Win Ratio Analyses of Piperacillin-Tazobactam Versus Meropenem for Ceftriaxone-Nonsusceptible Escherichia coli or Klebsiella pneumoniae Bloodstream Infections: Post Hoc Insights From the MERINO Trial.

BACKGROUND: Clinical trials of treatments for serious infections commonly use the primary endpoint of all-cause mortality. However, many trial participants survive their infection and this endpoint may not truly reflect important benefits and risks of therapy. The win ratio uses a hierarchical composite endpoint that can incorporate and prioritize outcome measures by relative clinical importance. METHODS: The win ratio methodology was applied post hoc to outcomes observed in the MERINO trial, which compared piperacillin-tazobactam with meropenem. We quantified the win ratio with a primary hierarchical composite endpoint, including all-cause mortality, microbiological relapse, and secondary infection. A win ratio of 1 would correspond to no difference between the 2 antibiotics, while a ratio <1 favors meropenem. Further analyses were performed to calculate the win odds and to introduce a continuous outcome variable in order to reduce ties. RESULTS: With the hierarchy of all-cause mortality, microbiological relapse, and secondary infection, the win ratio estimate was 0.40 (95% confidence interval [CI], .22-.71]; P = .002), favoring meropenem over piperacillin-tazobactam. However, 73.4% of the pairs were tied due to the small proportion of events. The win odds, a modification of the win ratio accounting for ties, was 0.79 (95% CI, .68-.92). The addition of length of stay to the primary composite greatly minimized the number of ties (4.6%) with a win ratio estimate of 0.77 (95% CI, .60-.99; P = .04). CONCLUSIONS: The application of the win ratio methodology to the MERINO trial data illustrates its utility and feasibility for use in antimicrobial trials.

Implementation of the EUCAST rapid antimicrobial susceptibility test (RAST) for carbapenemase/ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates, and its effect on mortality.

OBJECTIVES: With the rise in antimicrobial resistance, there is a growing demand for rapid antimicrobial susceptibility testing (RAST). In this study, we applied the EUCAST RAST method to ESBL/carbapenemase-producing Escherichia coli and Klebsiella pneumoniae isolates without using advanced identification systems and analysed the effect of this method on mortality rates Also the clinical impact of this method on patients infected with these bacteria and its effect on mortality rates were investigated. METHODS: RAST was used for clinical blood cultures containing carbapenemase/ESBL-producing E. coli and K. pneumoniae without advanced identification systems (e.g. MALDI TOF), with preliminary identification by simple diagnostic tests (predicted RAST, or p-RAST), and its categorical agreement was investigated. The impact of the method on mortality was analysed by comparing the clinical data of patients whose blood cultures were subject to p-RAST (p-RAST group, n = 49) and those who were not subject to p-RAST (non-RAST group, n = 145). RESULTS: p-RAST results were analysed based on 539 antibiotic-bacteria combinations. Total error rates at 4, 6 and 8 h of incubation were 2.9%, 3.9% and 3.8%, respectively. In the p-RAST group, patients who did not receive appropriate antibiotics (29/45, 59.1%) were switched to appropriate treatment within 8 h at the latest. In contrast, in the non-RAST group, treatment of patients who received inappropriate antibiotics (79/145, 54.5%) could be changed after at least 24 h. Mortality rates were lower in the p-RAST group than in the non-RAST group (28.6% versus 51.7%, P = 0.005). CONCLUSIONS: p-RAST can be used safely in hospital laboratories with high rates of antimicrobial resistance and can reduce mortality rates by shortening the transition time to appropriate treatment.

Predicting Adverse Outcomes for Shiga Toxin-Producing Escherichia coli Infections in Emergency Departments.

