using Chi-square or Fisher Exact test and quantitative data were analyzed using Student's t-test. Primary outcome measure was ICU mortality.

RESULTS

Of 567 patients, 42% patients were on antibiotics. Sixty-four percent of the patients were direct ICU admission from casualty, 10.76% were from wards and 6.17% from other ICUs, and 19.05% were transfers from other hospitals. Blood cultures were positive in 10.6% patients. Mortality was significantly higher in patients with positive blood cultures (45% vs. 13.6%; P=0.000). On univariate analysis, only previous antibiotic use was statistically associated with higher mortality (P=0.011). Bacteremic patients who were already on antibiotics had a significantly higher mortality (OR 12.9, 95% CI: 1.6-100).

CONCLUSIONS

Blood cultures may be positive in only minority of the patients with suspected infection admitted to ICU. Nevertheless, the prognosis of those patients with positive blood culture is worse, especially if culture is positive in spite of the patient being on antibiotics.

Prognostic factors of mortality in patients with community-acquired bloodstream infection with severe sepsis and septic shock

PURPOSE

The purpose of the study was to determine the independent risk factors on mortality in patients with community-acquired severe sepsis and septic shock.

METHODS

A single-site prospective cohort study was carried out in a medical-surgical intensive care unit in an academic tertiary care center. One hundred twelve patients with community-acquired bloodstream infection with severe sepsis and septic shock were identified. Clinical, microbiologic, and laboratory parameters were compared between hospital survivors and hospital deaths.

RESULTS

One-hundred twelve patients were included. The global mortality rate was 41.9%, 44.5% in septic shock and 34.4% in severe sepsis. One or more comorbidities were present in 66% of patients. The most commonly identified bloodstream pathogens were Escherichia coli (25%) and Staphylococcus aureus (21.4%). The proportion of patients receiving inadequate antimicrobial treatment was 8.9%. By univariate analysis, age, Acute Physiology and Chronic Health Evaluation II score, at least 3 organ dysfunctions, and albumin, but neither microbiologic characteristics nor site of infection, differed significantly between survivors and nonsurvivors. Acute Physiology and Chronic Health Evaluation II (odds ratio, 1.13; 95% confidence interval, 1.06-1.21) and albumin (odds ratio, 0.34; 95% confidence interval, 0.15-0.76) were independent risk factors associated with global mortality in logistic regression analysis.

CONCLUSION

In addition to the severity of illness, hypoalbuminemia was identified as the most important prognostic factor in community-acquired bloodstream infection with severe sepsis and septic shock.

Pharmacokinetic issues for antibiotics in the critically ill patient

OBJECTIVE

To discuss the altered pharmacokinetic properties of selected antibiotics in critically ill patients and to develop basic dose adjustment principles for this patient population.

DATA SOURCES

PubMed, EMBASE, and the Cochrane-Controlled Trial Register.

STUDY SELECTION

Relevant papers that reported pharmacokinetics of selected antibiotic classes in critically ill patients and antibiotic pharmacodynamic properties were reviewed. Antibiotics and/or antibiotic classes reviewed included aminoglycosides, beta-lactams (including carbapenems), glycopeptides, fluoroquinolones, tigecycline, linezolid, lincosamides, and colistin.

DATA SYNTHESIS

Antibiotics can be broadly categorized according to their solubility characteristics which can, in turn, help describe possible altered pharmacokinetics that can be caused by the pathophysiological changes common to critical illness. Hydrophilic antibiotics (e.g., aminoglycosides, beta-lactams, glycopeptides, and colistin) are mostly affected with the pathphysiological changes observed in critically ill patients with increased volumes of distribution and altered drug clearance (related to changes in creatinine clearance). Lipophilic antibiotics (e.g., fluoroquinolones, macrolides, tigecycline, and lincosamides) have lesser volume of distribution alterations, but may develop altered drug clearances. Using antibiotic pharmacodynamic bacterial kill characteristics, altered dosing regimens can be devised that also account for such pharmacokinetic changes.

CONCLUSIONS

Knowledge of antibiotic pharmacodynamic properties and the potential altered antibiotic pharmacokinetics in critically ill patients can allow the intensivist to develop individualized dosing regimens. Specifically, for renally cleared drugs, measured creatinine clearance can be used to drive many dose adjustments. Maximizing clinical outcomes and minimizing antibiotic resistance using individualized doses may be best achieved with therapeutic drug monitoring.

Risk factors for death in children and adolescents with cancer and sepsis/septic shock

OBJECTIVE

To assess risk factors for mortality in children and adolescents with cancer and sepsis/septic shock, admitted to intensive care unit.

