Antimicrobial Activity of Milk Whey in Different Mammals.

Antimicrobial activity of milk whey in different mammals against Candida albicans yeast cells was studied by a spectrophotometric method. The activity increased in the order goat→horse→camel→cow→human→mouse. The level of whey activity in mice was higher by 3 and 10 times than in humans and goats, respectively. Similar changes were noted for activity of the whey fraction <100 kDa containing a complex of antimicrobial polypeptides, and there was a direct correlation between these two parameters (r=0.881; p<0.05). The total activity of whey had a high degree of correlation with the content of serum albumin (r=0.992); in mice, the level of serum albumin in the milk whey was close to that in blood serum. Interspecific differences between the activity of whey in mammals may be associated with qualitative and quantitative variability of the antimicrobial polypeptide composition, as well as their synergistic or antagonistic interaction with each other.

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.

Antimicrobial Activity of the Serum before and after Vaccination with EpiVacCorona.

We evaluated the effect of vaccination with anti-COVID-19 vaccine EpiVacCorona on serum antimicrobial activity, formation of specific IgG antibodies, and expression of some antimicrobial peptides. Antimicrobial activity of the serum from 55 volunteers towards S. aureus cells was measured spectrophotometrically; IgG-antibodies against SARS-CoV-2 antigen were assayed by ELISA; expression of genes encoding antimicrobial peptides LL37, HBD1, and HBD2 was evaluated by PCR with reverse transcription. Total antimicrobial serum activity and activity of its low-molecular-weight fraction containing antimicrobial peptides demonstrated an inverse correlation. Both activities after vaccination increased in case of low initial values, but decreased in case of high initial values. The vector of change of specific IgG antibodies to coronavirus inversely correlated with the vector of change of activity of antimicrobial peptide fraction. The expression of genes of antimicrobial peptides LL37, HBD1, and HBD2 looked like normal distribution depending on activities of the antimicrobial peptides in the corresponding sera.

Alternative Methods of Evaluation of Antimicrobial Activity of Breast Milk Serum.

Antimicrobial properties are traditionally evaluated by the seeding technique, which is laborious, time-consuming, and rather imprecise. We studied the possibility of using microscopy and spectrophotometry methods for evaluation of cytotoxic activity of breast milk serum against opportunistic microbes. Activity of 50 breast milk samples obtained from healthy women at different lactation stages was tested against opportunistic yeast C. albicans. Microscopy showed that incubation of cell suspension with lactoserum led to destruction of cell walls and cytoplasmic membranes with the formation of vesicular debris that absorbed the dye from the medium. Spectrophotometric measurement of the dye remained in the medium revealed a dose-depended effect of the lactoserum on C. albicans cells and strong inverse correlation between the lactation period and cytotoxic activity of the lactoserum (r=-0.948). These methods can be used in veterinary and food processing for estimation of biological activity of milk.

Method of salivary histatins determination.

Histatins are the most significant antimicrobial peptides (AMP) of saliva and there are 12 types of such AMP. Histatin molecules contain relatively high percent of histidine and tyrosine residues. This property allows to use well known from organic chemistry Pauly reaction for detection of protein bounded histidine and tyrosine residues (BHT), which are in fact characterize the summary content of all histatins in saliva. Aim of the present study was comparison of BHT with antimicrobial activity of salivary AMP fraction in patients with inflammatory diseases of upper airways (IDUA). Group of examined persons include 28 patients with different diagnoses: chronic pharyngitis (n=11), chronic tonsillitis (n=7), nasopharyngitis (n=5), pollinosis (n=5). Degree of intensity of inflammatory symptoms was estimated in balls. The algorithm of BHT analysis include following steps: freezing - thawing of saliva; removal of microparticles by centrifugation; separation of fraction lower than100 kDa; dialysis for free amino acids removal; Pauly reaction carrying out. Antimicrobial activities of saliva and its low molecular fractions were estimated towards Candida albicans cells by the spectrophotometric method with bromocresol purpur. Analysis of saliva sediments for coccoid microbiota was carried out by PCR method. Pauly reaction for histatins estimation in saliva of IDUA patients use here for the first time. The histatins levels (BHT) were significantly correlated with the intensity of inflammatory symptoms (r=0,975) and activity of low molecular salivary fraction (AMP activity) (r=0,824). The AMP activity/ BHT ratio, i.e. antimicrobial activity of histatin unit, decreased together with growth of inflammatory symptoms intensity (r=-0,944). Any considerable differences in coccoid microbiota frequency of finding at different diagnoses were not detected. The S. aureus frequency of occurrence was connected neither with inflammatory symptoms intensity (r=0,118), nor with BHT concentration (r=0,318). However S. pyogenes and S. pneumoniae frequencies of occurrence demonstrated the invert correlation towards these indexes: (r=-0,627/-0,614) and (r=-0,827/-0,864). Probably at the exacerbation forms of IDUA the S. pyogenes and S. pneumoniae growth controlled by high levels of histatins.