A Genetic Modifier of the Gut Microbiome Influences the Risk of Graft-versus-Host Disease and Bacteremia After Hematopoietic Stem Cell Transplantation.

The human gut microbiome is involved in vital biological functions, such as maintenance of immune homeostasis and modulation of intestinal development and enhanced metabolic capabilities. Disturbances of the intestinal microbiota have been associated with development and progression of inflammatory conditions, including graft-versus-host disease (GVHD). The fucosyltransferase 2 (FUT2) gene produces an enzyme that is responsible for the synthesis of the H antigen in body fluids and on the intestinal mucosa. FUT2 genotype has been shown to modify the gut microbiome. We hypothesized that FUT2 genotype influences risk of GVHD and bacterial translocation after allogeneic hematopoietic stem cell transplantation (HSCT). FUT2 genotype was determined in 150 consecutive patients receiving allogeneic HSCT at our center. We abstracted clinical characteristics and outcomes from the transplantation database. Cumulative risk of any acute GVHD varied by FUT2 genotype, with decreased risk in those with A/A genotype and increased risk in those with G/G genotype. In contrast, the cumulative incidence of bacteremia was increased in those with A/A genotype. We conclude that the FUT2 genotype influences risk of acute GVHD and bacteremia after HSCT. We hypothesize that the mechanisms involve altered intestinal surface glycosylation and microbial composition but this requires additional study.

Role of Biological Characteristics of Staphylococcus epidermidis in Intraerythrocytic Invasion and in Modulation of Erythrocyte Catalase and Superoxide Dismutase Activities in Experimental Generalized Infection.

Studies on mouse model of generalized Staphylococcus epidermidis infection have demonstrated that erythrocytes more often contained microorganisms with pronounced antihemoglobin activity and less frequently with hemolytic activity. Infection with S. epidermidis strains characterized by pronounced hemolytic or antihemoglobin activities was associated with inhibition of erythrocyte catalase and superoxide dismutase activities in all cases, except infection with strains with high antihemoglobin activity, when superoxide dismutase activity increased.

Cyclooxygenase-2 deficiency leads to intestinal barrier dysfunction and increased mortality during polymicrobial sepsis.

Sepsis remains the leading cause of death in critically ill patients, despite modern advances in critical care. Intestinal barrier dysfunction may lead to secondary bacterial translocation and the development of the multiple organ dysfunction syndrome during sepsis. Cyclooxygenase (COX)-2 is highly upregulated in the intestine during sepsis, and we hypothesized that it may be critical in the maintenance of intestinal epithelial barrier function during peritonitis-induced polymicrobial sepsis. COX-2(-/-) and COX-2(+/+) BALB/c mice underwent cecal ligation and puncture (CLP) or sham surgery. Mice chimeric for COX-2 were derived by bone marrow transplantation and underwent CLP. C2BBe1 cells, an intestinal epithelial cell line, were treated with the COX-2 inhibitor NS-398, PGD(2), or vehicle and stimulated with cytokines. COX-2(-/-) mice developed exaggerated bacteremia and increased mortality compared with COX-2(+/+) mice following CLP. Mice chimeric for COX-2 exhibited the recipient phenotype, suggesting that epithelial COX-2 expression in the ileum attenuates bacteremia following CLP. Absence of COX-2 significantly increased epithelial permeability of the ileum and reduced expression of the tight junction proteins zonula occludens-1, occludin, and claudin-1 in the ileum following CLP. Furthermore, PGD(2) attenuated cytokine-induced hyperpermeability and zonula occludens-1 downregulation in NS-398-treated C2BBe1 cells. Our findings reveal that absence of COX-2 is associated with enhanced intestinal epithelial permeability and leads to exaggerated bacterial translocation and increased mortality during peritonitis-induced sepsis. Taken together, our results suggest that epithelial expression of COX-2 in the ileum is a critical modulator of tight junction protein expression and intestinal barrier function during sepsis.

Simple indictor of increased blood culture contamination rate by detection of coagulase-negative staphylococci.