OBJECTIVE: To assess the performance of a hemolytic uremic syndrome (HUS) severity score among children with Shiga toxin-producing Escherichia coli (STEC) infections and HUS by stratifying them according to their risk of adverse events. The score has not been previously evaluated in a North American acute care setting. STUDY DESIGN: We reviewed medical records of children <18 years old infected with STEC and treated in 1 of 38 participating emergency departments in North America between 2011 and 2015. The HUS severity score (hemoglobin [g/dL] plus 2-times serum creatinine [mg/dL]) was calculated using first available laboratory results. Children with scores >13 were designated as high-risk. We assessed score performance to predict severe adverse events (ie, dialysis, neurologic complication, respiratory failure, and death) using discrimination and net benefit (ie, threshold probability), with subgroup analyses by age and day-of-illness. RESULTS: A total of 167 children had HUS, of whom 92.8% (155/167) had relevant data to calculate the score; 60.6% (94/155) experienced a severe adverse event. Discrimination was acceptable overall (area under the curve 0.71, 95% CI 0.63-0.79) and better among children <5 years old (area under the curve 0.77, 95% CI 0.68-0.87). For children <5 years, greatest net benefit was achieved for a threshold probability >26%. CONCLUSIONS: The HUS severity score was able to discriminate between high- and low-risk children <5 years old with STEC-associated HUS at a statistically acceptable level; however, it did not appear to provide clinical benefit at a meaningful risk threshold.

Escherichia coli bloodstream infections in the western interior of British Columbia, Canada: a population-based cohort study.

Our population-based study objectives were to describe characteristics and outcomes of Escherichia coli bloodstream infections (BSIs), and to evaluate factors associated with outcomes. We included incident E. coli BSIs from western interior residents (British Columbia, Canada; 04/2010-03/2020). We obtained data including patient demographics, location of onset, infection focus, Charlson comorbidity index (CCI), antimicrobial resistance, 30-day all-cause mortality and length of hospital stay (LOS). Using multivariable logistic regression models fitted with generalised estimating equations, we estimated factors associated with 30-day mortality and long post-infection LOS (>75th percentile). We identified 1080 incident E. coli BSIs in 1009 patients. The crude incidence and 30-day mortality rates were 59.1 BSIs and 6.8 deaths/100 000 person-years, respectively. The 30-day case fatality risk was 11.5%. Compared to community-acquired E. coli BSIs, either healthcare-associated or nosocomial cases had higher odds of 30-day mortality. Older cases, non-urogenital BSI foci and CCI ⩾ 3 had higher odds of 30-day mortality compared to younger cases, urogenital foci and CCI < 3. In patients that survived to discharge, those with extended-spectrum ß-lactamase (ESBL)-producing E. coli BSIs, nosocomial BSIs, and CCI ⩾ 3 had higher odds of long post-infection LOS compared to those with non-ESBL-producing, community-acquired and healthcare-associated, and CCI < 3. There is a substantial disease burden from E. coli BSIs.

Mortality in Escherichia coli bloodstream infections: a multinational population-based cohort study.

BACKGROUND: Escherichia coli is the most common cause of bloodstream infections (BSIs) and mortality is an important aspect of burden of disease. Using a multinational population-based cohort of E. coli BSIs, our objectives were to evaluate 30-day case fatality risk and mortality rate, and determine factors associated with each. METHODS: During 2014-2018, we identified 30-day deaths from all incident E. coli BSIs from surveillance nationally in Finland, and regionally in Sweden (Skaraborg) and Canada (Calgary, Sherbrooke, western interior). We used a multivariable logistic regression model to estimate factors associated with 30-day case fatality risk. The explanatory variables considered for inclusion were year (2014-2018), region (five areas), age (< 70-years-old, ≥70-years-old), sex (female, male), third-generation cephalosporin (3GC) resistance (susceptible, resistant), and location of onset (community-onset, hospital-onset). The European Union 28-country 2018 population was used to directly age and sex standardize mortality rates. We used a multivariable Poisson model to estimate factors associated with mortality rate, and year, region, age and sex were considered for inclusion. RESULTS: From 38.7 million person-years of surveillance, we identified 2961 30-day deaths in 30,923 incident E. coli BSIs. The overall 30-day case fatality risk was 9.6% (2961/30923). Calgary, Skaraborg, and western interior had significantly increased odds of 30-day mortality compared to Finland. Hospital-onset and 3GC-resistant E. coli BSIs had significantly increased odds of mortality compared to community-onset and 3GC-susceptible. The significant association between age and odds of mortality varied with sex, and contrasts were used to interpret this interaction relationship. The overall standardized 30-day mortality rate was 8.5 deaths/100,000 person-years. Sherbrooke had a significantly lower 30-day mortality rate compared to Finland. Patients that were either ≥70-years-old or male both experienced significantly higher mortality rates than those < 70-years-old or female. CONCLUSIONS: In our study populations, region, age, and sex were significantly associated with both 30-day case fatality risk and mortality rate. Additionally, 3GC resistance and location of onset were significantly associated with 30-day case fatality risk. Escherichia coli BSIs caused a considerable burden of disease from 30-day mortality. When analyzing population-based mortality data, it is important to explore mortality through two lenses, mortality rate and case fatality risk.

