Synthesis, spectral properties and antimicrobial activity of a new cationic water-soluble pH-dependent poly(propylene imine) dendrimer modified with 1,8-naphthalimides.

A three-step synthesis was implemented to prepare a quaternary ammonium functionalized blue fluorescent poly(propylene imine) dendrimer modified with pyridinium salt of 4-acylamino-1,8-naphthalimide. The new cationic dendrimer absorbs in the ultraviolet light region and emits blue fluorescence. Its spectral characteristics in organic solvents and in an aqueous solution were studied. The influence of pH on the fluorescence intensity of the dendrimer was established with regard to its use as a pH sensor. The effect of hydroxyl ions on the absorption and fluorescence spectra in dry N,N-dimethylformamide was also investigated. The antimicrobial activity of the dendrimer was assessed against model pathogenic microorganisms in agar, liquid medium, and after its deposition on cotton fabric.

Precious metal-free molecular machines for solar thermal energy storage.

Four benzothiazolium crown ether-containing styryl dyes were prepared through an optimized synthetic procedure. Two of the dyes (4b and 4d) having substituents in the 5-position of the benzothiazole ring are newly synthesized compounds. They demonstrated a higher degree of trans-cis photoisomerization and a longer life time of the higher energy forms in comparison with the known analogs. The chemical structures of all dyes in the series were characterized by NMR, UV-vis, IR spectroscopy and elemental analysis. The steady-state photophysical properties of the dyes were elucidated. The stability constants of metal complexes were determined and are in good agreement with the literature data for reference dyes. The temporal evolution of trans-to-cis isomerization was observed in a real-time regime. The dyes demonstrated a low intrinsic fluorescence of their Ba2+ complexes and high yield of E/Z photoisomerization with lifetimes of the higher energy form longer than 500 seconds. Density functional theory (DFT) calculations at the B3LYP/6-31+G(d,p) level were performed in order to predict the enthalpies (H) of the cis and trans isomers and the storage energies (ΔH) for the systems studied.

Halogen-containing thiazole orange analogues - new fluorogenic DNA stains.

Novel asymmetric monomeric monomethine cyanine dyes 5a-d, which are analogues of the commercial dsDNA fluorescence binder thiazole orange (TO), have been synthesized. The synthesis was achieved by using a simple, efficient and environmetally benign synthetic procedure to obtain these cationic dyes in good to excellent yields. Interactions of the new derivatives of TO with dsDNA have been investigated by absorption and fluorescence spectroscopy. The longest wavelength absorption bands in the UV-vis spectra of the target compounds are in the range of 509-519 nm and these are characterized by high molar absorptivities (63000-91480 L·mol-1·cm-1). All investigated dyes from the series are either not fluorescent or their fluorescence is quite low, but they become strongly fluorescent after binding to dsDNA. The influence of the substituents attached to the chromophores was investigated by combination of spectroscopic (UV-vis and fluorescence spectroscopy) and theoretical (DFT and TDDFT calculations) methods.

Beijing lineage of MDR Mycobacterium tuberculosis in Bulgaria, 2007-2011.

To assess the spread of the Mycobacterium tuberculosis Beijing genotype among patients with multidrug-resistant and extensively resistant tuberculosis in Bulgaria, we genotyped 188 (72%) of 261 microbiologically confirmed resistant isolates obtained during 2007-2011. The estimated prevalence of the Beijing genotype among these patients was 3.2%.

Comparison of health-related quality-of-life measurement instruments in diabetic patients.

The objective of the study was to compare three different questionnaires (Short Form (SF)-6D, EuroQuol (EQ)-5D and WHO-5) to establish which one is more sensitive and which one gives an adequate assessment of the quality of life in patients with diabetes. In an observational and transversal study with duration of 4 months, in 5 Bulgarian cities, 146 patients were randomly selected. The following quality-of-life measuring instruments were applied: 146 questionnaires SF-6D, 146 questionnaires EQ-5D and 103 questionnaires of WHO-5. Descriptive statistics, chi-Square and correlation coefficients were used for data analysis. The study assessed the quality of life of patients suffering from diabetes mellitus with a mean age of 57.39 years (standard deviation (SD) 17.087); 95% confidence interval (CI) 54.60-60.19; 76% of the patients had diabetes type 2. The patients received a mean SF-6D score of 0.6290, an EQ-5D score of 0.6272, a visual analogue scale score of 0.7158 and a WHO-5 score of 0.4635. Preferences measured by the SF-6D and by the EQ-5D showed significant correlations with one another, and the Pearson coefficient was r = 0.906 (p < 0.01). The most current version of SF-6D, based on the 2002 model, was found to be valid and reliable when compared to the EQ-5D and is a questionnaire alternative to assess preferences in economic analysis carried out in health care.