Coagulase-negative staphylococci (CoNS) are the most frequent contaminating bacteria; therefore, we aimed to investigate an indicator of CoNS to predict the increase in blood culture contamination rate (ConR). We performed a retrospective study of selected patients, who underwent blood culture testing. Contamination was defined as the presence of either one of two or more sets of skin-resident bacteria, except for cases with a low likelihood of contamination based on clinical aspects. We calculated the monthly ConR [(total number of contaminated cases per month)/(total number of blood culture sets collected per month) × 100] and analysed the ConR prediction ability using the following four indicators: the number of CoNS-positive sets of blood cultures, cases with at least one CoNS-positive blood culture set, cases with only one CoNS-positive blood culture set, and cases of contamination by CoNS. Cases with CoNS-positive blood cultures correlated with ConR (r = 0.85). Although the area under the receiver operating characteristic curve for the number of cases with ConR ≥ 2.5 differed significantly from that of the number of cases contaminated by CoNS, the negative predictive value was high, reaching up to 95.5% (95% confidential interval 87.3-99.1). The number of CoNS-positive cases could help predict an increase in ConR ≥ 2.5.

Endogenous hydrogen sulfide regulates inflammatory response by activating the ERK pathway in polymicrobial sepsis.

Hydrogen sulfide (H(2)S) up-regulates inflammatory response in several inflammatory diseases. However, to date, little is known about the molecular mechanism by which H(2)S provokes the inflammatory response in sepsis. Thus, the aim of this study was to investigate the signaling pathway underlying the proinflammatory role of H(2)S in cecal ligation and puncture (CLP)-induced sepsis. Male Swiss mice were subjected to CLP and treated with dl-propargylglycine (PAG; 50 mg/kg i.p., an inhibitor of H(2)S formation), NaHS (10 mg/kg, i.p., an H(2)S donor), or saline. PAG was administered 1 h before CLP, whereas NaHS was given at the time of CLP. CLP-induced sepsis resulted in a time-dependent increase in the synthesis of endogenous H(2)S. Maximum phosphorylation of ERK1/2 and degradation of IkappaBalpha in lung and liver were observed 4 h after CLP. Inhibition of H(2)S formation by PAG significantly reduced the phosphorylation of ERK1/2 in lung and liver 4 h after CLP, coupled with decreased degradation of IkappaBalpha and activation of NF-kappaB. In contrast, injection of NaHS significantly enhanced the activation of ERK1/2 in lung and liver, therefore leading to a further rise in tissue NF-kappaB activity. As a result, pretreatment with PAG significantly reduced the production of cytokines and chemokines in sepsis, whereas exogenous H(2)S greatly increased it. In addition, pretreatment with PD98059, an inhibitor of ERK kinase (MEK-1), significantly prevented NaHS from aggravating systemic inflammation in sepsis. In conclusion, the present study shows for the first time that H(2)S may regulate systemic inflammatory response in sepsis via ERK pathway.

Human diamine oxidase is readily released from activated neutrophils ex vivo and in vivo but is rarely elevated in bacteremic patients.

During human diamine oxidase (DAO) ELISA development we noticed that in serum DAO concentrations appear to be higher when compared to plasma. Neutrophils contain DAO in the specific granules and we hypothesized that DAO is released from neutrophils during serum coagulation. If activation of neutrophils can release DAO, its concentrations might be elevated in vivo after lipopolysaccharide (LPS) administration and in bacteremic patients. Using blood from healthy volunteers DAO concentrations were measured ex vivo in serum, citrate, EDTA and heparin plasma over several hours and after activation of neutrophils. Lipopolysaccharide and granulocyte-colony stimulating factor (G-CSF) were administered to 15 and 8 healthy volunteers, respectively and DAO concentrations were measured at different timepoints. DAO antigen levels were also determined in three different subcohorts of patients with culture-proven bacteremia and high C-reactive protein (CRP) levels. DAO concentrations were elevated in a time-dependent manner in serum but not in EDTA or citrate plasma (P < 0.01). Neutrophil activation using phorbol myristate acetate (PMA) and zymosan dose-dependently caused DAO concentrations to be elevated more than 10-fold at both 22°C and 37°C (both P-values <0.001). Administration of LPS to healthy volunteers released DAO from neutrophils (P < 0.001). Of the 55 different bacteremic patients selected from three independent cohorts only 3 (5.4%) showed highly elevated DAO concentrations. Serum DAO concentrations do not accurately reflect circulating enzyme levels but coagulation-induced neutrophil activation and consequently DAO release. Only a few bacteremic patients show high DAO concentrations able to degrade histamine rapidly.