PATIENTS AND METHODS

Retrospective study of a cohort of cancer and sepsis/septic shock patients (n=155) admitted to Oncological Pediatric Intensive Care Unit, between October 1998 and October 2001, with assessment of 12 potential risk factors for mortality by univariate analysis, followed by multivariable analysis.

RESULTS

Forty-seven out of 155 patients died (30.3%). In the present sample, after multivariable analysis, 3/12 variables proved to be statistically significant: respiratory infection [hazard ratio (HR)=2.3 and 95% confidence interval (CI)=1.3-4.2], duration of granulocytopenia (HR=2.4 and 95% CI=1.2-4.9), and number of organ dysfunction (HR=7.4 and 95% CI=2.6-21.3).

CONCLUSIONS

Our data suggest that mortality in Oncological Pediatric Intensive Care Unit is high and the main factors involved in prognosis are number of dysfunctional organs, respiratory infections, and duration of granulocytopenia; the mortality rises 7.4 times for each dysfunctional organ. We believe that prospective and multicenter studies are necessary to better characterize risk factors that are specific for cancer patients to produce a particular score to predict severity of complications and mortality of children with cancer.

Does severe non-infectious SIRS differ from severe sepsis? Results from a multi-centre Australian and New Zealand intensive care unit study

OBJECTIVE

To compare the time course of organ dysfunction/failure, mortality and cause of death in patients with severe sepsis (SS) and patients with severe non-infectious systemic inflammatory response syndrome (SNISIRS).

DESIGN

Secondary analysis of a multi-centre inception cohort study.

SETTING

Twenty-three multidisciplinary intensive care units (ICUs) in Australia and New Zealand.

PATIENTS AND PARTICIPANTS

3,543 ICU admissions > or = 48 h or <48 h if SIRS and organ dysfunction present.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

ICU prevalence of SS and SNISIRS was 20% (707/3,543) and 28% (980/3,543), respectively. ICU mortality was similar in patients with SNISIRS and with SS (25 vs. 27%, P = 0.40). Central nervous system (CNS) failure occurred more frequently in patients with SNISIRS (33 vs. 22%, P < 0.001) and resulted in death more commonly than in SS (relative risk = 1.6, 95% confidence interval 1.4-1.7, P < 0.001). The time to peak organ dysfunction (0.67 vs. 0.91 days, P = 0.004), overall episode length (3.6 vs. 5.6 days, P < 0.001) and ICU stay (geometric mean: 4.1 vs. 5.8 days, P < 0.001) were significantly shorter in patients with SNISIRS.

CONCLUSIONS

Whilst SNISIRS and SS have similarities, including their crude mortality rate, important differences exist. SNISIRS is more common on admission to the ICU, and is more commonly coupled with CNS dysfunction and death from neurological failure.

DESCRIPTORS

SIRS/sepsis: clinical studies.

Prevention of primary bacteraemia

This overview provides information on recent advances in the prevention of primary bacteraemia, commonly defined as bloodstream infection without a documented source of infection, but including those resulting from an intravenous or arterial line infection. The potential to prevent community-acquired, primary bacteraemia is still limited and may be targeted mainly at vaccines for high-risk groups. In contrast, the prevention of catheter-related bacteraemia has seen substantial progress within the last 10 years. Consequently, intravascular device-related bacteraemia has become largely preventable under routine working conditions. Independent of the use of antibiotic-coated catheters, the implementation of clinical pathways and multimodal preventive strategies directed at several risk factors of catheter-related bacteraemia is a successful strategy to reduce this potentially life-threatening infection and deserves future health services research.

Sepsis in 2003: are we still in the middle of nowhere?

PURPOSE OF REVIEW

Although enthusiasm of intensivists has been raised during the last 2-3 years due to several successful clinical trials, severe sepsis and septic shock still have an increasing incidence with more or less unchanged mortality. Within the last 12 months, the progress in sepsis research covering definitions, epidemiology, pathophysiology, diagnosis, standard and adjunctive therapy, as well as experimental approaches is encouraging. In this review, state-of-the-art publications of 2003 are presented to elucidate the possible impact on clinical routine.

RECENT FINDINGS

The rationale for using a new definition based on the PIRO system has been widely acknowledged, although it is not yet applicable in clinical practice. This includes genomic information for stratifying subgroups of patients, and a broader field of laboratory diagnostics due to clinical studies and basic research on the cellular mechanisms of inflammation and organ dysfunction. Early diagnosis is important for a fast implementation of specific therapies, and it has been confirmed that the time until the start of therapy has an impact on patient outcome. Thorough data analysis of successful trials with activated protein C has revealed encouraging details on long-term outcome and subgroup effects. Together with new findings on low-dose hydrocortisone, this stresses the relevance of adjunctive therapy in severe sepsis and septic shock.

