ABSTRACT The in vitro activity of the novel antimicrobial peptide dendrimer G3KL was evaluated against 32 Acinetobacter baumannii (including 10 OXA-23, 7 OXA-24, and 11 OXA-58 carbapenemase producers) and 35 Pseudomonas aeruginosa (including 18 VIM and 3 IMP carbapenemase producers) strains and compared to the activities of standard antibiotics. Overall, both species collections showed MIC 50/90 values of 8/8 μg/ml and minimum bactericidal concentrations at which 50% or 90% of strains tested are killed (MBC 50/90 ) of 8/8 μg/ml. G3KL is a promising molecule with antibacterial activity against multidrug-resistant and extensively drug-resistant A. baumannii and P. aeruginosa isolates.
Abstract Background Depending on geographic location causes of encephalitis, meningoencephalitis and meningitis vary substantially. We aimed to identify most frequent causes, clinical presentation as well as long-term outcome of encephalitis, meningoencephalitis and meningitis cases treated in the Inselspital, University Hospital Bern, Switzerland. Methods In this monocentric, observational retro- and prospective cohort study, we performed a retrospective review of clinical patient records for all patients treated during 3 years. Patients were contacted prospectively for a telephone follow-up interview and to fill out questionnaires, especially related disturbances of sleep and wakefulness. Results We included 258 patients: encephalitis (18%), non-bacterial meningoencephalitis (42%), non-bacterial meningitis (27%) and bacterial meningoencephalitis/meningitis (13%). Herpes simplex virus (HSV) was the most frequent cause of encephalitis (18%), tick borne encephalitis virus (TBEV) of non-bacterial meningoencephalitis (46%), enterovirus of non-bacterial meningitis (21%) and Streptococcus pneumoniae of bacterial meningoencephalitis/meningitis (49%). Overall, 35% patients remained without known cause. After a median time of 16 months, 162 patients participated in the follow-up interview, thereof 56% indicated to suffer from neurological long-term sequels such as fatigue and/or excessive daytime sleepiness (34%), cognitive impairment and memory deficits (22%), headache (14%) and epileptic seizures (11%). Conclusions In the largest tertiary care University hospital in Switzerland TBEV was the overall most frequently detected infectious cause, with a clinical manifestation of meningoencephalitis in the majority of cases. Long-term neurological sequels, most importantly cognitive impairment, fatigue and headache were frequently self-reported not only in encephalitis and meningoencephalitis but also viral meningitis survivors up to 40 months after the acute infection.
ABSTRACT The expression and function of psoriasin in the brain have been insufficiently characterized. Here, we show the induction of psoriasin expression in the central nervous system (CNS) after bacterial and viral stimulation. We used a pneumococcal meningitis in vivo model that revealed S100A15 expression in astrocytes and meningeal cells. These results were confirmed by a cell-based in vivo assay using primary rat glial and meningeal cell cultures. We investigated psoriasin expression in glial and meningeal cells using polyinosinic-polycytidylic acid, a synthetic analog of double-stranded RNA that mimics viral infection. Furthermore, previous results showed that antimicrobial peptides have not only bactericidal but also immunomodulatory functions. To test this statement, we used recombinant psoriasin as a stimulus. Glial and meningeal cells were treated with recombinant psoriasin at concentrations from 25 to 500 ng/ml. Treated microglia and meningeal cells showed phosphorylation of the extracellular signal-regulated kinase 1 (ERK1)/ERK2 (ERK1/2) signal transduction pathway. We demonstrated that this activation of ERK depends on RAGE, the receptor for advanced glycation end products. Furthermore, microglia cells treated with recombinant psoriasin change their phenotype to an enlarged shape. In conclusion, our results indicate an occurrence of psoriasin in the brain. An involvement of psoriasin as an antimicrobial protein that modulates the innate immune system after bacterial or viral stimulation is possible.
Extracellular AMP inhibits cell proliferation of MCF-7 and MDA-MB-453 whereas cell proliferation of the highly malignant Novikoff cell line is not affected. In medium with low glucose supply MDA-MB-453 cells grow well, Novikoff cells are slightly inhibited and MCF-7 cells are totally unable to grow. Isoelectric focusing revealed that a glyclytic enzyme complex exists in all three cell lines. In addition to the glycolytic enzymes, c-Raf-kinase, adenylate kinase, and nucleoside diphosphate kinase are also found within the complex. The differences in glucose in dependence of the three cell lines can be explained by the different constitutions of shuttle enzymes. MDA-MB-453 and Novikoff cells contain cytsolic glycerol 3-phosphate dehydrogenase which is associated with glyceraldehyde 3-phosphate dehydrogenase within the glycolytic enzyme complex and which is responsible for the transport of cytoslic hydrogen in the mitochondria. MCF-7 and Novikoff cells contain the pI 7.8 form of malate dehydrogenase which couples glycolysis with glutaminolysis.
