Two-year analysis of Clostridium difficile ribotypes associated with increased severity.

BACKGROUND: Certain Clostridium difficile ribotypes have been associated with complex disease phenotypes including recurrence and increased severity, especially the well-described hypervirulent RT027. This study aimed to determine the pattern of ribotypes causing infection and the association, if any, with severity. METHODS: All faecal samples submitted to a large diagnostic laboratory for C. difficile testing between 2011 and 2013 were subject to routine testing and culture. All C. difficile isolates were ribotyped, and associated clinical and demographic patient data were retrieved and linked to ribotyping data. RESULTS: In total, 86 distinct ribotypes were identified from 705 isolates of C. difficile. RT002 and RT015 were the most prevalent (22.5%, N=159). Only five isolates (0.7%) were hypervirulent RT027. Ninety of 450 (20%) patients with clinical information available died within 30 days of C. difficile isolation. RT220, one of the 10 most common ribotypes, was associated with elevated median C-reactive protein and significantly increased 30-day all-cause mortality compared with RT002 and RT015, and with all other ribotypes found in the study. CONCLUSIONS: A wide range of C. difficile ribotypes were responsible for C. difficile infection presentations. Although C. difficile-associated mortality has reduced in recent years, expansion of lineages associated with increased severity could herald increases in future mortality. Enhanced surveillance for emerging lineages such as RT220 that are associated with more severe disease is required, with genomic approaches to dissect pathogenicity.

Evaluating serial screening cultures to detect carbapenemase-producing Enterobacteriaceae following hospital admission.

BACKGROUND: Carbapenem-producing Enterobacteriaceae (CPE) are on the rise worldwide. National guidelines for the prevention and control of CPE recommend screening for the detection of asymptomatic carriers on admission. AIM: To evaluate the benefit of serial screens for detecting the carriage of CPE and other antibiotic-resistant Gram-negative bacteria following hospital admission. METHODS: All CPE screens, which were cultured on chromogenic media and the presence of a carbapenemase confirmed by polymerase chain reaction, were analysed for a six-month period. National guidelines in England recommend three serial screens for CPE separated by 48 h for admission screening for 'at-risk' patients, during which the patient is isolated. Two screening scenarios were tested. In scenario A, patients received three screens at the specified timepoints, in line with English national guidelines; in scenario B, patients received three consecutive screens, but not necessarily within the specified timepoints, during one admission. General linear models or conditional logistic regression were used to detect any significant change in the rate of carriage. FINDINGS: There was no significant increase in the detected carriage rate of CPE across any of the three timepoints in the scenarios tested. However, there was a significant increase in the detected rate of carriage of Gram-negative bacteria, Enterobacteriaceae, and resistant Enterobacteriaceae (excluding CPE) in scenario B. CONCLUSION: Three serial screens were not useful for the detection of CPE carriage on admission. The increase in the carriage rate of other Gram-negative bacteria may be explained by 'unmasking' of pre-existing carriage, or acquisition. This argues for regular screening of long-stay patients.

Forecasting carbapenem resistance from antimicrobial consumption surveillance: Lessons learnt from an OXA-48-producing Klebsiella pneumoniae outbreak in a West London renal unit.

This study aimed to forecast the incidence rate of carbapenem resistance and to assess the impact of an antimicrobial stewardship intervention using routine antimicrobial consumption surveillance data. Following an outbreak of OXA-48-producing Klebsiella pneumoniae (January 2008-April 2010) in a renal cohort in London, a forecasting ARIMA model was derived using meropenem consumption data [defined daily dose per 100 occupied bed-days (DDD/100OBD)] from 2005-2014 as a predictor of the incidence rate of OXA-48-producing organisms (number of new cases/year/100,000OBD). Interrupted times series assessed the impact of meropenem consumption restriction as part of the outbreak control. Meropenem consumption at lag -1 year (the preceding year), highly correlated with the incidence of OXA-48-producing organisms (r=0.71; P=0.005), was included as a predictor within the forecasting model. The number of cases/100,000OBD for 2014-2015 was estimated to be 4.96 (95% CI 2.53-7.39). Analysis of meropenem consumption pre- and post-intervention demonstrated an increase of 7.12 DDD/100OBD/year (95% CI 2.97-11.27; P<0.001) in the 4 years preceding the intervention, but a decrease thereafter. The change in slope was -9.11 DDD/100OBD/year (95% CI -13.82 to -4.39). Analysis of alternative antimicrobials showed a significant increase in amikacin consumption post-intervention from 0.54 to 3.41 DDD/100OBD/year (slope +0.72, 95% CI 0.29-1.15; P=0.01). Total antimicrobials significantly decreased from 176.21 to 126.24 DDD/100OBD/year (P=0.05). Surveillance of routinely collected antimicrobial consumption data may provide a key warning indicator to anticipate increased incidence of carbapenem-resistant organisms. Further validation using real-time data is needed.

