Random forest differentiation of Escherichia coli in elderly sepsis using biomarkers and infectious sites.

This study addresses the challenge of accurately diagnosing sepsis subtypes in elderly patients, particularly distinguishing between Escherichia coli (E. coli) and non-E. coli infections. Utilizing machine learning, we conducted a retrospective analysis of 119 elderly sepsis patients, employing a random forest model to evaluate clinical biomarkers and infection sites. The model demonstrated high diagnostic accuracy, with an overall accuracy of 87.5%, and impressive precision and recall rates of 93.3% and 87.5%, respectively. It identified infection sites, platelet distribution width, reduced platelet count, and procalcitonin levels as key predictors. The model achieved an F1 Score of 90.3% and an area under the receiver operating characteristic curve of 88.0%, effectively differentiating between sepsis subtypes. Similarly, logistic regression and least absolute shrinkage and selection operator analysis underscored the significance of infectious sites. This methodology shows promise for enhancing elderly sepsis diagnosis and contributing to the advancement of precision medicine in the field of infectious diseases.

Characterization of the pathophysiological determinants of diarrheagenic Escherichia coli infection using a challenge model in healthy adults.

An experimental human challenge model with an attenuated diarrheagenic Escherichia coli (E. coli) strain has been used in food intervention studies aimed to increase resistance to E. coli infection. This study was designed to refine and expand this challenge model. In a double-blind study, healthy male subjects were orally challenged with 1E10 or 5E10 colony-forming units (CFU) of E. coli strain E1392/75-2A. Three weeks later, subjects were rechallenged with 1E10 CFU of E. coli. Before and after both challenges, clinical symptoms and infection- and immune-related biomarkers were analyzed. Subset analysis was performed on clinically high- and low-responders. Regardless of inoculation dose, the first challenge induced clinical symptoms for 2-3 days. In blood, neutrophils, CRP, CXCL10, and CFA/II-specific IgG were induced, and in feces calprotectin and CFA/II-specific IgA. Despite clinical differences between high- and low-responders, infection and immune biomarkers did not differ. The first inoculation induced protection at the second challenge, with a minor clinical response, and no change in biomarkers. The refined study design resulted in a larger dynamic range of symptoms, and identification of biomarkers induced by a challenge with the attenuated E. coli strain E1392/75-2A, which is of value for future intervention studies. Addition of a second inoculation allows to study the protective response induced by a primary infection.Clinicaltrials.gov registration: NCT02541695 (04/09/2015).

Immunogenicity and protective efficacy of enterotoxigenic Escherichia coli (ETEC) total RNA against ETEC challenge in a mouse model.

Enterotoxigenic Escherichia coli (ETEC), an essential cause of post-weaning diarrhea (PWD) in piglets, leads to significant economic losses to the pig industry. The present study aims to identify the role of ETEC total RNA in eliciting immune responses to protect animals against ETEC infection. The results showed that the total RNA isolated from pig-derived ETEC K88ac strain effectively stimulated the IL-1ß secretion of porcine intestinal epithelial cells (IPEC-J2). The mouse model immunized with ETEC total RNA via intramuscular injection (IM) or oral route (OR) was used to evaluate the protective efficiency of the ETEC total RNA. The results suggested that 70 µg ETEC total RNA administered by either route significantly promoted the production of the serum IL-1ß and K88ac specific immunoglobulins (IgG, IgM, and IgA). Besides, the ETEC RNA administration augmented strong mucosal immunity by elevating K88ac specific IgA level in the intestinal fluid. Intramuscularly administered RNA induced a Th1/Th2 shift toward a Th2 response, while the orally administered RNA did not. The ETEC total RNA efficiently protected the animals against the ETEC challenge either by itself or as an adjuvant. The histology characterization of the small intestines also suggested the ETEC RNA administration protected the small intestinal structure against the ETEC infection. Particularly of note was that the immunity level and protective efficacy caused by ETEC RNA were dose-dependent. These findings will help understand the role of bacterial RNA in eliciting immune responses, and benefit the development of RNA-based vaccines or adjuvants.

Sympathetic nerves control bacterial clearance.

