Detection of Naganishia albida Yeasts in Dermatological Patients.

The yeasts Cryptococcus albidus (Naganishia albida) usually occur on natural substrates and rarely are the etiological factor of different mycoses. More than a half of mycosis cases described in the literature were reported during the period from 2004 to 2021. In this regard, evaluation of yeast sensitivity to antimycotic drugs is as important as their identification. In the present study, two yeast isolates from the skin of female patients (age 7 and 74 years) with infective dermatitis (ICD-10-CM Code L30.3) were studied. Common identification of the isolates, MALDI-TOF mass spectrometry, and analysis of the nucleotide sequences of the ITS1-5.8S-ITS2 rDNA region showed that they belong to the species N. albida. The sensitivity of the obtained strains to antimycotics of three different chemical groups, namely itraconazole, naftifine, and amphotericin B, determined by microdilution method in a synthetic medium showed the following minimum inhibitory concentrations: 64-128, 16, and 0.125-4 µg/ml, respectively. It was found that the sensitivity of this yeast to pooled human serum was 30-47%, i.e. lower by 1.9-2.9 times than the sensitivity of the collection strains of C. albicans and C. neoformans. This result could be explained by lower prevalence of N. albida in the human population in comparison with these species. However, the sensitivity of N. albida strains to the low-molecular-weight fraction of serum was approximately the same as in C. albicans and C. neoformans, which indicates their high sensitivity to antimicrobial peptides.

[Vaccination with virus-like particles containing hemagglutinin protects the lungs of mice with postifluenza bacterial pneumonia: virological, microbiological and clinical data].

INTRODUCTION: Influenza is a severe viral disease, a frequent complication of which is a secondary bacterial pneumonia. Influenza vaccines prevent secondary bacterial complications. Virus-like particles are one of the promising areas for the development of new vaccines. The aim of this work is to study the correlation of the pathomorphological characteristics of the lungs with clinical, virological, and microbiological markers of the disease at vaccination with virus-like particles (VLPs), containing hemagglutinin (HA) of influenza virus (HA-Gag-VLPs) in a murine model of secondary bacterial pneumonia induced by S. pneumoniae after influenza infection. MATERIAL AND METHODS: BALB/c mice were vaccinated with VLPs containing influenza HA. After 21 days, mice were infected with two strains of influenza viruses, homologous and non-homologous, and 5 days after viral infection, were infected with S. pneumoniae. The vaccination effect was evaluated by morphological, virological (titer of the virus in the lungs) and microbiological (titer of bacteria in the lungs) data, and was confirmed by clinical data (survival, change in body weight). RESULTS: Immunization with HA-Gag-VLPs, followed by infection with a homologous influenza virus and S. pneumoniae, reduced the area of foci of inflammation, inhibited the replication of the virus and bacteria in the lungs, and also protected animals from death and reduced their weight loss. Immunization with HA-Gag-VLPs upon infection with a heterologous strain and S. pneumoniae did not affect these criteria. CONCLUSION: The immunization with HA-Gag-VLPs prevented the viral replication, providing a reduction of S. pneumoniae titer and the degree of lung damage, protecting animals from the disease in a murine model of secondary bacterial pneumonia, induced by S. pneumoniae, after influenza infection with homologous strain of the virus.

[Influence of stressors on formation of uncultured microorganism forms and their recovery].

Data of the last decade on the studies of influence of various inductors of microorganism uncultured state and reasons of reversion that include not only effect of appropriate cultivation conditions but also simple cancellation of unfavorable effects are analyzed. Reasons for transition to uncultured state are discussed; those could be a variety of factors such as heat, alkaline, acid and osmotic stress. Factors that promote recovery from uncultured state with the main being Rpf (Resustication promoting factor) factor isolated from Micrococcus luteus and cancellation of endogenic peroxide effect by addition of catalase and sodium pyruvate are analyzed.

Congenital immune defense of the hair.