The Galleria mellonella-Enteropathogenic Escherichia coli Model System: Characterization of Pathogen Virulence and Insect Immune Responses.

The use of Galleria mellonella (Linnaeus) (Lepidoptera: Pyralidae), an economical insect model, for the study of enteropathogenic Escherichia coli (Migula) (EPEC), a diarrheagenic human pathogen, has been demonstrated previously but remains poorly understood. The present study characterizes the Galleria-EPEC system extensively for future studies using this system. We found that EPEC causes disease in G. mellonella larvae when injected intrahemocoelically but not orally. Disease manifests as increased mortality, decreased survival time, delayed pupation, decreased pupal mass, increased pupal duration, and hemocytopenia. Disease symptoms are dose-dependent and can be used as metrics for measuring EPEC virulence in future studies. The type III secretion system was only partially responsible for EPEC virulence in G. mellonella while the majority of the virulence remains unknown in origin. EPEC elicits insect anti-bacterial immune responses including melanization, hemolymph coagulation, nodulation, and phagocytosis. The immune responses were unable to control EPEC replication in the early stage of infection (≤3 h post-injection). EPEC clearance from the hemocoel does not guarantee insect survival. Overall, this study provided insights into EPEC virulence and pathogenesis in G. mellonella and identified areas of future research using this system.

Necrotizing fasciitis in haematological patients: a different scenario.

To describe and compare the characteristics of necrotizing fasciitis (NF) in patients with and without haematological malignancy. All adult patients diagnosed with NF and treated at our hospital were included (January 2010-March 2019). Diagnosis was based on intraoperative findings or consistent clinical/radiological characteristics, and patients were classified as group A (with haematological malignancy) or group B (without haematological malignancy). Student's t (quantitative), Fisher's exact (qualitative), and Kaplan-Meyer tests were used for the statistical analysis. The study included 29 patients: 8 in group A and 21 in group B. All haematological patients had severe neutropenia (0.2 [0.02-0.5] ×109 cells/L; p < 0.001) and positive blood cultures (100% vs. 61.9%; p = 0.04) at diagnosis. Gram-negative bacilli NF was more common in group A (87.5% vs. 9.5%; p = 0.001), predominantly due to Escherichia coli (50% vs. 9.5%; p = 0.056). Surgical treatment was less common in haematological patients (5 [62.5%] vs. 21 [100%]; p = 0.015). Overall, 9 (31%) patients died: 4 (50%) in group A and 5 (23.8%) in group B (p = 0.17). The univariate analysis showed that mortality tended to be higher (OR 3.2; 95%CI 0.57-17.7; p = 0.17) and to occur earlier (2.2 ± 2.6 vs. 14.2 ± 19.9 days; p = 0.13) in haematological patients. The LRINEC index > 6 did not predict mortality in either group. In our study, NF in patients with haematological malignancies was mainly due to Gram-negative bacilli, associated to high and early mortality rates. In our experience, the LRINEC scale was not useful for predicting mortality.

Factors associated with typical enteropathogenic Escherichia coli infection among children <5 years old with moderate-to-severe diarrhoea in rural western Kenya, 2008-2012.

