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Gram-negative Organisms (gram-negative + organism)
Selected AbstractsCharacterisation of a novel Mannheimia sp from Australian feedlot cattleAUSTRALIAN VETERINARY JOURNAL, Issue 9 2001PJ BLACKALL Objective To characterise eight isolates of a Gram-negative organism obtained from the upper respiratory tract of cattle showing evidence of mild upper respiratory tract disease. Design The isolates were compared with the five recognised species within the genus Mannheimia - M haemolytica, M glucosida, M granulomatis, M ruminalis and M varigena - using a range of phenotypic and genotypic methods. Results Phenotypic characterisation indicated that the isolates belonged to the trehalose-negative [Pasteurella] haemolytica complex. This complex has recently been reorganised into five species within the new genus Mannheimia. Ribotyping performed using Hin dIII and a computerised analysis system indicated that the eight Australian isolates formed a distinct cluster that was related to, but different from, the five recognised species of Mannheimia. The 16S rRNA sequence of one isolate (BNO311) was determined and a phylogenetic analysis performed. Isolate BNO311 was distinct from the five named Mannheimia spp but did join a larger cluster consisting of rRNA cluster IV (M varigena) and the unnamed rRNA cluster V of Mannheimia. DNA:DNA hybridisation between isolate BNO311 and M haemolytica NCTC 9380T, M granulomatis P411 and Actinobacillus ligniersii NCTC 4189T all suggested similarities of approximately 30%. Conclusions These phenotypic and genotypic characterisation studies suggest that the eight Australian isolates represent a new species of Mannheimia. Until further characterisation studies are performed, we are unwilling to propose a name for this taxon, preferring to refer to this possible new species as Bisgaard taxon 39 of cluster V of Mannheimia. [source] Bacteroides thetaiotaomicron: a dynamic, niche-adapted human symbiontBIOESSAYS, Issue 10 2003Laurie E. Comstock The coevolution of humans with their intestinal microflora has resulted in cooperative relationships that have shaped the biology and the genomes of these symbiotic partners. Bacteroides thetaiotaomicron is one such bacterial symbiont that is a dominant member of the intestinal microbiota of humans and other mammals. The recent report of the genome sequence of B. thetaiotaomicron1 is the first reported for an abundant Gram-negative organism of the human colonic microbiota and, as such, provides the first glimpse on a genomic scale of the genetic arsenal used by a Gram-negative symbiont to dominate in this ecosystem. The genome has revealed large expansions of many paralogous groups of genes that encode products essential to the organism's ability to successfully compete in this environment. Most noteable is the organism's abundant machinery for utilizing a large variety of complex polysaccharides as a source of carbon and energy. The proteome also reveals the organism's extensive ability to adapt and regulate expression of its genes in response to the changing ecosystem. These factors, as well as others highlighted below, suggest an incredibly flexible and adaptable organism that is exquisitely equipped to dominate in its challenging and competitive niche. BioEssays 25:926,929, 2003. © 2003 Wiley Periodicals, Inc. [source] Gram-negative meningitis and infections in individuals treated with intrathecal baclofen for spasticity: a retrospective studyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 6 2006Colleen A Wunderlich MD MSc The aim of this retrospective study was to describe signs, symptoms, and clinical outcomes of individuals undergoing intrathecal baclofen (ITB) therapy who experienced pumprelated Gram-negative infections including meningitis. Participants included 12 individuals (nine males, three females) aged 10 to 32 years (mean 17y 9mo), nine of whom had quadriplegic CP. A total of 571 baclofen pump surgeries were performed with 45 total infections. Of the 45 infections, 12 were by Gram-negative organisms, two resulting in meningitis. Ten of 12 Gram-negative infections (21 site encounters) occurred within 60 days of surgery. Eleven of 12 pumps were explanted. By site encounters, Pseudomonas aeruginosa accounted for eight Gram-negative infections, Escherichia coli for five, Proteus for three, Enterobacter cloacae for two, and Klebsiella, Enterobacter aerogenes, and Enterobacter vulnaris for one each. Two individuals with