Catheter-associated urinary tract infection is a common clinical condition among hospitalized patients with numerous health and economic implications. With judicious use of indwelling urinary catheters, along with strict adherence to basic infection prevention measures, such as hand hygiene and aseptic technique during catheter insertion, these infections are most often preventable. However, these devices continue to be used inappropriately or unnecessarily, which has led the Center for Medicare and Medicaid Services (CMS), the Centers for Disease Control and Prevention (CDC), and numerous infectious disease professional societies to focus attention on how these infections can be diagnosed, prevented, and managed. Despite these efforts, consensus on how best to identify cases of CAUTI has been elusive. Perhaps the most widely used guidelines for the diagnosis, prevention, and treatment of CAUTI are those published in 2010 in the American Journal of Infection Control by Hooton and colleagues. These authors are very clear that CAUTI is a problem if, and only if, it is associated with clinical manifestations; the presence of urinary microorganisms alone is not a clear indication for antimicrobial therapy. Moreover, these authors provide a list of accepted clinical manifestations of CAUTI, which are substantially different from those in previous guidelines. Among others, the manifestations listed include: fever, suprapubic tenderness, flank tenderness, and delirium. However, these are supported by expert opinion only, and neither their diagnostic validity nor their inter-rater reliability have been reported in the literature. The purpose of this study was to examine the diagnostic validity and inter-rater reliability of fever, suprapubic tenderness, flank tenderness, and delirium in hospitalized adult with an indwelling urinary catheter. Briefly, these clinical manifestations were compared against three diagnostic criteria for CAUTI based on microbiologic and molecular methods, and their inter-rater reliability was examined using assessments conducted by three advanced practice nurses. Because significant microbial growth was only present in two urine samples, the diagnostic validity of these manifestations could not be established. However, it was possible to examine the inter-rater reliability of these manifestations. To summarize these findings, the nurse raters were in perfect agreement with the identification of fever, moderate agreement with the identification of delirium, and fair agreement with the identification of suprapubic tenderness and flank tenderness. With the exception of flank tenderness, these findings are statistically significant, and they provide evidence that nurses can consistently identify the presence and absence of fever, suprapubic tenderness, and delirium in hospitalized patients with indwelling urinary catheters. As CAUTI receives more attention from multiple stakeholders, nurses must take an active role in correctly identifying patients with this condition. However, this study had several limitations, and further research is necessary to understand the overall clinical utility and value of these manifestations in terms of patient outcomes and cost.

Pseudomonas aeruginosa is an opportunistic bacterial pathogen associated with severe nosocomial infections in immunocompromised hosts and patients with cystic fibrosis (CF). During infection the bacteria secrete proteins that are essential to the infection process. Several of these virulence-associated proteins have been identified using genetic methods. The aim of this research, using a proteomic approach, was to identify novel extracellular proteins that are secreted by P. aeruginosa during infection of a CF patient. Extracellular proteins from P. aeruginosa strain PAO1 grown in vitro were separated by two-dimensional gel electrophoresis (2-DE). The humoral response of chronically infected CF patients to the separated proteins was elucidated using western blotting. Growth phase, cell population and iron limitation were identified as important regulators of the extracellular proteome. The number of extracellular proteins significantly increased upon entry into stationary phase, as did the number of proteins detected by CF patient sera. The detection of several known quorum-controlled proteins by patient sera indicated the importance of this regulatory mechanism during infection. In iron-limiting medium, the proportion of proteins detected by CF patient sera significantly increased compared to extracellular proteins from cells grown in iron-replete conditions. Proteomic analysis of a PAO1 pvdS mutant strain showed that PvdS (an iron-regulated alternative sigma factor) directs production of many extracellular proteins made during infection of a CF patient. Examination of extracellular proteins from a second strain, PA4, indicated it had a shared set of extracellular proteins. The identities of selected proteins were determined and these included well-characterised extracellular virulence factors such as elastase (LasB). Also identified were proteins with a potential virulence role such as azurin (a copper containing redox protein), PA2939 (a likely aminopeptidase) and proteins with unknown functions. This study provides the first evidence for the production of these proteins during infection. In summary, the proteomics methodology developed here facilitated the rapid identification and enumeration of proteins secreted by P. aeruginosa during infection.

