Pathogenic Microorganisms (pathogenic + microorganism)

Distribution by Scientific Domains
Distribution within Medical Sciences


Selected Abstracts


Local control of the immune response in the liver

IMMUNOLOGICAL REVIEWS, Issue 1 2000
Percy A. Knolle
Summary: The physiological function of the liver , such as removal of pathogens and antigens from the blood, protein synthesis and metabolism , requires an immune response that is adapted to these tasks and is locally regulated. Pathogenic microorganisms must be efficiently eliminated while the large number of antigens derived from the gastrointestinal tract must be tolerized. From experimental observations it is evident that the liver favours the induction of tolerance rather than the induction of immunity. The liver probably not only is involved in transplantation tolerance but contributes as well to tolerance to orally ingested antigens (entering the liver with portal-venous blood) and to containment of systemic immune responses (antigen from the systemic circulation entering the liver with arterial blood). This review summarizes the experimental data that shed light on the molecular mechanisms and the cell populations of the liver involved in local immune regulation in the liver. Although hepatocytes constitute the major cell population of the liver, direct interaction of hepatocytes with leukocytes in the blood is unlikely. Sinusoidal endothelial cells, which line the hepatic sinusoids and separate hepatocytes from leukocytes in the sinusoidal lumen, and Kupffer cells, the resident macrophage population of the liver, can directly interact with passenger leukocytes. In the liver, clearance of antigen from the blood occurs mainly by sinusoidal endothelial cells through very efficient receptor-mediated endocytosis. Liver sinusoidal endothelial cells constitutively express all molecules necessary for antigen presentation (CD54, CD80, CD86, MHC class I and class II and CD40) and can function as antigen-presenting cells for CD4+ and CD8+ T cells. Thus, these cells probably contribute to hepatic immune surveillance by activation of effector T cells. Antigen-specific T-cell activation is influenced by the local microenvironment. This microenvironment is characterized by the physiological presence of bacterial constituents such as endotoxin and by the local release of immunosuppressive mediators such as interleukin-10, prostaglandin E2 and transforming growth factor-b. Different hepatic cell populations may contribute in different ways to tolerance induction in the liver. In vitro experiments revealed that naive T cells are activated by resident sinusoidal endothelial cells but do not differentiate into effector T cells. These T cells show a cytokine profile and a functional phenotype that is compatible with the induction of tolerance. Besides sinusoidal endothelial cells, other cell populations of the liver, such as dendritic cells, Kupffer cells and perhaps also hepatocytes, may contribute to tolerance induction by deletion of T cells through induction of apoptosis. [source]


Bacterial exotoxins downregulate cathelicidin (hCAP-18/LL-37) and human ,-defensin 1 (HBD-1) expression in the intestinal epithelial cells

CELLULAR MICROBIOLOGY, Issue 12 2008
Krishnendu Chakraborty
Summary Cathelicidin (hCAP-18/LL-37) and ,-defensin 1 (HBD-1) are human antimicrobial peptides (AMPs) with high basal expression levels, which form the first line of host defence against infections over the epithelial surfaces. The antimicrobial functions owe to their direct microbicidal effects as well as the immunomodulatory role. Pathogenic microorganisms have developed multiple modalities including transcriptional repression to combat this arm of the host immune response. The precise mechanisms and the pathogen-derived molecules responsible for transcriptional downregulation remain unknown. Here, we have shown that enteric pathogens suppress LL-37 and HBD-1 expression in the intestinal epithelial cells (IECs) with Vibrio cholerae and enterotoxigenic Escherichia coli (ETEC) exerting the most dramatic effects. Cholera toxin (CT) and labile toxin (LT), the major virulence proteins of V. cholerae and ETEC, respectively, are predominantly responsible for these effects, both in vitro and in vivo. CT transcriptionally downregulates the AMPs by activating several intracellular signalling pathways involving protein kinase A (PKA), ERK MAPKinase and Cox-2 downstream of cAMP accumulation and inducible cAMP early repressor (ICER) may mediate this role of CT, at least in part. This is the first report to show transcriptional repression of the AMPs through the activation of cellular signal transduction pathways by well-known virulence proteins of pathogenic microorganisms. [source]


Structural Studies of the O-Chain Polysaccharide from Plesiomonas shigelloides Strain 302,73 (Serotype O1)

