Assessing the feasibility of employing a combination of a bacteriophage-derived endolysin and spore germinants to treat relapsing clostridioides difficile infection

Clostridioides difficile is a Gram-positive, anaerobic, spore-forming bacillus and is a major cause of healthcare-associated infections. Whereas the vegetative form of the pathogen is susceptible to treatment with antibiotics, its ability to persist in the gut as antibiotic-resistant spores means that reinfection can occur in cases were the individual fails to re-establish a protective microflora. Bacteriophages and their lysins are currently being explored as treatment options due to their specificity, which minimizes the disruption to the other members of the gut microflora that are protective. The feasibility of employing recombinant endolysins to target the vegetative form of C. difficile has been demonstrated in animal models. In this study, we cloned and expressed the enzyme active domain of LysCD6356 and confirmed its ability to lyse the vegetative forms of a diverse range of clinical isolates of C. difficile, which included members of the hypervirulent 027 ribotype. Lytic activity was adversely affected by calcium, which is naturally found in the gut and is released from the spore upon germination. Our results suggests that a strategy in which the triggering of spore germination is separated in time from the application of the lysin could be developed as a strategy to reduce the risk of relapsing C. difficile infections

Can bees help us find new antibiotics?

Antibiotics are very important for treating bacterial infections in humans, pets, and livestock. However, improper use of antibiotics has resulted in antibiotic resistance, making it difficult to treat some infections. There is an urgent need to discover new antibiotics, but how do we find them? The answer potentially lies with bees and the honey they produce. Bees who feed on unique plants produce honey with high levels of antibiotic activity, due to the presence of antibacterial compounds in the nectar that the bees collect to make honey. In addition to nectar, the bees also collect pollen, which contains a sample of each visited plant’s unique DNA. By studying this DNA, we have identified plants that are sources of the antibacterial compounds found in honey. We are now working to develop new antibiotics from this honey, and we have installed beehives on university buildings to create our own super honey

Surface morphology differences in Clostridium difficile spores, based on different strains and methods of purification

Infections linked to Clostridium difficile are a significant cause of suffering. In hospitals, the organism is primarily acquired through the faecal-oral route as spores excreted by infected patients contaminate the healthcare environment. We previously reported that members of the C. difficile group varied widely in their ability to adhere to stainless steel and proposed that these differences were a consequence of variations in spore architecture. In this study of clinical isolates and spore coat protein mutants of C. difficile we identified three distinct spore surfaces morphotypes; smooth, bag-like and "pineapple-like" using scanning electron microscopy (SEM). The frequency of each morphotype in a spore population derived from a single isolate varied depending on the host strain and the method used to produce and purify the spores. Our results suggest that the inclusion of a sonication step in the purification process had a marked effect on spore structure. In an attempt to link differences in spore appearance with key structural spore proteins we compared the morphology of spores of CD630 to those produced by CD630 variants lacking either CotE or BclA. While SEM images revealed no obvious structural differences between CD630 and its mutants we did observe significant differences (p < 0.001) in relative hydrophobicity suggesting that modifications had occurred but not at a level to be detectable by SEM. In conclusion, we observed significant variation in the spore morphology of clinical isolates of C. difficile due in part to the methods used to produce them. Sonication in particular can markedly change spore appearance and properties. The results of this study highlight the importance of adopting "standard" methods when attempting to compare results between studies and to understand the significance of their differences

Target discovery focused approaches to overcome bottlenecks in the exploitation of antimycobacterial natural products

Tuberculosis is a major global health hazard. The search for new antimycobacterials has focused on such as screening combinational chemistry libraries or designing chemicals to target predefined pockets of essential bacterial proteins. The relative ineffectiveness of these has led to a reappraisal of natural products for new antimycobacterial drug leads. However, progress has been limited, we suggest through a failure in many cases to define the drug target and optimize the hits using this information. We highlight methods of target discovery needed to develop a drug into a candidate for clinical trials. We incorporate these into suggested analysis pipelines which could inform the research strategies to accelerate the development of new drug leads from natural products

Development of the School Science Club at Cardiff University

Challenges faced by schools include how to make science interesting, relevant and engaging for their pupils. This can perhaps be made more difficult by staff members not having direct experience in many areas of the science they are tasked to teach, and therefore lacking the confidence to teach in these areas ( Murphy et al., 2007). Within the higher education sector, there is demand for researchers to actively engage with the local community ( Linder and Spear, 2003; Wynne, 2006). Working with eight schools, we co-developed a programme that both highlights academic research and complements the Key Stage 2 national curriculum with the aims of improving science aspirations, knowledge and confidence in Key Stage 2 (Year 6) children, supporting teachers in the delivery of areas of the curriculum identified as challenging, and increasing science communication and engagement within the university. We delivered two separate sessions with all eight primary schools, interacting with approximately three hundred and fifty pupils. Overall, the project had a positive impact on teachers, children and academic staff. Key findings indicated that 92.9 per cent of 348 children surveyed felt that they had learned something new, while 85.7 per cent surveyed felt they were more interested in science, and 14.3 per cent reported no change in their feelings towards science. The School Science Club represents a collaborative engagement project which highlights the requirement of accurate co-development and outcome settings from both the university and school in order to have a positive impact on all those involved. Findings suggested improvements in planning and delivery for future such endeavours

Untargeted metabolomics reveals a new mode of action of pretomanid (PA-824)