Studies of two recent decades provided ample data on antibacterial peptides protecting animal and human epithelium of different types; however, no reports about the presence of these compounds in hair keratinocytes appeared up to the present time. Peptides were extracted from specimens of normal intact hair with citric acid solution in 50% ethanol. Antibacterial activity of the resultant extracts was evaluated on Candida albicans test culture by staining and microscopy, by evaluation of growth inhibition zones, and by inoculations. Direct contact with the extract destroyed the greater part of Candida albicans cells up to complete destruction of membranes. Application of the extract to dishes with agar with Candida albicans led in the formation of apparent zones of growth inhibition. The percentage of killed cells increased with prolongation of incubation with the extract. Electrophoresis of hair extract showed bands characteristic of antibacterial peptides RNase, psoriasin, and ß-defensins. Removal of the peptides from the extract by filtration through membrane filter led to loss of its activity. The results indicate that human hair keratinocytes possess congenital antibacterial immunity.

[Assessment of rate of hydroxyl anions production by Helicobacter pylori in stomach].

Production of hydroxyl anions by tissue samples of pylorus mucous membrane obtained from 45 patients with gastric or duodenal ulcers was investigated. The production was estimated using the recently developed method based on measurement of rate of pH change in urea-containing reaction mixture. The rate of [OH-] generation as a result of H. pylori metabolism accounted on pylorus square varied from 0.4 to 1318.9 mcmol [OH-]/min, and in 90.2% of cases it did not exceed 128.1 mcmol [OH-]/min. This rate is comparable to mean rate of [H+] generation in stomach of healthy man--114.2-238.4 mcmol [H+]/min. Obtained results allow to conclude that this bacterium may participate in regulation of stomach acid-base balance.

Creation of a new synthetic medium for culturing Helicobacter pylori.

We developed a scheme of consecutive replacement of complex components of a known Brucella medium containing peptones and blood with simple analogs and created a synthetic medium for Helicobacter pylori culturing. H. pylori cells require hemic iron for their growth; an appreciable increment in biomass was ensured by hemoglobin, but not simpler hemocontaining compounds (hemin and cytochrome C). Glutamine (20 g/liter) was used as the main nitrogen-containing component, and other amino acids were added in trace amounts. Adhesion was provided by adding agarose gel (0.1%) also promoting the increase in biomass. The proposed medium of a certain chemical composition differs from the known foreign analogs by the presence of hemocontaining component (hemoglobin), short period of exponential growth, and appreciable accumulation of cell protein.

[Quantitative urease test for Helicobacter pylori infection in patients with gastric and duodenal ulcer].

The monitoring for the presence of H. pylori carrier state in a group of patients with gastric and duodenal ulcer was carried out with subsequent determination of the relationship between the intensity of the urease activity of the bioptic specimen of the mucous membrane and the severity of the course of the disease. For this purpose we developed the scheme for the evaluation of the severity of the disease with quantitative criteria. The data obtained in this work showed no correlation between the severity of this disease and usease activity. Still the method of the quantitative determination of the urease activity of the bioptic specimen made it possible to evaluate the rate of the production of hydroxyl anions by a given H. pylori strain and thus quickly establish the presence of carrier state.

A method for estimation of urease activity in gastric mucosa biopsy specimens and Helicobacter pylori cell suspensions.

A method for measuring urease activity in biopsy specimens and Helicobacter pylori cultures from these specimens is proposed. The method is based on measurement (with a portable pH-meter) of the rate of pH changes in a reaction mixture consisting of buffer, substrate (urea), and biopsy specimen or bacterial cells. This method revealed that urease activity of biopsy specimens correlated with that of H. pylori suspension in the same experiment. High urease activity was found in biopsy specimens containing the greatest number of Helicobacter cells; only one of 14 specimens free of H. pylori cells showed no urease activity. Introduction of this method into clinical practice will help to evaluate the contribution of H. pylori to the pathological process.