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2008
Giuseppina Pieretti
Abstract Plesiomonas shigelloides is a Gram-negative bacterium belonging to the Enterobacteriaceae family. It has been found in an aquatic environment in the tropical and subtropical regions and is responsible for many gastrointestinal infections in humans, which take place from drinking untreated water or eating uncooked shellfish. Plesiomonas shigelloides has also been reported to provoke extraintestinal infections such as meningitis and bacteremia in immunocompromised adults and neonates. Despite the emerging importance of this pathogenic microorganism, only three different O-antigens have been characterised so far. The structure of the O-chain of the lipopolysaccharide (LPS) from Plesiomonasshigelloides strain 302,73 (serotype O1) was determined by chemical analysis, 1D and 2D NMR spectroscopy and MALDI-TOF mass spectrometry. The polysaccharide was constituted by a linear pentasaccharidic repeating unit as follows: ,3)-,- L -PneNAc4OAc(1,4)-,- L -FucNAc(1,4)-,- L -FucNAc(1,4)-,- L -FucNAc(1,3)-,- D -QuiNAc4NHb(1, (PneNAc = 2-acetamido-2,6-dideoxy-talose, Hb = (S)-3-hydroxybutanoyl) PneNAc O -acetylation was not stoichiometric and was found to be about 75,%. The position of the O -acetyl group and the amount of acetylation were deduced by NMR spectroscopic analysis. All the monosaccharides included in the repeating unit were deoxyamino sugars, which most probably, together with the presence of O -acetyl groups, were responsible for the recovery of the LPS in the phenol layer of the phenol/water extract of dried bacteria cells.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]


Detection of Treponema denticola in endodontic infections by 16S rRNA gene-directed polymerase chain reaction

MOLECULAR ORAL MICROBIOLOGY, Issue 5 2000
J. F. Siqueira Jr.
A 16S rDNA-based polymerase chain reaction (PCR) method was used to detect the occurrence of Treponema denticola in root canal infections. Samples were collected from 21 single-root teeth having carious lesions, necrotic pulps and radiographic evidences of periradicular bone loss. DNA extracted from the samples was amplified using the PCR assay, which yielded specific fragment of T. denticola 16S rDNA. T. denticola was detected in 11 of 21 cases (52.4%), regardless of the presence or absence of symptoms. Since this spirochete was found in a relatively high percentage of the endodontic infections examined and because it is a pathogenic microorganism involved in periodontal diseases, there are reasons to believe that T. denticola can also participate in the pathogenesis of periradicular lesions of endodontic origin. [source]


Molecular mechanisms of pathogenicity: how do pathogenic microorganisms develop cross-kingdom host jumps?

FEMS MICROBIOLOGY REVIEWS, Issue 3 2007
Peter Van Baarlen
Abstract It is common knowledge that pathogenic viruses can change hosts, with avian influenza, the HIV, and the causal agent of variant Creutzfeldt,Jacob encephalitis as well-known examples. Less well known, however, is that host jumps also occur with more complex pathogenic microorganisms such as bacteria and fungi. In extreme cases, these host jumps even cross kingdom of life barriers. A number of requirements need to be met to enable a microorganism to cross such kingdom barriers. Potential cross-kingdom pathogenic microorganisms must be able to come into close and frequent contact with potential hosts, and must be able to overcome or evade host defences. Reproduction on, in, or near the new host will ensure the transmission or release of successful genotypes. An unexpectedly high number of cross-kingdom host shifts of bacterial and fungal pathogens are described in the literature. Interestingly, the molecular mechanisms underlying these shifts show commonalities. The evolution of pathogenicity towards novel hosts may be based on traits that were originally developed to ensure survival in the microorganism's original habitat, including former hosts. [source]


Evolution and phylogenetic relationships of APSES proteins from Hemiascomycetes

FEMS YEAST RESEARCH, Issue 4 2008
Bernardo Ramírez-Zavala
Abstract Available complete genomic sequences of hemiascomycetous yeast species were analysed in order to identify the APSES protein family, which belongs to transcriptional factors of the basic helix,loop,helix (bHLH) class. Phylogenetic analyses of the amino acid sequences revealed that a similar set of proteins were present in all yeast species studied. The genome duplication event of Saccharomycetales allows the acquisition of complementary functions between the APSES proteins. Putative ancestors, such as Ashbya gossypii, the Kluyveromyces group and filamentous fungi, only have one APSES protein. Conserved gene order relationships allow the possibility of tracing the evolution of this family and the detection of duplication events. Multiple alignments revealed strict conservation of the APSES motif, although other regions of the APSES proteins were diversified. This review focuses on the evolution of the gene family of APSES proteins in related Hemiascomycetes species; the comparisons could shed light on the functional overlap of these proteins with regard to the regulation of morphogenetic processes and their involvement in the virulence of pathogenic microorganisms. [source]