N,N'-diacetylchitobiose, an inhibitor of lysozyme, reverses myocardial depression and lessens norepinephrine requirements in Escherichia coli sepsis in dogs.

Cardiovascular dysfunction in septic shock (SS) is ascribed to the release of inflammatory mediators. Norepinephrine (NE) is often administered to treat low MAP in SS. We recently found that lysozyme c (Lzm-S) released from leukocytes was a mediator of myocardial depression in an Escherichia coil model of SS in dogs. This effect can be blocked in an in vitro preparation by chitobiose, a competitive inhibitor of Lzm-S. In the present study, we examined whether chitobiose treatment can reverse myocardial depression and obviate NE requirements in two respective canine E. coli preparations. In a 6-h study, we administered chitobiose after 3.5 h of E. coli bacteremia and compared stroke work (SW) and MAP at 6 h with a sepsis control group. In a 12-h study, we determined whether chitobiose treatment can reduce the need for NE requirements during 12 h of bacteremia. In the latter study, either chitobiose or NE was given when MAP decreased approximately 20% from the presepsis value in respective groups. In anesthetized, mechanically ventilated dogs, we monitored hemodynamic parameters during continuous E. coli infusion. In the 6-h study, chitobiose improved SW and MAP at the 6-h period as compared with the nontreated sepsis group. In the 12-h study, SW and MAP increased after chitobiose without the necessity of NE administration. These results suggest that inhibitors of Lzm-S such as chitobiose may improve myocardial depression and reduce the need for NE requirements in SS.

Mobilization of potent plasma bactericidal activity during systemic bacterial challenge. Role of group IIA phospholipase A2.

Extracellular mobilization of Group IIA 14-kD phospholipase A2 (PLA2) in glycogen-induced rabbit inflammatory peritoneal exudates is responsible for the potent bactericidal activity of the inflammatory fluid toward Staphylococcus aureus (1996. J. Clin. Invest. 97:250-257). Because similar levels of PLA2 are induced in plasma during systemic inflammation, we have tested whether this gives rise to plasma bactericidal activity not present in resting animals. Baboons were injected intravenously (i.v.) with a lethal dose of Escherichia coli and plasma or serum was collected before and at hourly intervals after injection. After infusion of bacteria, PLA2 levels in plasma and serum rose > 100-fold over 24 h to approximately 1 microg PLA2/ml. Serum collected at 24 h possessed potent bactericidal activity toward S. aureus, Streptococcus pyogenes, and encapsulated E. coli not exhibited by serum collected from unchallenged animals. Bactericidal activity toward S. aureus and S. pyogenes was nearly completely blocked by a monoclonal antibody to human Group IIA PLA2 and addition of purified human Group IIA PLA2 to prechallenge serum conferred potent antistaphylococcal and antistreptococcal activity equal to that of the 24 h post-challenge serum. PLA2-dependent bactericidal activity was enhanced approximately 10x by factor(s) present constitutively in serum or plasma. Bactericidal activity toward encapsulated E. coli was accompanied by extensive bacterial phospholipid degradation mediated, at least in part, by the mobilized Group IIA PLA2 but depended on the action of other bactericidal factors in the 24-h serum. These findings further demonstrate the contribution of Group IIA PLA2 to the antibacterial potency of biological fluids and suggest that mobilization of this enzyme during inflammation may play an important role in host defense against invading bacteria.

Compatibility of pulsed-field gel electrophoresis findings and clinical criteria commonly used to distinguish between true coagulase-negative staphylococcal bacteremia and contamination.

