Etiology and clinical features of 229 cases of bloodstream infection among Chinese HIV/AIDS patients: a retrospective cross-sectional study

Bloodstream infections (BSIs) are prevalent among people living with HIV/AIDS. The etiology varies in different regions and different periods. We aimed to survey the etiological and clinical features of BSIs in HIV patients in mainland China. We assessed all HIV patients with a positive blood culture in a Chinese teaching hospital from September 2009 through December 2014. We excluded those with specimens likely to have been contaminated. We used Pearson's chi-squared test to measure the differences in characteristics among subgroups of different pathogens. Among 2442 Chinese HIV-seropositive inpatients, 229 (9.38 %) experienced BSIs. The most common pathogens detected included Cryptococcus neoformans (22.7 %), Penicillium marneffei (18.8 %), Mycobacterium tuberculosis (15.3 %), and non-tuberculous mycobacterium (14.8 %). 30/229 (13.1 %) HIV patients with BSIs had a poor prognosis. BSIs are prevalent in hospitalized patients with HIV/AIDS in China. Fungi and mycobacteria are the predominant pathogens.

Sulfate disinfection, stabilisation and heavy metal removal from sewage sludge--process description and preliminary results

A new, closed loop process for the disinfection, stabilisation and removal of heavy metal from sewage sludge (consisting of a sludge/sulfuric acid reactor, hybrid H2S generator and H2S bioscrubber) is described. Preliminary results for total solids (TS), volatile suspended solids (VSS), chemical oxygen demand (COD), acetate and propionate destruction in the hybrid H2S generator have shown that digestion efficiency is not compromised in a hybrid reactor generating H2S compared to a methanogenic reactor. 70% of the electron flow in the hybrid H2S generator was diverted to methane at a COD:SO4 ratio of 5.45:1. Enough H2SO4 could be generated from the H2S emitted at this ratio to effect sufficient metal solubilisation and pathogen removal from primary sludge.

A DNA vaccine encoding MPB83 from Mycobacterium bovis reduces M. bovis dissemination to the kidneys of mice and is expressed in primary cell cultures of the European badger (Meles meles)

Nucleic acid (DNA) vaccination against tuberculosis in the European badger (Meles meles) is one approach to addressing the escalating problem of bovine tuberculosis in Great Britain. The aim of vaccination is to reduce the burden of tuberculosis within the badger population and the shedding of Mycobacterium bovis to levels that would break the transmission of infection to cattle. To this end, the vaccine would be required to limit the amount of disseminated tuberculosis in the badger, especially dissemination to the kidney from where M. bovis can be shed in the urine. A promising candidate DNA vaccine encoding a 26 kDa major antigen (MPB83) of M. bovis was evaluated in a mouse model of disseminated M. bovis infection. Using the DNA vaccine, protection against infection of the kidney was found to be greater than that achieved with the current live vaccine, Bacille Calmette-Guerin (BCG). Kidney tissue and skeletal muscle from the badger was used to derive primary cell cultures in which to examine the expression of MPB83 following transfection with the DNA vaccine. Kidney cortex gave rise to a monotypic culture of epithelial cells whilst the muscle gave rise to a mixed culture of fibroblasts and myoblasts. During culture the myoblasts differentiated into multinucleated myotubes, verified by immunofluorescent detection of mammalian desmin. Successful expression of MPB83 by transfected epithelial and myotube cells was confirmed by immunofluorescence using a monoclonal antibody specific to the protein. These observations fulfil the early requirements for the development of a DNA vaccine for badger tuberculosis.

Laser scanning of patient outlines for three-dimensional radiotherapy treatment planning

In the planning of radiation treatments it is important to have a knowledge of the patient outline in order to correctly calculate the dose distribution that can be expected within the patient. This information is routinely obtained using x-ray computed tomography (CT). Although the CT data set is the ultimate data set, it can be impractical for economic and physical reasons. These impracticalities have been overcome using a commercial three dimensional (3D) laser scanning system. The system scans a laser line across the surface of the patient while a CCD camera views the patient from an offset angle. From a knowledge of the spatial orientation of the camera and the laser source, the system is able to detect the patient's surface and generate an equivalent 3D point cloud. Manipulation of 3D data sets allows the appropriate outlines of the patient to be obtained, that can then be used with the radiotherapy planning system. This has enabled the evaluation of 3D dose distributions for patients, and hence will allow the development of techniques for improving the uniformity of dose in breast treatments. The technique has no radiation overhead associated with it, is quick and is relatively cheap.

