We studied the sensitivity of clinically significant (opportunistic) bacteria to blood serum fraction with a molecular weight <100 kDa containing antimicrobial peptides and proteins. The degree of damage to cytoplasmic membranes of bacterial cells was assessed by a spectrophotometric method. A total of 129 bacterial isolates belonging to 46 species, 19 genera, 13 families, 8 orders, 4 classes, and 3 types were studied. The mean sensitivity varied from -5.2 to 36.6%. The sensitivity depends on the structure of bacterial cell wall: higher sensitivity was demonstrated by taxonomic ranks related to gram-negative bacteria (median 19.1%) and lower values were observed in gram-positive bacteria (median 9.3%) (p<0.01). Among all orders, Lactobacilliales showed the lowest sensitivity (3.6%). Ranking of the studied species by their sensitivity showed that 7 of the first 15 species with sensitivity >19% are among to the leading causative agents of sepsis.

The species identity of the studied lactobacillus strains was confirmed by matrix-activated laser desorption/ionization with time-of-flight ion separation (MALDI-TOF mass spectrometry). Lactobacillus strains differed in the dynamics of lactic acid accumulation and changes in the pH of the culture medium. The culture medium affected adhesion ability of lactobacilli. The ability to adhere does not affect the formation of biofilms by lactobacillus strains except for the L. acidophilus La5 strain, which has low adhesion ability and fewer microbial cells detected after mechanical destruction of the biofilm. The metabiotics of the lactobacillus culture medium have an antagonistic effect on conditionally pathogenic microorganisms. Adhesion, biofilm formation, and antagonistic activity of probiotic lactobacillus strains are strain-specific properties.

BACKGROUND: Oral lichen planus is a chronic inflammatory condition of the oral mucosa characterized by white, lacy lesions. The etiology of oral lichen planus is complex and remains unclear, but it is thought to be a T-cell mediated autoimmune disease. Several factors have been implicated in the pathogenesis of oral lichen planus, including genetic predisposition, dental materials, iatrogenic factors, infections, autoimmunity, and bowel disease. The microflora of the oral cavity plays an important role in maintaining oral health and preventing disease. However, its role in the development and progression of oral lichen planus is not yet totally understood. Some studies have shown that there are differences in the microflora of oral lichen planus patients compared to healthy controls. These differences may be related to the inflammatory process in oral lichen planus, or they may be a contributing factor to the disease. AIM: Identify the prevalence of the detection of periodontopathogenic microorganisms in oral lichen planus patients and compare their prevalence in healthy non-oral lichen planus patients. MATERIALS AND METHODS: A cross-sectional, single-center study was conducted. A total of 75 patients were recruited, 45 with oral lichen planus and 30 healthy controls. The groups were formed by simple random sampling. The diagnosis of oral lichen planus was confirmed histologically in the main group. The forms and localization of oral lichen planus were determined in the main group based on clinical examination. In the control group, patients were divided into two subgroups depending on the presence of chronic periodontitis or gingivitis. The prevalence of periodontal pathogens was assessed based on the analysis of culture results. Among the 48 bacteria isolated from the oral mucosa of the affected site in the main and control groups, we focused on the microbiota of only periodontal bacteria to study their role and assess their impact on disease progression. RESULTS: Among the 45 patients with a clinical diagnosis of oral lichen planus, there were 10 (22.22%) men and 35 (77.78%) women, with a mean age of 55.3±13.4 years. The control group included 30 healthy volunteers, 8 (26.67%) men and 22 (73.33%) women, with a mean age of 54.8±12.7 years. In patients with oral lichen planus regardless of their periodontal status the percentage of seropositivity for A. actinomycetemcomitans, V. parvula, P. gingivalis, T. denticola is higher compared to their healthy counterparts with gingivitis and periodontitis. CONCLUSION: The study found an increased frequency of detection of pathogenic microorganisms, such as A. actinomycetemcomitans, V. parvula, P. gingivalis, and T. denticola, in patients with oral lichen planus, regardless of the presence of periodontitis. These periodontopathogens may be associated with oral lichen planus. However, further studies are needed to clarify their role in the pathogenesis of the disease.