SUMMARY

Scientific progress in areas of sepsis has been continuing throughout 2003, although the challenges are still enormous. The identification of more specific markers and new therapeutic approaches will hopefully improve the diagnosis, monitoring of therapy, and outcome in the septic patient.

Rapid increase in hospitalization and mortality rates for severe sepsis in the United States: a trend analysis from 1993 to 2003

OBJECTIVE

To determine recent trends in rates of hospitalization, mortality, and hospital case fatality for severe sepsis in the United States.

DESIGN

Trend analysis for the period from 1993 to 2003.

SETTING

U.S. community hospitals from the Nationwide Inpatient Sample that is a 20% stratified sample of all U.S. community hospitals.

PATIENTS

Subjects of any age with sepsis including severe sepsis who were hospitalized in the United States during the study period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Utilizing International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for septicemia and major organ dysfunction, we identified 8,403,766 patients with sepsis, including 2,857,476 patients with severe sepsis, who were hospitalized in the United States from 1993 to 2003. The percentage of severe sepsis cases among all sepsis cases increased continuously from 25.6% in 1993 to 43.8% in 2003 (p < .001). Age-adjusted rate of hospitalization for severe sepsis grew from 66.8 +/- 0.16 to 132.0 +/- 0.21 per 100,000 population (p < .001). Age-adjusted, population-based mortality rate within these years increased from 30.3 +/- 0.11 to 49.7 +/- 0.13 per 100,000 population (p < .001), whereas hospital case fatality rate fell from 45.8% +/- 0.17% to 37.8% +/- 0.10% (p < .001). During each study year, the rates of hospitalization, mortality, and case fatality increased with age. Hospitalization and mortality rates in males exceeded those in females, but case fatality rate was greater in females. From 1993 to 2003, age-adjusted rates for severe sepsis hospitalization and mortality increased annually by 8.2% (p < .001) and 5.6% (p < .001), respectively, whereas case fatality rate decreased by 1.4% (p < .001).

CONCLUSIONS

The rate of severe sepsis hospitalization almost doubled during the 11-yr period studied and is considerably greater than has been previously predicted. Mortality from severe sepsis also increased significantly. However, case fatality rates decreased during the same study period.

Lipopolysaccharide O-antigen promotes persistent murine bacteremia

Bacteremia is a common complication of pneumonia with Klebsiella pneumoniae. In the previous work, we have shown that the lipopolysaccharide (LPS) O-antigen in K. pneumoniae O1:K2 contributes to lethality during pneumonia in part by promoting bacteremia. In the current work, we studied an O-antigen-deficient K. pneumoniae strain to further evaluate this polysaccharide's role in bloodstream infection. Cultured macrophage and murine bacteremia models were studied. In vitro, O-antigen-deficient bacteria, compared with wild-type organisms, were stronger activators of the murine alveolar macrophage cell line MH-S as assessed by nuclear localization of RelA/p65 and by secretion of cytokines and chemokines. O-antigen-deficient Klebsiellae were also more susceptible to killing by murine neutrophils. In vivo, the absence of O-antigen allowed more rapid and complete clearance of bacteria from the bloodstream, liver, and spleen after intravenous injection in mice. Survival was also greater among animals infected with bacteria missing the O-antigen. Gene expression profiling (via reverse transcriptase-polymerase chain reaction of 84 inflammatory mediator complementary DNA) revealed that by 24 h postinfection, the livers and spleens of animals infected with O-antigen-deficient organisms had significantly downregulated cytokine and chemokine expression compared with wild-type infected animals. The O-antigen surface carbohydrate of O1:K2 serotype K. pneumoniae appears to contribute to bacterial virulence by lessening the activation of macrophages, conveying resistance to killing by neutrophils, and by promoting persistent infection in the blood, liver, and spleen after the onset of bacteremia.

Impact of diabetes on mortality among patients with community-acquired bacteremia

OBJECTIVES

To assess the impact of diabetes on 30-day mortality in patients with community-acquired bacteremia

METHODS

We conducted a hospital-based observational study in patients with community-acquired bacteremia who were admitted from the emergency department (ED). Consecutive admitted patients with positive blood cultures obtained in the ED were interviewed and their charts were reviewed. We compared 30-day mortality in diabetic patients with nondiabetic patients. Cox proportional hazards regression was used to estimate the independent effect of diabetes on 30-day mortality.

