82,304,532 research outputs found
AgandCuloadedonTiO2/graphite as a catalyst for �Escherichia coli- contaminated water disinfection
No full textTiO2 film was synthesized by means of the chemical bath deposition (CBD) method from TiCl4
as a precursor and surfactant cetyl trimethyl ammonium bromide (CTAB) as a linking and assem-
bling agent of the titanium hydroxide network on a graphite substrate. Ag and Cu were loaded
on the TiO2 film by means of electrodeposition at various applied currents. Photoelectrochemical
testing on the composite of Ag–TiO2/G and Cu–TiO2/G was used to define the composite for
Escherichia coli-contaminated water disinfection. Disinfection efficiency and the rate of disinfection
of E. coli-contaminated water with Ag–TiO2/G as a catalyst was higher than that observed for
Cu–TiO2/G in all disinfection methods including photocatalysis (PC), electrocatalysis (EC), and
photoelectrocatalysis (PEC). The highest rate constant was achieved by the PEC method using
Ag–TiO2/G, k was 6.49 × 10−2
CFU mL−1
min−1
. Effective disinfection times of 24 h (EDT24)
and 48 h (EDT48) were achieved in all methods except the EC method using Cu–TiO2/G.
Keywords: Ag–TiO2/G, Cu–TiO2/G, Escherichia coli, disinfectio
A fuzzy approach to the measurement of employment and unemployment
No full textThis chapter defines fuzzy measures of employment and unemployment using available information on the weekly number of hours worked and on the desire or need of workers to work more hours. The way in which the employed, unemployed and inactive population groups are identified affects the value of employment and unemployment rates. The unemployment rate is defined as the share of the total labour force that is unemployed, whereas the employment rate is the share of the working age population that is employed. A fuzzy measure of employment reflects the unmet need among the employed for working additional hours, thus accounting for labour under-utilisation. The concept of labour under-utilisation encompasses both time-related underemployment and involuntary part-time employment. The largest upward correction is seen among female workers, workers between 55 and 64 years old, foreign-born workers, third-secondary educated and those living in the North
Preferential attachment of Escherichia coli to different particle size fractions of an agricultural grassland soil.
No full textThis study reports on the attachment preference of a faecally derived bacterium, Escherichia coli, to soil particles of defined size fractions. In a batch sorption experiment using a clay loam soil it was found that 35% of introduced E. coli cells were associated with soil particulates >2 μm diameter. Of this 35%, most of the E. coli (14%) were found to be associated with the size fraction 15-4 μm. This was attributed to the larger number of particles within this size range and its consequently greater surface area available for attachment. When results were normalised with respect to estimates of the surface area available for bacterial cell attachment to each size fraction, it was found that E. coli preferentially attached to those soil particles within the size range 30-16 μm. For soil particles > 2 μm, E. coli showed at least 3.9 times more preference to associate with the 30-16 μm than any other fraction. We report that E. coli can associate with different soil particle size fractions in varying proportions and that this is likely to impact on the hydrological transfer of cells through soil and have clear implications for our wider understanding of the attachment dynamics of faecally derived bacteria in soils of different compositions
Histiocytosis X arising in Hodgkin's disease: immunophenotypic characterization with a panel of monoclonal antibodies
No full textThis report describes the antigenic profile of the proliferating cells of pulmonary histiocytosis X (HX) in a patient treated with chemotherapy for Hodgkin's lymphoma; the association of pulmonary HX and Hodgkin's disease has rarely been described in the literature. The histopathological diagnosis of HX was confirmed with the aid of monoclonal antibodies (mAbs) to CD4, CD1a, and polyclonal serum anti S-100 protein. The phenotype of HX cells has been analysed using a panel of mAbs against HLA class I A, B, C monomorphic determinants, locus A and B, beta 2-microglobulin, HLA class II distinct monomorphic determinants, DP, DQ, DR, intercellular adhesion molecule-1 (ICAM-1) and vitronectin receptors. Our results indicate that HX cells express HLA class I and II, including locus A, locus B and DP, DQ, DR, like their normal counterpart (represented by Langerhans cells) and detectable levels of ICAM-1 but not vitronectin receptors. We would like to stress the possibility of the association of HX and Hodgkin's lymphoma extending the immunophenotypic profile of HX cells
Phenotypic microarrays suggest Escherichia coli ST131 is not a metabolically distinct lineage of extra-intestinal pathogenic E. coli
No full textExtraintestinal pathogenic E. coli (ExPEC) are the major aetiological agent of urinary tract infections (UTIs) in humans. The emergence of the CTX-M producing clone E. coli ST131 represents a major challenge to public health worldwide. A recent study on the metabolic potential of E. coli isolates demonstrated an association between the E. coli ST131 clone and enhanced utilisation of a panel of metabolic substrates. The studies presented here investigated the metabolic potential of ST131 and other major ExPEC ST isolates using 120 API test reagents and found that ST131 isolates demonstrated a lower metabolic activity for 5 of 120 biochemical tests in comparison to non-ST131 ExPEC isolates. Furthermore, comparative phenotypic microarray analysis showed a lack of specific metabolic profile for ST131 isolates countering the suggestion that these bacteria are metabolically fitter and therefore more successful human pathogens
Unexplained plexogenic pulmonary arteriopathy: an unusual rapidly progressive case in childhood
No full textA 4-year-old child died because of unexplained plexogenic arteriopathy only seven months after the onset of the symptoms. Cardiac catheterization revealed a primary pulmonary hypertension sensible to nifedipine, but after the initial favourable results the clinical course rapidly went down and the child died from right sided congestive heart failure. The post-mortem pulmonary histology revealed reversible structural abnormalities. It also demonstrates that the vasodilatator drugs are effective only for short time in primary pulmonary hypertension, and moreover that it is even hazardous to generalize when one talks about reversibility of such lesions in each case
Fluoroquinolone-resistant Escherichia coli, Indonesia
No full textIn a recent, population-based survey of 3,996 persons
in Indonesia, fluoroquinolone (FQ)-resistant Escherichia coli
was prevalent in the fecal flora of 6% of patients at hospital
admission and 23% of patients at discharge, but not among
healthy relatives or patients visiting primary healthcare centers
(2%). Molecular typing showed extensive genetic diversity
with only limited clonality among isolates. This finding
suggests that independent selection of resistant mutants
occurs frequently. FQ-resistant isolates exhibited a higher
rate of spontaneous mutation, but sparser virulence profiles,
than FQ-susceptible isolates from the same population. The
resistant isolates belonged predominantly to phylogenetic
groups A (57%) and B1 (22%) but also to the moderately virulent
group D (20%). Hypervirulent strains from the B2 cluster
were underrepresented (1%). Because FQ-resistant E.