The use of killer sensitivity patterns for biotyping yeast strains: the state of the art, potentialities and limitations

FEMS YEAST RESEARCH, Issue 6 2007
Pietro Buzzini
Abstract In recent years molecular techniques have been the most useful tools for the unequivocal identification of undetermined strains at the species level. In many instances, however, a further discrimination at the strain level (biotyping) is required, such as during epidemiological investigations, in which the distribution of pathogenic microorganisms is studied, and for patent protection purposes. Although molecular methods are routinely used also for yeast biotyping, several nonmolecular techniques have been proposed. One of these, the determination of the killer sensitivity pattern (KSP) towards a panel of selected killer toxins has proven to be a good auxiliary method. Despite the plethora of studies published, the potential and limitations of the determination of KSPs have never been critically evaluated. In this review the use of this nonmolecular technique as a biotyping tool is discussed and compared with some currently used DNA-based procedures. In addition, methodological, mechanistic and ecological implications are evaluated. [source]


Whey-derived free fatty acids suppress the germination of Candida albicans in vitro

FEMS YEAST RESEARCH, Issue 2 2007
Martin Clément
Abstract Bovine whey from the cheese-making industry contains several bioactive factors that promote health and prevent disease. Although many efforts have been made over the years to show that immunoglobulins, lactoperoxidase, lactoferrin, lysosyme and small peptides present in whey have antimicrobial activities against several pathogenic microorganisms, such activities have not been investigated so far for the lipid fraction of whey. Here, we have used an in vitro assay-based fractionation procedure to show that free fatty acids derived from whey cream specifically inhibit the germination of Candida albicans, a morphologic change associated with pathogenicity. Further fractionation by HPLC demonstrated that this activity can be mainly attributed to lauric acid, myristoleic acid, linoleic acid and arachidonic acid. [source]


Raw materials: the importance of quality and safety.

FLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2010
A review.
Abstract Aromatic plants and spices are used throughout the world for flavouring food and beverages, as well as for food supplements, novel foods and as a source of essential oils and aromatic extracts. The non-availability or inadequacy of standards for checking and assuring the quality of aromatic plants and spices is one of the main problems that arise for industry when using such raw materials. As many aromatic plants are harvested from the wild, standardization to assure their quality is important for their safe and effective utilization in food and beverage industries. On the other hand, there are numerous parameters that influence the chemical composition of plants, which play an important role in the final quality of the product and possibly in any risk arising to the consumer. Also, from a safety point of view, aromatic plants and spices should be free of undeclared contaminants and adulterants, such as toxic botanicals, pathogenic microorganisms and excessive levels of microbial toxins, pesticides or fumigation agents. We focus on these aspects and examine ways to assure their appropriate utilization from the quality and safety standpoint. The regulatory situation of medicinal and aromatic plants (MAPs) is very complicated; several differences in standards and regulations between countries can be found, a situation that can result in more health risks arising for consumers. To clarify some of the existing problems, the major regulations of the USA and the European Union (EU) and the borderlines between food supplements and medicines and other international standards, are briefly described and discussed. Copyright © 2010 John Wiley & Sons, Ltd. [source]


Fermentation characteristics and aerobic stability of grass silage inoculated with Lactobacillus buchneri, with or without homofermentative lactic acid bacteria

