Bacterial colonization in hemodialysis temporary dual lumen catheters: A prospective study

Aims. The use of hemodialysis temporary dual-lumen catheters is often complicated by infections, which may be a significant cause of death among patients with end stage renal disease (ESRD). The aim of this study was to assess the incidence of bacteremia and bacterial colonization related to non-tunneled, non-cuffed, dual-lumen temporary catheters in patients with ESRD submitted to hemodialysis. Methods. This study included 29 patients with ESRD. After catheter implantation, patients were monitored throughout the period of catheter permanence by means of blood samples collected weekly from a peripheral vein. Bacteria were isolated and identified according to CLSI recommendations. When catheters were removed for any reason, their tips were evaluated microbiologically. Results. A total of 194 blood samples from the 29 patients implanted with 55 catheters were analyzed. Of these, 15.5% (30 samples) demonstrated bacterial growth, principally Staphylococcus epidermidis (64.5%). Twenty patients (68.9%) presented at least one positive blood culture during follow-up. The median time for catheter colonization was 18.5 days (95% CI: 16.8-30.3). Of the 55 catheters implanted, 28 (50.9%) showed bacterial colonization, corresponding to 23.4 episodes/1000 catheter/days and 9.2 episodes of bacteremia /1000 catheter/days. Fifteen of 28 catheter tips analyzed showed bacterial growth (53.5%). In 14 of these (93.3%), there was agreement between the isolates from the catheter tip and blood cultures. Of 24 episodes of positive blood cultures from 20 different patients in 17 episodes (70.8%), the patients showed no clinical signs or symptoms of bacteremia. Conclusions. The high incidence of catheter colonization, the correlation between blood and catheter tip cultures, and the occurrence of frequent cases of asymptomatic bacteremia justify the proposal of routine peripheral blood collections to monitor patients undergoing hemodialysis with temporary dual-lumen catheters.

Diagnostic value of interleukin-6 and C-reactive protein on early onset bacterial infection in preterm neonates with respiratory distress

Aims: To evaluate the C-reactive protein (CRP) and interleukin-6 (IL-6) as diagnostic tools for early onset infection in preterm infants with early respiratory distress (RD). Methods: CRP and IL-6 were quantified at identification of RD and 24 h after in 186 newborns. Effects of maternal hypertension, mode of delivery, Apgar score, birth weight, gestational age, mechanical ventilation, being small for gestational age (SGA), and the presence of infection were analyzed. Results: Forty-four infants were classified as infected, 42 as possibly infected, and 100 as uninfected. Serum levels of IL-6 (0 h), CRP (0 h), and CRP (24 h), but not IL-6 (24 h) were significantly higher in infected infants compared to the remaining groups. The best test for identification of infection was the combination of IL-6 (0 h) 36 pg/dL and/or CRP (24 h) 0.6 mg/dL, which yielded 93% sensitivity and 37% specificity. The presence of infection and vaginal delivery independently increased IL-6 (0 h), CRP (0 h) and CRP (24 h) levels. Being SGA also increased the CRP (24 h) levels. IL-6 (24 h) was independently increased by mechanical ventilation. Conclusions: The combination of IL-6 (0 h) and/or CRP (24 h) is helpful for excluding early onset infection in preterm infants with RD but the poor specificity limits its potential benefit as a diagnostic tool.

Local profile of cytokines and nitric oxide in patients with bacterial vaginosis and cervical intraepithelial neoplasia