The challenge of establishing, growing and sustaining a large biobank: a personal perspective.

Laboratory medicine professionals have a unique understanding of the wealth that biological samples bring to clinical research, and of the need for quality standards for the collection, transportation, storage and analytical phases. The expertise of laboratory physicians and scientists also adds value to the interpretation and publication of the results of clinical research studies. This is an account of the evolution of over thirty five years of the Biobank/Clinical Research Clinical Trials Laboratory at one Canadian health sciences centre. The logistical, financial, and quality management challenges are presented in growing from a small-scale facility to one that now stores three million well-characterized samples from more than seventy countries, representing five continents and five major ethnic groups. This is an account of a journey, it is not intended as a guide as to how to create an 'ideal' biobank. Collaboration, collegiality, consistency, creativity and clinical collaborators, are the keys to progress, but there must first be a vision, one that can expand to embrace new opportunities.

Patients' views and experience of intravenous and oral antimicrobial therapy: room for change.

Little is known about patients' views or preferences about the route of administration of antimicrobials. In this study semi-structured interviews were carried out to assess patients' perceptions of an infection that required IV antimicrobial therapy in hospital, their preference for intravenous, IV followed by oral and discharge on oral therapy or home IV therapy. Interviews were transcribed and the content analysed. Twelve patients were interviewed while in hospital or by telephone after discharge. Patients' information about their infection was incomplete and many expressed the view that they would like more information. Many patients expressed a preference for oral therapy over IV therapy although this was dependent on it being of equal efficacy. Contrary views were related to personal difficulty with tablets. Patients varied in their acceptance of home IV therapy and expressed concern about adequate support but the majority expressed a preference for being discharged on oral therapy once they were well enough.

Prevalent genotypes of meticillin-resistant Staphylococcus aureus: report from Pakistan.

Meticillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen in Pakistan and is emerging in the community. This is one of the first reports of the prevalent genotypes of MRSA in both hospital and community settings in Pakistan. Isolates collected in 2006-2007 were characterized by PFGE, staphylococcal cassette chromosome mec (SCCmec) typing and multilocus sequence typing (MLST). PFGE identified nine pulsotypes, the majority of isolates belonging to pulsotypes A (n=70) and B (n=38), which were predominant among hospital-onset MRSA (HO-MRSA) and community-onset MRSA (CO-MRSA) isolates, respectively. Among the HO-MRSA isolates, variants of SCCmec type III were prevalent, whilst SCCmec type IV or variants were predominant in the CO-MRSA isolates. MLST identified two principal sequence types, ST8 and ST239. An association was observed between ST8, PFGE pulsotype B and SCCmec type IV in the CO-MRSA (ST8-MRSA-IV). Similarly, ST239, PFGE pulsotype A and SCCmec type III were associated with HO-MRSA (ST239-MRSA-III). Therefore, the prevalent genotypes circulating in Pakistan at the time of study were ST8-MRSA-IV and ST239-MRSA-III in the community and hospital settings, respectively. A set of HO-MRSA isolates collected in 1997 were characterized by PFGE and SCCmec typing for comparison. The isolates belonged to two PFGE pulsotypes (A, n=28; B, n=11) and contained just two SCCmec types. These results suggest that an increase in genetic diversity occurred over the period 1997-2007 as a result of either microevolution or the importation of strains from surrounding areas.