BACKGROUND & AIMS: CD46 is a C3b/C4b binding complement regulator and a receptor for several human pathogens. We examined the interaction between CD46 and Helicobacter pylori (a bacterium that colonizes the human gastric mucosa and causes gastritis), peptic ulcers, and cancer. METHODS: Using gastric epithelial cells, we analyzed a set of H pylori strains and mutants for their ability to interact with CD46 and/or influence CD46 expression. Bacterial interaction with full-length CD46 and small CD46 peptides was evaluated by flow cytometry, fluorescence microscopy, enzyme-linked immunosorbent assay, and bacterial survival analyses. RESULTS: H pylori infection caused shedding of CD46 into the extracellular environment. A soluble form of CD46 bound to H pylori and inhibited growth, in a dose- and time-dependent manner, by interacting with urease and alkyl hydroperoxide reductase, which are essential bacterial pathogenicity-associated factors. Binding of CD46 or CD46-derived synthetic peptides blocked the urease activity and ability of bacteria to survive in acidic environments. Oral administration of one CD46 peptide eradicated H pylori from infected mice. CONCLUSIONS: CD46 is an antimicrobial agent that can eradicate H pylori. CD46 peptides might be developed to treat H pylori infection.

ABSTRACT Adenovirus Death Protein (ADP) expression during late stages of a lytic infection releases mature virions to promote viral spread, thus leading to death of the host cell. We sought to investigate ADP expression patterns in persistently infected human lymphocytes cells. We hypothesized that low expression of ADP allows the virus to persist while high expression would promote lytic infection in lymphocytes. Accordingly, we found ADP expressed in low amount in BJAB and KE37 cells, while lytically infected Jurkat cells demonstrated higher ADP expression in both protein and transcript levels. ADP overexpression in persistently infected lymphocytes did not alter the viability of these cells, or their level of ADP expression. In contrast, Jurkat cells infected with an ADP-deleted virus had increased survival and maintained viral DNA for greater than 1-month, suggesting conversion to a persistent infection. Also manipulating ADP expression had minimal impact on the total virus yield from infected lymphocytes.

Thèse : Médecine : Paris : 1889. / N° d'ordre : 123.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2010.

Pulses are a major source of human protein intake nowadays and will continue to be so because of their high protein content. Pulse crops are members of the family Leguminosae. The five major pulse crops grown in Canada are chick peas, green peas, lentils, pinto bean and kidney beans. Over the past 20 years, Canada has emerged as the world’s largest exporter of lentils and one of world’s top five exporters of beans. These contribute more than $2 billion income to the Canadian economy. The major causes of fungal infection in these pulses are Aspergillus flavus and Penicillium commune. Early stages of fungal infections in pulses are not detectable with human eyes. Near infrared (NIR) hyperspectral imaging system is an advanced technique widely used for detection of insect infestation and fungal infection in cereal grains and oil seeds. A typical NIR instrument captures images across the electromagnetic spectrum at evenly spaced wavelengths from 700 to 2500 nm (a system at the University of Manitoba captures images in the 960 nm to 1700 nm range). From the captured images, the spatial relationships for different spectra in the neighborhood can be found allowing more elaborate spectral-spatial methods for a more accurate classification of the images. The primary objective of this study was to assess the feasibility of the NIR hyperspectral system to identify fungal infections in pulses. Hyperspectral images of healthy and fungal infected chick peas, green peas, lentils, pinto bean and kidney beans were acquired and features (statistical and histogram) were used to develop classification models to identify fungal infection caused by Aspergillus flavus and Penicillium commune. Images of healthy and fungal infected kernels were acquired at 2 week intervals (0, 2, 4, 6, 8 and 10 weeks from artificial inoculation). Six-way (healthy vs the five different stages of infection) and two-way (healthy vs every stage of infection) models were developed and classifications were done using linear discriminant analysis (LDA) and quadratic discriminant analysis (QDA) classifiers. The LDA classifier identified with 90-94% accuracy while using the six-way model, and with 98-100% accuracy when using the two-way models for all five types of pulses and for both types of fungal infections. The QDA classifier also showed promising results as it identified 85-90% while using the six-way model and 96-100% when using the two-way models. Hence, hyperspectral imaging is a promising and non-destructive method for the rapid detection of fungal infections in pulses, which cannot be detected using human eyes. / October 2015