Objective: To evaluate the local immune response in patients with bacterial vaginosis (BV) and cervical intraepithelial neoplasia (CIN), as assessed by cytokine and nitric oxide (NO) concentrations. Study design: Patients attending for routine gynaecological examination were prospectively enrolled in groups: BV (n = 25) diagnosed by clinical criteria, CIN graded I to III (n = 35, 6 CIN 1, 8 CIN 11 and 21 CIN 111) by histological analysis, and controls (n = 15) without clinical and cytological findings. Randomly selected patients within CIN group at grades 11 or III (n = 15) were re-evaluated at 60 days after surgical treatment. Endocervical (EC) and vaginal secretion samples were collected by cytobrush and the levels of cytokines (ELISA) and NO metabolite (Griess reaction) were assayed. Results: NO was assessed in all subjects, and cytokines in all controls, 15 BV and 30 CIN patients. Interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10) and nitrite levels were higher in EC than in vaginal secretions in BV and CIN groups. In CIN group, IL-8, IL-10 and nitrite concentrations were greater in EC and/or vaginal secretions than in BV or controls. Surgical treatment reduced IL-8 levels in EC and vaginal secretions. Conclusion: A similar local immune profile was found in BV and CIN groups. The increased local production of IL-8, IL-10 and NO in CIN suggests a role for these mediators in the immune response against tumour or tumour development. (c) 2007 Elsevier Ireland Ltd. All rights reserved.

Role of cytokines (TNF-alpha, IL-1 beta and KC) in the pathogenesis of CPT-11-induced intestinal mucositis in mice: effect of pentoxifylline and thalidomide

Introduction Irinotecan (CPT-11) is an inhibitor of DNA topoisomerase I and is clinically effective against several cancers. A major toxic effect of CPT-11 is delayed diarrhea; however, the exact mechanism by which the drug induces diarrhea has not been established. Purpose Elucidate the mechanisms of induction of delayed diarrhea and determine the effects of the cytokine production inhibitor pentoxifylline (PTX) and thalidomide (TLD) in the experimental model of intestinal mucositis, induced by CPT-11. Materials and methods Intestinal mucositis was induced in male Swiss mice by intraperitoneal administration of CPT-11 (75 mg/kg) daily for 4 days. Animals received subcutaneous PTX (1.7, 5 and 15 mg/kg) or TLD (15, 30, 60 mg/kg) or 0.5 ml of saline daily for 5 and 7 days, starting 1 day before the first CPT-11 injection. The incidence of delayed diarrhea was monitored by scores and the animals were sacrificed on the 5th and 7th experimental day for histological analysis, immunohistochemistry for TNF-alpha and assay of myeloperoxidase (MPO) activity, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and KC ELISA. Results CPT-11 caused significant diarrhea, histopathological alterations (inflammatory cell infiltration, loss of crypt architecture and villus shortening) and increased intestinal tissue MPO activity, TNF-alpha, IL-1 beta and KC level and TNF-alpha immuno-staining. PTX inhibited delayed diarrhea of mice submitted to intestinal mucositis and reduced histopathological damage, intestinal MPO activity, tissue level of TNF-alpha, IL-1 beta and KC and TNF-alpha immuno-staining. TLD significantly reduced the lesions induced by CPT-11 in intestinal mucosa, decreased MPO activity, TNF-alpha tissue level and TNF-alpha immuno-staining, but did not reduce the severity of diarrhea. Conclusion These results suggest an important role of TNF-alpha, IL-1 beta and KC in the pathogenesis of intestinal mucositis induced by CPT-11.

Role of platelet-activating factor in the pathogenesis of 5-fluorouracil-induced intestinal mucositis in mice

Gastrointestinal mucositis is a common side effect of cancer chemotherapy. Platelet-activating factor (PAF) is produced during gut inflammation. There is no evidence that PAF participates in antineoplastic-induced intestinal mucositis. This study evaluated the role of PAF in 5-fluorouracil (5-FU)-induced intestinal mucositis using a pharmacological approach and PAF receptor knockout mice (PAFR(-/-)). Wild-type mice or PAFR(-/-) mice were treated with 5-FU (450 mg/kg, i.p.). Other mice were treated with saline or BN52021 (20 mg/kg, s.c.), an antagonist of the PAF receptor, once daily followed by 5-FU administration. After the third day of treatment, animals were sacrificed and tissue samples from the duodenum were removed for morphologic evaluation. In addition, myeloperoxidase activity and the cytokine concentration were measured. 5-FU treatment decreased the duodenal villus height/crypt depth ratio, increased MPO activity, and increased the concentration of TNF-alpha, IL-1 beta and KC in comparison with saline-treated animals. In PAFR(-/-) mice and PAFR antagonist-treated mice, 5-FU-dependent intestinal damage was reduced and a decrease in duodenal villus height/crypt depth ratio was attenuated. However, the 5-FU-dependent increase in duodenum MPO activity was not affected. Without PAFR activation, 5-FU treatment did not increase the TNF-alpha, IL-1 beta and KC concentration. In conclusion, our study establishes the role of PAFR activation in 5-FU-induced intestinal mucositis. This study implicates treatment with PAFR antagonists as novel therapeutic strategy for this condition.

