Pseudomonas - current and emerging issues.

Susan Pearson reports on some of the most interesting presentations at an International Biodeterioration and Biodegradation Society (IBBS) and Public Health England conference on 'Water microbiology - current and emerging issues in healthcare', held at the University of Winchester in early September. Two and a half years after the publication of the Addendum to HTM 04-01 - which gave advice on controlling and minimising the risk of morbidity and mortality due to P. aeruginosa in augmented care units - a major focus at the event was on how well the Addendum had been working for those 'at the frontline of infection control', and what improvements, if any, might be needed.

Silver biocide's real-world success.

Although temperature control has been the UK's longest-serving means of controlling the growth and proliferation of Legionella in hot and cold water systems, there are other factors, including major rises in energy costs, that warrant the use of biocides--including in the healthcare sector. In 2000, the HSE's new 'L8' guidelines took this into account, giving equal weight to both temperature reg~mes and biocides, such as chlorine dioxide, as control methods. Susan Pearson BSc reports on one potentially effective biocide- silver hydrogen peroxide, explains how it 'works' in practice, and highlights the recent 'real-world' evidence of its effectiveness and advantages.

Navigating through 'a labyrinth' of guidance.

Devising a strategy to deliver safe water to thousands of outlets spread across numerous buildings is always going to be a challenge, so how do you navigate your way through a bewildering labyrinth of sometimes contradictory guidance documents? Is there, in fact, simply too much guidance? Posing this question at a recent one-day conference on waterborne infections in healthcare facilities, Paul Nolan, authorised water engineer (AE), and operations manager for PFI provider, Lend Lease, took delegates through a review of the latest guidance and regulations, as Susan Pearson reports.

Pilot project for rapid Legionella testing.

Susan Pearson BSc, a freelance journalist and communications consultant specialising in medicine and the environment (see also HEJ - April 2013), reports on discussions, at a recent educational seminar, on a pilot project undertaken by the Environmental Microbiology Unit at the Brighton and Sussex University Hospitals (BSUH) NHS Trust, which compared the effectiveness and accuracy of conventional 'culture' testing for Legionella in water systems, with a new, 'less labour-intensive', DNA-based testing system that can produce results 'in a matter of hours'.

Brain atrophy in type 2 diabetes: regional distribution and influence on cognition.

OBJECTIVE: Type 2 diabetes (T2DM) is associated with brain atrophy and cerebrovascular disease. We aimed to define the regional distribution of brain atrophy in T2DM and to examine whether atrophy or cerebrovascular lesions are feasible links between T2DM and cognitive function. RESEARCH DESIGN AND METHODS: This cross-sectional study used magnetic resonance imaging (MRI) scans and cognitive tests in 350 participants with T2DM and 363 participants without T2DM. With voxel-based morphometry, we studied the regional distribution of atrophy in T2DM. We measured cerebrovascular lesions (infarcts, microbleeds, and white matter hyperintensity [WMH] volume) and atrophy (gray matter, white matter, and hippocampal volumes) while blinded to T2DM status. With use of multivariable regression, we examined for mediation or effect modification of the association between T2DM and cognitive measures by MRI measures. RESULTS: T2DM was associated with more cerebral infarcts and lower total gray, white, and hippocampal volumes (all P < 0.05) but not with microbleeds or WMH. T2DM-related gray matter loss was distributed mainly in medial temporal, anterior cingulate, and medial frontal lobes, and white matter loss was distributed in frontal and temporal regions. T2DM was associated with poorer visuospatial construction, planning, visual memory, and speed (P ≤ 0.05) independent of age, sex, education, and vascular risk factors. The strength of these associations was attenuated by almost one-half when adjusted for hippocampal and total gray volumes but was unchanged by adjustment for cerebrovascular lesions or white matter volume. CONCLUSIONS: Cortical atrophy in T2DM resembles patterns seen in preclinical Alzheimer disease. Neurodegeneration rather than cerebrovascular lesions may play a key role in T2DM-related cognitive impairment.

Does compliance make a facility safe?

