The Role of Nitroreductases in Resistance to Nitroimidazoles

Antimicrobial resistance is a major challenge facing modern medicine, with an estimated 700,000 people dying annually and a global cost in excess of $100 trillion. This has led to an increased need to develop new, effective treatments. This review focuses on nitroimidazoles, which have seen a resurgence in interest due to their broad spectrum of activity against anaerobic Gram-negative and Gram-positive bacteria. The role of nitroreductases is to activate the antimicrobial by reducing the nitro group. A decrease in the activity of nitroreductases is associated with resistance. This review will discuss the resistance mechanisms of different disease organisms, including Mycobacterium tuberculosis, Helicobacter pylori and Staphylococcus aureus, and how these impact the effectiveness of specific nitroimidazoles. Perspectives in the field of nitroimidazole drug development are also summarised

Rapid Detection of Botulinum Neurotoxins—A Review

A toxin is a poisonous substance produced within living cells or organisms. One of the most potent groups of toxins currently known are the Botulinum Neurotoxins (BoNTs). These are so deadly that as little as 62 ng could kill an average human; to put this into context that is approximately 200,000 × less than the weight of a grain of sand. The extreme toxicity of BoNTs leads to the need for methods of determining their concentration at very low levels of sensitivity. Currently the mouse bioassay is the most widely used detection method monitoring the activity of the toxin; however, this assay is not only lengthy, it also has both cost and ethical issues due to the use of live animals. This review focuses on detection methods both existing and emerging that remove the need for the use of animals and will look at three areas; speed of detection, sensitivity of detection and finally cost. The assays will have wide reaching interest, ranging from the pharmaceutical/clinical industry for production quality management or as a point of care sensor in suspected cases of botulism, the food industry as a quality control measure, to the military, detecting BoNT that has been potentially used as a bio warfare agent

Elevated serum antibody responses to synthetic mycobacterial lipid antigens among UK farmers: an indication of exposure to environmental mycobacteria?

Background: mycobacterial cells contain complex mixtures of mycolic acid esters. These can be used as antigens recognised by antibodies in the serum of individuals with active tuberculosis, caused by Mycobacterium tuberculosis. In high burden populations, a significant number of false positives are observed; possibly these antigens are also recognised by antibodies generated by other mycobacterial infections, particularly ubiquitous ‘environmental mycobacteria’. This suggests similar responses may be observed in a low burden TB population, particularly in groups regularly exposed to mycobacteria. Methods: ELISA using single synthetic trehalose mycolates corresponding to major classes in many mycobacteria was used to detect antibodies in serum of individuals with no known mycobacterial infection, comprising farmers, abattoir workers, and rural and urban populations. Results: serum from four Welsh or Scottish cohorts showed lower (with some antigens significantly lower) median responses than those reported for TB negatives from high-burden TB populations, and significantly lower responses than those with active TB. A small fraction, particularly older farmers, showed strong responses. A second study examined BCG vaccinated and non-vaccinated farmers and non-farmers. Farmers gave significantly higher median responses than non-farmers with three of five antigens, while there was no significant difference between vaccinated or non-vaccinated for either farmer or non-farmer groups. Conclusions: this initial study shows that serodiagnosis with mycobacterial lipid antigens can detect antibodies in a population sub-group that is significantly exposed to mycobacteria, in an assay that is not interfered with by vaccination. Given the links between mycobacterial exposure and a range of immune system diseases, further understanding such responses may provide a new opportunity for monitoring public health and directing treatment

Results of the blind analysis of the ELISA for 249 sera (75 culture positive PTB and 174 culture negative patients) using selected combinations of compounds and antibodies.

<p>Results of the blind analysis of the ELISA for 249 sera (75 culture positive PTB and 174 culture negative patients) using selected combinations of compounds and antibodies.</p

Risk of Obesity-Related Cancer After Obesity Surgery in a Population-Based Cohort Study