Typical enteropathogenic Escherichia coli (tEPEC) infection is a major cause of diarrhoea and contributor to mortality in children <5 years old in developing countries. Data were analysed from the Global Enteric Multicenter Study examining children <5 years old seeking care for moderate-to-severe diarrhoea (MSD) in Kenya. Stool specimens were tested for enteric pathogens, including by multiplex polymerase chain reaction for gene targets of tEPEC. Demographic, clinical and anthropometric data were collected at enrolment and ~60-days later; multivariable logistic regressions were constructed. Of 1778 MSD cases enrolled from 2008 to 2012, 135 (7.6%) children tested positive for tEPEC. In a case-to-case comparison among MSD cases, tEPEC was independently associated with presentation at enrolment with a loss of skin turgor (adjusted odds ratio (aOR) 2.08, 95% confidence interval (CI) 1.37-3.17), and convulsions (aOR 2.83, 95% CI 1.12-7.14). At follow-up, infants with tEPEC compared to those without were associated with being underweight (OR 2.2, 95% CI 1.3-3.6) and wasted (OR 2.5, 95% CI 1.3-4.6). Among MSD cases, tEPEC was associated with mortality (aOR 2.85, 95% CI 1.47-5.55). This study suggests that tEPEC contributes to morbidity and mortality in children. Interventions aimed at defining and reducing the burden of tEPEC and its sequelae should be urgently investigated, prioritised and implemented.

Prognosis of Patients with Sepsis and Non-Hepatic Hyperammonemia: A Cohort Study.

BACKGROUND Hyperammonemia has been reported in some critically ill patients with sepsis who do not have hepatic failure. A significant proportion of patients with non-hepatic hyperammonemia have underlying sepsis, but the association between non-hepatic hyperammonemia and prognosis is unclear. MATERIAL AND METHODS Information about patients with sepsis and non-hepatic hyperammonemia was retrieved from the Medical Information Mart for Intensive Care-III database. Survival rates were analyzed using the Kaplan-Meier method. Multivariate logistic regression models were employed to identify prognostic factors. Receiver operating characteristic (ROC) curve analysis was used to measure the predictive ability of ammonia in terms of patient mortality. RESULTS A total of 265 patients with sepsis were enrolled in this study. Compared with the non-hyperammonemia group, the patients with hyperammonemia had significantly higher rates of hospital (59.8% vs. 43.0%, P=0.007), 30-day (47.7% vs. 34.8%, P=0.036), 90-day (61.7% vs. 43.7%, P=0.004), and 1-year mortality (67.3% vs. 49.4%, P=0.004). In the survival analysis, hyperammonemia was associated with these outcomes. Serum ammonia level was an independent predictor of hospital mortality. The area under the ROC curve for the ammonia levels had poor discriminative capacity. The hyperammonemia group also had significantly lower Glasgow Coma Scale scores (P=0.020) and higher incidences of delirium (15.9% vs. 8.2%, P=0.034) and encephalopathy (37.4% vs. 19.6%, P=0.001). Intestinal infection and urinary tract infection with organisms such as Escherichia coli may be risk factors for hyperammonemia in patients who have sepsis. CONCLUSIONS Higher ammonia levels are associated with poorer prognosis in patients with sepsis. Ammonia also may be associated with sepsis-associated encephalopathy. Therefore, we recommend that serum ammonia levels be measured in patients who are suspected of having sepsis.

National trend of blood-stream infection attributable deaths caused by Staphylococcus aureus and Escherichia coli in Japan.

There has been scarce evidence about deaths due to blood stream infection (BSI) in Japan so far. The main objective of this study is to understand the epidemiological trend of deaths caused by BSIs due to Staphylococcus aureus and Escherichia coli including Methicillin-resistant S. aureus (MRSA) and fluoroquinolone-resistant E. coli (FQREC) at national level. We annually estimated the number of BSI caused by S. aureus and E. coli between 2011 and 2017 across Japan using comprehensive data of bacterial culturing and drug susceptibilities collected in Japan Nosocomial Infection Surveillance (JANIS). The number of death was estimated by using BSI mortality obtained from previous studies in Japan. The number of BSI death attributable to S. aureus was estimated to 17,412 in 2011 and 17,157 in 2017, respectively, out of the whole population (126.8 million) in Japan. Among them, cases attributed to MRSA accounted for 5924 (34.0%) in 2011, and decreased to 4224 (24.6%) cases in 2017. On the other hand, the number of BSI death attributable to E. coli was estimated to 9044 in 2011 and increased to 14,016 in 2017. Among them, cases attributed to FQREC accounted for 2045 (22.6%) in 2011 and increased to 3915 (27.9%) cases in 2017. The number of BSI death attributable to MRSA has been decreasing and that attributable to FQREC has been increasing. This study provides the first annual estimate of disease burden of BSI caused by antimicrobial resistant (AMR) bacteria in Japan, and basis for formulating health policy to deal with AMR.