GRASS & FORAGE SCIENCE, Issue 4 2001
F. Driehuis
Aerobic spoilage by yeasts and moulds is a major cause of reduced nutritional value of silage and increases the risk of potential pathogenic microorganisms. Recent studies have shown that inoculation with Lactobacillus buchneri inhibits yeast growth and reduces the susceptibility to aerobic spoilage of various ensiled forages. The aim of this study was to determine whether these effects are retained when L. buchneri is added in combination with homofermentative lactic acid bacteria. In three experiments, silages were produced from perennial ryegrass [240,421 g kg,1 dry matter (DM)] inoculated with L. buchneri or L. buchneri plus a mixture of Pediococcus pentosaceus and Lactobacillus plantarum (inoculant PL). Uninoculated silage and silage inoculated with PL alone served as controls. Silages were examined for pH and DM loss in the course of ensilage and chemical and microbiological composition and aerobic stability after 3,4 months. L. buchneri plus PL and PL alone increased the initial rate of pH decline. L. buchneri alone and L. buchneri plus PL enhanced aerobic stability and, in general, reduced yeast and mould counts. In addition, these inoculants increased the final pH and DM loss and the concentrations of acetic acid and 1,2-propanediol (or propionic acid and 1-propanol instead of 1,2-propanediol), and decreased the concentration of lactic acid. The effects of L. buchneri on fermentation products increased with decreasing DM content. In silages of less than 270 g kg,1 DM, L. buchneri increased the ammonia-N concentration. It is suggested that this was associated with the relatively high final pH resulting from the high metabolic activity of L. buchneri in these silages. [source]


Isolation and Characterization of Lactobacillus Species Having Potential for Use as Probiotic Cultures for Dogs

JOURNAL OF FOOD SCIENCE, Issue 3 2007
S. McCoy
ABSTRACT:, The need to control pathogenic microorganisms in the intestinal tract of dogs is a growing concern. There is interest in using probiotics such as species of Lactobacillus to help control canine intestinal infections. For successful use as a probiotic, the bacterial species should be of canine intestinal origin since these species exhibit host specificity. Serial dilutions of freshly voided dog feces were plated on Lactobacillus selection (LBS) agar to isolate the cultures. Isolates were identified based on Gram stain, catalase test, and fermentation patterns using API 50 CH kits. All potential isolates were compared for bile resistance based on relative ability to grow in broth containing 0.3% Oxgall, the ability to inhibit Salmonella Typhimurium in associative broth cultures, and the production of reuterin. Of the lactobacilli isolated, Lactobacillus reuteri was the dominant species. However, some cultures of L. acidophilus also were isolated. We found variations among the isolates of L. reuteri and L. acidophilus with respect to bile tolerance. In general, isolates of L. reuteri appeared to be more bile resistant than were isolates of L. acidophilus. There were also variations in the ability to inhibit growth of S. Typhimurium. Some isolates of L. reuteri produced reuterin while others did not. [source]


Prevalence of enteric pathogens among community based asymptomatic individuals

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 3 2000
Margaret E Hellard
Abstract Background and Aims: The objective of this study was to describe the prevalence of pathogenic microorganisms in asymptomatic individuals in a community study in Melbourne, Australia. Methods: The study population was a subset of 2803 individuals participating in the Water Quality Study; a community based randomized trial. Faecal specimens (1091) were collected over a 3-month period from asymptomatic individuals. Specimens were tested for a range of bacteria including Salmonella, Shigella and Campylobacter species. Rotavirus and adenovirus were detected using a Rota-Adeno latex kit, and protozoa were detected using a permanent stain (modified iron-haemotoxylin). Results: Twenty-eight known pathogens were identified from the 1091 faecal specimens, a total carriage rate of 2.6%. Giardia species were present in 18 specimens (1.6%), Salmonella in four (0.4%), Campylobacter in one (0.1%), Cryptosporidium in four (0.4%) and adenovirus in one (0.1%). Blastocystis hominis was found in 65 specimens. The median age of those without a pathogen was 12.5 years compared with 6.6 years for those with a pathogen (P = 0.02). Conclusions: Except for Giardia, pathogens were rarely found in asymptomatic individuals in the community. The prevalence of pathogens was higher in children than adults. © 2000 Blackwell Science Asia Pty Ltd [source]


Probiotics and gastrointestinal diseases

JOURNAL OF INTERNAL MEDICINE, Issue 1 2005
Ĺ. SULLIVAN
Abstract. There is increasing evidence indicating health benefits by consumption of foods containing microorganisms, i.e. probiotics. A number of clinical trials have been performed to evaluate the effects in the prevention and treatment of gastrointestinal diseases caused by pathogenic microorganisms or by disturbances in the normal microflora. Gastrointestinal infections caused by Helicobacter pylori, traveller's diarrhoea, rotavirus diarrhoea, antibiotic-associated diarrhoea (AAD) and Clostridium difficile -induced diarrhoea are conditions that have been studied. There are also studies performed on the preventive effect of probiotics on radiation-induced diarrhoea and diarrhoea in tube-fed patients. Inflammatory bowel disease and irritable bowel syndrome, two idiopathic conditions where alterations in the normal microflora have been implicated as responsible for initiation, are two further areas where the use of probiotics has been regarded as promising. The results from clinical studies have not been conclusive in that the effects of probiotics have been strain-dependent and different study designs have been used. Treatment of acute diarrhoea in children and prevention of AAD are the two most justified areas for the application of probiotics. [source]