Today, the proportion of elderly and senile people is steadily growing throughout the world. The most important factors in the first line of immune defense of the mucous membranes of the upper respiratory tract are β-defensins, which are a group of secretory proteins with antimicrobial activity. The aim of this study was to study the expression of genes for antimicrobial peptides β-defensins and the composition of the microbiome of the mucous membranes of the upper respiratory tract in elderly people and long-livers with various aging phenotypes.The main study group included 67 centenarians and 49 elderly people, who were further divided into two subgroups depending on the course of aging (pathological and successful aging). Nucleic acids were isolated from nasopharyngeal scrapings and the expression levels of the DEFB1 and DEFB4 genes were determined using real-time polymerase chain reaction. The composition of the microbiota in nasopharyngeal swabs was determined by MALDI-TOF mass spectrometry.In analyzing the expression of the DEFB1 gene in elderly people and centenarians with successful and pathological aging phenotypes, no difference was revealed between the groups. Expression of the DEFB4 gene was increased in centenarians with pathological aging compared to centenarians with successful aging and in the elderly group. Excessive production of antimicrobial peptides is dual in nature; on the one hand, they provide the first line of defense against microorganisms, and on the other, they are cytotoxic to their own cells. An increase in the expression of the DEFB4 gene during aging may be due to an increase in the number of pathogen-associated molecular patterns, which can be one’s own microbiota and/or components of microbial metabolism. Analysis of the microbiota composition showed an increase in biodiversity in individuals with a successful aging phenotype compared to a pathological phenotype. Particular attention is paid to Staphylococcus spp., the species composition of which depends on the aging phenotype. In the pathological aging group, the frequency of St. aureus colonization is significantly higher than in the successful aging group.Thus, overexpression of the DEFB4 gene and changes in the composition of the microbiota of the mucous membranes of the upper respiratory tract may be one of the mechanisms explaining the increased susceptibility to infections in various aging phenotypes.

BACKGROUND: Autoimmune pemphigus is a group of severe, potentially fatal bullous dermatoses affecting both skin and mucous membranes. To date, the pathogenesis and therapeutic approaches to the disease have been well studied; despite this, secondary bacterial complications remain the leading cause of death in these patients. Study of qualitative and quantitative composition of skin microbiome in chronic dermatoses is an actual contemporary problem. These data allow one to investigate the influence of microorganisms on the disease severity, relapse rate and remission duration. Analysis of literature sources shows a high interest of scientific groups in the study of microbiome components of the skin and mucous membranes in patients with bullous dermatoses, however, similar works on autoimmune bullous vesicles are still limited. AIM: to compare the composition of the skin microbiome in patients with autoimmune pemphigus and a healthy control group based on the results of the culture method performed. MATERIALS AND METHODS: Experimental, prospective, comparative study. Seventeen patients with previously or first-time diagnosis of autoimmune vesicular disease, as well as a control group of 10 people were included in the study. Patients were enrolled between November 2021 and November 2022. Rakhmanov clinic. All study participants had their skin swabs taken (for patients with rash elements and with apparently unchanged skin in the back or chest area; for the control group, from healthy skin in the back area), after which the material was taken to the laboratory for culture study. RESULTS: Data from 17 patients (5 men, 29.5%; and 12 women, 70.5%; average age 5113.3 years) were analyzed. Also included were 10 individuals from the control group (7 women, 70%; and 3 men, 30%; mean age 4014.7 years). Bacterial growth was detected in all samples submitted. No other microgranisms were identified. Eleven bacterial species were detected on the skin from the rash elements. The most frequent species encountered were: Staphylococcus aureus (in 70.59% of patients), Staphylococcus epidermidis (35.3%), Staphylococcus hominis (17.63%), Staphylococcus haemolyticus and Corynebacterium aurimucosum (11.8%). Twelve bacterial species were isolated on visibly unchanged skin. The most frequent were S. epidermidis (52.9%), S. aureus and S. hominis (35.3%), Staphylococcus capitis and Staphylococcus warneri (17.65%), Micrococcus luteus (11.76%). Fifteen bacterial species were identified in the control group. The following species were found most frequently: S. hominis (60%), S. capitis (50%), M. luteus (40%), S. epidermidis, S. haemolyticus and S. warneri (20%). The mean value of bacterial colony-forming units per 1 ml on rash elements was 5106.338752.46; on visibly unchanged skin 593.231223.06; in the control group 349.33915.52. CONCLUSIONS: We were able to obtain primary data on the composition of the skin microbiome in 17 patients with various types of autoimmune pemphigus and compare them with the control group. The data obtained demonstrate a great variety of microbial communities on the skin and a significant quantitative difference in the composition on the skin of patients and controls. A limitation of the study is the chosen cultural method, which cannot fully reflect all the diversity of microorganisms. To confirm the hypotheses put forward, we plan to conduct an additional study involving a larger number of patients and using genomic sequencing methods to identify microbial communities.