Globally, 500 million people are obese (body mass index [BMI] ≥30). In Sweden, 14% of the population is obese. Obesity is associated with an increased risk of mortality, cancer and several co morbidities. Bariatric surgery is the only treatment with documented long-term benefits, i.e. decreased mortality and co morbidities and sustainable weight loss. The aim of the thesis was to clarify effects of clinically relevant aspects of bariatric surgery and make comparisons with the general population of corresponding age, sex and calendar period. The included studies are nationwide Swedish population based retrospective cohort studies, comparing defined outcomes before and after bariatric surgery. Study I tested the hypothesis that the risk of obesity-related cancer decreases with increasing time after bariatric surgery. It included 13,123 patients who had undergone bariatric surgery in 1980-2006 in Sweden. Standardised incidence ratios (SIR) were calculated to assess risk. There was no overall decreased risk of cancer with increasing time after bariatric surgery (p for trend 0.4). Rather, the risk of colorectal cancer was increased with time after bariatric surgery (p=0.01). In study II, the risk of in-hospital care for obesity related diseases before and after bariatric surgery in 13,273 patients during 1980-2006 was compared to a matched random sample of 132,730 individuals from the general population. Preoperative incidence rate ratios (IRR) and postoperative hazard ratios (HR) were calculated. The postoperative risk of diabetes, myocardial infarction, hypertension, stroke and angina remained increased compared to the general population. The risk estimates for diabetes (HR 1.2, 95% CI 0.9-1.7) and myocardial infarction (HR 0.8, 0.4-1.5) were lower after gastric bypass than after restrictive bariatric procedures (HR 2.8, 96% CI 2.5-3.1 and HR 1.6, 95% CI 1.4-1.9, respectively). Study III assessed whether cholecystectomy is indicated as part of the bariatric surgery due to the known increased preoperative risk of gallstone formation. The need for cholecystectomy in a bariatric surgery cohort (n=13,443) during 1987-2008 was compared to the general population, and to two cohorts of patients who had undergone antireflux surgery (n=16,176) or appendectomy (n=154,751). An increased need for cholecystectomy after bariatric surgery was confirmed (SIR 5.5, 95% CI 5.1-5.8), but the absolute rate of cholecystectomy was low (8.5%) and the increased SIR after antireflux surgery (SIR 2.4, 95% CI 2.2-2.6) and appendectomy (SIR 1.7, 95% CI 1.6-1.7) indicated detection bias. Study IV addressed the risk of hospital admission for psychiatric disorders, including substance- and alcohol abuse, before (IRR) and after (HR) bariatric surgery was compared to such admissions of the general population. The bariatric surgery cohort (n=12,277) during 1980-2006 was compared to a matched sample from the general population (n=122,770). Patients undergoing bariatric surgery were more likely to be hospitalised for all studied diagnoses prior to surgery compared to the general population, e.g. IRR of depression was 2.8 (95% CI 2.5-3.0). After gastric bypass, there was an increased risk of inpatient care for alcohol abuse compared to those undergoing a restrictive surgical procedure (HR 2.3, 95% CI 1.7-3.2). To conclude, bariatric surgery might not entail any reduced risk of obesity-related cancer with increasing time after surgery. The need for cholecystectomy following bariatric surgery was increased, but prophylactic cholecystectomy might not be generally recommended. Gastric bypass surgery seems to reduce the risk of inpatient care for diabetes and myocardial infarction, but increase the risk of inpatient care for alcohol abuse as compared to restrictive bariatric procedures

Combined results of the ELISA with the two sets of 50 sera (27 culture positive PTB and 73 culture negative patients) using selected antigen/antibody combinations.

<p>Combined results of the ELISA with the two sets of 50 sera (27 culture positive PTB and 73 culture negative patients) using selected antigen/antibody combinations.</p

Demographic and clinical characteristics of the first 50 patients whose sera were evaluated.

<p>Demographic and clinical characteristics of the first 50 patients whose sera were evaluated.</p

Proximity of individual cases using a Random Forest classifier [59] trained with the absorbances with the 349 serum samples for the antigens n15, n20, n3, n28, n32, n1, n39.

<p>The ROC AUC for this analysis based on the principal co-ordinate (x-axis) compared to PTB or no PTB diagnosis was 0.95. AUC: area under curve.</p

Demographic and clinical characteristics of the third set of patients: Validation study performed on 249 samples.

<p>Demographic and clinical characteristics of the third set of patients: Validation study performed on 249 samples.</p

The distribution of responses (absorbances) from the first 100 serum samples from patients with culture positive PTB or culture negative (no TB).

<p>Each method n15—n39 is described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181414#pone.0181414.t007" target="_blank">Table 7</a>. The bars indicate the medians. In each case the secondary antibody was peroxidase conjugated and the binding was measured by addition of o-phenylenediamine and H₂O₂ in citrate buffer and the colour reaction was terminated by the addition of acid. Each individual measurement was carried out in quadruplicate. The bars indicate the medians.</p