OBJECTIVES: To evaluate the specificity and sensitivity of the clinical criteria widely used to differentiate true coagulase-negative staphylococcal (CoNS) bacteremia from contamination, using pulsed-field gel electrophoresis (PFGE) as the reference test. DESIGN: The study sample consisted of 79 CoNS isolates recovered from cultures of blood from 38 patients. Medical charts of the patients were reviewed for demographic and clinical information. The relatedness of CoNS strains recovered from 2 or more successive blood cultures was analyzed by PFGE. Patients from whom similar strains were recovered were assumed to have true bacteremia, whereas patients from whom different strains were recovered were considered to have contaminated blood cultures. The clinical criteria comprised Centers for Disease Control and Prevention (CDC) surveillance definitions for bloodstream infection (BSI), as well as an alternative criterion based on the presence of fever, the presence of leukocytosis, the absence of another recognized infection, and the recovery of CoNS from 2 or more successive blood cultures. RESULTS: Nineteen (50%) of the 38 patients had bacteremia due to similar strains; the remaining patients had bacteremia due to different strains. Criterion 2a of the CDC definition for BSI had a sensitivity of 100% and a specificity of 31.6% for distinguishing between true bacteremia and contamination. CDC criterion 2b had a sensitivity of 78.9% and a specificity of 52.6%. CONCLUSIONS: Molecular typing correlated poorly with the clinical criteria for true bacteremia. In view of the limited applicability of clinical criteria, more studies are needed to improve them. Periodic cross-sectional studies based on PFGE findings might be useful to estimate local contamination rates in an institution, which in turn can be used to improve the accuracy of the clinical diagnosis of bacteremia.

Rapid Blue-Carba test: reduction in the detection time of carbapenemases performed from a 4-hour bacterial lawn.

The increase in carbapenem-resistant gram-negative bacteria is a matter of concern due to the limited therapeutic options available. In severe infections caused by these isolates, the rapid detection of the mechanisms of resistance is vital. We described a slightly modified version of the Blue-Carba test, rapid Blue-Carba test, which allows the detection of carbapenemases at 4 h of incubation from a haze of bacterial growth obtained from a positive blood culture. It was able to detect carbapenemase-producing isolates (Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii) with a sensitivity and specificity of 98.1 and 100%, respectively. It is a rapid, easy-to-perform and an inexpensive technique that can be applied to routine laboratories, together with the simultaneous identification by mass spectrometry which would help to screen non-enzymatic carbapenem resistance; this method allows the detection of clinically relevant multidrug-resistant bacteria and the early implementation of accurate therapeutic interventions.

Extremely high levels of alkaline phosphatase in adult patients as a manifestation of bacteremia.

BACKGROUND/AIMS: Jaundice resulting from severe bacterial infection is well known, particularly in pediatric literature. Extremely high levels of alkaline phosphatase (ALP) have rarely been emphasized as a manifestation of bacteremia in adults. The aim of this study was to evaluate the characteristics of extremely high levels of ALP in adult patients as a manifestation of bacteremia. METHODOLOGY: Extremely high levels of ALP were defined as being more than 1000 U/L. From April 1998 to May 1999, we retrospectively reviewed those patients' charts who had ALP above 1000 U/L. Sixteen patients that had bacteremia among 96 patients with extremely high levels of ALP at the emergency department of Taichung Veterans General Hospital were included in this study. RESULTS: Sixteen patients had bacteremia with extremely high levels of ALP, including 9 patients with malignant biliary obstruction (MBO), and 7 patients without MBO. The ALP levels ranged from 1002 to 2061 (1430.13+/-353.84) U/L. Ten patients were male, and 6 were female. Their ages ranged from 19 to 83 (56.13+/-16.51) years. A variety of gram-negative, and gram-positive organisms were identified, and Escherichia coli was the most common pathogen. Among the seven patients of bacteremia without MBO, 5 patients had underlying diabetes mellitus as the predisposing factor for development of the bacteremia. The ages of the bacteremia patients with MBO were older than those of patients without MBO (66.3+/-10.1 us. 43.0+/-13.7 years, P=0.0025). CONCLUSIONS: Bacteremia from a variety of organisms is a common cause for extreme elevation of ALP. Escherichia coli is the most common pathogen and presented more often in patients with MBO than those without MBO. In the setting o f extremely high levels of ALP as a manifestation of bacteremia, the patients with MBO are as common as those without MBO. We have demonstrated clinically that hepatic dysfunction during bacteremia may be manifested predominantly by extreme elevation of alkaline phosphatase with little abnormality in serum bilirubin.

Expression of inflammation-associated genes in circulating leukocytes and activity of indoleamine-2,3-dioxygenase in dairy cattle with acute puerperal metritis and bacteremia.