A neural reflex mediated by the splanchnic sympathetic nerves regulates systemic inflammation in negative feedback fashion, but its consequences for host responses to live infection are unknown. To test this, conscious instrumented sheep were infected intravenously with live E. coli bacteria and followed for 48 h. A month previously, animals had undergone either bilateral splanchnic nerve section or a sham operation. As established for rodents, sheep with cut splanchnic nerves mounted a stronger systemic inflammatory response: higher blood levels of tumor necrosis factor alpha and interleukin-6 but lower levels of the anti-inflammatory cytokine interleukin-10, compared with sham-operated animals. Sequential blood cultures revealed that most sham-operated sheep maintained high circulating levels of live E. coli throughout the 48-h study period, while all sheep without splanchnic nerves rapidly cleared their bacteraemia and recovered clinically. The sympathetic inflammatory reflex evidently has a profound influence on the clearance of systemic bacterial infection.

Epidemiology of invasive early-onset neonatal infection in a French administrative district: A 10-year population-based study.

BACKGROUND: In light of the pending update of the French guidelines for the management of neonatal infections, knowing the current epidemiology of early-onset neonatal infection (EONI) is essential. OBJECTIVES: The aim of this study was to assess the current epidemiology of a French administrative district population of proven EONI, including umbilical cord blood procalcitonin levels. METHODS: We conducted a retrospective population-based study in the Nantes metropolitan area. We included all infants treated for proven EONI in the maternity, neonatology, and intensive care wards between 1 January 2006 and 31 December 2015 in the Nantes University Hospital. RESULTS: Among the 140,502 children born during the study period, 61 cases of EONI were documented. The overall incidence of confirmed EONI was 0.43/1000 live births, with 0.23/1000 GBS (group B streptococcus) infections and 0.08/1000 Escherichia coli infections. The majority of infected newborns were full-term or late-preterm infants (67% were≥34 weeks of gestation), 88% had symptoms of EONI in the first 24h of life, most of which were respiratory. The mortality rate was 8% (in premature infants). Available in 51% of the population, the cord blood PCT value could contribute to an earlier diagnostic screening in 10% of cases but with a very low sensitivity. CONCLUSIONS: The incidence of confirmed EONI is low in this French district. The diagnostic value of PCT umbilical blood cord should be assessed based on further studies before confirming its value. We suggest that a national registry of these rare but serious cases of EONI could contribute to monitoring the epidemiological progression as well as to optimizing our diagnostic and therapeutic strategies.

Molecularly defined extraintestinal pathogenic Escherichia coli status predicts virulence in a murine sepsis model better than does virotype, individual virulence genes, or clonal subset among E. coli ST131 isolates.

BACKGROUND: Escherichia coli ST131, mainly its H30 clade, is the leading cause of extraintestinal E. coli infections but its correlates of virulence are undefined. MATERIALS AND METHODS: We tested in a murine sepsis model 84 ST131 isolates that differed by country of origin (Spain vs. USA), clonal subset, resistance markers, and virulence genes (VGs). Virulence outcomes, including illness severity score (ISS) and "killer" status (>80% mouse lethality), were compared statistically with clonal subset, individual and combined VGs, molecularly defined extraintestinal and uropathogenic E. coli (ExPEC, UPEC) status, and country of origin. RESULTS: Virulence varied widely by strain. Univariable correlates of median ISS and percent "killer" (outcomes if variable present vs. absent) included pap (ISS, 4.4 vs. 3.8; "killer", 71% vs. 46%), kpsMII (4.1 vs. 2.3; 59% vs. 25%), K2/K100 (4.4 vs. 3.2; 77% vs. 41%), ExPEC (4.2 vs. 2.2; 62% vs. 17%), Spanish origin (4.3 vs. 3.1; 65% vs. 36%), and H30R1 subset (2.5 vs. 4.1; 35% vs. 59%). With multivariable adjustment, ExPEC status was the only consistently significantly predictive variable. CONCLUSION: Within ST131 the strongest predictor of experimental virulence was molecularly defined ExPEC status. Clonal subsets seemed to behave differently in the murine sepsis model by country of origin.

Low-molecular-weight chitosan relieves enterotoxigenic Escherichia coli-induced growth retardation in weaned pigs.