Gram-negative meningitis were admitted 72 to 96 hours after hospital discharge following pump replacement. Both patients had rapid deterioration requiring transfer to the pediatric intensive care unit, and developed coagulopathy and decrease in responsiveness. Both have improved and have elected not to replace the ITB pump. In Gram-negative infections in ITB therapy, the progression of signs and symptoms can be swift and devastating. Identification of the infectious agent in such cases is imperative; these infections can quickly become life threatening. [source] Premature Salmonella Typhimurium growth inhibition in competition with other Gram-negative organisms is redox potential regulated via RpoS inductionJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2004E. Komitopoulou Abstract Aims:, To identify the role of oxidation,reduction (redox) potential in the premature growth inhibition and RpoS induction in Salmonella serotype Typhimurium in competitive growth experiments. Methods and Results:, Oxidation,reduction potential was measured throughout the growth of a minority population of Salm. Typhimurium in mixed cultures with other Gram-negative and Gram-positive organisms. A lux -based reporter was also used to evaluate RpoS activity in Salm. Typhimurium in competitor studies. In a mixed culture, the multiplication of a minority population of Salm. Typhimurium was inhibited when competing Gram-negative organisms entered the stationary phase. This was not seen when the competing flora was Gram-positive. The change in redox potential during growth in mixed cultures was closely linked to the inhibition of Salm. Typhimurium growth by Gram-negative competitors. An artificially induced drop in redox potential earlier during growth in mixed cultures with Gram-negative organisms reduced the time to RpoS induction in Salm. Typhimurium and thus inhibited its multiplication prematurely. In contrast, RpoS induction and growth inhibition were prevented under high redox potential conditions. Conclusions:, This work shows that the inhibitory activity of competitive organisms can be mediated through their effect on redox potential-regulated RpoS induction. Significance and Impact of the Study:, Redox potential is shown to be an important determinant of Salm. Typhimurium growth, an observation with practical implications both for its control and detection. [source] Bacteriological quality of skin-moisturizing creams and lotions distributed in a tropical developing countryJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2001I.N. Okeke Aims: To evaluate the bacteriological quality of skin moisturizing products in the South-west part of Nigeria and study factors predisposing their bacterial contamination under tropical conditions. Methods and Results: Viable counts for bacteria exceeded 103 cfu ml,1or cfu g,1 in 8 (16·3%) commercially available creams and lotions at time of purchase. Escherichia coli (8), Pseudomonas spp. (7), Staphylococcus spp. (9) and Bacillus spp. (6) were the most commonly recovered bacteria. Following use by volunteers, the proportion of E. coli and other Gram-negative organisms recovered increased. Organic matter, particularly in the absence of preservatives, enhanced survival and growth of bacteria in creams stored under ambient tropical conditions during challenge experiments. Conclusions: Contaminated products are relatively uncommon but some products present a potential health hazard because they are unable to suppress the growth of organisms of likely faecal origin during use. Significance and Impact of the Study: Quality assurance during manufacture, pack size, preservative evaluation, organic matter and water content were identified as factors to be considered during the development of creams and lotions for use in tropical developing countries. [source] Identification of the membrane penetrating domain of Vibrio cholerae cytolysin as a ,-barrel structureMOLECULAR MICROBIOLOGY, Issue 1 2005Angela Valeva Summary Vibrio cholerae cytolysin (VCC) is an oligomerizing pore-forming toxin that is related to cytolysins of many other Gram-negative organisms. VCC contains six cysteine residues, of which two were found to be present in free sulphydryl form. The positions of two intramolecular disulphide bonds were mapped, and one was shown to be essential for correct folding of protoxin. Mutations were created in which the two free cysteines were deleted, so that single cysteine substitution mutants could be generated for