OBJECTIVE: To investigate whether expression of genes associated with inflammation and activity of indoleamine-2,3-dioxygenase (IDO) correlated with disease status and prevalence of bacteremia in post-partum dairy cattle with and without acute puerperal metritis (APM). PROCEDURES: Blood was collected from cattle with APM and control cattle matched by parity and days in milk. Leukocytes were isolated and expression of 6 genes was quantified. Activity of IDO was measured in serum with higher performance liquid chromatography (HPLC). RESULTS: The relative expression of IL-1ß in cattle with APM was significantly lower than that in controls. IDO activity was not significantly different between bacteremic and non-bacteremic cattle CONCLUSIONS AND CLINICAL RELEVANCE: The expression of IL-1ß was lower in cattle with APM. The lower levels of IL-1ß expression in PBMCs of cattle with APM suggest impaired inflammatory responses and may contribute to the development of the disease in this population of animals.

First report of New Delhi metallo-ß-lactamase-1-producing strains in Slovakia.

Occurrence of carbapenemase-producing organisms, including New Delhi metallo-ß-lactamase-1 (NDM-1) is increasingly reported worldwide. The aim of this study was to assess the distribution of carbapenemase producers among multidrug-resistant Gram-negative bacteria isolated from blood cultures. All carbapenem-resistant strains collected from December 2011 to December 2012 were analyzed. Presence of carbapenemases was assessed with combined disc test and Carba NP test followed by polymerase chain reaction for carbapenemase genes. Altogether, 30 strains were detected, of which 7 were positive for VIM (23.3%), 6 for NDM-1 (20%), 5 for IMP (16.7%), and KPC was present in one isolate (3.3%). Four Pseudomonas aeruginosa strains were found to produce more than one carbapenemase. We also present the case report of a patient with Acinetobacter baumannii ventilator-associated pneumonia, followed by sepsis due to Enterococcus faecalis and pan-resistant NDM-1-producing P. aeruginosa. Despite the inappropriate therapy, the patient was successfully treated. This is the first report of NDM-1-producing strains in Slovakia and it contributes to a number of studies mapping the distribution of carbapenemase producers in Europe.

Liver enzyme abnormalities in gram-negative bacteremia of premature infants.

BACKGROUND: Hyperbilirubinemia and liver enzyme abnormalities are commonly observed in sepsis. However, the frequency in premature neonates and the specific relation to gram-negative bacteria are not known. PATIENTS AND METHODS: Charts of all preterm infants who had positive blood cultures for either gram-negative bacteria or coagulase-negative staphylococci were reviewed. Neonates with gram-negative bacteremia (n = 54) were compared with neonates with coagulase-negative staphylococcal bacteremia (n = 31). In addition infants with gram-negative bacteremia and elevated liver enzymes (n = 25) were compared with infants with gram-negative bacteremia and normal liver enzymes (n = 29). RESULTS: Liver enzyme abnormalities accompanied 46.3% (25 of 54) of gram-negative bacteremia and 12.9% (4 of 31) of episodes of coagulase-negative staphylococcal bacteremia (P = 0.002). Serum concentrations of liver enzymes were significantly higher in infants with gram-negative bacteremia than in those with coagulase-negative staphylococcal bacteremia (P < 0.0001), but no difference in alkaline phosphatase serum values was observed. Infants with gram-negative bacteremia and elevated liver enzymes were not fed for a longer period than infants with gram-negative bacteremia and normal liver enzymes (7.3 +/- 6.3 days vs. 4.0 +/- 4.3 days, P = 0.03), and this was accompanied by significant conjugated hyperbilirubinemia (P < 0.0001). Ventilation, total parenteral nutrition and medications were not responsible for the observed differences. Klebsiella pneumoniae bacteremia was commonly associated with elevated liver enzymes (12 of 18), whereas none of the infants with Pseudomonas aeruginosa bacteremia had elevated liver enzymes. CONCLUSIONS: Gram-negative bacteremia is commonly associated with cholestasis in premature neonates. Liver enzyme abnormalities are more common than elevated conjugated bilirubin, not all gram-negative bacteria have the same effect and the lack of enteral feeding seems to play a more significant role than the administration of parenteral nutrition.