The objective of the present study was to evaluate the effects of low-molecular-weight chitosan (LMWC) on the growth performance, immune responses and intestinal health of weaned pigs challenged by enterotoxigenic Escherichia coli (ETEC). A total of 32 weaned pigs were randomly allocated to four treatments: non-challenged (fed with basal diet), ETEC-challenged (fed with basal diet) and ETEC-challenged plus 50 or 100 mg/kg LMWC supplementation, respectively. After 11 days feeding, the non-challenged pigs were infused with sterilised Luria-Bertani culture, while the remaining pigs were infused with 2.6 × 1011 colony-forming units of ETEC. At 3 days post-challenge, all pigs were administered d-xylose at 0.1 g/kg body weight. One hour later, blood samples were obtained, and the pigs then euthanised to collect intestinal samples. Data showed that only 100 mg/kg LMWC supplementation attenuated (P < 0.05) the average daily gain reduction caused by ETEC. Furthermore, besides the decreased (P < 0.05) serum tumour necrosis factor-α and immunoglobulin (Ig) G concentrations detected in ETEC-challenged pigs supplemented with LMWC at 50 or 100 mg/kg, the higher dose (100 mg/kg) also decreased (P < 0.05) the serum IgM concentration and increased (P < 0.05) the villus height and villus height-to-crypt depth ratio in both the jejunum and ileum, and the sucrase activity in the ileal mucosa. Moreover, LMWC supplementation (50 or 100 mg/kg) in ETEC-challenged pigs elevated (P < 0.05) the mRNA levels of jejunal mucosal peptide transporter 1 and ileal mucosal peptide transporter 1, divalent metal transporter 1 and zinc transporter 1, and decreased (P < 0.05) the ileal and caecal E. coli abundances, while 100 mg/kg LMWC additionally elevated (P < 0.05) the ileal Bacillus abundance, and caecal and colonic Bifidobacterium abundances. These results suggest that LMWC helps alleviate ETEC-induced growth retardation in weaned pigs, which could be associated with the inhibition of the immune responses and improved intestinal health.

Initial Immune Response in Escherichia coli, Staphylococcus aureus, and Candida albicans Bacteremia.

Sepsis remains a leading cause of mortality worldwide and is characterized by sustained inflammatory responses, reflected as changes in the expression profile of cytokines with time. The aim of the present study was to investigate the dynamic changes in complete blood count, serum chemistry, procalcitonin (PCT), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) in Escherichia coli, Staphylococcus aureus, and Candida albicans bacteremia. Study subjects were 32 healthy male Landrace-Large White pigs, aged 10-15 weeks and of average weight 19 ± 2 kg. Bacteremia was induced by continuous intravenous infusion of microbial suspensions during a period of 8 h. E. coli and S. aureus bacteremia were associated with a significant gradual decrease in white blood cells and platelets, respectively (p = 0.002 and p = 0.004), while candidemia was characterized by a significant gradual decrease in lymphocytes (p = 0.009). Serum PCT levels were either undetectable or very low, with no significant changes with time in all groups. E. coli bacteremia elicited a strong pro-inflammatory response, characterized by a significant increase in TNF-α expression from the onset of bacteremia (p = 0.042). C. albicans exhibited a different profile with an early, moderate increase in TNF-α followed by a subsequent marked increase in IL-6 levels (p = 0.03). The differential regulation of inflammatory and hematological responses depending on the pathogenic agent can reveal differences in the underlying inflammatory mechanisms, which may assist in the ongoing quest for the identification of a panel of circulating biomarkers during bacteremia.

Pathogenic functions and diagnostic utility of cytokines/chemokines in EHEC-HUS.

Hemolytic - uremic syndrome (HUS) is a severe complication of infection by Shiga toxin (STx)-producing enterohemorrhagic Escherichia coli. Hemolytic - uremic syndrome is defined clinically as a triad of non-immune microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injuries. Neurologic complications such as acute encephalopathy are also observed. In humans, endothelial cells, proximal tubular epithelial cells, mesangial cells, podocytes, intestinal epithelial cells, and monocytes / macrophages are susceptible to STx-mediated injury. Shiga toxin induces the secretion of inflammatory cytokines and chemokines from susceptible cells, including tumor necrosis factor-α interleukin (IL)-1, IL-6, and IL-8. These cytokines and chemokines contribute to the pathogenesis of HUS and encephalopathy by enhancing STx-induced cytotoxicity and inducing inflammatory cell infiltration. Serum cytokine/chemokine levels are therefore useful as indicators of disease activity and predictors of progression from acute kidney injury to chronic kidney disease. Anti-inflammation therapy combined with apheresis to remove excessive cytokines / chemokines and methylprednisolone pulse therapy to suppress cytokine/chemokine production may be an effective treatment regimen for severe E. coli-associated HUS. However, this regimen requires careful monitoring of potential side effects, such as infections, thrombus formation, and hypertension.