Review article: anti-inflammatory mechanisms of action of Saccharomyces boulardii

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2009
C. POTHOULAKIS
Aliment Pharmacol Ther,30, 826,833 Summary Background,Saccharomyces boulardii, a well-studied probiotic, can be effective in inflammatory gastrointestinal diseases with diverse pathophysiology, such as inflammatory bowel disease (IBD), and bacterially mediated or enterotoxin-mediated diarrhoea and inflammation. Aim, To discuss the mechanisms of action involved in the intestinal anti-inflammatory action of S. boulardii. Methods, Review of the literature related to the anti-inflammatory effects of this probiotic. Results, Several mechanisms of action have been identified directed against the host and pathogenic microorganisms. S. boulardii and S. boulardii secreted-protein(s) inhibit production of proinflammatory cytokines by interfering with the global mediator of inflammation nuclear factor ,B, and modulating the activity of the mitogen-activated protein kinases ERK1/2 and p38. S. boulardii activates expression of peroxisome proliferator-activated receptor-gamma (PPAR-,) that protects from gut inflammation and IBD. S. boulardii also suppresses ,bacteria overgrowth' and host cell adherence, releases a protease that cleaves C. difficile toxin A and its intestinal receptor and stimulates antibody production against toxin A. Recent results indicate that S. boulardii may interfere with IBD pathogenesis by trapping T cells in mesenteric lymph nodes. Conclusions, The multiple anti-inflammatory mechanisms exerted by S. boulardii provide molecular explanations supporting its effectiveness in intestinal inflammatory states. [source]


Microbial contamination of contact lenses and lens care accessories of soft contact lens wearers (university students) in Hong Kong

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2007
M. S. Yung
Abstract Purpose:, This study aimed to examine the rates of microbial contamination, and identify contaminants associated with contact lenses and lens care accessories used by a group of young contact lens wearers. Methods:, Collected contact lenses, lens cases, and lens care solutions were studied by bacterial culture. Contamination rates of these samples were recorded and compared with those reported in previous studies. Results:, Of the samples tested, 9% of lens extracts, 34% of case extracts and 11% of solution samples were contaminated with ocular pathogenic microorganisms. Serratia spp., Staphylococcus aureus and coagulase-negative staphylococci were the most common microorganisms isolated. Lens cases were the most frequently contaminated item. Lens cases also yielded the widest range of bacterial isolates. Contact lenses used by occasional wearers were associated with a higher contamination rate. Using either saline or multipurpose solution to rinse lenses before use appeared to be effective in reducing incidence of contamination. Conclusion:, Our findings demonstrate that contact lenses and lens care accessories are not well maintained by contact lens wearers. Regular reviews and reinforcement of lens care procedures for the usage and care of contact lenses and lens care accessories is therefore important and essential. [source]


Airway epithelial cell signaling in response to bacterial pathogens

PEDIATRIC PULMONOLOGY, Issue 1 2008
Marisa I. Gómez PhD
Abstract The airway epithelium represents a primary site for the introduction and deposition of potentially pathogenic microorganisms into the body, through inspired air. The epithelial mucosa is an important component of the innate immune system that recognizes conserved structures in microorganisms and initiates appropriate signaling to recruit and activate phagocytic cells to the airways. This review focuses on how airway epithelial cells sense and respond to the presence of bacterial pathogens. The major signaling cascades initiated by epithelial receptors that lead to phagocyte recruitment to the airways as well as the ability of the epithelium to regulate inflammation are discussed. Pediatr Pulmonol. 2008; 43:11,19. © 2007 Wiley-Liss, Inc. [source]


