Causalities of war: The connection between type VI secretion system and microbiota

Cellular Microbiology published by John Wiley & Sons Ltd Microbiota niches have space and/or nutrient restrictions, which has led to the coevolution of cooperation, specialisation, and competition within the population. Different animal and environmental niches contain defined resident microbiota that tend to be stable over time and offer protection against undesired intruders. Yet fluxes can occur, which alter the composition of a bacterial population. In humans, the microbiota are now considered a key contributor to maintenance of health and homeostasis, and its alteration leads to dysbiosis. The bacterial type VI secretion system (T6SS) transports proteins into the environment, directly into host cells or can function as an antibacterial weapon by killing surrounding competitors. Upon contact with neighbouring cells, the T6SS fires, delivering a payload of effector proteins. In the absence of an immunity protein, this results in growth inhibition or death of prey leading to a competitive advantage for the attacker. It is becoming apparent that the T6SS has a role in modulating and shaping the microbiota at multiple levels, which is the focus of this review. Discussed here is the T6SS, its role in competition, key examples of its effect upon the microbiota, and future avenues of researc

Field Assessment of a Model Tuberculosis Outbreak Response Plan for Low-Incidence Areas

Background: For a regional project in four low-incidence states, we designed a customizable tuberculosis outbreak response plan. Prior to dissemination of the plan, a tuberculosis outbreak occurred, presenting an opportunity to perform a field assessment of the plan. The purpose of the assessment was to ensure that the plan included essential elements to help public health professionals recognize and respond to outbreaks. Methods: We designed a semi-structured questionnaire and interviewed all key stakeholders involved in the response. We used common themes to assess validity of and identify gaps in the plan. A subset of participants provided structured feedback on the plan. Results: We interviewed 11 public health and six community stakeholders. The assessment demonstrated that (1) almost all of the main response activities were reflected in the plan; (2) the plan added value by providing a definition of a tuberculosis outbreak and guidelines for communication and evaluation. These were areas that lacked written protocols during the actual outbreak response; and (3) basic education about tuberculosis and the interpretation and use of genotyping data were important needs. Stakeholders also suggested adding to the plan questions for evaluation and a section for specific steps to take when an outbreak is suspected. Conclusion: An interactive field assessment of a programmatic tool revealed the value of a systematic outbreak response plan with a standard definition of a tuberculosis outbreak, guidelines for communication and evaluation, and response steps. The assessment highlighted the importance of education and training for tuberculosis in low-incidence areas

Synthesis and reactivity of [Au(NHC)(Bpin)] complexes

The authors gratefully acknowledge the Royal Society (University Research Fellowship to C.S.J.C.), AstraZeneca (Studenship to C.M.Z) and VLAIO (CO2PERATE) for support of this work. We thank King Saud University (DSF Program) and KAUST (Award No.OSR-2015-CCF-1974-03) for support.A new class of [Au(NHC)(Bpin)] complexes has been synthesized and their unusual reactivity was investigated using computational and experimental methods. The gold-boryl complexes exhibit unexpected high stability and reactivity.PostprintPeer reviewe

Harm reduction: A missing piece to the holistic care of patients who inject drugs

BACKGROUND: The rise in injection drug use (IDU) has led to an increase in drug-related infections. Harm reduction is an important strategy for preventing infections among people who inject drugs (PWID). We attempted to evaluate the harm reduction counseling that infectious diseases physicians provide to PWID presenting with infections. METHODS: An electronic survey was distributed to physician members of the Emerging Infections Network to inquire about practices used when caring for patients with IDU-related infections. RESULTS: In total, 534 ID physicians responded to the survey. Of those, 375 (70%) reported routinely caring for PWID. Most respondents report screening for human immunodeficiency virus (HIV) and viral hepatitis (98%) and discussing the risk of these infections (87%); 63% prescribe immunization against viral hepatitis, and 45% discuss HIV preexposure prophylaxis (PrEP). However, 55% of respondents (n = 205) reported not counseling patients on safer injection strategies. Common reasons for not counseling included limited time and a desire to emphasize antibiotic therapy/medical issues (62%), lack of training (55%), and believing that it would be better addressed by other services (47%). Among respondents who reported counseling PWID, most recommended abstinence from IDU (72%), handwashing and skin cleansing before injection (62%), and safe disposal of needles/drug equipment used before admission (54%). CONCLUSIONS: Almost all ID physicians report screening PWID for HIV and viral hepatitis and discussing the risks of these infections. Despite frequently encountering PWID, fewer than half of ID physicians provide safer injection advice. Opportunities exist to standardize harm reduction education, emphasizing safer injection practices in conjunction with other strategies to prevent infections (eg, HIV PrEP or hepatitis A virus/hepatitis B virus vaccination)