site-specific labelling. Employment of polarity-sensitive fluorophores identified amino acid side-chains that formed part of the pore-forming domain of VCC. The sequence commenced at residue 311, and was deduced to form a ,-barrel in the assembled oligomer with the subsequent odd-numbered residues facing the lipid bilayer and even-numbered residues facing the lumen. Pro328/Lys329 were tentatively identified as the position at which the sequence turns back into the membrane and where the antiparallel ,-strand commences. This was deduced from fluorimetric analyses combined with experiments in which the pore was reversibly occluded by derivatization of sulphydryl groups with a bulky moiety. Our data support computer-based predictions that the membrane-permeabilizing amino acid sequence of VCC is homologous to the ,-barrel-forming sequence of staphylococcal cytolysins and identify the ,-barrel as a membrane-perforating structure that is highly conserved in evolution. [source] Early bacteremia in pediatric hematopoietic stem cell transplant patients on oral antibiotic prophylaxisPEDIATRIC BLOOD & CANCER, Issue 2 2005Leslie S. Kersun MD, MSCE Abstract Background Bacteremia occurs during hematopoietic stem cell transplant (HSCT) in 20%,25% of patients and the use of gut decontamination (GD) to decrease this risk is controversial. Our purpose was to determine the incidence of bacteremia and antimicrobial resistance post-HSCT in pediatric patients receiving GD, and to identify risk factors associated with infection. Procedures This was a retrospective cohort study of 182 pediatric patients undergoing first HSCT for malignant disease at The Children's Hospital of Philadelphia from January, 1999 to December, 2002. We examined the impact of age, sex, race, diagnosis, disease status, conditioning regimen, recent bacteremia, stem cell source, donor, graft versus host disease prophylaxis agents, and mucositis severity using Cox proportional hazard models. GD consisted of amoxicillin (azithromycin, if penicillin allergic) and oral gentamicin. Outcome was first episode of bacteremia prior to absolute neutrophil count (ANC) 500/mm3. Antibiotic susceptibilities were performed on all isolates. Results Seventy-four patients (41%) developed bacteremia. The majority were Gram-positive cocci, with Staphylococcal (50%) and Streptococcal species (28%) the most common. Gram-negative organisms were identified in 22% with Pseudomonas (5.7%) and Klebsiella species (3.4%) the most common. Of the Streptococcal infections, 72% were resistant to ampicillin; only 25% of the Gram-negative bacteria were resistant to gentamicin. Race was the only factor associated with early bacteremia (hazard ratio 2.3 for non-Caucasian, non-African-American patients, CI 1.3,4.3, P,=,0.007) Conclusions Early bacteremia is common after HSCT, despite the use of GD. Resistant Gram-positive organisms predominate, consistent with recent trends in immunocompromised patients. Although used in practice, there is no clear evidence for the efficacy of GD and this study provides the basis upon which to develop a randomized clinical trial evaluating the current GD regimen with placebo. © 2004 Wiley-Liss, Inc. [source] Bloodstream infections in hospitalized adults with sickle cell disease: A retrospective analysisAMERICAN JOURNAL OF HEMATOLOGY, Issue 10 2006Lalita Chulamokha Abstract Bloodstream infections (BSI) are a common cause of morbidity and mortality in people with sickle cell disease (SCD). In children with SCD, BSI are most often caused by encapsulated organisms. There is a surprising paucity of medical literature that is focused on evaluating SCD adults with BSI. We reviewed the charts of adults with SCD and BSI who were admitted to our hospital between April 1999 and August 2003. During this period a total of 1,692 hospital admissions for 193 adults with SCD were identified and 28% of these patients had at least 1 episode of positive blood cultures, with 69 episodes (17%) considered true BSI. Nosocomial BSI occurred in 34 episodes (49%). Among community BSI, in contrast to BSI in children with SCD, Streptococcus pneumoniae was rarely encountered. A high incidence of staphylococcal BSI in adults with SCD was noted. Twenty-eight percent of all BSI were caused by Staphylococcus aureus, and 15 of 22 isolates (68%) of these were methicillin-resistant. Gram-negative organisms, anaerobes, and yeast were found in 21 (27%), 3 (4%), and 4 isolates (5%) of BSI, respectively. Since over 80% of BSI were considered