A retrospective study on Escherichia coli bacteremia in immunocompromised patients: Microbiological features, clinical characteristics, and risk factors for shock and death.

BACKGROUND: To evaluate clinical features, bacterial characteristics, and risk factors for shock and mortality of immunocompromised patients with Escherichia coli bacteremia. METHODS: A nearly 6-year retrospective study of E coli bacteremia in 188 immunocompromised patients at Xiangya Hospital was conducted. Demographic, clinical, and laboratory data were documented. Phylogenetic background and virulence factors of E coli isolates were detected by polymerase chain reaction. Risk factors for shock and mortality were also investigated. RESULTS: Of all 188 E coli isolates, most prevalent virulence factors were fimH (91.0%), followed by traT (68.6%) and iutA (67.0%), while papG allele I, gafD, and cdtB were not detected. Phylogenetic group D was dominant (42.0%) among all isolates, and group B2 accounted for 17.6%, while group A and B1 accounted for 28.2% and 12.2%, respectively. In univariate analysis, ibeA and cnf1 were associated with mortality, which were not found in multivariate regression analysis. 22.3% of patients suffered shock, and 30-day mortality rate was 21.3%. MDR (HR 2.956; 95% CI, 1.091-8.012) was the only risk factor for shock, while adult (HR 0.239; 95% CI, 0.108-0.527) was a protective factor. Multivariate analysis revealed that shock (HR 4.268; 95% CI, 2.208-8.248; P < .001) and Charlson index > 2 (HR 2.073; 95% CI, 1.087-3.952; P = .027) were associated with fatal outcome. CONCLUSIONS: Escherichia coli bacteremia was highly lethal in immunocompromised patients, and host-related factors played major roles in poor prognosis, while bacterial determinants had little effect on outcome. This study also provided additional information about the virulence and phylogenetic group characteristics of E coli bacteremia.

The Role of Iron in the Susceptibility of Neonatal Mice to Escherichia coli K1 Sepsis.

Sepsis from Escherichia coli expressing the K1 antigen is a leading cause of death in neonates. In a murine model, E. coli K1 grew rapidly in the peritoneal cavity of neonatal mice, causing fatal disease. In contrast, adult mice cleared the infection. Neonatal mice mounted a rapid and equivalent antimicrobial immune response compared to adult mice. Interestingly, peritoneal fluid from neonatal mice contained significantly more total iron than that of adult mice, which was sufficient to support enhanced E. coli growth. Transient iron overload in adult mice infected with E. coli resulted in 100% mortality. Maternal diet-induced mild iron deficiency decreased offspring peritoneal iron, decreased bacterial growth, and conferred protection against sepsis. Taken together, neonatal susceptibility to E. coli K1 sepsis is enhanced by a localized excess of peritoneal iron that allows for unchecked bacterial growth. Targeting this excess iron may provide a new therapeutic target in human patients.

Multicenter Population Pharmacokinetic Study of Colistimethate Sodium and Colistin Dosed as in Normal Renal Function in Patients on Continuous Renal Replacement Therapy.

Intravenous colistimethate sodium (CMS) is used to treat infections with multiresistant Gram-negative bacteria. Optimal dosing in patients undergoing continuous renal replacement therapy (CRRT) is unclear. In a prospective study, we determined CMS and colistin pharmacokinetics in 10 critically ill patients requiring CRRT (8 underwent continuous venovenous hemodialysis [CVVHD]; median blood flow, 100 ml/min). Intensive sampling was performed on treatment days 1, 3, and 5 after an intravenous CMS loading dose of 9 million international units (MU) (6 MU if body weight was <60 kg) with a consecutive 3-MU (respectively, 2 MU) maintenance dose at 8 h. CMS and colistin concentrations were determined by liquid chromatography with mass spectroscopy. A model-based population pharmacokinetic analysis incorporating CRRT settings was applied to the observations. Sequential model building indicated a monocompartmental distribution for both CMS and colistin, with interindividual variability in both volume and clearance. Hematocrit was shown to affect the efficacy of drug transfer across the filter. CRRT clearance accounted for, on average, 41% of total CMS and 28% of total colistin clearance, confirming enhanced elimination of colistin compared to normal renal function. Target colistin steady-state trough concentrations of at least 2.5 mg/liter were achieved in all patients receiving 3 MU at 8 h. In conclusion, a loading dose of 9 MU followed after 8 h by a maintenance dose of 3 MU every 8 h independent of body weight is expected to achieve therapeutic colistin concentrations in patients undergoing CVVHD using low blood flows. Colistin therapeutic drug monitoring might help to further ensure optimal dosing in individual patients. (This study has been registered at ClinicalTrials.gov under identifier NCT02081560.).