Clinical and epidemiologic significance of coagulase-negative staphylococci bacteremia in a tertiary care university Israeli hospital.

OBJECTIVES: To characterize the clinical significance of coagulase-negative staphylococci (CNS) bacteremia. DESIGN: Prospective cohort study. SETTING: A 900-bed hospital in Haifa, Israel, from November 1996 to March 1997. RESULTS: Of 137 episodes of positive blood cultures for CNS, 41 (30%) were considered as true infection. Twenty-seven of 119 episodes associated with only 1 blood culture positive for CNS (23%) met the definition of infection as compared with 14 of 18 episodes (78%) associated with 2 or more blood cultures positive for CNS (P <.001). Methicillin resistance was significantly more frequent among Staphylococcus epidermidis isolates of episodes of true bacteremia than of episodes of contamination (15 of 22 [68%] vs. 11 of 33 [33%], respectively; P =.02). S hominis was isolated only in episodes considered as contamination (P =.01). It was estimated that CNS represents 24% of all nosocomial bloodstream pathogens. When CNS were isolated in the first 48 hours of hospitalization, an intravascular device was more frequently associated with episodes of true bacteremia than in those considered as contamination (7 of 7 [100%] vs. 10 of 57 [18%], respectively; P <.001). The mortality rate among patients with true CNS bacteremia was 16%. CONCLUSION: Some laboratory parameters may help identify episodes of true CNS bacteremia, which appears to be more common than previously considered.

TNF-alpha and cyclooxygenase metabolites do not modulate C. albicans septic shock with disseminated candidiasis.

We analyzed differences in host regulation of tumor necrosis factor-alpha (TNF-alpha) production and pathophysiological responses in conscious rats after infection with two strains of pathogenic Candida albicans spp. (CA-1 and CA-2) compared with Escherichia coli serotype 055:B5 (EC). The hypothesis was tested that, in contrast to EC, hypotension, organ injury, and mortality after candidemia are not obligatorily dependent on TNF-alpha or TNF-alpha-induced cyclooxygenase pathway metabolites. Dose, viability, and strain-specific dependencies were established after intravenous 10(6) or 10(9) viable CA, as well as heat-killed (HK) or Formalin-inactivated (FI) CA blastospores, compared with live EC at the 24-h LD25 [10(9) colony-forming units (CFU)] and LD100 (10(10) CFU). Shock without endotoxemia developed 4-8 h after 10(9) live CA-1 or CA-2 (LD100 at 24 h) with disseminated yeast-mycelial transformation and increased microvascular permeability in multiple organs but not after HK or FI CA-1. Peak serum TNF-alpha after an LD100 of CA-1 or CA-2 was < 3% of LD25 EC values and was < 1% of peak values during lethal bacteremia. Similar pathogen-specific differences were found in liver- and lung-associated TNF. Production of functionally inactive TNF-alpha during candidemia was excluded by enzyme-linked immunosorbent assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis with Western blotting. Passive immunization against TNF-alpha 2 h before microbial challenge was not protective against CA but prevented otherwise lethal EC sepsis. Cyclooxygenase inhibition also failed to attenuate candidemic shock. We conclude that the magnitude and kinetics of TNF-alpha production and TNF-alpha-dependent immunophysiological responses are differentially regulated after lethal fungal vs. gram-negative bacterial infection. Thus TNF-alpha is not a pivotal mediator of the acute Candida septic shock syndrome with disseminated candidiasis.

Clinical implications of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae bacteraemia.

To identify the clinical implications of extended-spectrum beta-lactamase (ESBL) production, 162 cases of Klebsiella pneumoniae bacteraemia in 154 adults were analysed. Of these cases, 44 (27.2%) were ESBL-producing (ESBLKP). Common sources of ESBLKP bacteraemia included primary bacteraemia (34.1%) and biliary infection (29.5%). The placement of a biliary drainage catheter, nosocomial acquisition, and prior antibiotic therapy were independently associated with ESBL production in multivariate analysis. More cases of ESBLKP than non-ESBLKP received inappropriate antibiotic therapy before culture results were reported (54.5 vs. 3.4%; P = 0.001). In 19 cases of ESBLKP, no significant difference in mortality was observed between patients who received appropriate empiric antibiotic therapy and those who did not (26.3 vs. 20.8%; P = 0.67). The mean length of hospital stay after the onset of bacteraemia was longer in the cases of ESBLKP than in the cases of non-ESBLKP (39.6 vs. 23.9 days; P = 0.008). Directly related mortality was not significantly different between the cases of ESBLKP and the cases of non-ESBLKP (23.3 vs. 20.0%; P = 0.65). None of the patients with biliary infection due to ESBLKP died (0/12; P = 0.03). In conclusion, ESBL production was not significantly associated with death but it had a considerable impact on patients with K. pneumoniae bacteraemia.

