Mycobacterium tuberculosis SecA2-dependent activation of host Rig-I/MAVs signaling is not conserved in Mycobacterium marinum.

Retinoic acid inducible gene I (Rig-I) is a cytosolic pattern recognition receptor canonically described for its important role in sensing viral RNAs. Increasingly, bacterially-derived RNA from intracellular bacteria such as Mycobacterium tuberculosis, have been shown to activate the same host Rig-I/Mitochondrial antiviral sensing protein (MAVS) signaling pathway to drive a type-I interferon response that contributes to bacterial pathogenesis in vivo. In M. tuberculosis, this response is mediated by the protein secretion system SecA2, but little is known about whether this process is conserved in other pathogenic mycobacteria or the mechanism by which these nucleic acids gain access to the host cytoplasm. Because the M. tuberculosis and M. marinum SecA2 protein secretion systems share a high degree of genetic and functional conservation, we hypothesized that Rig-I/MAVS activation and subsequent induction of IFN-ß secretion by host macrophages will also be conserved between these two mycobacterial species. To test this, we generated a ΔsecA2 M. marinum strain along with complementation strains expressing either the M. marinum or M. tuberculosis secA2 genes. Our results suggest that the ΔsecA2 strain has a growth defect in vitro but not in host macrophages. These intracellular growth curves also suggested that the calculation applied to estimate the number of bacteria added to macrophage monolayers in infection assays underestimates bacterial inputs for the ΔsecA2 strain. Therefore, to better examine secreted IFN-ß levels when bacterial infection levels are equal across strains we plated bacterial CFUs at 2hpi alongside our ELISA based infections. This enabled us to normalize secreted levels of IFN-ß to a standard number of bacteria. Applying this approach to both WT and MAVS-/- bone marrow derived macrophages we observed equal or higher levels of secreted IFN-ß from macrophages infected with the ΔsecA2 M. marinum strain as compared to WT. Together our findings suggest that activation of host Rig-I/MAVS cytosolic sensors and subsequent induction of IFN-ß response in a SecA2-dependent manner is not conserved in M. marinum under the conditions tested.

Activation of host nucleic acid sensors by Mycobacterium: good for us or good for them?

Although the importance of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) sensors in controlling viral infection is well established, their role in promoting an effective immune response to pathogens other than viruses is less clear. This is particularly true for infections with mycobacteria, as studies point to both protective and detrimental roles for activation of nucleic acid sensors in controlling a mycobacterial infection. Some of the contradiction likely stems from the use of different model systems and different mycobacterial species/strains as well as from which nucleic acid sensors were studied and what downstream effectors were evaluated. In this review, we will describe the different nucleic acid sensors that have been studied in the context of mycobacterial infections, and how the different studies compare. We conclude with a section on how nucleic acid sensor agonists have been used therapeutically and what further information is needed to enhance their potential as therapeutic agents.

A pentaplex real-time PCR assay for rapid identification of major beta-lactamase genes KPC, NDM, CTX, CMY, and OXA-48 directly from bacteria in blood.

Introduction. Antibiotic resistance, particularly in cases of sepsis, has emerged as a growing global public health concern and economic burden. Current methods of blood culture and antimicrobial susceptibility testing of agents involved in sepsis can take as long as 3-5 days. It is vital to rapidly identify which antimicrobials can be used to effectively treat sepsis cases on an individual basis. Here, we present a pentaplex, real-time PCR-based assay that can quickly identify the most common beta-lactamase genes (Klebsiella pneumoniae carbapenemase (KPC); New Delhi metallo-beta-lactamase (NDM); cefotaximase-Munich (CTX-M); cephamycin AmpC beta-lactamases (CMY); and Oxacillinase-48 (OXA-48)) from pathogens derived directly from the blood of patients presenting with bacterial septicemia.Aim. To develop an assay which can rapidly identify the most common beta-lactamase genes in Carbapenem-resistant Enterobacteriaceae bacteria (CREs) from the United States.Hypothesis/Gap Statement. Septicemia caused by carbapenem-resistant bacteria has a death rate of 40-60 %. Rapid diagnosis of antibiotic susceptibility directly from bacteria in blood by identification of beta-lactamase genes will greatly improve survival rates. In this work, we develop an assay capable of concurrently identifying the five most common beta-lactamase and carbapenemase genes.Methodology. Primers and probes were created which can identify all subtypes of Klebsiella pneumoniae carbapenemase (KPC); New Delhi metallo-beta-lactamase (NDM); cefotaximase-Munich (CTX); cephamycin AmpC beta-lactamase (CMY); and oxacillinase-48 (OXA-48). The assay was validated using 13 isolates containing various PCR targets from the Centre for Disease Control Antimicrobial Resistance Isolate Bank Enterobacterales Carbapenemase Diversity Panel. Blood obtained from volunteers was spiked with CREs and bacteria were separated, lysed, and subjected to analysis via the pentaplex assay.Results. This pentaplex assay successfully identified beta-lactamase genes derived from bacteria separated from blood at concentrations of 4-8 c.f.u. ml-1.Conclusion. This assay will improve patient outcomes by supplying physicians with critical drug resistance information within 2 h of septicemia onset, allowing them to prescribe effective antimicrobials corresponding to the resistance gene(s) present in the pathogen. In addition, information supplied by this assay will lessen the inappropriate use of broad-spectrum antimicrobials and prevent the evolution of further antibiotic resistance.