Effective DNA vaccination of cattle with the mycobacterial antigens MPB83 and MPB70 does not compromise the specificity of the comparative intradermal tuberculin skin test

The current tuberculin test and slaughter strategy for the control of bovine tuberculosis in cattle has failed to prevent a sharp rise in cases over recent years, especially in the south-west of England. A recent scientific review has concluded that the development of a cattle vaccine holds the best prospect for tuberculosis control in British herds. In order to continue with test and slaughter-based control strategies, the development of TB vaccines that do not compromise the specificity of the tuberculin skin test are required. This report describes results of cattle vaccination experiments with TB DNA vaccines expressing the mycobacterial antigens MPB70, MPB83, and Ag85A and constitutes the first published vaccination study with DNA vaccines undertaken in a target host species. All calves vaccinated with the MPB83 expressing plasmid demonstrated potent cellular immune responses, characterised by CD4(+) T cells producing interferon-gamma as well as humoral immunity characterised by IgG1 biased specific antibodies. Vaccination with MPB70 was less effective with immune responses only observed in half of the vaccinated animals, while vaccination with Ag85A did not result in vaccine-induced immune responses. Intramuscular vaccination was found to stimulate stronger cellular responses than intradermal immunisation. Significantly, the specificity of tuberculin skin testing was not compromised by DNA vaccination since none of the vaccinated calves showed positive skin test reactivity.

Vaccination of mice and cattle with plasmid DNA encoding the Mycobacterium bovis antigen MPB83

A scientific review of bovine tuberculosis in Great Britain has concluded that the development of a cattle vaccine holds the best prospect for long-term disease control. Recent reports of successful DNA vaccination against Mycobacterium tuberculosis in small animal models have raised the possibility of using a similar strategy to produce vaccines against Mycobacterium bovis infection in cattle. To test this possibility, BALB/c mice were immunized with DNA encoding the M. bovis antigen MPB83. The mice responded to vaccination with a mixed IgG1/IgG2a response to the antigen and were protected from intravenous challenge with virulent M. bovis to a similar extent as those vaccinated with bacille Calmette-Guérin. The immunogenicity of the DNA vaccine in cattle was tested, after having established that DNA encoding MPB83 was immunogenic and elicited protective immunity in mice. In these studies, vaccinated animals had strong proliferative responses to MPB83.

DNA vaccination: transfection and activation of dendritic cells as key events for immunity

The mechanisms underlying initiation and maintenance of CD4 T cell responses after DNA vaccination were studied using a construct coding for nonsecreted fifth component of complement (C5) protein, thus restricting the availability of antigen. The only cell types to express C5 were keratinocytes at the site of DNA application and a small number of dendritic cells present in the draining lymph nodes. Antigen expression persisted for up to 12 wk in keratinocytes, but dendritic cells did not express C5 beyond 2 wk after vaccination. Cross-priming of dendritic cells by C5 expressed in keratinocytes did not occur unless keratinocyte death was induced by irradiation in vitro. CD4 T cells were activated in the draining lymph nodes only and subsequently migrated to the spleen, where memory T cells persisted for longer than 40 wk despite the absence of a source of persistent antigen. While DNA vaccination resulted in transfection of a small proportion of dendritic cells only, it led to general activation of all dendritic cells, thus providing optimal conditions for effective T cell activation and maintenance of memory.

Detection of rifampicin-resistance mutations in Mycobacterium tuberculosis

Control of tuberculosis is threatened by widespread emergence of drug resistance in Mycobacterium tuberculosis. Understanding the molecular basis of resistance might lead to development of novel rapid methods for diagnosing drug resistance. We set out to determine the molecular basis of resistance to rifampicin, a major component of multidrug regimens used for treating tuberculosis. Resistance to rifampicin involves alterations of RNA polymerase. The gene that encodes the RNA polymerase subunit beta (rpoB) was cloned. Sequence information from this gene was used to design primers for direct amplification and sequencing of a 411 bp rpoB fragment from 122 isolates of M tuberculosis. Mutations involving 8 conserved aminoacids were identified in 64 of 66 rifampicin-resistant isolates of diverse geographical origin, but in none of 56 sensitive isolates. All mutations were clustered within a region of 23 aminoacids. Thus, substitution of a limited number of highly conserved aminoacids encoded by the rpoB gene appears to be the molecular mechanism responsible for "single step" high-level resistance to rifampicin in M tuberculosis. This information was used to develop a strategy (polymerase chain reaction-single-strand conformation polymorphism) that allowed efficient detection of all known rifampicin-resistant mutants. These findings provide the basis for rapid detection of rifampicin resistance, a marker of multidrug-resistant tuberculosis.