Background L. monocytogenes meningoencephalitis has a mortality rate of up to 50% and neurofunctional sequelae are common. Type I restriction-modification systems (RMS) are capable of adding methyl groups to the host genome. Some contain multiple sequence recognition (hsdS) genes that recombine, resulting in distinct DNA methylation patterns and patterns of gene expression. These phenotypic switches have been linked to virulence and have recently been discovered in multiple clonal complexes of L. monocytogenes. Methods L. monocytogenes strains containing RMS systems were identified, and purified clones enriched for single hsdS alleles were isolated. In vivo, 11-day old Wistar rats were infected with an inoculum containing a) one of 4 single RMS allele variants (A, B, C, D) treated with amoxicillin (AMX 50 mg/kg/dosis, q8h), b) a mixture of all 4 variants with or without AMX treatment or c) different mixtures of 2 RMS allele variants. At selected time points after infection, clinical and inflammatory parameters, bacterial titers and brain damage were determined. Changes in the relative frequency of the occurring RMS allele in the inoculum and in CSF or cerebellum of infected animals were analyzed by capillary electrophoresis. Results We have identified a phase variable RMS locus within L. monocytogenes CC4 and generated stocks that stably expressed each of the possible hsdS genes within that loci. Generation of these allele variants (A, B, C, D) allowed us to determine the methylation pattern associated with each hsdS through SMRT sequencing. In vivo infections with these single allele variants revealed differences in disease severity in that C induced the worst clinical outcome and more pronounced hippocampal apoptosis; D showed the most pronounced weight loss and the highest bacterial titer in the cerebellum. A caused the least severe disease. Conclusion We identified that L. monocytogenes expressing hsdS (A) causes less damage than when other hsdS genes are expressed. While expression of hsdSC and D worsened the outcome in L.monocytogenes meningitis. We also demonstrate a competitive advantage of variants C and B over variant A in this model. Phenotypical switching may therefore represent a mechanism of virulence regulation in CNS infections with L. monocytogenes.
The rapid spread of the SARS-CoV-2 lineages B.1.1.7 (N501Y.V1) throughout the UK, B.1.351 (N501Y.V2) in South Africa, and P.1 (B.1.1.28.1; N501Y.V3) in Brazil has led to the definition of variants of concern (VoCs) and recommendations for lineage specific surveillance. In Switzerland, during the last weeks of December 2020, we established a nationwide screening protocol across multiple laboratories, focusing first on epidemiological and microbiological definitions. In January 2021, we validated and implemented an N501Y-specific PCR to rapidly screen for VoCs, which are then confirmed using amplicon sequencing or whole genome sequencing (WGS). A total of 13,387 VoCs have been identified since the detection of the first Swiss case in October 2020, with 4194 being B.1.1.7, 172 B.1.351, and 7 P.1. The remaining 9014 cases of VoCs have been described without further lineage specification. Overall, all diagnostic centers reported a rapid increase of the percentage of detected VOCs, with a range of 6 to 46% between 25 to 31 of January 2021 increasing towards 41 to 82% between 22 to 28 of February. A total of 739 N501Y positive genomes were analysed and show a broad range of introduction events to Switzerland. In this paper, we describe the nationwide coordination and implementation process across laboratories, public health institutions, and researchers, the first results of our N501Y-specific variant screening, and the phylogenetic analysis of all available WGS data in Switzerland, that together identified the early introduction events and subsequent community spreading of the VoCs.
ABSTRACT The antibacterial activities of amoxicillin-gentamicin, trovafloxacin, trimethoprim-sulfamethoxazole (TMP-SMX) and the combination of trovafloxacin with TMP-SMX were compared in a model of meningoencephalitis due to Listeria monocytogenes in infant rats. At 22 h after intracisternal infection, the cerebrospinal fluid was cultured to document meningitis, and the treatment was started. Treatment was instituted for 48 h, and efficacy was evaluated 24 h after administration of the last dose. All tested treatment regimens exhibited significant activities in brain, liver, and blood compared to infected rats receiving saline ( P < 0.001). In the brain, amoxicillin plus gentamicin was more active than all of the other regimens, and trovafloxacin was more active than TMP-SMX (bacterial titers of 4.1 ± 0.5 log 10 CFU/ml for amoxicillin-gentamicin, 5.0 ± 0.4 log 10 CFU/ml for trovafloxacin, and 5.8 ± 0.5 log 10 CFU/ml for TMP-SMX; P < 0.05). In liver, amoxicillin-gentamicin and trovafloxacin were similarly active (2.8 ± 0.8 and 2.7 ± 0.8 log 10 CFU/ml, respectively) but more active than TMP-SMX (4.4 ± 0.6 log 10 CFU/ml; P < 0.05). The combination of trovafloxacin with TMP-SMX did not alter the antibacterial effect in the brain, but it did reduce the effect of trovafloxacin in the liver. Amoxicillin-gentamicin was the most active therapy in this study, but the activity of trovafloxacin suggests that further studies with this drug for the treatment of Listeria infections may be warranted.