The BacA protein plays a key role in the symbiosis of Sinorhizobium meliloti with the leguminous plant alfalfa (Medicago sativa) and is proposed to be the transmembrane subunit of an ATP‐binding cassette (ABC) transporter. BacA homologues are also present in Brucella species, enteric bacteria (known as SbmA) and Mycobacterium tuberculosis. The S. meliloti‐alfalfa symbiosis, although beneficial to both partners, can also be viewed as a chronic infection. The M. tuberculosis BacA protein is important for M. tuberculosis for the maintenance of a chronic infection. In order to study the M. tuberculosis BacA protein a codon optimised M. tuberculosis bacA gene was synthesised and cloned into vectors for expression in an S. meliloti ΔbacA mutant. Evidence is presented that M. tuberculosis BacA sensitises an S. meliloti ΔbacA mutant towards the glycopeptide bleomycin and the truncated proline rich peptide Bac71‐16, and further that a functional ATPase domain is essential to perform BacA mediated peptide transport. The M. tuberculosis BacA protein protected an S. meliloti ΔbacA mutant from being killed by host defensins. In addition, it was determined that M. tuberculosis BacA‐mediated protection of the legume symbiont S. meliloti against legume defensins as well as mouse alveolar lavages and human ‐defensin 2 is dependent on an ATPase domain which is present in the M. tuberculosis BacA protein. M. tuberculosis encounters ‐defensins during mammalian infections in the host’s lungs and my data show that BacA is likely to be important in conferring immunity to these peptides. The mechanism of persistent infection by M. tuberculosis is therefore very reminiscent of the Sinorhizobium ‐ legume interaction. Also Salmonella enterica is able to cause asymptomatic infections and about 5% of these develop a chronic carrier state and are able to spread the pathogen. In enteric bacterial species SbmA is in close proximity to the putative lipoprotein YaiW. In this study it was determined that YaiW is exposed on the cell surface and that it is involved in the protection of E. coli and potentially Salmonella spp. against a cysteine rich host peptide. YaiW is potentially involved in swarming motility. It was also determined that an alfalfa plant infection model can distinguish between Salmonella strains forming acute and chronic infections. Staphylococcus aureus is one of the major hospital acquired and opportunistic pathogens. Asymptomatic carriers, infected with multi‐drug resistant strains (MRSA) pose a threat to immunocompromised individuals. Here, novel compounds and ways from a variety of sources have been tested for their potential antimicrobial activity against a range of multi‐drug resistant clinical S. aureus isolates. This project significantly advanced the molecular understanding of asymptomatic bacteria‐host infections and helped to understand and establish novel ways to treat infections with multi‐drug resistant clinical pathogens.