catheter-related, the higher incidence of gram-positive bacterial infections was likely due to the presence of indwelling central venous catheters. Empiric therapy for adults with SCD suspected of having BSI, especially in the presence of indwelling central venous catheters, should include antimicrobial therapy targeted at gram-positive bacteria (especially MRSA) and gram-negative bacteria. Also, if patients are critically ill, consideration should be made to include antifungal agents. Additional research into the adult SCD population appears necessary to further define this problem. Am. J. Hematol., 2006. © 2006 Wiley-Liss, Inc. [source] Clinical and Subclinical Endometritis in the Mare: Both Threats to FertilityREPRODUCTION IN DOMESTIC ANIMALS, Issue 2009MM LeBlanc Contents Endometritis, a major cause of mare infertility arising from failure to remove bacteria, spermatozoa and inflammatory exudate post-breeding, is often undiagnosed. Defects in genital anatomy, myometrial contractions, lymphatic drainage, mucociliary clearance, cervical function, plus vascular degeneration and inflamm-ageing underlie susceptibility to endometritis. Diagnosis is made through detecting uterine fluid, vaginitis, vaginal discharge, short inter-oestrous intervals, inflammatory uterine cytology and positive uterine culture. However, these signs may be absent in subclinical cases. Hypersecretion of an irritating, watery, neutrophilic exudate underlies classic, easy-to-detect streptococcal endometritis. In contrast, biofilm production, tenacious exudate and focal infection may characterize subclinical endometritis, commonly caused by Gram-negative organisms, fungi and staphylococci. Signs of subclinical endometritis include excessive oedema post-mating and a white line between endometrial folds on ultrasound. In addition, cultures of uterine biopsy tissue or of small volume uterine lavage are twice as sensitive as guarded swabs in detecting Gram-negative organisms, while uterine cytology is twice as sensitive as culture in detecting endometritis. Uterine biopsy may detect deep inflammatory and degenerative changes, such as disruption of the elastic fibres of uterine vessels (elastosis), while endoscopy reveals focal lesions invisible on ultrasound. Mares with subclinical endometritis require careful monitoring by ultrasound post-breeding. Treatments that may be added to traditional therapies, such as post-breeding uterine lavage, oxytocin and intrauterine antibiotics, include lavage 1-h before mating, carbetocin, cloprostenol, cervical dilators, systemic antibiotics, intrauterine chelators (EDTA,Tris), mucolytics (DMSO, kerosene, N -acetylcysteine), corticosteroids (prednisolone, dexamethasone) and immunomodulators (cell wall extracts of Mycobacterium phlei and Propionibacterium acnes). [source] Antibiotic-treated infections in intensive care patients in the UKANAESTHESIA, Issue 9 2004B. H. Cuthbertson Summary The purpose of this audit was to study reasons for starting antibiotic therapy, duration of antibiotic treatment, reasons for changing antibiotics and the agreement between clinical suspicion and microbiological results in intensive care practice. We conducted a multicentre observational audit of 316 patients. Data on demographic details, site, treatment and nature of infection were collected. The median duration of antibiotic therapy was 7 days. Infections were community-acquired in 160 patients (55%). Antibiotics were started on clinical suspicion of infection in 237 patients (75%). Pulmonary infections were the most common, representing 52% of all proven infections. Gram-negative organisms were the most common cause of proven infections (n = 90 (50%)). The antibiotic spectrum was narrowed in light of microbiology results in 78 patients (43%) and changed due to antibiotic resistance in 38 patients (21%). We conclude that the mean duration of treatment contrasts with existing published guidelines, highlighting the need for further studies on duration and efficacy of treatment in intensive care. [source] A conserved domain in type III secretion links the cytoplasmic domain of InvA to elements of the basal bodyACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2010Mirjana Lilic Protein type III secretion systems (T3SSs) are organic nanosyringes that achieve an energy-dependent translocation of bacterial proteins through the two membranes of Gram-negative organisms. Examples include the pathogenic systems of animals, plants and symbiotic bacteria that