RESULTS

Among 839 patients in this study, 242 (29%) had diabetes. The median age of these patients was 67 years (interquartile range: 53-77) and 48% were women. The probability of survival at 30 days was not different between the diabetic and the nondiabetic group (84% vs. 77%, respectively; P=0.15 by Wilcoxon test). On multivariate analysis, diabetes was not associated with an increased risk of 30-day mortality (hazard ratio, 0.82; 95% confidence interval, 0.53-1.26). By contrast, age and higher comorbidity index increased the risk of 30-day mortality. Several markers of disease severity at ED presentation (tachycardia, hypotension, and bandemia) predict 30-day mortality.

CONCLUSIONS

Diabetes appears not to have significant impact on 30-day mortality in this study population. This finding should be interpreted in the context that diabetes patients may have an increased incidence of bacteremia.

Epidemiology and prognostic determinants of patients with bacteremic cholecystitis or cholangitis

OBJECTIVES

To compare mortalities in patients with sepsis due to biliary tract infections (BTIs) and due to infections from other sources, and to identify independent predictors of mortality in these patients.

METHODS

This study was part of a community-acquired bloodstream infection (BSI) study that prospectively collected comprehensive clinical, laboratory, and outcome data from 937 consecutive patients with microbiologically documented BSI in the emergency department. BTI was the confirmed source of 145 of the 937 BSIs. We determined the independent prognostic factors by evaluating the correlation between 30-day mortality and various factors, for example, comorbidity, clinical severity, related hepatobiliary complication, and decompressive procedures.

RESULTS

Patients with biliary sepsis had a high percentage of Gram-negative (88.3%), polymicrobial (26.9%), and anaerobic infections (6.9%). The 30-day overall mortality was 11.7%. Cox proportional hazard regression analysis disclosed five significant independent predictors: acute renal failure (hazard ratio, 95% confidence interval: 6.86, 6.02-25.5), septic shock (5.83, 4.36-15.64), malignant obstruction (4.35, 1.89-12.96), direct type hyperbilirubinemia (1.26, 1.1-1.42), and Charlson score > or =6 (1.57, 1.12-2.22). Compared with the remaining 792 patients in the source population, patients with bacteremic BTI had significantly better prognosis (log-rank test, P= 0.007). Adjusting for age, comorbidity, and clinical severity, BTI was still independently associated with better 30-day survival (0.25-0.76).

CONCLUSIONS

Though the mortality rate in patients with bacteremic BTI is substantial, survival is better than in those with bacteremia from other sources. The main prognostic factors identified in this study may help clinicians recognize patients at high risk for early mortality so that they can give prompt, appropriate treatment.

Cefepime versus ceftazidime: considerations for empirical use in critically ill patients

Sepsis and nosocomial infections continue to be a significant problem in intensive care, contributing heavily to mortality and prolonged hospital stay. Early and appropriate antibiotic therapy is critical for optimising outcomes. However, the emergence of highly resistant bacteria, coupled with reduced development of novel antibiotics, means that there is a real threat of development of untreatable nosocomial infections. Cefepime and ceftazidime are broad-spectrum cephalosporins that are widely used to treat Gram-negative nosocomial infections in critically ill patients. Available data suggest that cefepime may have advantages over ceftazidime owing to a broader spectrum of activity and reduced potential for development of bacterial resistance. However, whether either of these agents is superior can only be determined by a head-to-head study evaluating clinical and bacteriological outcomes. Such a study to determine whether apparent differences translate into clinically relevant differences in outcome is indicated.

Tracheostomy after major vascular surgery

OBJECTIVES

Major vascular surgery such as aortic aneurysm repair may be associated with prolonged in-patient hospitalization. Certain patients undergo a tracheostomy to aid in weaning from mechanical ventilation or for secretion management. The authors hypothesized that tracheostomy after aortic reconstruction for aneurysmal disease was associated with poor outcomes.

DESIGN

A retrospective, observational study.

SETTING

Vascular surgical intensive care unit (ICU) of a tertiary referral hospital.

PARTICIPANTS

Eighty-one patients who underwent a tracheostomy after open thoracoabdominal or abdominal aortic aneurysm (AAA) repair between 1993 and 2002.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 1,940 patients who underwent aneurysm repair, 81 (4.2%) had a tracheostomy during their index hospitalization. Of those patients, 40.7% did not survive to hospital discharge. Postoperative sepsis was associated with an increased mortality (relative risk 2.45, 95% confidence interval [CI] 1.22-4.90). Many developed postoperative renal failure and were more likely to die in the hospital (relative risk 1.53, 95% CI 1.00-2.33). The preoperative diagnosis of chronic obstructive pulmonary disease (COPD) was not associated with increased mortality (relative risk 0.471, 95% CI 0.23-0.96). Thirty-two (39.5%) patients were transferred from the ICU to a chronic ventilator dependency unit (CVDU).