coli can cause disease, especially nosocomial infections in
immunocompromised patients, spread of such strains must
be stopped
Competitive exclusion as a means to reduce Escherichia coli regrowth in digested sludge
No full textIn recent years, it has been reported that numbers of Escherichia coli increase
significantly following centrifugation of sludge during the treatment process. E.
coli is used as an indicator of the microbiological quality of sludge-derived
products destined for agricultural recycling and of the efficacy of the sludge
treatment processes. The re-growth phenomenon is of concern because of the
potential for additional treatment requirement / higher disposal costs and loss of
consumer confidence associated with a compliance failure. It is hypothesised
that a competitive exclusion treatment could be the solution wherein the
digestate be exposed to a ‘probiotic’ or defined mixture of micro-organisms, to
effectively out compete or eliminate any resident E. coli remaining following
treatment. The competitive exclusion principle as a treatment method has
already seen application in various industrial sectors, the most well-known
being the poultry industry. In experiments it was determined that an
antimicrobial producing organism would be most likely to succeed. From the
candidates screened, Lactobacillus reuteri proved the most promising. L. reuteri
is a known producer of reuterin in the presence of glycerol and organic acids as
a part of its normal metabolic activity. In sludge derived nutrient broth in the
presence of glycerol and low pH, L. reuteri addition resulted in a reduction of E.
coli to undetectable levels. In sludge cake under the same conditions, L. reuteri
was less successful. However the addition of glycerol and L. reuteri to sludge
cake restricted E. coli growth to a 2 log increase from the initial concentration of
E. coli recorded following pasteurisation (an average of around 1x102 cfu/gDs),
in comparison in the positive control a 4 log increase was recorded. From this
result the sludge cake could be defined as conventionally treated. It can be
concluded that competitive exclusion and L. reuteri show promise as a
treatment for reducing E. coli re-growth in sludge cak
Generation of gene deletions and gene replacements in Escherichia coli O157:H7 using a temperature sensitive allelic exchange system
No full textIn this work we describe protocols for the generation of gene deletions and gene replacements using a temperature sensitive plasmid in Escherichia coli O157:H7. This technology requires flanking DNA to be cloned into a temperature sensitive vector but the resulting clone allows great flexibility for further modification of the target sequence. It is therefore highly suited to the study of genes in which several rounds of changes are envisaged. A number of examples are used to illustrate the flexibility of the system which has been used to create novel gene replacements including fusions for protein localisation work and reporters for transcriptional analyses. In this paper we describe protocols which can be used with a high degree of success when applied to E. coli O157. The deletion and replacement of the LEE4 operon of E. coli O157 is detailed to show the advantages and limitations of the technology
The molecular characterisation of Escherichia coli K1 isolated from neonatal nasogastric feeding tubes
No full textBackground: The most common cause of Gram-negative bacterial neonatal meningitis is E. coli K1. It has a mortality rate of 10–15%, and neurological sequelae in 30– 50% of cases. Infections can be attributable to nosocomial sources, however the pre-colonisation of enteral feeding tubes has not been considered as a specific risk factor. Methods: Thirty E. coli strains, which had been isolated in an earlier study, from the residual lumen liquid and biofilms of neonatal nasogastric feeding tubes were genotyped using pulsed-field gel electrophoresis, and 7-loci multilocus sequence typing. Potential pathogenicity and biofilm associated traits were determined using specific PCR probes, genome analysis, and in vitro tissue culture assays. Results: The E. coli strains clustered into five pulsotypes, which were genotyped as sequence types (ST) 95, 73, 127, 394 and 2076 (Achman scheme). The extra-intestinal pathogenic E. coli (ExPEC) phylogenetic group B2 ST95 serotype O1:K1:NM strains had been isolated over a 2 week period from 11 neonates who were on different feeding regimes. The E. coli K1 ST95 strains encoded for various virulence traits associated with neonatal meningitis and extracellular matrix formation. These strains attached and invaded intestinal, and both human and rat brain cell lines, and persisted for 48 h in U937 macrophages. E. coli STs 73, 394 and 2076 also persisted in macrophages and invaded Caco-2 and human brain cells, but only ST394 invaded rat brain cells. E. coli ST127 was notable as it did not invade any cell lines. Conclusions: Routes by which E. coli K1 can be disseminated within a neonatal intensive care unit are uncertain, however the colonisation of neonatal enteral feeding tubes may be one reservoir source which could constitute a serious health risk to neonates following ingestion
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