Bloodstream infections caused by Escherichia coli in onco-haematological patients: Risk factors and mortality in an Italian prospective survey.

Bloodstream infections (BSIs) remain life-threatening complications in the clinical course of patients with haematological malignancies (HM) and Escherichia coli represent one of the most frequent cause of such infections. In this study, we aimed to describe risk factors for resistance to third generation cephalosporins and prognostic factors, including the impact of third generation cephalosporins resistance, in patients with HM and BSIs caused by E. coli. Three hundred forty-two cases of E. coli BSIs were collected during the study period (from January 2016 to December 2017). The percentage of resistance to third generation cephalosporins was 25.7%. In multivariate analysis, the variables recent endoscopic procedures, culture-positive surveillance rectal swabs for multidrug-resistant bacteria, antibiotic prophylaxis with fluoroquinolones, and prolonged neutropenia were independently associated with bloodstream infections caused by a third generation cephalosporins resistant E. coli. The overall 30-day mortality rate was 7.1%. Cox regression revealed that significant predictors of mortality were acute hepatic failure, septic shock, male sex, refractory/relapsed HM, and third generation cephalosporins resistance by E. coli isolate. In conclusion, resistance to third generation cephalosporins adversely affected the outcomes of bloodstream infections caused by E. coli in our cohort of HM patients. We also found a significant correlation between prophylaxis with fluoroquinolones and resistance to third generation cephalosporins by E. coli isolates.

Serum peptide profiling for potential biomarkers in early diagnosis of Escherichia coli bloodstream infection.

BACKGROUND: Bacterial bloodstream infection (BSI) remains an important cause of morbidity and mortality, which is a widespread and uncontrolled inflammatory response. There are some cytokines for the auxiliary diagnosis, such as procalcitonin (PCT), C reactive protein (CRP), and interleukin 6 (IL-6), which are not sufficient. This study was aimed to explore a new method of diagnosing bacterial BSI and to find some new biomarkers that could differentiate bloodstream infected patients from healthy people. METHODS: An animal model was used to find relevant changes of peptides in the serum and was validated in clinical samples. Mice (25-27 g) were randomized to infection with Escherichia coli ATCC25922 or phosphate buffer saline. The serum samples were purified by weak cation exchange beads and the serum peptide profiling was established by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Statistical analysis and diagnostic modeling were conducted on BioExplorer. Amino acid sequences of the candidate peptides were identified by nano-liquid chromatography electrospray ionization-tandem mass spectrometry and relevant proteins were recognized on the Uniprot database. The identified proteins were confirmed via enzyme-linked immunosorbent assay on clinical samples. RESULTS: Five peptide peaks (m/z 1941, 2924.1, 3962.1, 4126.9 and 5514) were found as candidate biomarkers for E. coli infection, and the diagnostic model discriminated E. coli infected patients from healthy controls with an accuracy of 92.2%. Peptide peaks m/z 1941, 2924.1 and 4126.9 were identified as the fragments of Serotransferrin (TRF), Complement C3 and Serum amyloid A-1 protein (SAA1), respectively, but only C3 and SAA1 showed significant difference in clinical samples. CONCLUSION: MALDI-TOF MS could be a new method to find the changes of serum peptides after infection, C3 and SAA1 could be new biomarkers in diagnosing BSI.

α-Haemolysin production, as a single factor, causes fulminant sepsis in a model of Escherichia coli-induced bacteraemia.