CONCLUSIONS

Tracheostomy in patients after aortic reconstruction for aneurysmal disease is associated with a high incidence of in-hospital mortality. Patients who survive to ICU discharge are likely to be transferred to a CVDU for further respiratory management. The preoperative diagnosis of COPD is associated with improved survival, whereas postoperative sepsis is associated with an increased mortality. These observations should be considered when counseling patients and their families regarding tracheostomy after aortic surgery.

Cost of intensive care unit-acquired bloodstream infections

Intensive care unit-acquired (ICU-acquired) bloodstream infections (BSI) are an important complication of critical illness. The objective of this study was to quantify the excess length of stay, mortality and cost attributable to ICU-acquired BSI. A matched cohort study was conducted in all adult ICUs in the Calgary Health Region between 1 May 2000 and 30 April 2003. One hundred and forty-four patients with ICU-acquired BSI were matched (1:1) to patients without ICU-acquired BSI. Patients with ICU-acquired BSI had a significantly increased median length of ICU stay {15.5 [interquartile range (IQR) 8-26] days vs 12 [IQR 7-18.5] days, P=0.003} and median costs of hospital care [85,137 dollars (IQR 45,740-131,412 dollars) vs 67,879 dollars (IQR 35,043-115,915 dollars, P=0.02) compared with patients without ICU-acquired BSI. The median excess length of ICU stay was two days and the median cost attributable to ICU-acquired BSI was 12,321 dollars per case. Sixty (42%) of the cases died compared with 37 (26%) of the controls [P=0.002, attributable mortality 16%, 95% confidence interval (CI) 5.9-26.0%]. Patients with ICU-acquired BSI were at increased risk for in-hospital death (odds ratio=2.64, 95%CI 1.40-5.29). Among survivor-matched pairs, the median excess lengths of ICU and hospital stay attributable to development of ICU-acquired BSI were two and 13.5 days, respectively, and the attributable cost due to ICU-acquired BSI was 25,155 dollars per case survivor. Critically ill patients who develop ICU-acquired BSI suffer excess morbidity and mortality, and incur significantly increased healthcare costs. These data support expenditures on infection prevention and control programmes and further research into reducing the impact of these infections.

Excess risk of death from intensive care unit-acquired nosocomial bloodstream infections: a reappraisal

BACKGROUND

Overall rates of bloodstream infection (BSI) are often used as quality indicators in intensive care units (ICUs). We investigated whether ICU-acquired BSI increased mortality (by > or = 10%) after adjustment for severity of infection at ICU admission and during the pre-BSI stay.

METHODS

We conducted a matched, risk-adjusted (1:n), exposed-unexposed study of patients with stays longer than 72 h in 12 ICUs randomly selected from the Outcomerea database.

RESULTS

Patients with BSI after the third ICU day (exposed group) were matched on the basis of risk-exposure time and mortality predicted at admission using the Three-Day Recalibrated ICU Outcome (TRIO) score to patients without BSI (unexposed group). Severity was assessed daily using the Logistic Organ Dysfunction (LOD) score. Of 3247 patients with ICU stays of >3 days, 232 experienced BSI by day 30 (incidence, 6.8 cases per 100 admissions); among them, 226 patients were matched to 1023 unexposed patients. Crude hospital mortality was 61.5% among exposed and 36.7% among unexposed patients (P<.0001). Attributable mortality was 24.8%. The only variable associated with both BSI and hospital mortality was the LOD score determined 4 days before onset of BSI (odds ratio [OR], 1.10; 95% confidence interval [CI], 1.03-1.16; P = .0025). The adjusted OR for hospital mortality among exposed patients (OR, 3.20; 95% CI, 2.30-4.43) decreased when the LOD score determined 4 days before onset of BSI was taken into account (OR, 3.02; 95% CI, 2.17-4.22; P<.0001). The estimated risk of death from BSI varied considerably according to the source and resistance of organisms, time to onset, and appropriateness of treatment.

CONCLUSIONS

When adjusted for risk-exposure time and severity at admission and during the ICU stay, BSI was associated with a 3-fold increase in mortality, but considerable variation occurred across BSI subgroups. Focusing on BSI subgroups may be valuable for assessing quality of care in ICUs.

Prognostic indexes of septic syndrome in the emergency department

OBJECTIVE

Sepsis is a frequent and often lethal condition. Rapid identification and aggressive therapy in the emergency department (ED) are essential for outcome. Several indexes were found to be significantly related to short-term clinical outcome, but only bedside, rapidly available tests are thought to be useful in the ED. To define the prevalence and mortality of patients with severe sepsis presenting to the ED of a tertiary care hospital in Italy, we furthermore investigated the ability of bedside, non-invasive prognostic indexes to identify patients with adverse short-term clinical outcome.