Background. Atopic dermatitis is an inflammatory skin disease characterized by recurrent lesions and intense pruritus. Nowadays there is a stepwise approach to the treatment of atopic dermatitis, which is defined by disease intensity and complications such as secondary skin infections. However, the current management of atopic dermatitis may not always lead to the expected outcome due to not only immune dysregulation of both adaptive and innate immunity but also imbalance of the skin microbiome. Aims. The aim of the study was to evaluate changes in the composition of the skin microbiome in both lesional and non-lesional skin in patients with atopic dermatitis during standard treatment. Materials and methods. Twenty patients with atopic dermatitis and twenty six healthy controls over 18 years old were included into the study. All microbiome samples were obtained from lesional and non-lesional skin sites of atopic dermatitis patients before and after therapy. Whereas samples from healthy controls were taken once from a flexor surface of the elbow. Species identification of clinical isolates were identified using MALDI Biotyper Sirius (Bruker Daltonics). Results. At baseline, the prevalence of S. aureus colonization among patients with atopic dermatitis was 34.20% in lesional skin and 32.50% in non-lesional skin. After treatment, there was a significant decrease in the prevalence of S. aureus carriage in both lesional and non-lesional skin areas (р 0.05). However, no significant difference was observed in the proportion of all other staphylococci (р 0.1). Interestingly, S. aureus was not found in healthy controls. Conclusions. The results of the study demonstrated the effectiveness of standard therapy for managing patients with atopic dermatitis as it had a positive impact on the skin microbial community and showed a decrease in S. aureus proportion after the treatment.

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.

Relevance . Nowadays, in oral surgery, it is still relevant to increase the effectiveness of collagen membranes in the oral cavity in the condition of potential microbial contamination of the wound. Purpose . The study aimed to conduct a comparative analysis of the growth of opportunistic oral bacteria on various collagen membranes. Material and methods . Based on the I.I. Mechnikov Research Institute for Vaccines and Sera, the study conducted a comparative analysis of the growth of opportunistic oral bacteria on the surface of resorbable collagen membranes developed by the Institute of Regenerative Medicine of the Sechenov University and an already existing foreign alternative. Microbial growth was assessed for S. aureus, S. mutans and C. albicans as the most significant microorganisms isolated from the oral cavity. The quantitative composition of microorganisms was analyzed in the control group without membranes and in groups with membranes (Group 2 – customized collagen membrane 2, Group 3 – membrane 3 with recombinant human lactoferrin, Group 4 – Mucograft membrane) on days 3, 5, and 7 from the start of membrane surface colonization. In all groups, we also evaluated the pH change in a 10% sucrose solution under the influence of biofilm microorganisms. Statistical data processing included the calculation of mean, standard deviations and medians, and comparison between groups was carried out using the Kruskal-Wallis test after assessing the samples' distribution normality. The results were statistically significant at a minimum of 95%. Results . The performed analysis showed statistically significant differences in the quantitative composition of the microbial biofilm on the surface of all three membranes. The developed collagen membrane with lactoferrin showed the best result at all times, while the customized collagen membrane did not significantly differ from the Mucograft membrane in CFU values and medium pH change. This provision was statistically significant for all three studied microorganisms. Conclusion . The study showed the potential of using manufactured collagen membranes to eliminate soft tissue defects in the oral cavity under the condition of their surfaces' possible contamination as an alternative to foreign membranes.