Carbapenem versus Cefepime or Piperacillin-Tazobactam for Empiric Treatment of Bacteremia Due to Extended-Spectrum-ß-Lactamase-Producing Escherichia coli in Patients with Hematologic Malignancy.

Infections with extended-spectrum-ß-lactamase (ESBL)-producing Escherichia coli are common in patients with hematologic malignancy. The utility of cefepime and piperacillin-tazobactam as empiric therapy for ESBL-producing E. coli bacteremia in patients with hematologic malignancy is largely unknown. We conducted a single-center, retrospective cohort review of 103 adult inpatients with leukemia and/or hematopoietic stem cell transplant (HCT) recipients with monomicrobial ESBL-producing E. coli bacteremia. No association between increased 14-day mortality and empiric treatment with cefepime (8%) or piperacillin-tazobactam (0%) relative to that with carbapenems (19%) was observed (P = 0.19 and P = 0.04, respectively). This observation was consistent in multivariate Cox proportional hazards models adjusted for confounding and an inverse probability of treatment-weighted (IPTW) Cox proportional hazards model. Both fever and persistent bacteremia were more common in patients treated empirically with cefepime or piperacillin-tazobactam. Empiric treatment with cefepime or piperacillin-tazobactam did not result in increased mortality relative to that with treatment with carbapenems in patients with hematologic malignancy and ESBL-producing E. coli bacteremia, although most patients were changed to carbapenems early in treatment. However, due to prolonged fever and persistent bacteremia, their role may be limited in this patient population.

Risk factors for death among children 0-59 months of age with moderate-to-severe diarrhea in Manhiça district, southern Mozambique.

BACKGROUND: Despite major improvements in child survival rates, the number of deaths due to diarrhea remains unacceptably high. We aimed to describe diarrhea-associated mortality and evaluate risk factors for death among Mozambican children with moderate-to-severe diarrhea (MSD). METHODS: Between December 2007 and November 2012, children under-five with MSD were enrolled in Manhiça district, as part of the Global Enteric Multicenter study (GEMS). Clinical, epidemiological, and socio-demographic characteristics were collected. Anthropometric measurements were performed and stool samples collected upon recruitment. A follow-up visit ~ 60 days post-enrolment was conducted and verbal autopsies performed in all death cases. RESULTS: Of the 916 MSD-cases analyzed; 90% (821/916) completed 60 days follow-up and 69 patients died. The case fatality rate at follow-up was 8% (69/821), and the mortality rate 10.2 (95%CI: 7.75-13.59) deaths per 1000 persons-week at risk. Nearly half of the deaths 48% (33/69) among study participants clustered within 2 weeks of the onset of diarrhea. Typical enteropathogenic Escherichia coli (typical EPEC) and Cryptosporidium were the two pathogens associated to an increased risk of death in the univariate analysis with (HR = 4.16, p = 0.0461) and (H = 2.84, p = 0.0001) respectively. Conversely, Rotavirus infection was associated to a decreased risk of death (HR = 0.52, p = 0.0198). According to the multivariate analysis, risk factors for death included co-morbidities such as malnutrition (HR = 4.13, p <  0.0001), pneumonia/lower respiratory infection (HR = 3.51, p <  0.0001) or invasive bacterial disease (IBD) (HR = 6.80, p = 0.0009), presenting on arrival with lethargy or overt unconsciousness (HR = 1.73, p = 0.0302) or wrinkled skin (HR = 1.71, p = 0.0393), and cryptosporidium infection (HR = 2.14, p = 0.0038). When restricting the analysis to those with available HIV results (n = 191, 22% of the total study sample), HIV was shown to be a significant risk factor for death (HR = 5.05, p = 0.0009). Verbal autopsies were conducted in 100% of study deaths, and highlighted diarrhea as the main underlying cause of death 39%, (27/69); followed by HIV/AIDS related deaths 29.0% (20/69) and sepsis 11.6% (8/69). CONCLUSION: Preventive strategies targeting Cryptosporidium, malnutrition and early identification and treatment of associated co-morbidities could contribute to the prevention of the majority of diarrhea associated deaths in Mozambican children.