'Every defect is a treasure, if the company can uncover its cause and work to prevent it across the corporation' - Kiichiro Toyoda, founder, Toyota. This quote, as true in healthcare as it in the manufacturing sphere, set the tone for discussion at a recent Dublin conference, which examined the thorny issue of whether compliance is really enough to ensure safety. Focusing especially on water safety, the event aimed to promote collaboration and knowledge sharing between Irish and UK healthcare professionals, including technical services managers, infection control staff, quality and risk personnel, support service managers, hospital directors, and CEOs. Susan Pearson BSc, a freelance journalist and communications consultant specialising in medicine and the environment, reports.

Water quality key to protecting patients.

According to David Graham of the Scottish National Blood Transfusion Service (SNBTS), "the importance of the safe diagnosis and treatment of patients cannot be overstated - yet the role played by water quality in patient safety has sometimes been under-stated". David Graham was speaking at a one day Pall Medical-sponsored meeting on the prevention and control of healthcare-associated waterborne infections in healthcare facilities held in Edinburgh earlier this year. David Graham, other speakers, and the chair, Consultant Microbiologist and Infection Prevention and Control Doctor for NHS Grampian, Dr Anne Marie Karcher, stressed that good quality water is essential in healthcare premises to prevent the potentially catastrophic consequences of contaminated water for some patients. Susan Pearson BSc reports.

A practical approach to ensuring safe water.

Susan Pearson BSc reports on a recent specialist waterborne diseases 'masterclass' held in Nottingham, at which leading experts discussed not only the control of Pseudomonas, but also other problematic waterborne pathogens such as Legionella, the cause of Legionnaires' disease. The Pall Medical-sponsored event provided plenty of 'food for thought' for estates and facilities personnel responsible for hospital water systems, and clearly demonstrated how difficult and persistent a foe organisms such as Pseudomonas aeruginosa and Legionella pneumophila, which, if left unchecked, pose significant patient health risks, can be.

Making hospital water safe, examined.

What are the best methods for monitoring hospital water systems to prevent contamination by waterborne pathogens such as Pseudomonas aeruginosa and Legionella? How can hospital staff determine whether a Pseudomonas outbreak is due to cross-contamination between patients and staff, or to the contamination of a systemic water supply, and how can we best protect our most vulnerable patients from infection with the array of pathogenic organisms lurking in hospitals? As Susan Pearson reports, these were among the questions discussedby leading microbiologists at a recent one-day "waterborne infections" seminar organised by Pall Medical in Glasgow.

Faster Legionella testing on horizon.

While the "traditional" way to measure Legionella quantitatively in water is based on a complex culture method where results can take up to 14 days, the last few years have seen the availability of very rapid real-time monitoring of the bacterium in water systems, with the development of quantitative polymerase chain reaction (qPCR), a process which gives results "within hours". To date, however, a lack of consensus on how to interpret such results in relation to those from culture has been a stumbling block, although, as Susan Pearson, a freelance journalist and public relations consultant specialising in medicine and the environment, reports, the positive results of a recent multi-centre European study mean this could soon all change.

Human mucosal associated invariant T cells detect bacterially infected cells.

Control of infection with Mycobacterium tuberculosis (Mtb) requires Th1-type immunity, of which CD8+ T cells play a unique role. High frequency Mtb-reactive CD8+ T cells are present in both Mtb-infected and uninfected humans. We show by limiting dilution analysis that nonclassically restricted CD8+ T cells are universally present, but predominate in Mtb-uninfected individuals. Interestingly, these Mtb-reactive cells expressed the Valpha7.2 T-cell receptor (TCR), were restricted by the nonclassical MHC (HLA-Ib) molecule MR1, and were activated in a transporter associated with antigen processing and presentation (TAP) independent manner. These properties are all characteristics of mucosal associated invariant T cells (MAIT), an "innate" T-cell population of previously unknown function. These MAIT cells also detect cells infected with other bacteria. Direct ex vivo analysis demonstrates that Mtb-reactive MAIT cells are decreased in peripheral blood mononuclear cells (PBMCs) from individuals with active tuberculosis, are enriched in human lung, and respond to Mtb-infected MR1-expressing lung epithelial cells. Overall, these findings suggest a generalized role for MAIT cells in the detection of bacterially infected cells, and potentially in the control of bacterial infection.