α-Haemolysin (HlyA) from uropathogenic Escherichia coli has been demonstrated to be a significant virulence factor for ascending urinary tract infections. Once the E. coli reach the well-vascularised kidneys, there is a high risk of bacteraemia and a subsequent septic host response. Despite this, HlyA has the potential to accelerate the host response both directly and via its ability to facilitate adenosine triphosphate release from cells. It has not been settled whether HlyA aggravates bacteraemia into a septic state. To address this, we used an E. coli strain in a model of acute urosepsis that was either transfected with a plasmid containing the full HlyA operon or one with deletion in the HlyA gene. Here, we show that HlyA accelerates the host response to E. coli in the circulation. Mice exposed to HlyA-producing E. coli showed massively increased proinflammatory cytokines, a substantial fall in circulating thrombocytes, extensive haematuria, and intravascular haemolysis. This was not seen in mice exposed to either E. coli that do not secrete HlyA or vehicle controls. Consistent with the massive host response to the bacteria, the mice exposed to HlyA-producing E. coli died exceedingly early, whereas mice exposed to E. coli without HlyA production and vehicle controls survived the entire observation period. These data allow us to conclude that HlyA is a virulence factor that accelerates a state of bacteraemia into fulminant sepsis in a mouse model.

Impact of Escherichia coli K12 and O18:K1 on human platelets: Differential effects on platelet activation, RNAs and proteins.

Blood platelets can interact with bacteria, possibly leading to platelet activation, cytokine and microparticle release and immune signalling. Besides, bacteria can also affect the platelet RNA content. We investigated the impact of non-pathogenic K12 and pathogenic O18:K1 Escherichia (E.) coli strains on platelet activation, RNA expression patterns, and selected proteins. Depending on bacteria concentration, contact of platelets with E. coli K12 lead to an increase of P-selectin (24-51.3%), CD63 (15.9-24.3%), PAC-1 (3.8-14.9%) and bound fibrinogen (22.4-39%) on the surface. E. coli O18:K1 did not affect these markers. Sequencing analysis of total RNA showed that E. coli K12 caused a significant concentration change of 103 spliced mRNAs, of which 74 decreased. For the RNAs of HMBS (logFC = +5.73), ATP2C1 (logFC = -3.13) and LRCH4 (logFC = -4.07) changes were detectable by thromboSeq and Tuxedo pipelines. By Western blot we observed the conversion of HMBS protein from a 47 kDA to 40 kDa product by E. coli K12, O18:K1 and by purified lipopolysaccharide. While ATP2C1 protein was released from platelets, E. coli either reduced the secretion or broke down the released protein making it undetectable by antibodies. Our results demonstrate that different E. coli strains influence activation, RNA and protein levels differently which may affect platelet-bacteria crosstalk.

Therapeutic effects of 5,2'-dibromo-2,4',5'-trihydroxydiphenylmethanone (LM49) in an experimental rat model of acute pyelonephritis by immunomodulation and anti-inflammation.

Antibiotics are still the primary therapy for acute pyelonephritis (APN); rarely, natural polyphenols are also used. LM49 is a novel marine bromophenol derivative displaying strong anti-inflammatory effects. We investigated the therapeutic efficacy of LM49 in an experimental rat model of APN. The model was established by injecting 0.5 mL Escherichia coli (ATCC 25922, 108 CFU/mL) into the urinary bladders of Sprague Dawley rats. This model showed increased kidney viscera indices and renal bacterial growth scores, as well as pathological changes in kidneys. We also performed a broth microdilution antimicrobial susceptibility test of the E. coli strain. Both norfloxacin and LM49 treatment reduced kidney viscera indices and decreased microbial counts in urine cultures and kidney homogenates in APN rats. However, in vitro experiments showed that LM49 did not directly inhibit bacteria. Rather, LM49 treatment inhibited inflammatory cell infiltration or abscess and improved tissue lesions in the renal medullary junction, renal pelvis, and calyx, and high-dose LM49 treatment inhibited the production of inflammatory interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) in serum. CD4+ T cells were higher in the LM49 groups treated with high, medium, and low doses than in the model group, whereas only high-dose LM49 treatment increased the number of CD8+ T cells, as compared with that in the model group. However, LM49 treatment did not influence hematological parameters. Our results show that LM49 therapeutic effects in an APN animal model may be achieved by regulating immune responses and inhibiting inflammatory mediators, suggesting it as a candidate APN treatment.

Clinical predictors of escalating care in hepatic and renal cyst infection in autosomal dominant polycystic kidney and liver disease.