METHODS

All patients admitted to the ED with a diagnosis of severe sepsis or septic shock were included. Retrospective data were collected by a dedicated software program using predefined searching criteria including clinical data, vital sign parameters, sepsis-related organ failure assessment (SOFA) score, and blood tests. The relationship between prognostic indexes and 24-h or 28-day mortality was evaluated by multivariate logistic regression analysis.

RESULTS

Ninety patients were enrolled from June 2004 to June 2005 (0.2% of all incoming patients to ED and 0.7% of all critical patients). Mean age was 77 +/- 15 years, 54.4% were women. During follow-up (28 days) 46 patients died (51.1%), 21 patients (23.3%) within 24 h. At multivariate analyses, age >80 (odds ratio [OR] 4.10; 95% confidence intervals [CI] 1.39-11.90, p = 0.01), serum lactate >5 mmol/l (OR 3.40; 95% CI 1.21-9.60, p = 0.02) and acute renal failure (OR 18.90; 95% CI 1.80-200, p = 0.02) were independent predictors of 28-day mortality.

CONCLUSIONS

Among critical patients admitted to an Italian ED, those with severe sepsis/septic shock represent about 1%, with a very high mortality rate. Bedside non-invasive prognostic indexes are able to identify with high accuracy patients with adverse short-term clinical outcome.

Facing the challenge: decreasing case fatality rates in severe sepsis despite increasing hospitalizations

OBJECTIVE

To determine recent trends in severe sepsis-related rates of hospitalization, mortality, and hospital case fatality in a large geographic area and to determine the impact of age, race, and gender on these outcomes.

DESIGN

Trend analysis for the period of 1995 to 2002.

SETTING

Acute care hospitals in New Jersey.

PATIENTS

Subjects > or = 18 yrs of age with severe sepsis who were hospitalized in New Jersey during the period of 1995 to 2002.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We analyzed data from the 1995-2002 New Jersey State Inpatient Databases (SID) developed as part of the Healthcare Cost and Utilization Project (HCUP), covering all acute care hospitals in the state. On the basis of the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for septicemia and organ dysfunction, we identified 87,675 patients with severe sepsis. The percentage of patients with severe sepsis among all hospitalized patients with sepsis grew steadily, from 32.7% to 44.7% (p < .0001), during these years. The crude rate of hospitalization with severe sepsis increased 54.2%, from 135.0/100,000 population in 1995 to 208.2/100,000 population in 2002 (p < .0001). Over time, the crude mortality rate rose by 35.8% (p < .0001), whereas the crude case fatality rate (number of deaths/number of cases) fell from 51.0% to 45.0% (p < .0001). For any given year, the rates of hospitalization and mortality were greater among older patients. After adjustment by age, the rates among blacks were greater than among whites, and they were greater among males than females. At the same time, there was no significant difference in the age-adjusted hospital case fatality rates with regard to gender and race. There was a significant increase in age-adjusted gender- and race-specific rates for hospitalization and mortality from 1995 to 2002. Blacks were more likely than whites to be admitted to the intensive care unit: for males, odds ratio = 1.19 (95% confidence interval, 1.13-1.26), and for females, odds ratio = 1.35 (95% confidence interval, 1.29-1.42). However, although case fatality rate was increased among patients admitted to the intensive care unit, this was not reflected in an increased case fatality among blacks. In addition, age-adjusted gender- and race-specific case fatality rates declined during 1995-2002.

CONCLUSIONS

In spite of increasing rates of hospitalization and mortality, there is a decreasing case fatality rate for severe sepsis. These data suggest that advances in critical care practice before and during the study period have resulted in improved outcomes for this population.

The challenge of anticipating catheter tip colonization in major heart surgery patients in the intensive care unit: Are surface cultures useful?

OBJECTIVE

Patients undergoing heart surgery show a high risk of catheter colonization and catheter-related bloodstream infections. We evaluated whether skin insertion site and catheter hub surveillance cultures ("surface cultures") could predict catheter colonization and help establish the origin of bloodstream infections.

DESIGN

: Prospective cohort study.

SETTING

An 11-bed heart surgery intensive care unit in a tertiary university hospital.

PATIENTS

Heart surgery patients spending >4 days in intensive care over an 11-month period.