Hepcidin Protects against Lethal Escherichia coli Sepsis in Mice Inoculated with Isolates from Septic Patients.

Iron is an essential micronutrient for most microbes and their hosts. Mammalian hosts respond to infection by inducing the iron-regulatory hormone hepcidin, which causes iron sequestration and a rapid decrease in the plasma and extracellular iron concentration (hypoferremia). Previous studies showed that hepcidin regulation of iron is essential for protection from infection-associated mortality with the siderophilic pathogens Yersinia enterocolitica and Vibrio vulnificus However, the evolutionary conservation of the hypoferremic response to infection suggests that not only rare siderophilic bacteria but also common pathogens may be targeted by this mechanism. We tested 10 clinical isolates of Escherichia coli from children with sepsis and found that both genetic iron overload (by hepcidin-1 knockout [HKO]) and iatrogenic iron overload (by intravenous iron) potentiated infection with 8 out of the 10 studied isolates: after peritoneal injection of E. coli, iron-loaded mice developed sepsis with 60% to 100% mortality within 24 h, while control wild-type mice suffered 0% mortality. Using one strain for more detailed study, we show that iron overload allows rapid bacterial multiplication and dissemination. We further found that the presence of non-transferrin-bound iron (NTBI) in the circulation is more important than total plasma or tissue iron in rendering mice susceptible to infection and mortality. Postinfection treatment of HKO mice with just two doses of the hepcidin agonist PR73 abolished NTBI and completely prevented sepsis-associated mortality. We demonstrate that the siderophilic phenotype extends to clinically common pathogens. The use of hepcidin agonists promises to be an effective early intervention in patients with infections and dysregulated iron metabolism.

Azithromycin in Combination with Ceftriaxone Reduces Systemic Inflammation and Provides Survival Benefit in a Murine Model of Polymicrobial Sepsis.

Sepsis is a life-threatening systemic inflammatory condition triggered as a result of an excessive host immune response to infection. In the past, immunomodulators have demonstrated a protective effect in sepsis. Azithromycin (a macrolide antibiotic) has immunomodulatory activity and was therefore evaluated in combination with ceftriaxone in a clinically relevant murine model of sepsis induced by cecal ligation and puncture (CLP). First, mice underwent CLP and 3 h later were administered the vehicle or a subprotective dose of ceftriaxone (100 mg/kg of body weight subcutaneously) alone or in combination with an immunomodulatory dose of azithromycin (100 mg/kg intraperitoneally). Survival was monitored for 5 days. In order to assess the immunomodulatory activity, parameters such as plasma and lung cytokine (interleukin-6 [IL-6], IL-1ß, tumor necrosis factor alpha) concentrations, the plasma glutathione (GSH) concentration, plasma and lung myeloperoxidase (MPO) concentrations, body temperature, blood glucose concentration, and total white blood cell count, along with the bacterial load in blood, peritoneal lavage fluid, and lung homogenate, were measured 18 h after CLP challenge. Azithromycin in the presence of ceftriaxone significantly improved the survival of CLP-challenged mice. Further, the combination attenuated the elevated levels of inflammatory cytokines and MPO in plasma and lung tissue and increased the body temperature and blood glucose and GSH concentrations, which were otherwise markedly decreased in CLP-challenged mice. Ceftriaxone produced a significant reduction in the bacterial load, while coadministration of azithromycin did not produce a further reduction. Therefore, the survival benefit offered by azithromycin was due to immunomodulation and not its antibacterial action. The findings of this study indicate that azithromycin, in conjunction with appropriate antibacterial agents, could provide clinical benefits in sepsis.

A systematic review of the association between delayed appropriate therapy and mortality among patients hospitalized with infections due to Klebsiella pneumoniae or Escherichia coli: how long is too long?