Phosphoinositide-3 Kinase gamma Activity Contributes to Sepsis and Organ Damage by Altering Neutrophil Recruitment

Rationale Sepsis is a leading cause of death in the intensive care unit, characterized by a systemic inflammatory response (SIRS) and bacterial infection, which can often induce multiorgan damage and failure. Leukocyte recruitment, required to limit bacterial spread, depends on phosphoinositide-3 kinase gamma (PI3K gamma) signaling in vitro; however, the role of this enzyme in polymicrobial sepsis has remained unclear. Objectives: This study aimed to determine the specific role of the kinase activity of PI3K gamma in the pathogenesis of sepsis and multiorgan damage. Methods. PI3K gamma wild-type, knockout, and kinase-dead mice were exposed to cecal ligation and perforation induced sepsis and assessed for survival; pulmonary, hepatic, and cardiovascular damage; coagulation derangements; systemic inflammation; bacterial spread; and neutrophil recruitment. Additionally, wild-type mice were treated either before or after the onset of sepsis with a PI3K gamma inhibitor and assessed for survival, neutrophil recruitment, and bacterial spread. Measurements and Main Results: Both genetic and pharmaceutical PI3K gamma kinase inhibition significantly improved survival, reduced multiorgan damage, and limited bacterial decompartmentalization, while modestly affecting SIRS. Protection resulted from both neutrophil-independent mechanisms, involving improved cardiovascular function, and neutrophil-dependent mechanisms, through reduced susceptibility to neutrophil migration failure during severe sepsis by maintaining neutrophil surface expression of the chemokine receptor, CXCR2. Furthermore, PI3K gamma pharmacological inhibition significantly decreased mortality and improved neutrophil migration and bacterial control, even when administered during established septic shock. Conclusions: This study establishes PI3K gamma as a key molecule in the pathogenesis of septic infection and the transition from SIRS to organ damage and identifies it as a novel possible therapeutic target.

Essential role of platelet-activating factor receptor in the pathogenesis of Dengue virus infection

Severe dengue infection in humans causes a disease characterized by thrombocytopenia, increased levels of cytokines, increased vascular permeability, hemorrhage, and shock. Treatment is supportive. Activation of platelet-activating factor (PAF) receptor (PAFR) on endothelial cells and leukocytes induces increase in vascular permeability, hypotension, and production of cytokines. We hypothesized that activation of PAFR could account for the major systemic manifestations of dengue infection. Inoculation of adult mice with an adapted strain of Dengue virus caused a systemic disease, with several features of the infection in humans. In PAFR(-/-) mice, there was decreased thrombocytopenia, hemoconcentration, decreased systemic levels of cytokines, and delay of lethality, when compared with WT infected mice. Treatment with UK-74,505, an orally active PAFR antagonist, prevented the above-mentioned manifestations, as well as hypotension and increased vascular permeability, and decreased lethality, even when started 5 days after virus inoculation. Similar results were obtained with a distinct PAFR antagonist, PCA-4246. Despite decreased disease manifestation, viral loads were similar (PAFR(-/-)) or lower (PAFR antagonist) than in WT mice. Thus, activation of PAFR plays a major role in the pathogenesis of experimental dengue infection, and its blockade prevents more severe disease manifestation after infection with no increase in systemic viral titers, suggesting that there is no interference in the ability of the murine host to deal with the infection. PAFR antagonists are disease-modifying agents in experimental dengue infection.