Pseudomonas aeruginosa is capable of natural transformation in biofilms

Natural transformation is a mechanism that enables competent bacteria to acquire naked, exogenous DNA from the environment. It is a key process that facilitates the dissemination of antibiotic resistance and virulence determinants throughout bacterial populations. Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that produces large quantities of extracellular DNA (eDNA) that is required for biofilm formation. P. aeruginosa has a remarkable level of genome plasticity and diversity that suggests a high degree of horizontal gene transfer and recombination but is thought to be incapable of natural transformation. Here we show that P. aeruginosa possesses homologues of all proteins known to be involved in natural transformation in other bacterial species. We found that P. aeruginosa in biofilms is competent for natural transformation of both genomic and plasmid DNA. Furthermore, we demonstrate that type-IV pili (T4P) facilitate but are not absolutely essential for natural transformation in P. aeruginosa

Multiple holins contribute to extracellular DNA release in Pseudomonas aeruginosa biofilms

Bacterial biofilms are composed of aggregates of cells encased within a matrix of extracellular polymeric substances (EPS). One key EPS component is extracellular DNA (eDNA), which acts as a ‘glue’, facilitating cell–cell and cell–substratum interactions. We have previously demonstrated that eDNA is produced in Pseudomonas aeruginosa biofilms via explosive cell lysis. This phenomenon involves a subset of the bacterial population explosively lysing, due to peptidoglycan degradation by the endolysin Lys. Here we demonstrate that in P. aeruginosa three holins, AlpB, CidA and Hol, are involved in Lys-mediated eDNA release within both submerged (hydrated) and interstitial (actively expanding) biofilms, albeit to different extents, depending upon the type of biofilm and the stage of biofilm development. We also demonstrate that eDNA release events determine the sites at which cells begin to cluster to initiate microcolony formation during the early stages of submerged biofilm development. Furthermore, our results show that sustained release of eDNA is required for cell cluster consolidation and subsequent microcolony development in submerged biofilms. Overall, this study adds to our understanding of how eDNA release is controlled temporally and spatially within P. aeruginosa biofilms

Bacteriophage infection of Escherichia coli leads to the formation of membrane vesicles via both explosive cell lysis and membrane blebbing

Membrane vesicles (MVs) are membrane-bound spherical nanostructures that prevail in all three domains of life. In Gram-negative bacteria, MVs are thought to be produced through blebbing of the outer membrane and are often referred to as outer membrane vesicles (OMVs). We have recently described another mechanism of MV formation in Pseudomonas aeruginosa that involves explosive cell-lysis events, which shatters cellular membranes into fragments that rapidly anneal into MVs. Interestingly, MVs are often observed within preparations of lytic bacteriophage, however the source of these MVs and their association with bacteriophage infection has not been explored. In this study we aimed to determine if MV formation is associated with lytic bacteriophage infection. Live super-resolution microscopy demonstrated that explosive cell lysis of Escherichia coli cells infected with either bacteriophage T4 or T7, resulted in the formation of MVs derived from shattered membrane fragments. Infection by either bacteriophage was also associated with the formation of membrane blebs on intact bacteria. TEM revealed multiple classes of MVs within phage lysates, consistent with multiple mechanisms of MV formation. These findings suggest that bacteriophage infection may be a major contributor to the abundance of bacterial MVs in nature