BACKGROUND: Temporal relationships between the time to appropriate antibiotic therapy and outcomes are not well described. METHODS: A systematic literature review and meta-analysis was performed to examine this relationship in patients hospitalized with Klebsiella pneumoniae or Escherichia coli infections. RESULTS: Twenty identified studies contained data for patients who received delayed appropriate therapy (DAT) versus appropriate antibiotic therapy for these pathogens. Of the 20 included studies, the majority (19/20) focused on patients with bloodstream infections, and only 1 study evaluated patients with pneumonia. When all DAT results were combined (any delay > 24 h from culture collection or any delay after culture and susceptibility reporting [C& SR]), there was an increased risk of mortality (odds ratio [OR], 1.60 [95% CI, 1.25-2.50]). The risk of mortality was greater when DAT > 48 h from culture collection or DAT > C&SR results were combined (OR, 1.76 [95% CI, 1.27-2.44]). CONCLUSIONS: Our findings suggest there is a need to shift current treatment practices away from antibiotic escalation strategies that contribute to delayed appropriate therapy and toward early, relatively aggressive and comprehensive, antibiotic therapy, especially among patients with bloodstream infections due to K. pneumoniae or E. coli.

Co-infection of turkeys with Escherichia coli (O78) and H6N1 avian influenza virus.

Respiratory diseases are responsible for major economic losses in poultry farms. While in most cases a single pathogen is not alone responsible for the clinical outcome, the impact of co-infections is not well known, especially in turkeys. The purpose of this study was to assess the possible synergism between Escherichia coli (O78) and low pathogenic avian influenza virus (LPAIV, H6N1), in the turkey model. Four-week-old commercial turkeys were inoculated with either H6N1, O78 or both agents simultaneously or three days apart. We have established an experimental infection model of turkeys using aerosolization that better mimics field infections. Birds were observed clinically and swabbed on a daily basis. Necropsies were performed at 4 and 14 days post single or dual inoculation and followed by histological and immunohistochemical analyses. Combined LPAIV/E. coli infections resulted in more severe clinical signs, were associated with higher mortality and respiratory organ lesions (mucous or fibrinous exudative material in lungs and air sacs), in comparison with the groups given single infections (P < 0.05). The time interval or the sequence between H6N1 and E. coli inoculation (none or three days) did not have a significant effect on the outcome of the dual infection and disease although slightly greater (P > 0.05) respiratory signs were observed in turkeys of the E. coli followed by H6N1 inoculated group. Microscopic lesions and immunohistochemical staining supported clinical and macroscopic findings. Efficient virus and bacteria replication was observed in all inoculated groups. E. coli and H6N1 thus exercise an additive or synergistic pathogenic effect in the reproduction of respiratory disease.

Hyponatremia: a new predictor of mortality in patients with Shiga toxin-producing Escherichia coli hemolytic uremic syndrome.

OBJECTIVES: (1) Evaluate mortality rate in patients with Shiga toxin-producing Escherichia coli hemolytic uremic syndrome, (2) determine the leading causes of death, and (3) identify predictors of mortality at hospital admission. METHODS: We conducted a multicentric, observational, retrospective, cross-sectional study. It included patients under 18 years old with Shiga toxin-producing Escherichia coli hemolytic uremic syndrome hospitalized between January 2005 and June 2016. Clinical and laboratory data were obtained from the Argentine National Epidemiological Surveillance System of Hemolytic Uremic Syndrome. Clinical and laboratory variables were compared between deceased and non-deceased patients. Univariate and multivariate analyses were performed. ROC curves and area under the curve were obtained. RESULTS: Seventeen (3.65%) out of the 466 patients died, being central nervous system involvement the main cause of death. Predictors of death were central nervous system involvement, the number of days since the beginning of diarrhea to hospitalization, hyponatremia, high hemoglobin, high leukocyte counts, and low bicarbonate concentration on admission. In the multivariate analysis, central nervous system involvement, sodium concentration, and hemoglobin were independent predictors. The best cut off for sodium was ≤ 128 meq/l and for hemoglobin ≥ 10.8 g/dl. CONCLUSIONS: Mortality was low in children with Shiga toxin-producing Escherichia coli hemolytic uremic syndrome, being central nervous system involvement the main cause of death. The best mortality predictors found were central nervous system involvement, hemoglobin, and sodium concentration. Hyponatremia may be a new Shiga toxin-producing Escherichia coli hemolytic uremic syndrome mortality predictor.