Membrane transporter proteins are involved in Trichophyton rubrum pathogenesis

Trichophyton rubrum is a dermatophyte responsible for the majority of human superficial mycoses. The functional expression of proteins important for the initial step and the maintenance of the infection process were identified previously in T. rubrum by subtraction suppression hybridization after growth in the presence of keratin. In this study, sequences similar to genes encoding the multidrug-resistance ATP-binding cassette (ABC) transporter, copper ATPase, the major facilitator superfamily and a permease were isolated, and used in Northern blots to monitor the expression of the genes, which were upregulated in the presence of keratin. A sequence identical to the TruMDR2 gene, encoding an ABC transporter in T rubrum, was isolated in these experiments, and examination of a T rubrum Delta TruMDR2 mutant showed a reduction in infecting activity, characterized by low growth on human nails compared with the wild-type strain. The high expression levels of transporter genes by T. rubrum in mimetic infection and the reduction in virulence of the Delta TruMDR2 mutant in a disease model in vitro suggest that transporters are involved in T. rubrum pathogenicity.

Interferon-gamma, interleukin-10, intercellular adhesion molecule-1, and chemokine receptor 5, but not interleukin-4, attenuate the development of periapical lesions

This study examines the role of Th1 (interferon-gamma [IFN-gamma]) and Th2 (interleukin-4 [IL-4] and IL-10) cytokines, an intercellular adhesion molecule (ICAM-1), and a chemokine receptor (CCR5) in the pathogenesis of periapical lesions at different stages of development in knockout mice. For lesion induction, the first molar was opened and inoculated with 4 bacterial strains and left open to the oral environment. After 21 and 42 days, the IFN-gamma, IL-10, ICAM-1, and CCR5 knockout animals presented periapical lesions larger than those of wild-type animals. There was no statistically significant difference between periapical lesions induced in IL-4 knockout and wild-type animals during the periods evaluated. Our findings suggest an important role for IFN-gamma, IL-10, ICAM-1, and CCR5 in the pathogenesis of experimentally induced pulp infection and bone destruction as endogenous suppressor of periapical lesion development, whereas IL-4 appears to present a nonsignificant effect on periapical lesion modulation.

Intestinal bacterial overgrowth after Roux-en-Y gastric bypass

The aim of the present study was to report the occurrence of serious subnutrition, associated to intestinal bacterial overgrowth, in two patients submitted to bariatric surgery. Two female patients (body mass index, 49 and 50 kg/m(2), respectively) were submitted to Y-en-Roux gastric bypass. The first patient evolved a 52% loss of body weight within 21 months after surgery; the other, a 34% loss of initial body weight within 15 months after surgery, results corresponding, respectively, to 62 and 45 kg weight losses. However, both patients reported asthenia, hair fallout, and edema, and one also reported diarrhea, but none was feverish. Their respective albuminemias were of 24 and 23 g/l. A respiratory hydrogen test suggested bacterial hyperproliferation. Thirty days after ciprofloxacin and tetracyclin treatments, they showed improved albumin levels and nutritional states, both confirmed by results of hydrogen breath tests. Bacterial overgrowth is an important complication that can compromise clinical evolution of patients submitted to intestinal surgery like gastroplasty with Y-Roux anastomosis. In cases of clinical suspicion or a confirmed diagnosis, adequate antibiotics, sometimes requiring to be cyclically repeated, should be administered.

Disturbances in microbiota - cause or effect?