Background. Autoimmune pemphigus (AP) is a chronic, life-threatening disease of the skin and mucous membranes. Effective therapeutic options are currently available, but mortality in AP patients is higher than in the general population. The leading causes of death are infectious complications. Recent years have revealed the key role of microbiome alteration in a number of skin diseases. There is an increasing number of published studies examining the skin microbiome in patients with AP, but they have a number of limitations and require further research to understand the role of skin microbial composition in the course of AP. Aims: to study the composition of skin microbiome by culture method in patients with AP (in active stage and in remission), to perform correlation analysis of microbiome composition and therapy received. Materials and methods. Experimental prospective comparative study. Forty-four patients with diagnosed AP (16 men, 36.4%; 28 women, 63.6%; mean age 51.5±13.1 years) and 10 controls (7 women, 70%; 3 men, 30%; mean age 40±12.5 years) were included. Patients were enrolled between November 2021 and June 2023 at the V.A. Rakhmanov Clinic of Skin and Venereal Diseases. Results. Seventy-nine skin samples were obtained and analysed. Only bacterial growth was detected in all submitted samples. No statistically significant difference was found between the composition of the microbiome of the unchanged skin of patients with AP in the active stage and in remission and the control group. In patients in the active stage of AP, a significant difference was found between the composition of the microbiome from rash elements and unchanged skin. S. aureus prevails on the skin from rash elements, and S. hominis dominates on unchanged skin. In patients before the start of glucocortlcosteroid (GCS) therapy, a predominance of S. aureus in the samples and a decrease in microbial diversity is noted. In patients receiving GCS therapy, S. hominis and S. epidermidis predominate, and greater microbial diversity is also noted. Conclusions. The study revealed that the skin microbiome from the rash elements of patients with AP undergoes significant changes during the active stage of the disease, mainly due to colonisation of the skin by S. aureus. However, against the background of therapy with systemic GCS there is a tendency to normalisation of skin microflora composition, which demonstrates that there are no differences in the composition of the microbiome of patients in remission of AP and control groups.

Influenza is one of the most urgent global health problems today. The influenza virus has immunosuppressive properties, which can lead to the development of secondary immunodeficiencies, interfering with the functioning of the interferon system activation, thus leading to impaired production of pro-inflammatory cytokines. IL-1 is the most important player in development of antiviral immunity. This cytokine plays an important role in boosting the expression of the MCP-1 and MCP-3 genes and maturation of macrophages and dendritic cells. Induction of IL-1 production occurs due to interaction of the ligand with Toll-like receptors. Currently, there is a lot of drugs aimed at the prevention and treatment of influenza infection. However, their use in some cases is difficult due to high mutational variability of the influenza virus, thus making it resistant to these drugs. Therefore, the issue of developing and creating effective methods to combat such infections is of particular importance. A promising approach to the treatment and prevention of viral respiratory infections may be connected with RNA interference. This process consists of degradation of foreign mRNA by small interfering RNA (siRNA) molecules. The aim of the present study was to evaluate expression of the IL-1 gene upon transfection of miRNA complexes directed to the cellular FLT4, Nup98, Nup205 genes. Evaluation of changed viral reproduction was carried out using titration by CPE virus-containing fluid. Expression level of the IL-1 gene was determined by means of real-time RT-PCR. Assessment of the changes in viral reproduction allowed us to reveal that the use of all the miRNA complexes directed to the cellular genes lead to a significant decrease in viral reproduction on the 1st day after infection. Usage of Nup205 + FLT4 and FLT4 + Nup205 + Nup98 complexes proved to cause a decrease in viral reproduction on the second day as well (p 0.05), as compared with nonspecific and viral controls. When analyzing expression profile of the IL-1 gene, an increase in its expression was observed on the 1st day for all miRNA complexes and on the 2nd and 3rd days for the Nup98 + FLT4 and Nup205 + Nup98 complexes. In the course of the study, it was found that suppression of the cellular genes FLT4, Nup98 and Nup205 activities, which are necessary for viral reproduction, led to a significant decrease in viral activity and an increase in IL-1 expression.

