Community-acquired Staphylococcus aureus meningitis in adults

Identification of novel antistaphylococcal hit compounds

Staphylococcus aureus is one of the most common nosocomial biofilm-forming pathogens worldwide that has developed resistance mechanisms against majority of the antibiotics. Therefore, the search of novel antistaphylococcal agents with unexploited mechanisms of action, especially with antibiofilm activity, is of great interest. Seryl-tRNA synthetase is recognized as a promising drug target for the development of antibacterials. We have carried out molecular docking of compounds with antistaphycoccal activity, which were earlier found by us using phenotypic screening, into synthetic site of S. aureus SerRS and found seven hit compounds with low inhibitory activity. Further, we have performed search of S. aureus SerRS inhibitors among compounds which were previously tested by us for inhibitory activity toward S. aureus ThrRS, that belong to the same class of aminoacyl-tRNA synthetases. Among them six hits were identified. We have selected four compounds for antibacterial study and found that the most active compound 1-methyl-3-(1H-imidazol-1-methyl-2-yl)-5-nitro-1H-indazole has MIC values toward S. aureus multidrug-resistant clinical isolates ranging from 78.12 to 156.2 µg/ml. However, this compound precipitated during anti-biofilm study. Therefore, we used 3-[N'-(2-hydroxy-3-methoxybenzylidene)hydrazino]-6-methyl-4H-[1,2,4]triazin-5-one with better solubility (ClogS value = 2.9) among investigated compounds toward SerRS for anti-biofilm study. It was found that this compound has a significant inhibitory effect on the growth of planktonic and biofilm culture of S. aureus 25923 with MIC value of 32 µg ml-1. At the same time, this compound does not reveal antibacterial activity toward Esherichia coli ATCC 47076. Therefore, this compound can be proposed as effective antiseptic toward multidrug-resistant biofilm-forming S. aureus isolates.

MoO3/MIL-125-NH2 with boosted peroxidase-like activity for electrochemical staphylococcus aureus sensing via specific recognition of bacteriophages

Herein, novel nanozyme mimics MoO3/MIL-125-NH2 were reported and conjugated with bacteriophages as a new electrochemical probe for high sensitivity and specific electrochemical detection of staphylococcus aureus. The excellent peroxidase-like activity of MoO3/MIL-125-NH2 composites was attributed to the integration of MIL-125-NH2 with MoO3, which can boost the generation of superoxide radicals (O• 2-) and thus promote the oxidation of TMB in the presence of H2O2. In this work, two bacteriophages named SapYZU04 and SapYZU10 were isolated from sewage samples by using staphylococcus aureus YZUsa12 as the host. In comparison, MoO3/MIL-125-NH2@SapYZU04 was selected as a recognition agent. The DPV current declined linearly with staphylococcus aureus YZUsa12 concentration in the range of 101-108 CFU mL-1, with a low detection limit of 16 CFU mL-1 (S/N = 3). 20 strains including 13 host strains and 7 non-host strains were used to evaluate the selectivity of the proposed sensor. Regardless of the differences in the degrees of lytic performance for phage SapYZU04, all selected host strains can be screened with merely the same DPV current. Host spectrum-oriented bacteriophage sensing is of great importance for the practical application of bacteriophage-based biosensors in the future.

Demographic profiles and risk factors for mortality in acute meningitis: A nationwide population-based observational study

Aim

Acute meningitis encompasses bacterial, viral (aseptic), fungal, tuberculous, and carcinomatous meningitis. The rate and risks of mortality in each type remain uncertain. This study aimed to elucidate these aspects in each type of meningitis.

Methods

This study utilized Japan's nationwide administrative Diagnosis Procedure Combination (DPC) database. Patients with acute meningitis, treated at 1132 DPC-covered hospitals from 2016 to 2022, were enrolled.

Results

Among 47,366,222 cumulative hospitalized patients, 48,758 (0.10%) were hospitalized with acute meningitis. The types of meningitis were as follows: 10,338 with bacterial, 29,486 with viral/aseptic, 965 with fungal, 678 with tuberculous, and 3790 with carcinomatous meningitis. Bacterial and viral meningitis exhibited bimodal age distributions, with the first peak occurring at 0-9 years. The median onset age was below 50 years only in viral meningitis. The mortality rate was the highest in carcinomatous meningitis (39%), followed by fungal meningitis (21%), and the lowest in viral meningitis (0.61%). Mortality rates increased with age across all meningitis types, but this trend was less prominent in carcinomatous meningitis. The duration from admission to mortality was longer in fungal and tuberculous meningitis compared with other types. Staphylococcus aureus in bacterial meningitis (adjusted odds ratio 1.71; p = 0.0016) and herpes simplex virus in viral meningitis (adjusted odds ratio 1.53; p = 0.0467) exhibited elevated mortality rates.

Conclusion

Distinct demographic profiles and mortality rates were observed among different meningitis types. The high mortality rates in less common types of meningitis emphasize the necessity to further optimize the required diagnostic and treatment strategies.