A case definition for national and international neonatal bloodstream infection surveillance.

OBJECTIVE: Neonatal bloodstream infection (BSI) is a major contributor to mortality, health service costs, and the population burden of lifelong neurodisability. BSI surveillance, an essential component of infection control, requires an unambiguous standardised case definition as variability would invalidate any comparative analyses. In neonates a high proportion of blood cultures yield a mixed growth or skin commensals, principally coagulase-negative staphylococci (CoNS). As this might represent either genuine BSI or contamination, clinical correlates are necessary, but this adds to the difficulty of agreeing an objective, standardised case definition. DESIGN: Utilising data from 26 UK neonatal units, the population prevalence of 12 predefined clinical signs of infection captured daily for 28 days was evaluated. The sensitivity, specificity, odds ratio and positive predictive value of each sign and sequential numbers of grouped signs were determined to develop a predictive model for a positive blood culture. Sandwich estimates of the standard errors of the logistic regression coefficients were used to take account of the correlations between these repeated measures. The model was tested in an independent data set. RESULTS: > or =3 clinical signs had the best predictive accuracy for a positive blood culture (76.2% specificity; 61.5%, 46.9% and 78.2% sensitivity for all positive cultures, cultures yielding CoNS, or a recognised pathogen, respectively). CONCLUSION: This study suggests that a simple case definition for national and international neonatal BSI surveillance is provided by a blood culture yielding a recognised pathogen in pure culture, or a mixed growth or skin commensal plus > or =3 predefined clinical signs.

Post-NICE 2008: Antibiotic prophylaxis prior to dental procedures for patients with pulmonary arteriovenous malformations (PAVMs) and hereditary haemorrhagic telangiectasia.

Recently published guidance from NICE highlights that antibiotic prophylaxis is no longer required for patients with structural heart disease at risk of infective endocarditis. The American Heart Association has published similarly less interventive guidance. Individuals with pulmonary arteriovenous malformations and hereditary haemorrhagic telangiectasia are at risk of brain abscess from dental bacteraemias. In this article we explore why these patients do not fall into the groups considered by NICE and provide recommendations to reduce their risks of dental bacteraemias, including optimising dental hygiene and use of antibiotic prophylaxis prior to dental procedures.

Risk factors and recommendations for rate stratification for surveillance of neonatal healthcare-associated bloodstream infection.

Neonates are among the most vulnerable patient groups for healthcare-associated infection with multiple endogenous and exogenous risks. Interpretation of neonatal bloodstream infection (BSI) rates requires stratification for case-mix. We assessed 1367 consecutive admissions to a single neonatal unit over a 34-month period. Four intrinsic and seven extrinsic risks were evaluated using Poisson regression analyses both individually and in combination. Nine of the 11 evaluated risk factors were significantly associated with BSI on univariate analyses. The only significant independent risks were parenteral nutrition, whether administered centrally or peripherally [incidence rate ratio (IRR): 14.2; 95% confidence interval (CI): 8.8-22.9; P<0.001], and gestational age <26 weeks (IRR: 2.5; 95% CI: 1.7-3.8; P<0.001). The rate of BSI per 1000 patient-days was 40 times higher in infants with both of these than in infants with neither. If validated in other settings, stratification of neonatal BSI rate by two unambiguous risk factors, parenteral nutrition and birth gestational age <26 weeks, offers a simple method to make meaningful intra- and inter-hospital comparisons.

Relationship between Helicobacter pylori infection and gastric atrophy and the stages of the oesophageal inflammation, metaplasia, adenocarcinoma sequence: results from the FINBAR case-control study.