Mycobacterium intracellulare among TB suspected patients in Bulgaria - microbiological aspects.

INTRODUCTION: Nontuberculous mycobacteria (NTM) are representatives of the genus Mycobacterium with a worldwide distribution, associated mainly with water, soil, and biofilms. Some of NTMs, such as Mycobacterium avium complex (MAC), are etiological agents of human diseases - disseminated or with different localization, most often pulmonary. AIM: In the present study, we analyzed Mycobacterium intracellulare isolates recovered from clinical specimens of tuberculosis (TB) suspected patients in Bulgaria, 2018-2020. MATERIALS AND METHODS: The cultures were grown on solid and liquid media. For species identification, we used immune chromatographic (TB Ag MPT64) test and Line Probe Assay (LPA) from the positive cultures. RESULTS: M. intracellulare was identified in 32 patients from 82,780 specimens. It was predominantly isolated in females - 62.5% vs. 37.5% in males. The most affected age group was 65 years and over (38%). The distribution of the isolates in Bulgaria was uneven. Most of them (65.6%) were concentrated in two districts of the country: Plovdiv and Sofia-city. All strains were sensitive to macrolides and aminoglycosides except one with macrolide resistance. NTM pulmonary disease was confirmed in 16 patients with M. intracellulare isolate. CONCLUSIONS: Analysing the 32 M. intracellulare isolates identified among TB suspected patients in Bulgaria between 2018 and 2020, we found that only half of them met the American Thoracic Society (ATS) diagnostic criteria for NTM pulmonary disease. For the remaining patients with M. intracellulare isolates we did not have sufficient data to support this diagnosis. Efforts by Bulgarian respiratory and microbiological societies are needed for adherence to the international guidelines.

Whole genome sequencing of Bulgarian rifampicin resistant Mycobacterium tuberculosis strains.

INTRODUCTION: The transmission of drug-resistant tuberculosis is one of the greatest challenges facing the global tuberculosis control. AIM: The aim of the study was to investigate the resent transmission of rifampicin resistant tuberculosis in Bulgaria and to describe the mutations related to the antimicrobials' resistance using whole genome sequencing. MATERIALS AND METHODS: As part of an ECDC funded pilot study for evaluation of the systematic use of whole genome sequencing (WGS) of Mycobacterium tuberculosis (MTB) surveillance (EUSeqMyTB), Bulgaria provided 65 rifampicin resistant isolates over a three years' timeframe (2017-2019) representing 87.5% of the notified rifampicin resistant cases. Drug resistance prediction and relatedness analysis of the resistant isolates was performed in collaboration with San Raffaele Scientific Institute, Milan, Italy. RESULTS: Almost all of the isolates were identified as Euro-American lineage (96.9%); 18.5% of the isolates were found to be resistant to fluoroquinolones, but no mutations conferring resistance to bedaquiline or linezolid could be identified. Less than half (43.3%) of the isolates were clustered (<5 SNPs distance) into a total of seven national SNP-based clusters, while a total of six isolates were found to be part of different cross-border clusters. All clustered cases originated from Bulgaria. CONCLUSIONS: WGS has proven to be a reliable tool for surveillance and tracing of recent transmission of tuberculosis and has the potential for resistance prediction for most of the antituberculosis drugs.

First Etiologically Confirmed Cases of Mycobacterium Marinum Infection in Bulgaria.

This study aimed to describe the first two microbiologically confirmed cases of cutaneous and soft tissue Mycobacterium marinum infection in Bulgaria. The isolation of the Nontuberculous Mycobacteria (NTM) strains and their species identification was performed at NRL TB, NCIPD using specific media and cultivation conditions, and PCR based Line Probe Assay (LPA) from the positive cultures. The two patients had closely related jobs to fishes and water reservoirs and both of them had a similar clinical manifestation of M. mari-num infection known as "swimming pool" or "fish tank" granuloma. The prolonged specific treatment with at least two-drug combina-tion of rifampicin plus ethambutol and some complications were a big challenge for clinicians as well as the patients.