Structure and heme binding properties of Escherichia coli O157:H7 ChuX

PROTEIN SCIENCE, Issue 4 2009
Michael D. L. Suits
Abstract For many pathogenic microorganisms, iron acquisition from host heme sources stimulates growth, multiplication, ultimately enabling successful survival and colonization. In gram-negative Escherichia coli O157:H7, Shigella dysenteriae and Yersinia enterocolitica the genes encoded within the heme utilization operon enable the effective uptake and utilization of heme as an iron source. While the complement of proteins responsible for heme internalization has been determined in these organisms, the fate of heme once it has reached the cytoplasm has only recently begun to be resolved. Here we report the first crystal structure of ChuX, a member of the conserved heme utilization operon from pathogenic E. coli O157:H7 determined at 2.05 Ĺ resolution. ChuX forms a dimer which remarkably given low sequence homology, displays a very similar fold to the monomer structure of ChuS and HemS, two other heme utilization proteins. Absorption spectral analysis of heme reconstituted ChuX demonstrates that ChuX binds heme in a 1:1 manner implying that each ChuX homodimer has the potential to coordinate two heme molecules in contrast to ChuS and HemS where only one heme molecule is bound. Resonance Raman spectroscopy indicates that the heme of ferric ChuX is composed of a mixture of coordination states: 5-coordinate and high-spin, 6-coordinate and low-spin, and 6-coordinate and high-spin. In contrast, the reduced ferrous form displays mainly a 5-coordinate and high-spin state with a minor contribution from a 6-coordinate and low-spin state. The ,Fe-CO and ,C-O frequencies of ChuX-bound CO fall on the correlation line expected for histidine-coordinated hemoproteins indicating that the fifth axial ligand of the ferrous heme is the imidazole ring of a histidine residue. Based on sequence and structural comparisons, we designed a number of site-directed mutations in ChuX to probe the heme binding sites and dimer interface. Spectral analysis of ChuX and mutants suggests involvement of H65 and H98 in heme coordination as mutations of both residues were required to abolish the formation of the hexacoordination state of heme-bound ChuX. [source]


Sputum bacteriology in hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease in Taiwan with an emphasis on Klebsiella pneumoniae and Pseudomonas aeruginosa

RESPIROLOGY, Issue 1 2007
Sheng-Hsiang LIN
Background and objective: Bacterial infection is one of the major causes of acute exacerbation of COPD (AECOPD). This study was undertaken to investigate the microbiology of AECOPD. Methods: Medical records from 494 episodes of AECOPD in patients admitted to the National Taiwan University Hospital from January 2000 to June 2004 were reviewed. Severity of COPD was classified according to the 2003 Global Initiative for Chronic Obstructive Lung Disease guideline. Results: Potential pathogenic microorganisms were isolated from patients in 328 (66.4%) episodes of AECOPD. The predominant bacteria were Klebsiella pneumoniae (19.6%), Pseudomonas aeruginosa (16.8%) and Haemophilus influenzae (7.5%), followed by Acinetobacter baumannii (6.9%), Enterobacter species (6.1%) and Staphylococcus aureus (6.1%). The incidence of Streptococcus pneumoniae was 2.4%. Spirometry results obtained within 1 year of the exacerbation were available in 186 cases. K. pneumoniae was more frequently isolated in stage I COPD (39.1%) than stage II (16.6%), III (13.8%) and IV (9.4%). No glucose non-fermentative Gram-negative bacilli were isolated in stage I patients. Multivariate logistic regression analysis revealed that P. aeruginosa (odds ratio (OR) 3.19; 95% confidence interval (CI): 1.21,8.38), intubation (OR 14.81; 95% CI: 5.08,43.12) and age (OR 1.1; 95% CI: 1.03,1.17) were independent risk factors for mortality. Conclusions: Klebsiella pneumoniae and P. aeruginosa are the most common sputum pathogens in hospitalized patients with AECOPD in Taiwan, with the former being more commonly isolated from mild COPD and the latter associated with poor clinical outcome. These results should be considered when deciding which antibiotics should initially be used to treat patients with AECOPD. [source]


Passage of pathogenic microorganisms through breathing system filters used in anaesthesia and intensive care

ANAESTHESIA, Issue 7 2010
D. H. T. Scott
Summary Invasive ventilation poses a risk of respiratory infection that can be drug-resistant. One means of reducing transmission of infection is the use of a breathing system filter. Filters are intended to be used with dry gas. Current international standards do not require that filters prevent bacterial transfer when wet. It is not known whether microorganisms pass through wet filters, but theory predicts that this might occur. We tested six filters from three different manufacturers. We passed a suspension of microorganisms through the filters using the least pressure necessary, and incubated a sample of the filtrate on blood agar. All the filters tested allowed free passage of both Candida albicans and coagulase-negative staphylococci. The median (IQR [range]) pressure required for fluid to flow across the filter varied greatly between different filter types (20 (0,48 [0,138]) cmH2O). We conclude that even large microorganisms pass across moist breathing system filters in conditions that are found in clinical practice. [source]