OBJECTIVE: A number of studies have shown an inverse association between infection with Helicobacter pylori and oesophageal adenocarcinoma (OAC). The mechanism of the apparent protection against OAC by H pylori infection and, in particular, the role of gastric atrophy is disputed. The relationship between all stages of the oesophageal inflammation, metaplasia, adenocarcinoma sequence and H pylori infection and gastric atrophy was explored. METHODS: A case-control study involving 260 population controls, 227 OAC, 224 Barrett's oesophagus (BO) and 230 reflux oesophagitis (RO) patients recruited within Ireland was carried out. H pylori and CagA (cytotoxin-associated gene product A) infection was diagnosed serologically by western blot, and pepsinogen I and II levels were measured by enzyme immunoassay. Gastric atrophy was defined as a pepsinogen I/II ratio of <3. RESULTS: H pylori seropositivity was inversely associated with OAC, BO and RO; adjusted ORs (95% CIs), 0.49 (0.31 to 0.76), 0.35 (0.22 to 0.56) and 0.42 (0.27 to 0.65), respectively. Gastric atrophy was uncommon (5.3% of all subjects), but was inversely associated with non-junctional OAC, BO and RO; adjusted ORs (95% CIs), 0.34 (0.10 to 1.24), 0.23 (0.05 to 0.96) and 0.27 (0.08 to 0.88), respectively. Inverse associations between H pylori and the disease states remained in gastric atrophy-negative patients. CONCLUSION: H pylori infection and gastric atrophy are associated with a reduced risk of OAC, BO and RO. While use of the pepsinogen I/II ratio as a marker for gastric atrophy has limitations, these data suggest that although gastric atrophy is involved it may not fully explain the inverse associations observed with H pylori infection.

Primary determinants of ischaemic stroke/brain abscess risks are independent of severity of pulmonary arteriovenous malformations in hereditary haemorrhagic telangiectasia.

BACKGROUND: Brain abscesses and ischaemic strokes complicate pulmonary arteriovenous malformations (PAVMs). At risk individuals are poorly recognised. Stroke/abscess risk factors have not been defined. METHODS: A cohort study of 323 consecutive individuals with PAVMs (n = 219) and/or the commonly associated condition hereditary haemorrhagic telangiectasia (HHT, n = 305) was performed. Most of the 201 individuals with PAVMs and HHT had no respiratory symptoms, and were unaware they had HHT. Anderson-Gill models assessed constant and time dependent potential predictive variables for stroke/abscess, and rate reduction by PAVM embolisation. RESULTS: 57 individuals with PAVMs and HHT experienced brain abscess or ischaemic stroke, usually prior to the diagnosis of underlying PAVMs/HHT. The primary determinants of stroke and abscess risks were unrelated to severity of PAVMs. Males had higher brain abscess rates (hazard ratio 3.61 (95% CI 1.58, 8.25), p = 0.0024); interventional histories and bacteriological isolates suggested dental sources. Once adjusted for gender, there was a marginal association between brain abscess and low oxygen saturation. For ischaemic stroke, there was no association with any marker of PAVM severity, or with conventional neurovascular risk factors. Surprisingly, low mean pulmonary artery pressure was strongly associated with ischaemic stroke (hazard ratio 0.89 (95% CI 0.83, 0.95) per mm Hg increase; p = 6.2x10(-5)). PAVM embolisation significantly reduced ischaemic stroke rate (p = 0.028); no strokes/abscesses occurred following obliteration of all angiographically visible PAVMs. The mean PAVM diagnosis-treatment interval was longer, however, when neurological risks were unrecognised. CONCLUSIONS: Ischaemic strokes and brain abscesses occur commonly in undiagnosed HHT patients with PAVMs. Risk reduction could be improved.

Standards for gene therapy clinical trials based on pro-active risk assessment in a London NHS Teaching Hospital Trust.

Conducting gene therapy clinical trials with genetically modified organisms as the vectors presents unique safety and infection control issues. The area is governed by a range of legislation and guidelines, some unique to this field, as well as those pertinent to any area of clinical work. The relevant regulations covering gene therapy using genetically modified vectors are reviewed and illustrated with the approach taken by a large teaching hospital NHS Trust. Key elements were Trust-wide communication and involvement of staff in a pro-active approach to risk management, with specific emphasis on staff training and engagement, waste management, audit and record keeping. This process has led to the development of proposed standards for clinical trials involving genetically modified micro-organisms.

Non-detection of Chlamydia species in carotid atheroma using generic primers by nested PCR in a population with a high prevalence of Chlamydia pneumoniae antibody.