Loss of naive T cells and repertoire constriction predict poor response to vaccination in old primates.

Aging is usually accompanied by diminished immune protection upon infection or vaccination. Although aging results in well-characterized changes in the T cell compartment of long-lived, outbred, and pathogen-exposed organisms, their relevance for primary Ag responses remain unclear. Therefore, it remains unclear whether and to what extent the loss of naive T cells, their partial replacement by oligoclonal memory populations, and the consequent constriction of TCR repertoire limit the Ag responses in aging primates. We show in this study that aging rhesus monkeys (Macaca mulatta) exhibit poor CD8 T cell and B cell responses in the blood and poor CD8 responses in the lungs upon vaccination with the modified vaccinia strain Ankara. The function of APCs appeared to be maintained in aging monkeys, suggesting that the poor response was likely intrinsic to lymphocytes. We found that the loss of naive CD4 and CD8 T cells, and the appearance of persisting T cell clonal expansions predicted poor CD8 responses in individual monkeys. There was strong correlation between early CD8 responses in the transitory CD28+ CD62L- CD8+ T cell compartment and the peak Ab titers upon boost in individual animals, as well as a correlation of both parameters of immune response to the frequency of naive CD8+ T cells in old but not in adult monkeys. Therefore, our results argue that T cell repertoire constriction and naive cell loss have prognostic value for global immune function in aging primates.

NHS plans to lead on carbon cutting.

While the UK's Climate Change Bill is debated in Parliament, the NHS has been putting in place its plans to lead the way in public sector carbon cutting, which aim for a 60% reduction in CO2 emissions by 2050. Susan Pearson talks to Dr David Pencheon, director of the new NHS Sustainable Development Unit.

Human innate Mycobacterium tuberculosis-reactive alphabetaTCR+ thymocytes.

The control of Mycobacterium tuberculosis (Mtb) infection is heavily dependent on the adaptive Th1 cellular immune response. Paradoxically, optimal priming of the Th1 response requires activation of priming dendritic cells with Th1 cytokine IFN-gamma. At present, the innate cellular mechanisms required for the generation of an optimal Th1 T cell response remain poorly characterized. We hypothesized that innate Mtb-reactive T cells provide an early source of IFN-gamma to fully activate Mtb-exposed dendritic cells. Here, we report the identification of a novel population of Mtb-reactive CD4(-) alphabetaTCR(+) innate thymocytes. These cells are present at high frequencies, respond to Mtb-infected cells by producing IFN-gamma directly ex vivo, and display characteristics of effector memory T cells. This novel innate population of Mtb-reactive T cells will drive further investigation into the role of these cells in the containment of Mtb following infectious exposure. Furthermore, this is the first demonstration of a human innate pathogen-specific alphabetaTCR(+) T cell and is likely to inspire further investigation into innate T cells recognizing other important human pathogens.

Functional suppression by FoxP3+CD4+CD25(high) regulatory T cells during acute hepatitis C virus infection.

BACKGROUND: Infection with hepatitis C virus (HCV) is characterized by impairment of viral effector T cell responses and a high propensity for viral persistence. Previous studies have demonstrated that chronic HCV infection is associated with an increased frequency of regulatory T (T(reg)) cells, compared with that in persons whose infection resolved and in healthy persons. However, all patients in prior analyses had exposures in the distant past, precluding the ability to determine whether T(reg) cells play a causal role in establishing persistence during the earliest stages of infection or whether they are expanded because of viral persistence. METHODS: For the first time, we longitudinally analyzed T(reg) cells in patients with acute HCV infection (n = 27). We used a multiparameter approach, including fluorescence-activated cell sorting analysis of cell-surface and intracellular antigens, coculture experiments with highly purified CD4(+)CD25(high) regulatory and CD4(+)CD25(-) responder cell populations, and multiplex analysis of secreted cytokines. RESULTS: Forkhead transcription factor 3 (FoxP3) expression and T(reg) cell suppression were greater in patients with acute HCV infection than in healthy control subjects but were not different at the first time point among patients who subsequently developed persistence or resolved HCV infection spontaneously; however, 6 months later, the resolution of disease was associated with a relative loss of functional suppression. CONCLUSIONS: Collectively, these data indicate that patients with acute HCV infection who develop chronicity versus spontaneous resolution exhibit temporal changes in T(reg) cell function. It is possible that repetitive viral antigenic stimulation alters the function of T(reg) cells over time.