INTERVENTIONS

All catheters were surveyed. Cultures were obtained from the skin insertion site and all hubs on day 5 after surgery, every 72 hrs thereafter, and on catheter removal. Swabs were processed semiquantitatively by streaking the surface of a Columbia agar plate. Catheters were processed using Maki's method. The observation of > or = 15 colonies/plate was taken to indicate a positive skin or catheter colonization culture result.

MEASUREMENTS AND MAIN RESULTS

Over the study period, 561 catheters were inserted in 130 patients. The median time a catheter was in place was 6 days (interquartile range 3-11), and 3,712 surface cultures were obtained (median four per patient). Catheter colonization occurred in 133 catheters, and there were 15 episodes of catheter-related bloodstream infection (incidence density of colonization 29.3 and of catheter-related bloodstream infection 8.8 per 1,000 catheter-days). Validity indexes for the capacity of surface cultures to predict catheter colonization and catheter-related bloodstream infection, respectively, were as follows: accuracy, 71.4, 65.6; sensitivity, 83.5%, 100%; specificity, 67.1%, 64.7%; positive predictive value, 47.6%, 7.2%; negative predictive value, 91.9%, 100%; positive likelihood ratio, 2.5, 2.83; and negative likelihood ratio, 0.2, 0. Surface cultures correctly predicted 77.4% of all bacteremia episodes (catheter-related and non-catheter-related).

CONCLUSIONS

Systematic surveillance cultures of catheter hub and skin insertion sites in patients admitted to a heart surgery intensive care unit could help identify patients who would benefit from decontamination and preventive measures and establish whether catheters are the portal of entry of bloodstream infection.

One-year mortality of bloodstream infection-associated sepsis and septic shock among patients presenting to a regional critical care system

OBJECTIVE

The long-term mortality outcome associated with sepsis and septic shock has not been well defined in a nonselected critically ill population. This study investigated the occurrence and the role of bloodstream infection (BSI) associated sepsis and septic shock at time of intensive care unit (ICU) admission on the 1-year mortality of patients admitted to a regional critical care system.

DESIGN AND SETTING

Population-based inception cohort in all adult multidisciplinary and cardiovascular ICUs in the Calgary Health Region (population approx. 1 million) between 1 July 1999 and 31 March 2002.

PATIENTS AND PARTICIPANTS

Adults (>/=18 years; n=4,845) who had at least one ICU admission to CHR ICUs.

RESULTS

In 251 (5%) patients there was BSI-associated sepsis at presentation to ICU, and 159 of these also had septic shock. The 28-day, 90-day, and 1-year mortality rates overall were 18%, 21%, and 24%: 23%, 30%, and 36% for BSI-associated sepsis without shock, and 51%, 57%, and 61% with shock, respectively. Surgical diagnosis, BSI-associated sepsis, and increasing age were independently associated with late (28-day to 1-year) mortality whereas higher APACHE II and TISS scores were associated with reduced odds in logistic regression analysis.

CONCLUSIONS

BSI-associated sepsis and septic shock are associated with increased risk of mortality persisting after 28-days up to 1 year or more. Follow-up duration beyond 28 days better defines the burden of illness associated with these syndromes.

Production of arginine by the kidney is impaired in a model of sepsis: early events following LPS

Lipopolysaccharide (LPS) is used experimentally to elicit the innate physiological responses observed in human sepsis. We have previously shown that LPS causes depletion of plasma arginine before inducible nitric oxide synthase (iNOS) activity, indicating that changes in arginine uptake and/or production rather than enhanced consumption are responsible. Because the kidney is the primary source of circulating arginine and renal failure is a hallmark of septicemia, we determined the time course of changes in arginine metabolism and kidney function relative to iNOS expression. LPS given intravenously to anesthetized rats caused a decrease in mean arterial blood pressure after 120 min that coincided with increased plasma nitric oxide end products (NOx) and iNOS expression in lung and liver. Interestingly, impairment of renal function preceded iNOS activity by 30–60 min and occurred in tandem with decreased renal arginine production. The baseline rate of renal arginine production was ∼60 μmol·h−1·kg−1, corresponding to an apparent plasma half-life of ∼20 min, and decreased by one-half within 60 min of LPS. Calculations based on the systemic production and clearance show that normally only 5% of kidney arginine output is destined to become nitric oxide and that <25% of LPS-impaired renal production was converted to NOx in the first 4 h. In addition, we provide novel observations indicating that the kidney appears refractory to iNOS induction by LPS because no discernible enhancement of renal NOx production occurred within 4 h, and iNOS expression in the kidney was muted compared with that in liver or lung. These studies demonstrate that the major factor responsible for the rapid decrease in extracellular arginine content following LPS is impaired production by the kidney, a phenomenon that appears linked to reduced renal perfusion.

