The Glymphatic System: a Potential Key Player in Bacterial Meningitis

The glial-lymphatic system (glymphatic system) is a recently characterized fluid clearance pathway of the central nervous system. Glymphatic system disfunctions leading to defects in drainage of the cerebrospinal fluid have been associated with several neurological disorders. In their article, J. S. Generoso, S. Thorsdottir, A. Collodel, R. R. E. Santo, et al. (mBio 13:e01886-22, 2022, https://doi.org/10.1128/mBio.01886-22) have now associated impaired glymphatic system functionality to neurological sequelae of murine meningitis caused by Streptococcus pneumoniae. Their work provides an initial and important step into the systematic evaluation of a potential impact of glymphatic system functionality on disease severity and sequelae in meningitis

Selection and characterization of a promoter for expression of single-copy recombinant genes in Gram-positive bacteria

BACKGROUND: In the past ten years there has been a growing interest in engineering Gram-positive bacteria for biotechnological applications, including vaccine delivery and production of recombinant proteins. Usually, bacteria are manipulated using plasmid expression vectors. The major limitation of this approach is due to the fact that recombinant plasmids are often lost from the bacterial culture upon removal of antibiotic selection. We have developed a genetic system based on suicide vectors on conjugative transposons allowing stable integration of recombinant DNA into the chromosome of transformable and non-transformable Gram-positive bacteria. RESULTS: The aim of this work was to select a strong chromosomal promoter from Streptococcus gordonii to improve this genetic system making it suitable for expression of single-copy recombinant genes. To achieve this task, a promoterless gene encoding a chloramphenicol acetyltransferase (cat), was randomly integrated into the S. gordonii chromosome and transformants were selected for chloramphenicol resistance. Three out of eighteen chloramphenicol resistant transformants selected exhibited 100% stability of the phenotype and only one of them, GP215, carried the cat gene integrated as a single copy. A DNA fragment of 600 base pairs exhibiting promoter activity was isolated from GP215 and sequenced. The 5' end of its corresponding mRNA was determined by primer extention analysis and the putative -10 and a -35 regions were identified. To study the possibility of using this promoter (PP) for single copy heterologous gene expression, we created transcriptional fusions of PP with genes encoding surface recombinant proteins in a vector capable of integrating into the conjugative transposon Tn916. Surface recombinant proteins whose expression was controlled by the PP promoter were detected in Tn916-containing strains of S. gordonii and Bacillus subtilis after single copy chromosomal integration of the recombinant insertion vectors into the resident Tn916. The surface recombinant protein synthesized under the control of PP was also detected in Enterococcus faecalis after conjugal transfer of a recombinant Tn916 containing the transcriptional fusion. CONCLUSION: We isolated and characterized a S. gordonii chromosomal promoter. We demonstrated that this promoter can be used to direct expression of heterologous genes in different Gram-positive bacteria, when integrated in a single copy into the chromosome

Sistema binario di sonde fluorescenti per PCR real-time, metodo diagnostico e kit relativo

L' Invenzione concerne un sistema binario di sonde delle quali almeno una presenta geometria circolare, ad elevata specificità, da utilizzare nella tecnica della PCR real-time come kit diagnostico per la rilevazione specifica di sequenze geniche e la discriminazione di specie microbiche , quali ad esempio , la sequenza IS 6110 di Mycobacterium tuberculosis

Characteristics of drug-resistant tuberculosis in Abkhazia (Georgia), a high-prevalence area in Eastern Europe

Although multidrug-resistant (MDR) tuberculosis (TB) is a major public health problem in Eastern Europe, the factors contributing to emergence, spread and containment of MDR-TB are not well defined. Here, we analysed the characteristics of drug-resistant TB in a cross-sectional study in Abkhazia (Georgia) between 2003 and 2005, where standard short-course chemotherapy is supplemented with individualized drug-resistance therapy. Drug susceptibility testing (DST) and molecular typing were carried out for Mycobacterium tuberculosis complex strains from consecutive smear-positive TB patients. Out of 366 patients, 60.4% were resistant to any first-line drugs and 21% had MDR-TB. Overall, 25% of all strains belong to the Beijing genotype, which was found to be strongly associated with the risk of MDR-TB (OR 25.9, 95% CI 10.2-66.0) and transmission (OR 2.8, 95% CI 1.6-5.0). One dominant MDR Beijing clone represents 23% of all MDR-TB cases. The level of MDR-TB did not decline during the study period, coinciding with increasing levels of MDR Beijing strains among previously treated cases. Standard chemotherapy plus individualized drug-resistance therapy, guided by conventional DST, might be not sufficient to control MDR-TB in Eastern Europe in light of the spread of "highly transmissible" MDR Beijing strains circulating in the community

Treatment of tuberculosis in a region with high drug resistance: Outcomes, drug resistance amplification and re-infection