In the South African context, upgrading to, and delivery of a basic water-supply service to small-community households is expected to bring benefits such as reduced exposure to contaminated drinking water. A basic water-supply service mostly means that water is distributed to the community via communal taps that are not on the households’ premises (DWA, 2003). While this is seen as an improvement, people still have to use plastic containers (mostly 20-25ℓ volume) to collect water from the taps and store in their houses (Nala et al., 2003). Authors report that, from a health-related microbial water quality perspective, the management (e.g. poor container-hygiene practices) of household containers cause microbial re-contamination of good quality water (Gundry et al., 2004; Jagals et al., 2004; Jensen et al., 2002). This implies that household container water pose a risk of microbial infection to an individual if used for drinking without any household level disinfection. Providing clean water to households, even thought they might still have to use the containers, does limit the extent of the recontamination because of consistent use with the clean water as opposed to when communities use these containers to source contaminated surface waters (Mokoena et al., 2010). When the supply system fails, which was reported to happen frequently in the study area (Rietveld et al., 2009), the affected communities will return to their original source of water, using the same containers to collect what is often contaminated water (Momba et al., 2006). While it is plausible that the probable risk of infection will change with these service inconsistencies, it has not conclusively been shown what the effect of it might be on risk. This submission demonstrates how a quantitative microbial risk assessment (WHO, 2004) can be used as a tool to assess these shifts in risk, offering another technique to assess the effectiveness of a small-community water supply service. The aim of the study was assess, after implementation with subsequent operation and maintenance of two small-community water supply schemes, the effect of service delivery on the annual risk of bacterial infection for individuals based on pathogenic E. coli in the water that the people in the community drink.

Colletotrichum gloeosporioides is the causal agent of anthracnose disease of mangoes. Infection occurs when humidity is high and rain-dispersed spores germinate and form an appressorium on immature mangoes. The infection then becomes quiescent until the fruit is harvested. On ripe fruit infection is visible as black, sunken lesions on the surface. At the pre-harvest stage, the disease is controlled with the application of a range of fungicides, and at the post-harvest stage by hot benomyl treatment. The extensive use of benomyl, both pre- and post-harvest, has resulted in the occurrence of isolates of C. gloeosporioides resistant to this fungicide. To devise an alternative strategy of disease control, the potential for biological control of anthracnose has been investigated. Potential microbial antagonists of C. gloeosporioides were isolated from blossom, leaves and fruit of mango, and screened using a series of assay techniques. In total 650 microorganisms, including bacteria, yeasts and filamentous fungi, were isolated and tested for their inhibition of growth of C. gloeosporioides on malt extract agar. Of these 650 isolates, 121 inhibited the fungus and were further tested on their ability to inhibit spore germination in vitro. Of these, 45 isolates, all bacteria and yeasts, were inoculated onto mangoes, which were artificially inoculated with C. gloeosporioides, and assessed for their potential to reduce the development of anthracnose lesions. A further selection was made, and 7 isolates were chosen to be used in a semi-commercial trial in the Philippines. This final screening procedure yielded two potential candidates for field trials, isolate 204 (identified as Bacillus cereus) and isolate 558 (identified as Pseudomonas fiuorescens). A field trial involving pre-harvest application of the biological control agent, was conducted using isolate 558. This isolate was chosen for this purpose since in in vitro experiments it significantly reduced germination of C. gloeosporioides spores. In the field trial 558 was applied in combination with nutrients and compared to treatments which had received no treatment or which had received conventional fungicide (benomyl) application. On spraying, high numbers of 558 were recorded on the leaf surface, but no reduction in post-harvest development of disease was observed. Failure of disease control was attributed to rapid death of the bacterium on the phylloplane. Inpost-harvest trials, isolates 204 and 558 were both tested in combination with different application methods, including the addition of sticker, peptone, fruit wax or a sucrose polyester. Application of 204 did not reduce disease development. Application of 558, however, did significantly reduce anthracnose development compared to the control fruit. No additional benefit was achieved by incorporating the bacteria in peptone, fruit wax or sucrose polyester. The mode of action of isolate 558 was investigated in detail. There was no evidence for parasitism taking place, or the production of volatile compounds, in the suppression of disease development. No antibiotic compounds were detected, but isolate 558 did produce a siderophore. A sharp increase in pH was also observed in culture media in which 558 was grown. Disease control may result from a combination of these two factors.