inject factors into eukaryotic cells, and the flagellar export system that secretes flagellin. T3SSs possess a core of several membrane-associated proteins that are conserved across all known bacterial species that use this system. The Salmonella protein InvA is one of the most highly conserved proteins of this core of critical T3SS components. The crystal structure of a C-terminal domain of InvA reveals an unexpected homology to domains that have been repeatedly found as building blocks of other elements of the T3SS apparatus. This suggests the surprising hypothesis that evolution has produced a significant component of the apparatus structure through a series of gene-duplication and gene-rearrangement events. [source] Emesis predicts bacteremia in immunocompromised children with central venous catheters and fever,CANCER, Issue 14 2009Matthew W. Richardson MD Abstract BACKGROUND: The objective of this study was to determine whether vomiting at presentation of a febrile illness in immunocompromised children with central venous catheters (CVCs) predicts bacteremia. METHODS: A chart review was conducted of children who were admitted to the hospital with a diagnosis of cancer or aplastic anemia, fever, and a CVC. Data were collected on the presence or absence of vomiting, catheter type, presence or absence of severe neutropenia, C-reactive protein (Crp) value, and culture results. RESULTS: There were 143 admissions for fever among 48 children. Among 35 admissions with emesis, 19 included bacteremia; whereas, among 107 admissions without emesis, 19 included bacteremia (P < .001). There was a 5-fold greater risk of bacteremia in children with children without vomiting (odds ratio, 5.50; 95% confidence interval, 2.20-13.67). Gram-negative organisms were more likely to be associated with vomiting than Gram-positive organisms (P = .008). Children with severe neutropenia did not have a significantly higher rate of bacteremia than children who had neutrophil counts >500 cells/mm3. Other factors that were associated with higher rates of bacteremia were underlying diagnosis and catheter type. CONCLUSIONS: Immunocompromised children with a CVC and a fever who presented with vomiting were more likely to have bacteremia than similar children who presented without vomiting. Gram-negative organisms were more likely to be associated with emesis than Gram-positive organisms. The absence of severe neutropenia was not associated with a decreased likelihood of bacteremia. These findings may be useful in identifying children who are at high risk for bacteremia and in determining initial, empiric therapy. Cancer 2009. © 2009 American Cancer Society. [source] Seasonal variation in Escherichia coli bloodstream infection: a population-based studyCLINICAL MICROBIOLOGY AND INFECTION, Issue 10 2009M. N. Al-Hasan Abstract Seasonal variation in the rates of infection with certain Gram-negative organisms has been previously examined in tertiary-care centres. We performed a population-based investigation to evaluate the seasonal variation in Escherichia coli bloodstream infection (BSI). We identified 461 unique patients in Olmsted County, Minnesota, from 1 January 1998 to 31 December 2007, with E. coli BSI. Incidence rates (IR) and IR ratios were calculated using Rochester Epidemiology Project tools. Multivariable Poisson regression was used to examine the association between the IR of E. coli BSI and average temperature. The age- and gender-adjusted IR of E. coli BSI per 100 000 person-years was 50.2 (95% CI 42.9,57.5) during the warmest 4 months (June through September) compared with 37.1 (95% CI 32.7,41.5) during the remainder of the year, resulting in a 35% (95% CI 12,66%) increase in IR during the warmest 4 months. The average temperature was predictive of increasing IR of E. coli BSI (p 0.004); there was a 7% (95% CI 2,12%) increase in the IR for each 10-degree Fahrenheit (c. 5.5°C) increase in average temperature. To our knowledge, this is the first study to demonstrate seasonal variation in E. coli BSI, with a higher IR during the warmest 4 months than during the remainder of the year. [source] A case of fulminant septic shock with a rare gram-negative organism (Case Presentation)ACTA PAEDIATRICA, Issue 7 2009Rusheng Chew No abstract is available for this article. [source] A case of fulminant septic shock with a rare gram-negative organism (Discussion and Diagnosis)ACTA PAEDIATRICA, Issue 7 2009Rusheng Chew No abstract is available for this article. [source] The role