Cervical ripening before first trimester surgical evacuation for non-viable pregnancy.

BACKGROUND: Medications or mechanical dilators are often used to soften and dilate the cervix prior to surgical evacuation of the uterus for non-viable pregnancy, or miscarriage. The majority of miscarriages occur in the first trimester. The aim of cervical ripening is to reduce the possibility of injury to the uterus and cervix and improve the surgical ease of the procedure. Cervical ripening agents can have adverse effects and it is uncertain as to whether these risks outweigh the benefits of their use. OBJECTIVES: To systematically review the benefits and harms of using cervical ripening agents prior to surgical evacuation of non-viable pregnancy prior to 14 weeks' gestation. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 April 2015) and reference lists of retrieved papers. SELECTION CRITERIA: Randomised controlled trials (published in full-text form, or as abstracts only), which assessed the use of pharmacological or mechanical agents to ripen the cervix in women undergoing dilation and curettage or vacuum aspiration for non-viable pregnancy at less than 14 weeks' gestation were eligible for inclusion. Cluster-randomised controlled trials and trials using a cross-over design were not eligible for inclusion.Unpublished randomised controlled trials and quasi-randomised trials would have been eligible for inclusion but none were identified. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data were checked for accuracy. MAIN RESULTS: We included nine trials with 469 women. A diverse set of medications and regimens were studied in these trials, making the comparisons available for meta-analysis limited. The comparisons draw data from six trials with 383 participants. All trials were relatively small and had several aspects of unclear risk of bias with few of this review's outcomes reported. Due to this, no data from three trials were able to be used despite them meeting inclusion criteria.We carried out four comparisons: isosorbide mononitrate or dinitrate compared with misoprostol; misoprostol compared with placebo; chemical dilation (use of medications) compared with mechanical dilation; and any cervical preparation compared with placebo.None of the included studies reported data on the review's primary outcome: cervical or uterine injury (perforation, laceration, creation of a false passage).No clear difference was shown between isosorbide compounds and misoprostol for the outcome need for manual cervical dilation (average risk ratio (RR) 0.76, 95% confidence interval (CI) 0.10 to 5.64; three trials, 150 women; Tau² = 2.11; I² = 69%), however the data were heterogenous. In terms of adverse effects, misoprostol was associated with more vomiting (RR 0.11, 95% CI 0.01 to 0.85; two trials, 120 women), however there were no clear differences between isosorbide compounds and misoprostol in relation to other reported adverse effects (headache, nausea or hypotension). The dosing regimens differed in terms of dose, number of administrations and route of administration in the different trials. Mechanical (Dilapan-S hygroscopic) dilators performed similarly to chemical dilators in a single trial (65 women) that measured difficulty in cervical dilation, excessive bleeding and adverse effects.Misoprostol was shown to be more effective than placebo for cervical ripening (reduced need for manual cervical dilation) (RR 0.14, 95% CI 0.08 to 0.26; one trial, 120 women), and surgical time was reduced when misoprostol was used (mean difference (MD) -3.15, 95% CI -3.59 to -2.70; one trial, 120 women). However, compared to placebo, misoprostol, was associated with more abdominal pain (RR 29.00, 95% CI 1.77 to 475.35; one trial, 120 women), although no clear differences in the risk of other adverse effects (nausea, vomiting, headache or fever) were observed between groups.There was no clear differences between chemical dilation and mechanical dilators for the outcomes: difficulty in cervical dilation, excessive bleeding or adverse effects.Compared with placebo, any cervical preparation reduced the need for manual cervical dilatation (average RR 0.25, 95% CI 0.07 to 0.89; two trials, 168 women; Tau² = 0.67; I² = 81%), and reduced surgical time (MD -2.55, 95% CI -3.67 to -1.43, two trials, 168 women; Tau² = 0.63; I² = 96%).None of the included trials reported on the review's other secondary outcomes, including: injury to bladder or bowel, miscarriage/preterm birth in a subsequent pregnancy, analgesia use after administration of ripening agent but before surgery, or analgesia use after surgery. AUTHORS' CONCLUSIONS: This review found no evidence to evaluate cervical ripening prior to first trimester surgical evacuation for miscarriage for reducing the rate of cervical or uterine injury, however, this may be because these outcomes are very rare. Cervical preparation was shown to reduce the need for manual cervical dilatation compared with placebo.Misoprostol and isosorbide mononitrate and dinitrate were similarly effective in ripening the cervix, however there was more vomiting with misoprostol. Mechanical (Dilapan-S hygroscopic) dilators performed similarly to chemical dilators.The nine studies included in this review were small and the methodological quality of the trials was mixed, and for the most part, not well-described; thus any conclusions drawn from the data included in this review must be treated with caution. Consequently, large, high-quality trials are required to determine whether the benefits of this treatment outweigh the risks. Further research should be powered to assess the rate of cervical and uterine injury between interventions. Future research should also guide clinicians in deciding whether the benefits of reduced manual cervical dilatation outweigh the risks of adverse effects associated with these agents (nausea, vomiting, headache, fever, diarrhoea and pain). Women's satisfaction and outcomes of future pregnancies should also be assessed.