BACKGROUND: Cyst infection may occur in autosomal dominant polycystic kidney disease (ADPKD) and autosomal dominant polycystic liver disease (ADPLD). Antimicrobial agents often fail to control infection, leading to invasive action. We aimed to identify factors predicting escalation of care. METHODS: ADPKD and ADPLD patients were identified from local/national databases (2001-2013). Records were screened for patients meeting criteria for cyst infection (positive cyst aspirate and/or clinical findings). Factors that predict escalated care were identified with multivariate modified Poisson regression. RESULTS: We screened 1773 patients. A total of 77 patients with cyst infection (4.3%) were included for analysis (hepatic 36%; male 49%; age 54 ±; 13 years; ADPKD 95%; dialysis 9%, diabetes 18%, renal transplant 56%, eGFR [IQR 24-78] ml/min/1.73 m2 (excluding patients with a history of renal transplant or receiving dialysis)). A pathogen was identified in 71% of cases. Escherichia coli was the most common pathogen and accounted for 69% of cases. Initial treatment was limited to antibiotics in 87% of patients (n = 67), 40% included a fluoroquinolone. Ultimately, 48% of patients underwent some form of invasive action (escalation of care). Increasing white blood cell count (WBC) (RR 1.04 95%-CI 1.01-1.07, p = 0.008) was associated with escalating care, whereas an increase in time between transplant and infection (RR 0.92 95% CI 0.86-0.97, p = 0.005) and E. coli isolation (RR 0.55 95% CI 0.34-0.89, p = 0.02) were protective. CONCLUSION: High serum WBC, isolation of atypical pathogens and early infection after transplantation are factors that increase the risk of escalation of care in hepatic and renal cyst infection patients.

[Antibiotic Resistance and Risk Factors for Mortality of Blood Stream Infections (BSIs) with Escherichia coli in Patients with Hematological Malignancies].

OBJECTIVE: To analyze the risk factors for mortality of blood stream infections (BSIs) caused by Escherichia coli in the patients with hematological malignancies. METHODS: There were 110 Escherichia coli BSIs patients with hematological malignancies included in recent five years. Among them,77 cases had BSIs caused by extended-spectrum-beta-lactamase (ESBL)-producing Escherichia coli (ESBL-EC group),while 33 cases had BSIs with non-ESBL-producing Escherichia coli (non-ESBL-EC group). The antibiotic resistance and clinical features were compared between the two groups,and the risk factors for death within 30 d were analyzed. RESULTS: Less than 10% of the isolates were resistant to carbapenems and amikacin. Between ESBL-EC group and non-ESBL-EC group,the clinical symptoms,prior use of antibiotics or antifungal agents,risk factors for infection,30 d mortality rates were not significantly different (P>0.05). A logistic regression analysis confirmed that non remission of hematologic malignancies (odds ratio=9.575,95% confidence interval 1.546-59.312,P=0.015) and inappropriate initial antibiotic therapy (odds ratio=8.806,95% confidence interval 1.527-50.772, P=0.015) were independent risk factors for 30 d mortality. CONCLUSION: The use of effective antimicrobial treatment as early as possible could reduce the risk of death for hematological malignancies patients suffering Escherichia coli BSIs.

Pathogenic role of inflammatory response during Shiga toxin-associated hemolytic uremic syndrome (HUS).

Hemolytic uremic syndrome (HUS) is defined as a triad of noninmune microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. The most frequent presentation is secondary to Shiga toxin (Stx)-producing Escherichia coli (STEC) infections, which is termed postdiarrheal, epidemiologic or Stx-HUS, considering that Stx is the necessary etiological factor. After ingestion, STEC colonize the intestine and produce Stx, which translocates across the intestinal epithelium. Once Stx enters the bloodstream, it interacts with renal endothelial and epithelial cells, and leukocytes. This review summarizes the current evidence about the involvement of inflammatory components as central pathogenic factors that could determine outcome of STEC infections. Intestinal inflammation may favor epithelial leakage and subsequent passage of Stx to the systemic circulation. Vascular damage triggered by Stx promotes not only release of thrombin and increased fibrin concentration but also production of cytokines and chemokines by endothelial cells. Recent evidence from animal models and patients strongly indicate that several immune cells types may participate in HUS physiopathology: neutrophils, through release of proteases and reactive oxygen species (ROS); monocytes/macrophages through secretion of cytokines and chemokines. In addition, high levels of Bb factor and soluble C5b-9 (sC5b-9) in plasma as well as complement factors adhered to platelet-leukocyte complexes, microparticles and microvesicles, suggest activation of the alternative pathway of complement. Thus, acute immune response secondary to STEC infection, the Stx stimulatory effect on different immune cells, and inflammatory stimulus secondary to endothelial damage all together converge to define a strong inflammatory status that worsens Stx toxicity and disease.