of selective digestive decontamination for reducing infection in patients undergoing liver transplantation: A systematic review and meta-analysis,LIVER TRANSPLANTATION, Issue 7 2004Nasia Safdar Selective digestive decontamination (SDD) refers to the use of antimicrobials to reduce the burden of aerobic gram-negative bacteria and/or yeast in the intestinal tract to prevent infections caused by these organisms. Liver transplant patients are highly vulnerable to bacterial infection particularly with gram-negative organisms within the first month after transplantation, and SDD has been proposed as a potential measure to prevent these infections. However, the benefit of this procedure remains controversial. We undertook a systematic review and meta-analysis to determine whether SDD is beneficial in reducing infections overall and those caused by gram-negative bacteria in patients following liver transplantation. All studies that evaluated the efficacy of SDD in liver transplant patients were included. Randomized trials that included liver transplant patients given SDD versus either placebo or no treatment or minimal treatment (e.g., oral nystatin alone), and that provided adequate data to calculate a relative risk ratio, were included in the meta-analysis. Our review shows that most studies found SDD to be effective in reducing gram-negative infection. The nonrandomized and uncontrolled trials also showed benefit with SDD in reducing overall infection; however, the effect on overall infection was limited in the 4 randomized trials, in which the pooled relative risk was 0.88 (95% CI, 0.7-1.1), indicating no statistically significant reduction in infection with the use of SDD. The summary risk ratio for the association between SDD and gram-negative infection was 0.16 (95% CI, 0.07-0.37), indicating an 84% relative risk reduction in the incidence of infection caused by gram-negative bacteria in patients receiving SDD in randomized trials. In conclusion, the available literature supports a beneficial effect of SDD on gram-negative infection following liver transplantation; however, the risk of antimicrobial resistance must be considered. Larger multicenter randomized trials in this patient population to assess the effect of SDD in reducing infection and mortality, while assessing the risk of antimicrobial resistance, are needed. (Liver Transpl 2004;10:817,827.) [source] Microbiology of Normal External Auditory Canal,THE LARYNGOSCOPE, Issue 11 2001David W. Stroman PhD Abstract Objectives To isolate and characterize bacteria and fungi from the healthy ear and to obtain susceptibility profiles on each bacterial isolate. Study Design Prospective. Methods Specimens were collected from the external canals and cerumen of healthy subjects. Species-level identification was obtained by combining phenotypic and genotypic data. End-point minimal inhibitory concentration testing was performed using National Committee for Clinical Laboratory Standards recommended methods. Results One hundred sixty-four subjects were cultured. Seventeen canal and 16 cerumen specimens showed no growth. One hundred forty-eight cerumen specimens yielded 314 organisms, including 23 fungi. One hundred forty-seven canal specimens yielded 310 organisms, including 7 fungi. Of 291 bacteria isolated from cerumen, 99% were Gram-positive. Of 302 bacteria isolated from the canal, 96% were Gram-positive. Staphylococci were 63% of both the cerumen bacteria and the canal bacteria. Coryneforms represented 22% of the bacteria in cerumen and 19% in the canal. Turicellaotitidis was the primary coryneform isolated from both the canal and the cerumen. Streptococci-like bacteria were 10% from the cerumen, 7% from the canal. In both cerumen and canal, Alloiococcusotitis was more than 95% of the streptococci-like bacteria. Fifteen gram-negative organisms were isolated from the canal and cerumen, including four Pseudomonas aeruginosa strains. The percentages of Staphylococcus epidermidis isolates that had high-level resistance (,8 ,g/mL) were as follows: to neomycin, 28% from cerumen and 11% from the canal; to oxacillin, 28% from cerumen and 25% from the canal; and to ofloxacin, 15% from cerumen and 19% from the canal. ConclusionsTurcella otitidis and A. otitidis were present with a much higher frequency than previously described, lending evidence that they be considered normal otic flora. Corynebacterium auris, previously reported only in children, was isolated from normal adults. [source] | |||||||||||||