A global genomic approach uncovers novel components for twitching motility-mediated biofilm expansion in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is an extremely successful pathogen able to cause both acute and chronic infections in a range of hosts, utilizing a diverse arsenal of cell-associated and secreted virulence factors. A major cell-associated virulence factor, the Type IV pilus (T4P), is required for epithelial cell adherence and mediates a form of surface translocation termed twitching motility, which is necessary to establish a mature biofilm and actively expand these biofilms. P. aeruginosa twitching motility-mediated biofilm expansion is a coordinated, multicellular behaviour, allowing cells to rapidly colonize surfaces, including implanted medical devices. Although at least 44 proteins are known to be involved in the biogenesis, assembly and regulation of the T4P, with additional regulatory components and pathways implicated, it is unclear how these components and pathways interact to control these processes. In the current study, we used a global genomics-based random-mutagenesis technique, transposon directed insertion-site sequencing (TraDIS), coupled with a physical segregation approach, to identify all genes implicated in twitching motility-mediated biofilm expansion in P. aeruginosa. Our approach allowed identification of both known and novel genes, providing new insight into the complex molecular network that regulates this process in P. aeruginosa. Additionally, our data suggest that the flagellum-associated gene products have a differential effect on twitching motility, based on whether components are intra- or extracellular. Overall the success of our TraDIS approach supports the use of this global genomic technique for investigating virulence genes in bacterial pathogens

Energy drinks available in Ireland: a description of caffeine and sugar content

Objective: To describe the caffeine and sugar content of all energy drinks available on the island of Ireland. Design: Two retail outlets were selected from each of: multinational, convenience and discount stores in Northern Ireland and the Republic of Ireland, and all available single-serve energy drinks were purchased. The cross-sectional survey was conducted in February 2015 and brand name, price, volume, caffeine and sugar content were recorded for each product. Descriptive analysis was performed. Results: Seventy-eight products were identified on the island of Ireland (regular, n 59; diet/sugar-free/light, n 19). Caffeine and sugar content was in the range of 14–35 mg and 2·9–15·6 g per 100 ml, respectively. Mean caffeine content of 102·2 mg per serving represents 25·6 % of the maximum intake advised for adults by the European Food Safety Authority. Per serving, mean sugar content of regular energy drinks was 37 g. This exceeds WHO recommendations for maximum daily sugar intake of <5 % of total energy intake (25 g for adults consuming 8368 kJ (2000 kcal) diet). If displaying front-of-pack labelling, fifty-seven of the fifty-nine regular energy drinks would receive a Food Standards Agency ‘red’ colour-coded label for sugar. Conclusions: Energy drinks are freely available on the island of Ireland and all products surveyed can be defined as highly caffeinated products. This has potential health issues particularly for children and adolescents where safe limits of caffeine have not been determined. Energy drinks surveyed also contained high levels of sugar and could potentially contribute to weight gain and adverse dental health effects

Synthesis of gold(I)-trifluoromethyl complexes and their role in generating spectroscopic evidence for a gold(I)-difluorocarbene species

We thank the Ghent University (IoF), the Special Research Fund (BOF) starting (SPN, CSJC) and advanced (SPN, KVH) grants and Research Foundation Flanders (FWO) (fellowship to SVB and grant to CSJC and KVH) for funding.Readily-prepared and bench-stable [Au(CF3)(NHC)] compounds were synthesized using new methodologies, starting from [Au(OH)(NHC)], [Au(Cl)(NHC)] or [Au(L)(NHC)]HF2 precursors (NHC = N-heterocyclic carbene). The mechanism of formation of these species was investigated. Consequently, a new and straightforward strategy for the mild and selective cleavage of a single carbon-fluorine bond from [Au(CF3)(NHC)] complexes was attempted and found to be reversible in the presence of an additional nucleophilic fluoride source. This straightforward technique has led to the unprecedented spectroscopic observation of a gold(I)-NHC difluorocarbene species.PostprintPeer reviewe