IBD are a group of complex polygenetic diseases also involving environmental factors. Evidence for a role for bacteria in IBD include an increased abundance of mucosa-associated bacteria in IBD (which occurs even where there is no intestinal inflammation), and the positive impact of antibiotics on the progress of both Crohn's disease (CD) and ulcerative colitis (UC) of the pouch - pouchitis. Bacteria are necessary for most animal models of IBD. The increased abundance of mucosal bacteria in IBD is not non-specific because while some mucosal bacteria are more abundant this is not the case for all mucosal bacteria including the very abundant Bacteroides vulgatus. On the other hand, antibiotic treatments are not curative, and the humoral immune Ig response to bacterial antigens which is more evident in CD, appears to be polyclonal. While this argues against a role for specific bacteria causing a classical infection, certain mucosal bacteria may damage the mucosal barrier. This would promote invasion by other commensal mucosal bacteria triggering an immune response. Altered adaptive, and to a lesser extent, innate immunity have been extensively studied, and genetic defects in the CARD15 (or NOD2) gene that encodes a bacterial sensing protein modulating innate and adaptive immunity are strongly associated with ileal CD. However, the penetrance of the homozygous CARD15 frameshift mutation, which is the most strongly CD-associated genotype, is very low with only 4% of humans with this developing CD. Furthermore, mice with the same defects in CARD15 do not develop spontaneous ileitis or colitis. Therefore, there have to be other aetiological factor(s). Altered permeability is a consistent finding in subclinical CD. There are other data to suggest that altered mucin is an early event in UC. We propose that the pathogenesis of IBD is multifactorial involving specific mucosal bacteria, defective barrier function and altered mucosal immunity in an aetiology triangle.

In vitro evidence for immune evasion activity by human plasmin associated to pathogenic Leptospira interrogans

Leptospirosis is a widespread re-emerging zoonosis of human and veterinary concern. It has been shown that virulent leptospires protect themselves against the host`s innate immune system, a strategy that allows the bacteria to reach immunologically safe environments. Although extensive studies on host pathogen interactions have been performed, little is known on how leptospires deal with host immune attack. In a previous work, we demonstrated the ability of leptospires to bind human plasminogen (PLC), that after treatment with activators, conferred plasmin (PLA) activity on the bacteria surface. In this study, we show that the PLA activity associated to the outer surface of Leptospira could interfere with the host immune attack by conferring some evasion advantage during infection. We demonstrate that PLA-coated leptospires interfere with complement Ob and IgG depositions on the bacterial surface, probably through the degradation of these components, thus diminishing opsonization process. Similar decrease on the deposition was observed when normal and immune sera from patients diagnosed with leptospirosis were employed as a source of IgG. We believe that decreasing opsonization by PLA generation might be an important aspect of the leptospiral immune escape strategy and survival. To our knowledge, this is the first proteolytic activity of plasmin associated-Leptospira related to anti-opsonic properties reported to date. (C) 2011 Elsevier Ltd. All rights reserved.

Evaluation of Leptospiral Recombinant Antigens MPL17 and MPL21 for Serological Diagnosis of Leptospirosis by Enzyme-Linked Immunosorbent Assays

Leptospirosis is a zoonosis of multisystem involvement caused by pathogenic strains of the genus Leptospira. In the last few years, intensive studies aimed at the development of a vaccine have provided important knowledge about the nature of the immunological mechanisms of the host. The purpose of this study was to analyze the immune responses to two recombinant proteins, MPL17 and MPL21 (encoded by the genes LIC10765 and LIC13131, respectively) of Leptospira interrogans serovar Copenhageni in individuals during infection. The recombinant proteins were expressed in Escherichia coli as six-His tag fusion proteins and were purified from the soluble bacterial fraction by affinity chromatography with Ni2+ -charged resin. The recombinant proteins were used to evaluate their ability to bind to immunoglobulin G (IgG) (and IgG subclass) or IgM antibodies in serum samples from patients in the early and convalescent phases of leptospirosis (n = 52) by enzyme-linked immunosorbent assays. The prevalences of total IgG antibodies against MPL17 and MPL21 were 38.5% and 21.2%, respectively. The titers achieved with MPL17 were statistically significantly higher than those obtained by the reference microscopic agglutination test. The specificity of the assay was estimated to be 95.5% for MPL17 and 80.6% for MPL21 when serum samples from individuals with unrelated febrile diseases and control healthy donors were tested. The proteins are conserved among Leptospira strains that cause human and animal diseases. MPL17 and MPL21 are most likely new surface proteins of leptospires, as revealed by liquid-phase immunofluorescence assays with living organisms. Our results demonstrate that these recombinant proteins are highly immunogenic and, when they are used together, might be useful as a means of diagnosing leptospirosis.