BACKGROUND: The association of Chlamydia pneumoniae with atherosclerosis is controversial. We investigated the presence of C. pneumoniae and other Chlamydia spp. in atheromatous carotid artery tissue. METHODS: Forty elective carotid endarterectomy patients were recruited (27 males, mean age 65 and 13 females mean age 68), 4 had bilateral carotid endarterectomies (n= 44 endarterectomy specimens). Control specimens were taken from macroscopically normal carotid artery adjacent to the atheromatous lesions (internal controls), except in 8 cases where normal carotid arteries from post mortem (external controls) were used. Three case-control pairs were excluded when the HLA DRB gene failed to amplify from the DNA. Genus specific primers to the major outer membrane protein (MOMP) gene were used in a nested polymerase chain reaction (nPCR) in 41 atheromatous carotid specimens and paired controls. PCR inhibition was monitored by spiking with target C. trachomatis. Atheroma severity was graded histologically. Plasma samples were tested by microimmunofluorescence (MIF) for antibodies to C. pneumoniae, C. trachomatis and C. psittaci and the corresponding white cells were tested for Chlamydia spp. by nPCR. RESULTS: C. pneumoniae was not detected in any carotid specimen. Twenty-five of 38 (66%) plasma specimens were positive for C. pneumoniae IgG, 2/38 (5%) for C. trachomatis IgG and 1/38 (3%) for C. psittaci IgG. CONCLUSIONS: We were unable to show an association between the presence of Chlamydia spp. and atheroma in carotid arteries in the presence of a high seroprevalence of C. pneumoniae antibodies in Northern Ireland.

Negative selection of T cells by Helicobacter pylori as a model for bacterial strain selection by immune evasion.

The majority of humans infected with Helicobacter pylori maintain a lifelong infection with strains bearing the cag pathogenicity island (PAI). H. pylori inhibits T cell responses and evades immunity so the mechanism by which infection impairs responsiveness was investigated. H. pylori caused apoptotic T cell death, whereas Campylobacter jejuni did not. The induction of apoptosis by H. pylori was blocked by an anti-Fas Ab (ZB4) or a caspase 8 inhibitor. In addition, a T cell line with the Fas rendered nonfunctional by a frame shift mutation was resistant to H. pylori-induced death. H. pylori strains bearing the cag PAI preferentially induced the expression of Fas ligand (FasL) on T cells and T cell death, whereas isogenic mutants lacking these genes did not. Inhibiting protein synthesis blocked FasL expression and apoptosis of T cells. Preventing the cleavage of FasL with a metalloproteinase inhibitor increased H. pylori-mediated killing. Thus, H. pylori induced apoptosis in Fas-bearing T cells through the induction of FasL expression. Moreover, this effect was linked to bacterial products encoded by the cag PAI, suggesting that persistent infection with this strain may be favored through the negative selection of T cells encountering specific H. pylori Ags.

Infection with virulent strains of Helicobacter pylori is not associated with ischaemic heart disease: evidence from a population-based case-control study of myocardial infarction.

BACKGROUND: Although the majority of evidence does not support association between Helicobacter pylori infection and ischaemic heart disease, the nature of this relationship may differ when virulence of the infecting strains are examined. METHODS AND RESULTS: The prevalence of IgG antibody evidence of infection with CagA positive stains of H. pylori was investigated in stored plasma samples from 259 cases of myocardial infarction (aged 25-70 years, 74 males) and 259 population based controls from the same area in Northern Ireland. Two-hundred and seventy (52.1%) subjects were seropositive for anti-CagA IgG. CagA seropositivity was more common in cases than in controls: 56.4 vs 47.9%, odds ratio for seropositivity in cases (95% CI) 1.41 (1.00, 1.99). Substantial attenuation of this relationship occurred on adjustment for age, sex, number of siblings, smoking and measures of socio-economic status: odds ratio (95% CI) 1.16 (0.79, 1.70). A similar pattern was seen for seropositivity for all H. pylori strains. CONCLUSION: Infection with the more virulent strains of H. pylori, as with all strains, is not associated with myocardial infarction.