Spontaneous recovery in acute human hepatitis C virus infection: functional T-cell thresholds and relative importance of CD4 help.

The mechanisms mediating protective immunity to hepatitis C virus (HCV) infection are incompletely understood because early infection in humans is rarely identified, particularly in those individuals who subsequently demonstrate spontaneous virus eradication. We have established a large national network of patients with acute HCV infection. Here, we comprehensively examined total HCV-specific CD4(+) and CD8(+) T-cell responses and identified functional T-cell thresholds that predict recovery. Interestingly, we found that the presence of HCV-specific cytotoxic T lymphocytes (CTLs) that can proliferate, exhibit cytotoxicity, and produce gamma interferon does not ensure recovery, but whether these CTLs were primed in the presence or absence of CD4(+) T-cell help (HCV-specific interleukin-2 production) is a critical determinant. These results have important implications for early prediction of the virologic outcome following acute HCV and for the development of novel immunotherapeutic approaches.

Identification of ethanol responsive domains of adenylyl cyclase.

BACKGROUND: The activity of adenylyl cyclase (AC) is enhanced by pharmacologically relevant concentrations of ethanol. The enhancing effect of ethanol on AC activity is AC isoform-specific. Therefore, we hypothesized that within a cyclic AMP-generating system, AC is the target of ethanol's action and that ethanol-sensitive AC molecules contain structural elements modulated by ethanol. The structural elements are designated as "ethanol responsive domains." METHODS: By using a series of chimeric mutants, we searched regions of the AC molecule that are important for the ethanol effect. These chimeric mutants were derived from 3 isoforms of AC: AC7 (type 7), the most ethanol responsive isoform; AC3 (type 3), an isoform that is far less responsive to ethanol; and AC2 (type 2), an isoform that is homologous to AC7 but less responsive to ethanol. RESULTS: We identified 2 discrete regions of the AC molecule that are important for the enhancement of AC activity by ethanol. The first is the N-terminal 28-amino-acid (aa) region of the C(1a) domain. The second is the C-terminal region ( approximately 140 aa) of the AC molecule. Sequence differences in the N-terminal tail, 2 putative transmembrane domains, and the C(1b) domain are not important for ethanol's effect. CONCLUSIONS: The current study with mammalian ACs provides a new class of alcohol-responsive protein and possibly a new mechanism of alcohol action on cellular function. The identification of ethanol responsive domains will facilitate the elucidation of the mechanisms by which ethanol enhances the activity of AC.

Differential antigenic hierarchy associated with spontaneous recovery from hepatitis C virus infection: implications for vaccine design.

BACKGROUND: Cellular immune responses play a central role in the control of hepatitis C virus (HCV) infection, and in some individuals the adaptive immune response can spontaneously eradicate HCV infection. The development of vaccine candidates to prevent the spread of this infection remains a top priority; however, understanding the correlates of effective immunological containment is an important prerequisite. METHODS: Using 750 overlapping peptides, we directly characterized ex vivo total and subgenomic HCV-specific CD4(+) and CD8(+) T cell responses in a large cohort of participants with either chronic infection or spontaneously resolved infection. RESULTS: In chronic infection, the frequency of total CD4(+) T cells specific for HCV averaged 0.06%, compared with 0.38% in resolved infection. Total HCV-specific CD4(+) and CD8(+) T cell responses were strongly correlated in the setting of spontaneous resolution but not in the setting of viral persistence. NS3 protein-specific responses comprised a significantly greater proportion of the total response in resolved infection than in chronic infection, whereas responses to different regions comprised a larger proportion of responses in chronic infection. CONCLUSION: Because these data comprehensively define the breadth, specificity, and threshold of the T cell response associated with spontaneous recovery from HCV infection, they have important implications in the development of multigenic vaccine candidates for this common infection.