A novel non-invasive tool for disease surveillance of free-ranging whales and its relevance to conservation programs

ANIMAL CONSERVATION, Issue 2 2010
K. Acevedo-Whitehouse
Abstract The numbers of potentially pathogenic microorganisms that have been isolated from stranded cetaceans in the last three decades underscore the urgent need for methods of detection of microorganisms that might cause significant disease and increase the likelihood of population declines. We have designed and implemented two non-invasive techniques for the collection of exhaled breath condensate (blow) from free-ranging whales and demonstrated their suitability for the detection of respiratory bacteria. We successfully collected 22 individual blow samples from eight cetacean species. Using well-established molecular techniques we detected three bacterial genera (Haemophilus, Streptococcus and Staphylococcus). Haemophilus spp. was detected in fin whale Balaenoptera physalus, sperm whale Physeter macrocephalus, humpback whale Megaptera novaeangliae and gray whale Eschrichtius robustus blows, while unidentified , -hemolytic streptococci and Staphylococcus aureus were detected in gray whale and blue whale Balaenoptera musculus blows. The detection limit of the test was determined as 1 CFU mL,1. None of the identified bacteria were found in environmental (control) samples, suggesting that their presence in the blows was genuine and not due to inadvertent contamination. While the population-level relevance of these bacteria is as yet unclear and it is possible that they are commensal microorganisms, S. aureus has been identified previously as a high-risk pathogen to cetacean health, and streptococci have increasingly been associated with cetacean mortality events. We suggest that future cetacean monitoring programs of vulnerable or threatened species include blow sampling as a means to determine the prevalence of the respiratory bacteria in the populations and monitor spatiotemporal fluctuations as indicators of changes in cetacean health. [source]


Bacterial exotoxins downregulate cathelicidin (hCAP-18/LL-37) and human ,-defensin 1 (HBD-1) expression in the intestinal epithelial cells

CELLULAR MICROBIOLOGY, Issue 12 2008
Krishnendu Chakraborty
Summary Cathelicidin (hCAP-18/LL-37) and ,-defensin 1 (HBD-1) are human antimicrobial peptides (AMPs) with high basal expression levels, which form the first line of host defence against infections over the epithelial surfaces. The antimicrobial functions owe to their direct microbicidal effects as well as the immunomodulatory role. Pathogenic microorganisms have developed multiple modalities including transcriptional repression to combat this arm of the host immune response. The precise mechanisms and the pathogen-derived molecules responsible for transcriptional downregulation remain unknown. Here, we have shown that enteric pathogens suppress LL-37 and HBD-1 expression in the intestinal epithelial cells (IECs) with Vibrio cholerae and enterotoxigenic Escherichia coli (ETEC) exerting the most dramatic effects. Cholera toxin (CT) and labile toxin (LT), the major virulence proteins of V. cholerae and ETEC, respectively, are predominantly responsible for these effects, both in vitro and in vivo. CT transcriptionally downregulates the AMPs by activating several intracellular signalling pathways involving protein kinase A (PKA), ERK MAPKinase and Cox-2 downstream of cAMP accumulation and inducible cAMP early repressor (ICER) may mediate this role of CT, at least in part. This is the first report to show transcriptional repression of the AMPs through the activation of cellular signal transduction pathways by well-known virulence proteins of pathogenic microorganisms. [source]


Biofilm Formation and Control in Food Processing Facilities

COMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY, Issue 1 2003
R.A.N. Chmielewski
ABSTRACT Microorganisms on wet surfaces have the ability to aggregate, grow into microcolonies, and produce biofilm. Growth of biofilms in food processing environments leads to increased opportunity for microbial contamination of the processed product. These biofilms may contain spoilage and pathogenic microorganisms. Microorganisms within biofilms are protected from sanitizers increasing the likelihood of survival and subsequent contamination of food. This increases the risk of reduced shelf life and disease transmission. Extracellular polymeric substances associated with biofilm that are not removed by cleaning provide attachment sites for microorganisms newly arrived to the cleaned system. Biofilm formation can also cause the impairment of heat transfer and corrosion to metal surfaces. Some of the methods used to control biofilm formation include mechanical and manual cleaning, chemical cleaning and sanitation, and application of hot water. [source]