Atopic dermatitis (AD) is a multifactorial genetically determined inflammatory skin disease characterized by itching, chronic course, age-related features of localization and lesion morphology. Atopic dermatitis is caused by complex interactions between genetic, immunological, and environmental factors. The barrier function of the skin is impaired in atopic dermatitis. Antimicrobial peptides, e.g., LL-37, b-defensins are involved in maintaining the skin barrier function (especially, intercellular contacts). An imbalance of antimicrobial peptides may cause different disorders, including allergic pathologies. The aim of this study is to investigate gene expression profile of the HBD1 and LL37 encoding antimicrobial peptides in the samples of skin and blood mononuclear cells obtained from the children with moderate and severe atopic dermatitis before and after treatment. By means of real-time polymerase chain reaction, the levels of HBD1 and LL37 gene expression were evaluated in the samples. Statistical analysis showed significantly increased (p 0.017) expression levels of both HBD1 (H-test = 24.76; 2, n = 72; p = 0.00001), and LL37 genes (H-test = 15.69; 2, n = 72; p = 0.00039) in blood cells of AD patients compared to the control group, as well as decreased (p 0.05) levels of HBD1 expression in the affected skin compared to the control group. Our data on the cathelicidin gene in the skin do not differ from the literature data, since its expression is reduced in AD. In our series, an increase of the gene expression was revealed in PBMCs. The HBD1 peptide is expressed in both monocytes and macrophages, representing a link between innate and adaptive immunity. In our study, the expression of the HBD1 gene was increased only in blood, thus suggesting activation of innate immunity components at the systemic level in response to inflammation. Of importance, understanding the role of immunological markers in AD will help to develop novel prognostic approaches in management of the patients with atopic disorders. Therefore, one should understand pathogenetic mechanisms of allergic diseases.

Scientific relevance. A promising option for dysbiosis correction is the use of metabiotics, products based on metabolites of probiotic microorganisms. During fermentation, Bacillus subtilis bacteria (strains 3H and 1719) produce metabolites that exhibit probiotic properties in vitro. These observations in vitro motivate an in vivo investigation of B. subtilis metabolite effects on colonic mucosal microbiota in mice in experimentally induced dysbiosis and an assessment of the potential of B. subtilis metabolites as metabiotics.Aim. The authors aimed to compare the probiotic activity of B. subtilis 3H and B. subtilis 1719 metabolites and a commercial metabiotic in antibiotic-induced dysbiosis in mice.Materials and methods. The authors induced experimental dysbiosis in BALB/c mice weighing 18–20 g by intraperitoneal injection of gentamicin. For subsequent correction, the test groups received sorbent-bound B. subtilis metabolites, and the comparison group received a commercial metabiotic containing B. subtilis metabolites (VKPM B-2335(3)3) via intragastric injection for 21 days. The quantitative and qualitative analysis of colonic mucosal microbiota included microbial culturing and colony identification by MALDI-TOF mass spectrometry.Results. Antibiotic-induced colonic dysbiosis in mice manifested itself as a decrease in the dominant microbiota and an increase in opportunistic pathogens. After 7 days of metabolite administration, the Lactobacillus population returned to normal in all treatment groups. The mice that received B. subtilis 3H metabolites showed the best results: their Lactobacillus spp. composition corresponded to that of intact animals. The content of Lac+ Escherichia coli returned to 100% in all treatment groups. After 21 days of metabolite administration, the authors observed the elimination of bacteria (Rodentibacter spp., Aerococcus spp.) and fungi (Trichosporon spp., Kazachstania spp.) in the B. subtilis 3H group; Trichosporon spp. (no effect on Kazachstania spp.) in the B. subtilis 1719 group; and Enterococcus spp., Kazachstania spp., and Trichosporon spp. (no effect on Rodentibacter spp. and Aerococcus spp.) in the commercial metabiotic group.Conclusions. Metabolites of B. subtilis strains 3H and 1719 help to restore the diversity and abundance of colonic microbiota in antibiotic-induced dysbiosis. The differences observed in microbiota re-establishment in the treatment groups indicate that there is interstrain variability in the probiotic activity of B. subtilis metabolites.

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.

Aim. In this study we developed and characterized a mouse model of secondary S. aureus and S. pneumoniae pneumonia following influenza virus infection with H1N1 pandemic and laboratory strains and their reassortment. Materials and methods. BALB/с mice were infected intranasally with A/California/04/2009/(H1N1 pndm), A/Puerto Rico/8/34 or their reassortment NIBRG-121xp followed by different strains of S. аureus и S. pneumoniae. The pathogenicity of infection was assessed by mouse survival and weight change, viral titre and bacterial count in the lungs. Results. It was shown that the infection of mice with three strains of the H1N1 influenza virus with a comparable level of pathogenicity leads to a different severity of secondary bacterial infection. The mouse adapted A/California/04/2009 pandemic strain possessed the greatest ability to alter antibacterial immunity. Conclusion. An experimental model of post-influenza bacterial pneumonia utilizing three strains of the H1N1 influenza virus and various strains of S. aureus or S. pneumoniae was established. The ability of viruses to provoke bacterial superinfection of different severity is characterized.

индекса научного цитирования (РИНЦ)

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.

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 β-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.