Introduction: Emerging antituberculosis drug resistance is a serious threat for tuberculosis (TB) control, especially in Eastern European countries. Methods: We combined drug susceptibility results and molecular strain typing data with treatment outcome reports to assess the influence of drug resistance on TB treatment outcomes in a prospective cohort of patients from Abkhazia (Georgia). Patients received individualized treatment regimens based on drug susceptibility testing (DST) results. Definitions for antituberculosis drug resistance and treatment outcomes were in line with current WHO recommendations. First and second line DST, and molecular typing were performed in a supranational laboratory for Mycobacterium tuberculosis (MTB) strains from consecutive sputum smear-positive TB patients at baseline and during treatment. Results: At baseline, MTB strains were fully drug-susceptible in 189/326 (58.0%) of patients. Resistance to at least H or R (PDR-TB) and multidrug-resistance (MDR-TB) were found in 69/326 (21.2%) and 68/326 (20.9%) of strains, respectively. Three MDR-TB strains were also extensively resistant (XDR-TB). During treatment, 3/189 (1.6%) fully susceptible patients at baseline were re-infected with a MDR-TB strain and 2/58 (3.4%) PDR-TB patients became MDR-TB due to resistance amplification. 5/ 47 (10.6%) MDR- patients became XDR-TB during treatment. Treatment success was observed in 161/189 (85.2%), 54/69 (78.3%) and 22/68 (32.3%) of patients with fully drug susceptible, PDR- and MDR-TB, respectively. Development of ofloxacin resistance was significantly associated with a negative treatment outcome. Conclusion: In Abkhazia, a region with high prevalence of drug resistant TB, the use of individualized MDR-TB treatment regimens resulted in poor treatment outcomes and XDR-TB amplification. Nosocomial transmission of MDR-TB emphasizes the importance of infection control in hospitals

Inhibition of matrix metalloproteinases attenuates brain damage in experimental meningococcal meningitis

Background: Approximately 7% of survivors from meningococcal meningitis (MM) suffer from neurological sequelae due to brain damage in the course of meningitis. The present study focuses on the role of matrix metalloproteinases (MMPs) in a novel mouse model of MM-induced brain damage. Methods: The model is based on intracisternal infection of BALB/c mice with a serogroup C Neisseria meningitidis strain. Mice were infected with meningococci and randomised for treatment with the MMP inhibitor batimastat (BB-94) or vehicle. Animal survival, brain injury and host-response biomarkers were assessed 48 h after meningococcal challenge. Results: Mice that received BB-94 presented significantly diminished MMP-9 levels (p < 0.01), intracerebral bleeding (p < 0.01), and blood brain barrier (BBB) breakdown (p < 0.05) in comparison with untreated animals. In mice suffering from MM, the amount of MMP- 9 measured by zymography significantly correlated with both intracerebral haemorrhage (p < 0.01) and BBB disruption (p < 0.05). Conclusions: MMPs significantly contribute to brain damage associated with experimental MM. Inhibition of MMPs reduces intracranial complications in mice suffering from MM, representing a potential adjuvant strategy in MM post-infection sequelae

Peripheral nervous system involvement in Parkinson's disease: Evidence and controversies

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Susceptibility to chlorhexidine amongst multidrug-resistant clinical isolates of Staphylococcus epidermidis from bloodstream infections

We thank the staff of the Aberdeen Clinical Diagnostic Laboratory and the Centre for Genome-Enabled Biology and Medicine of the University of Aberdeen for their dedicated support to this study.Peer reviewedPostprintPostprintPostprin

Time for biocide stewardship?

Peer reviewedPostprin

Targeted deletions of complement lectin pathway genes improve outcome in traumatic brain injury, with MASP-2 playing a major role.

The lectin pathway (LP) of complement activation is believed to contribute to brain inflammation. The study aims to identify the key components of the LP contributing to TBI outcome as possible novel pharmacological targets. We compared the long-term neurological deficits and neuropathology of wild-type mice (WT) to that of mice carrying gene deletions of key LP components after experimental TBI. WT or MASP-2 (Masp2-/-), ficolin-A (Fcna-/-), CL-11 (Colec11-/-), MASP-1/3 (Masp1-/-), MBL-C (Mbl2-/-), MBL-A (Mbl1-/-) or MBL-/- (Mbl1-/-/Mbl2-/-) deficient male C57BL/6J mice were used. Mice underwent sham surgery or TBI by controlled cortical impact. The sensorimotor response was evaluated by neuroscore and beam walk tests weekly for 4 weeks. To obtain a comparative analysis of the functional outcome each transgenic line was rated according to a health score calculated on sensorimotor performance. For selected genotypes, brains were harvested 6 weeks after injury for histopathological analysis. MASP-2-/-, MBL-/- and FCN-A-/- mice had better outcome scores compared to WT. Of these, MASP-2-/- mice had the best recovery after TBI, showing reduced sensorimotor deficits (by 33% at 3 weeks and by 36% at 4 weeks). They also showed higher neuronal density in the lesioned cortex with a 31.5% increase compared to WT. Measurement of LP functional activity in plasma from MASP-2-/- mice revealed the absence of LP functional activity using a C4b deposition assay. The LP critically contributes to the post-traumatic inflammatory pathology following TBI with the highest degree of protection achieved through the absence of the LP key enzyme MASP-2, underlining a therapeutic utility of MASP-2 targeting in TBI