Glucocorticoid regulation of the inflammatory response to injury

During the first half of the 20th century, physiologists were interested in the adrenal glands primarily because adrenalectomized animals failed to survive even mild degrees of systemic stress. It eventually became clear that hormones secreted by the adrenal cortex were critical for survival and, in this context, adrenal cortical hormones were widely considered to support or stimulate important responses to stress or injury. With the purification and manufacture of adrenal cortical hormones in the 1930s and 1940s, clinicians suddenly discovered the potent anti-inflammatory actions of glucocorticoids (GCs). This dramatic, and unexpected, discovery has dominated clinical and laboratory research into GC actions throughout the second half of the 20th century. More recent research is again reporting GC-induced stimulatory effects on a variety of inflammatory response components. These effects are usually observed at low GC concentrations, close to concentrations that are observed in vivo during basal, unstimulated states. For example, GC-mediated stimulation has been reported for the hepatic acute-phase response, for cytokine secretion, expression of cytokine/chemokine receptors, and for the pro-inflammatory mediator, macrophage migration inhibition factor. It seems clear that the long-held clinical view that GCs act solely as anti-inflammatory agents needs to be re-assessed. Varying doses of GCs do not lead simply to varying degrees of inflammation suppression, but rather GCs can exert a full range of effects from permissive to stimulatory to suppressive.

Daily interruption of sedative infusions and complications of critical illness in mechanically ventilated patients

OBJECTIVE

In critically ill patients receiving mechanical ventilation, daily interruption of sedative infusions decreases duration of mechanical ventilation and intensive care unit length of stay. Whether this sedation strategy reduces the incidence of complications commonly associated with critical illness is not known.

DESIGN

Blinded, retrospective chart review.

SETTING

University-based hospital in Chicago, IL.

PATIENTS

One hundred twenty-eight patients receiving mechanical ventilation and continuous infusions of sedative drugs in a medical intensive care unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We performed a blinded, retrospective evaluation of the database from our previous trial of 128 patients randomized to daily interruption of sedative infusions vs. sedation as directed by the medical intensive care unit team without this strategy. Seven distinct complications associated with mechanical ventilation and critical illness were identified: a) ventilator-associated pneumonia; b) upper gastrointestinal hemorrhage; c) bacteremia; d) barotrauma; e) venous thromboembolic disease; and f) cholestasis or g) sinusitis requiring surgical intervention. The incidence of complications was evaluated for each patient's hospital course. One hundred twenty-six of 128 charts were available for review. Patients undergoing daily interruption of sedative infusions experienced 13 complications (2.8%) vs. 26 (6.2%) in those subjected to conventional sedation techniques (p =.04).

CONCLUSIONS

Daily interruption of sedative infusions in critically ill patients undergoing mechanical ventilation reduces intensive care unit length of stay and, in turn, decreases the incidence of complications of critical illness associated with prolonged intubation and mechanical ventilation.

High-molecular-weight polyethylene glycol prevents lethal sepsis due to intestinal Pseudomonas aeruginosa

BACKGROUND & AIMS

During stress, erosion of protective intestinal mucus occurs in association with adherence to and disruption of the intestinal epithelial barrier by invading opportunistic microbial pathogens. The aims of this study were to test the ability of a high-molecular-weight polyethylene glycol compound, polyethylene glycol 15-20, to protect the intestinal epithelium against microbial invasion during stress.

METHODS

The ability of polyethylene glycol 15-20 to protect the intestinal epithelium against the opportunistic pathogen Pseudomonas aeruginosa was tested in cultured Caco-2 cells. Bacterial virulence gene expression, bacterial adherence, and transepithelial electrical resistance were examined in response to apical inoculation of P. aeruginosa onto Caco-2 cells. Complementary in vivo studies were performed in a murine model of lethal sepsis due to intestinal P. aeruginosa in which surgical stress (30% hepatectomy) was combined with direct inoculation of P. aeruginosa into the cecum.

RESULTS

High-molecular-weight polyethylene glycol (polyethylene glycol 15-20) conferred complete protection against the barrier-dysregulating effects of P. aeruginosa in Caco-2 cells. Intestinal application of polyethylene glycol 15-20 in stressed mice protected against the lethal effects of intestinal P. aeruginosa. Mechanisms of this effect seem to involve the ability of polyethylene glycol 15-20 to distance P. aeruginosa from the intestinal epithelium and render it completely insensate to key environmental stimuli that activate its virulence.

CONCLUSIONS

High-molecular-weight polyethylene glycol has the potential to function as a surrogate mucin within the intestinal tract of a stressed host by inhibiting key interactive events between colonizing microbes and their epithelial cell targets.