A prospective randomised trial of a "test and treat" policy versus endoscopy based management in young Helicobacter pylori positive patients with ulcer-like dyspepsia, referred to a hospital clinic.

BACKGROUND: Management of dyspepsia remains a controversial area. Although the European Helicobacter pylori study group has advised empirical eradication therapy without oesophagogastroduodenoscopy (OGD) in young H pylori positive dyspeptic patients who do not exhibit alarm symptoms, this strategy has not been subjected to clinical trial. AIMS: To compare a "test and treat" eradication policy against management by OGD. PATIENTS: Consecutive subjects were prospectively recruited from open access OGD and outpatient referrals. METHODS: H pylori status was assessed using the carbon-13 urea breath test. H pylori positive patients were randomised to either empirical eradication or OGD. Symptoms and quality of life scores were assessed at baseline and subsequent reviews over a 12 month period. RESULTS: A total of 104 H pylori positive patients aged under 45 years were recruited. Fifty two were randomised to receive empirical eradication therapy and 52 to OGD. Results were analysed using an intention to treat policy. Dyspepsia scores significantly improved in both groups over 12 months compared with baseline; however, dyspepsia scores were significantly better in the empirical eradication group. Quality of life showed significant improvements in both groups at 12 months; however, physical role functioning was significantly improved in the empirical eradication group. Fourteen (27%) in the empirical eradication group subsequently proceeded to OGD because of no improvement in dyspepsia. CONCLUSIONS: This randomised study strongly supports the use of empirical H pylori eradication in patients referred to secondary practice; it is estimated that 73% of OGDs in this group would have been avoided with no detriment to clinical outcome.

Chronic gastrointestinal inflammation.

Chronic gastrointestinal inflammation is one of the most common types of inflammatory process which affects humans. It is diverse in aetiology, pathogenesis and manifestation. There are also features of chronic inflammation at different sites within the gastrointestinal tract which provide a common thread in terms of the approaches which may be used in investigating these intriguing processes. This paper provides an overview of the mucosal changes in chronic gastrointestinal inflammation. Conserved and variable features of inflammation at different sites extending from the oral cavity to the rectum are highlighted. The involvement of different inflammatory cell types within any diagnostic entity is considered and the progression from an acute to chronic inflammatory condition explored. Important issues in the maintenance of a chronic inflammatory state are the balance between pro- and anti-inflammatory pressures, the driving force behind the inflammation and immune response that is occurring and the mechanisms for curtailment of unwanted or harmful responses which may damage the host. Thus inflammation is likely to result when there is persistence of a driving force and/or imbalance in the pro- and anti-inflammatory mechanisms in the tissue involved.

Regulation of the mucosal immune response.

Infectious diseases continue to exact an extensive toll on populations living closest to the equatorial regions of the globe. A substantial proportion of these infections gain access to the host via the mucosal tissues. Thus, the development of new vaccines that enhance mucosal immunity is considered to be of paramount importance in order to prevent or limit the impact of these infections. Mucosal immune responses must discriminate between commensal flora within the lumen and potential pathogens. These responses are highly adapted to induce protection without excessive amounts of inflammation. The balances that regulate mucosal immune and inflammatory responses have to be understood if effective mucosal immunity is to be induced through local immunization. This review will summarize some of the unique properties of mucosal immune responses and focus on recent advances that have significantly influenced our understanding of the regulation of immune and inflammatory responses following infection.

Epidemiology of Chlamydia pneumoniae infection in a randomly selected population in a developed country.

This cross-sectional study of 400 sera from a randomly selected adult population in Northern Ireland, using a microimmunofluorescence assay, demonstrated high overall seropositivity (70%) for IgG Chlamydia pneumoniae antibodies in developed populations. Seropositivity was shown to be unrelated to gender, age or smoking but there was an inverse trend between infection and educational level achieved as a measure of socio-economic status. IgG levels were also higher during the winter months suggesting seasonal variation of Chlamydia pneumoniae infection. The high prevalence of evidence of exposure to Chlamydia pneumoniae as described in this study may have implications for prevention of cardiovascular disease if further evidence conclusively determines that infection with this organism is a risk factor for cardiovascular disease.