NADPH oxidase deficient mice develop colitis and bacteremia upon infection with normally avirulent, TTSS-1- and TTSS-2-deficient Salmonella Typhimurium.

Infections, microbe sampling and occasional leakage of commensal microbiota and their products across the intestinal epithelial cell layer represent a permanent challenge to the intestinal immune system. The production of reactive oxygen species by NADPH oxidase is thought to be a key element of defense. Patients suffering from chronic granulomatous disease are deficient in one of the subunits of NADPH oxidase. They display a high incidence of Crohn's disease-like intestinal inflammation and are hyper-susceptible to infection with fungi and bacteria, including a 10-fold increased risk of Salmonellosis. It is not completely understood which steps of the infection process are affected by the NADPH oxidase deficiency. We employed a mouse model for Salmonella diarrhea to study how NADPH oxidase deficiency (Cybb (-/-)) affects microbe handling by the large intestinal mucosa. In this animal model, wild type S. Typhimurium causes pronounced enteropathy in wild type mice. In contrast, an avirulent S. Typhimurium mutant (S.Tm(avir); invGsseD), which lacks virulence factors boosting trans-epithelial penetration and growth in the lamina propria, cannot cause enteropathy in wild type mice. We found that Cybb (-/-) mice are efficiently infected by S.Tm(avir) and develop enteropathy by day 4 post infection. Cell depletion experiments and infections in Cybb (-/-) Myd88 (-/-) mice indicated that the S.Tm(avir)-inflicted disease in Cybb (-/-) mice hinges on CD11c(+)CX3CR1(+) monocytic phagocytes mediating colonization of the cecal lamina propria and on Myd88-dependent proinflammatory immune responses. Interestingly, in mixed bone marrow chimeras a partial reconstitution of Cybb-proficiency in the bone marrow derived compartment was sufficient to ameliorate disease severity. Our data indicate that NADPH oxidase expression is of key importance for restricting the growth of S.Tm(avir) in the mucosal lamina propria. This provides important insights into microbe handling by the large intestinal mucosa and the role of NADPH oxidase in maintaining microbe-host mutualism at this exposed body surface.

Heme oxygenase inhibition enhances neutrophil migration into the bronchoalveolar spaces and improves the outcome of murine pneumonia-induced sepsis.

A reduction of the neutrophil migration into the site of infection during cecal ligation and puncture-induced sepsis increases host mortality. Inhibition of heme oxygenase (HO) prevents this neutrophil paralysis and improves host survival in the cecal ligation and puncture model. Taking into account that almost 50% of all sepsis cases are a consequence of pneumonia, we designed the present study to determine the role of HO in an experimental model of pneumonia-induced sepsis. The objective of this study was to evaluate whether the inhibition of HO improves the outcome and pathophysiologic changes of sepsis induced by an intratracheal instillation of Klebsiella pneumoniae. The pretreatment of mice subjected to pneumonia-induced sepsis with ZnDPBG (zinc deuteroporphyrin 2,4-bis glycol), a nonspecific HO inhibitor, increased the number of neutrophils in the bronchoalveolar spaces, reduced the bacterial load at the site of infection, and prevented the upregulation of CD11b and the downregulation of CXCR2 on blood neutrophils. Moreover, the pretreatment with ZnDPBG decreased alveolar collapse, attenuating the deleterious changes in pulmonary mechanics and gas exchanges and, as a consequence, improved the survival rate of mice from 0% to ∼20%. These results show that heme oxygenase is involved in the pathophysiology of pneumonia-induced sepsis and suggest that HO inhibitors could be helpful for the management of this disease.