Pretomanid is a promising anti-tubercular drug currently at clinical phase III, but its mechanisms of action are currently unclear. This study aimed to: (i) reveal the metabolome of Mycobacterium smegmatis under pretomanid treatment; (ii) compare major sources of metabolite variation in bacteria treated with pretomanid treatment and other antibiotics; and (iii) to target metabolites responsible for the killing activity of pretomanid in mycobacteria. Untargeted high-resolution metabolite profiling was carried out using flow infusion electrospray ion high resolution mass spectrometry (FIE-HRMS) to identify and quantify metabolites. The identification of key metabolites was independently confirmed by gas-chromatography time-of flight mass spectrometry (GC-tofMS) in comparison to standards. Pretomanid treatments generated a unique distinctive metabolite profile when compared to ampicillin, ethambutol, ethionamide, isoniazid, kanamycin, linezolid, rifampicin and streptomycin. Metabolites which differed significantly only with pretomanid treatment were identified and mapped on to bacterial metabolic pathways. This targeted the pentose phosphate pathway with significant accumulation seen with fructose-6-phosphate, ribose-5-phosphate and glyceraldehyde-3-phosphate. These effects were linked to the accumulation of a toxic metabolite methylglyoxal. This compound showed significant antimicrobial activity (MIC 0.65 mM) against M. smegmatis.publishersversionPeer reviewe

Bioinspired detoxification of blood: The efficient removal of anthrax toxin protective antigen using an extracorporeal macroporous adsorbent device

Whilst various remedial human monoclonal antibodies have been developed to treat the potentially life-threatening systemic complications associated with anthrax infection, an optimal and universally effective administration route has yet to be established. In the later stages of infection when antibody administration by injection is more likely to fail one possible route to improve outcome is via the use of an antibody-bound, adsorbent haemoperfusion device. We report here the development of an adsorbent macroporous polymer column containing immobilised B. anthracis exotoxin-specific antibodies, PANG (a non-glycosylated, version of a plant-produced human monoclonal antibody) and Valortim (a fully human monoclonal N-linked glycosylated antibody), for removal of anthrax protective antigen (PA) from freshly frozen human plasma and human whole blood. In addition, we have demonstrated that continuous extracorporeal blood recirculation through a Valortim-bound haemoperfusion column significantly reduced the blood plasma concentration of anthrax PA over 2 hours using an in vivo PA rat infusion model. This work provides proof-of-concept evidence to support the development of such alternative detoxification platforms

Colonial variation in vancomycin resistant Enterococcus faecium

Vancomycin resistant enterococci are increasingly being isolated from inpatients. This report describes the colonial variation present in most isolates of vancomycin resistant Enterococcus faecium obtained at this hospital. Colonial variants within the same culture were indistinguishable by antimicrobial susceptibility, biochemical reactions, and ribotyping. Failure to appreciate this colonial variation will lead to pure cultures being regarded as contaminated or mixed

Virucidal efficacy of gaseous ozone against type 1 herpes simplex virus (hsv-1)

Viruses represent a major threat to human health and are capable of spreading either via direct exposure or contamination of inanimate surfaces. Certain viruses have been shown to remain viable on surfaces of dental implants and devices, fabrics and on plastics for hours, days and weeks representing a source of continuous viral transmission which must be mitigated. In this study, we compared the effect of varying concentrations of gaseous ozone (40, 20, 10, 5, and 1 ppm) on Herpes Simplex Virus (HSV-1) coated on the surfaces of clear polystyrene tissue culture (TC) plates and stainless-steel disc at varying time intervals (1.5, 3, 6, and 8 h) at >90% relative humidity and at 21–25 ˙C (±2˙C). Test samples were placed at a height of 1 and 1.5 m from ozone source. Viral viability after ozone exposure was determined using Vero cells and the viral titer was quantified using the Spearman–Karber’s method. Overall, inactivation of HSV-1 was dependent on ozone concentration and the duration of exposure. At 20 and 40 ppm, ozone rapidly depleted virus viability after 6 h. At 5 and 10 ppm a time-dependent reduction in viral infectivity was observed. At 10 ppm, viral titer decreased from approximately 5.2 pfu/mL at T = 0 to 3.5 and 2.1 pfu/mL after 1.5- and 6-h exposure on plastic surfaces. Similarly, viral titer decreased from approximately 5.6 pfu/mL at T = 0 to 3.0 to 2.0 pfu/mL at same time frame on steel surfaces. This study builds on earlier research in the field and demonstrates the ability of gaseous ozone to inactivate HSV-1 on two surfaces commonly found in food, medical and dental settings. This study recommends that further work is completed to identify optimum ozone, humidity, and temperature combinations to inactivate such viruses on surfaces found within these environments

Human anthrax: Update of the diagnosis and treatment

Anthrax is one of the most important zoonotic diseases which primarily infects herbivores and occasionally humans. The etiological agent is Bacillus anthracis which is a Gram-positive, aerobic, spore-forming, nonmotile, rod-shaped bacillus. The spores are resistant to environmental conditions and remain viable for a long time in contaminated soil, which is the main reservoir for wild and domestic mammals. Infections still occur in low-income countries where they cause suffering and economic hardship. Humans are infected by contact with ill or dead animals, contaminated animal products, directly exposed to the spores in the environment or spores released as a consequence of a bioterrorist event. Three classical clinical forms of the disease, cutaneous, gastrointestinal and inhalation, are seen, all of which can potentially lead to sepsis or meningitis. A new clinical form in drug users has been described recently and named “injectional anthrax” with high mortality (>33%). The symptoms of anthrax in the early stage mimics many diseases and as a consequence it is important to confirm the diagnosis using a bacterial culture or a molecular test. With regards to treatment, human isolates are generally susceptible to most antibiotics with penicillin G and amoxicillin as the first choice, and ciprofloxacin and doxycycline serving as alternatives. A combination of one or more antibiotics is suggested in systemic anthrax. Controlling anthrax in humans depends primarily on effective control of the disease in animals. Spore vaccines are used in veterinary service, and an acellular vaccine is available for humans but its use is limited