Effects of low-dose irradiation on mice with Escherichia coli-induced sepsis.

Although favorable immune responses to low-dose irradiation (LDI) have been observed in normal mice, i.e., a hormesis effect, little is known about the effects of LDI in infectious diseases. In this study, we examined the effects of LDI on mice with sepsis, a severe and often lethal hyperinflammatory response to bacteria. Female C57BL/6 mice were whole-body irradiated with 10cGy 48h before Escherichia coli infection, and survival, bacterial clearance, cytokines, and antioxidants were quantified. LDI pretreatment significantly increased survival from 46.7% in control mice to 75% in mice with sepsis. The bacterial burden was significantly lower in the blood, spleen, and kidney of LDI-treated mice than in those of control septic mice. The levels of pro-inflammatory cytokines, e.g., IL-1ß and IL-6, as well as anti-inflammatory IL-10 were markedly reduced in pre-LDI septic mice. Nitric oxide production by peritoneal macrophages was also reduced in pre-LDI septic mice. Immune cells in the spleen increased and Nrf2 and HO-1 were induced in pre-LDI septic mice. LDI stimulates the immune response and minimizes lethality in septic mice via enhanced bacterial clearance and reduced initial proinflammatory responses.

Red blood cell and platelet parameters are sepsis predictors in an Escherichia coli induced lethal porcine model.

OBJECTIVE: In a fulminant porcine sepsis model, we determined the kinetics of hypoxia induced changes in relation to sepsis parameters and markers of organ damage. METHODS: Female pigs were challenged by live Escherichia coli and samples were analysed up to 4 hours. Bone marrow reactions were determined by analysing immature forms of peripheral blood cells by a hematology analyser and light microscopy. Platelet mitochondrial membrane depolarisation was determined by flow cytometry. RESULTS: Core temperature, modified shock index and lactate levels all became significantly elevated compared to baseline values at 4 hours in septic animals. At 2 hours already the reticulocyte count, nucleated red blood cell count and the absolute number of dysplastic platelets became significantly elevated. The platelet mitochondrial membrane depolarisation was significantly decreased by 2 hours in septic animals compared to the baseline values and to control animals. No massive organ damage was evident during the 4-hour observation period, but uric acid levels in septic animals became significantly elevated already by 2 hours. CONCLUSIONS: In this Escherichia coli induced porcine model, severe sepsis was evident by conventional criteria at 4 hours while several - mostly hypoxemia induced - biomarkers were already altered by 2 hours.

Serum ferritin as an indicator of the development of encephalopathy in enterohemorrhagic Escherichia coli-induced hemolytic uremic syndrome.

OBJECTIVES: To investigate the diagnostic value of serum ferritin levels as a marker of disease activity and the development of encephalopathy in hemolytic uremic syndrome (HUS) induced by enterohemorrhagic Escherichia coli. METHODS: Twenty patients with HUS were studied. Serum ferritin levels were compared with clinical features and serum soluble tumor necrosis factor receptor (sTNFR) I and sTNFRII levels. Serum sTNFRI and sTNFRII levels were quantified by enzyme-linked immunosorbent assays. RESULTS: Serum ferritin levels were significantly elevated at the time of the diagnosis of HUS. Serum ferritin levels were significantly elevated in patients with encephalopathy compared to patients without encephalopathy. HUS patients with serum ferritin levels of >687.5 ng/ml were at high risk of encephalopathy. Serum ferritin levels were significantly positively correlated with serum sTNFRI and sTNFRII levels. CONCLUSIONS: Serum ferritin levels are a promising indicator of the development of encephalopathy in HUS.