Corynebacterium hindlerae sp. nov., derived from a human granuloma, which forms black colonies and black halos on modified Tinsdale medium but is not closely related to Corynebacterium diphtheriae and related taxa

Corynebacterium diphtheriae , Corynebacterium belfantii , Corynebacterium rouxii , Corynebacterium ulcerans , Corynebacterium pseudotuberculosis and Corynebacterium silvaticum are the only taxa from among ~121 Corynebacterium species deemed potentially able to harbour diphtheria tox genes. Subsequently tox-gene bearing species may potentially produce diphtheria toxin, which is linked to fatal respiratory distress if a pharyngeal pseudomembrane is formed or toxaemia develops in those unimmunized or under-immunized. Detection of diphtheria toxin-producing species may also invoke a public health response and contact tracing. Recovery of such species from the respiratory tract or other contaminated sources such as non-healing ulcerative wounds are expedited by use of differential and selective media such as modified Tinsdale medium (MTM). This medium is supplemented with potassium tellurite, which supresses most normal flora present in contaminated specimens, as well as l-cystine and thiosulphate. Most diphtheria-tox-gene bearing species grow well on MTM, producing black colonies with a black halo around each colony. This is due to an ability to produce cystinase in the presence of tellurite, cystine and thiosulphate, resulting in black tellurium deposits being observed in the agar. Other Corynebacterium species may/may not be able to grow at all in the presence of tellurite but if able to grow, will have small beige or brownish colonies which do not exhibit black halos. We describe here an unusual non-tox-gene-bearing isolate, NML 93-0612T, recovered from a human wrist granuloma, which produced black colonies with black halos on MTM agar but was otherwise distinguishable from Corynebacterium species which can bear tox genes. Distinctive features included its unusual colony morphology on MTM and sheep blood agar, by proteomic, biochemical and chemotaxonomic properties and by molecular methods. Its genome contained 2 680 694 bytes, a G+C content of 60.65 mol% with features consistent with the genus Corynebacterium and so represents a new species for which we propose the name Corynebacterium hindlerae sp. nov.

Allium sativum antimicrobial potential in fresh cheese

Cheese consumption has shown an important increase throughout the Brazilian territory, being the second most imported product since 2015. Among the different types of cheese, minas frescal represents one of the most popular, due to its simple processing, low cost and high yield. However, its perishability requires refrigeration and relatively fast consumption, thus representing an important limiting factor in commercialization. Aspects such as having a high moisture content, not undergoing maturation, and containing no preservatives, provide favorable conditions for microbiological contamination. Thus, it was aimed to assess the antimicrobial potential of the aqueous suspension of garlic (SAA), in fresh cheese before and after contamination Staphylococcus aureus (ATCC 25923) 105 CFU mL-1. The minimum inhibitory concentration (MIC) was determined by microdilution, and the following treatments were evaluated in quintuplicate: SAa in freeze-dried and fresh forms (1.5; 2.5; 5; and 10%), negative control treatment (cheese absent contamination), and positive (cheese absent from SAa). After superficial inoculation in Agar Baird Parker, enriched with egg yolk and potassium tellurite, the incubation was performed at 35ºC for 48 hours. Although SAa in lyophilized and fresh form applied before contamination did not show antibacterial activity, the fresh form applied after contamination showed a MIC equivalent to 2.5%. So, based on the results obtained by the present study, it was possible to conclude that SAa above 2.5% had antimicrobial properties, thus favoring the conservation of fresh cheese.

A Comparative Study on the Effect of Spilanthes acmella and Chlorhexidine (0.2%) Mouth Rinses on Salivary Streptococcus mutans Count in Children

In the wake of an increased interest in finding natural alternatives for chemical medicinal products, this study assesses and compares the effects and acceptance of Spilanthes acmella, a widely used plant in various traditional systems of medicine, with Chlorhexidine (0.2%) mouth rinse on the dental caries causing pathogen Streptococcus mutans colonizing the oral cavity of children. The study included 40 healthy children in the age group of 8-12 years based on inclusion and extrusion criteria. In the beginning of the study, non-stimulated whole salivary samples were tested for the baseline count of colony forming units (CFU) of Streptococcus mutans using Mitis Salivarius Agar supplemented with potassium tellurite. The same process was repeated 24 hours after 15 days of regular use of mouth rinses twice daily. Results showed that there was statistically highly significant decrease in CFU in the post rinse phase in both the groups. S. acmella showed greater acceptance by study subjects when compared with the Chlorhexidine mouth rinse. It can be concluded based on the results of this study that S. acmella has beneficial effects against S. mutans and can be a potential option for preventive measures against dental caries, although more studies are needed for its validation.

Adaptation of the Yeast S. Cerevisiae Y-503, S. Cerevisiae Daw-3a, S. Oviformis M-12x to Various Ethanol Values. Solid Growth Media

The paper considers information on the determinants of the viability of yeast cultures cultivated in the form of gi-ant colonies on solid agar under various conditions of ethanol stress. Yeast strains tends to show higher viability along with slow growth. The effect of various concentrations of ethanol (6, 12, 18 %), glucose (20 %) on the morpho-physiological properties of the yeast S. cerevisiae Y-503, S. cerevisiae DAW-3a and S. oviformis M-12X is revealed. It has been determined that Y-503 and DAW-3a are most resistant to ethanol and osmotic stress. The antagonistic inter-action of several stressors most clearly affected the tolerance of the strains to all positions with “ethanol + glucose”. Phenotypic studies have found that the strains survival strategy in adverse conditions in the form of resistance to potassium tellurite inhibitor (K2TeO3) in Y-503, to a greater extent in M-12X. A need for DAW-3a for inositol, ornithine, and lysine was detected; M-12X – sorbitol, inositol. The strains are unsusceptible to synthetic broad-spectrum antimycotics - ketoconazole and fluconazole. However, antibiotic nystatin inhibited their growth, and a high sensitivity of strain M-12X was noted to a greater extent. A comparative analysis of the morphophysiological parameters of cells and giant colonies of the studied strains determined the advantage of polyploid Y-503 in survival and tolerance to the effects of various types of stress. The results can be applied in scientific research and biotechnology for various purposes, based on the use of stress-resistant S. cerevisiae yeast.

Status and problems of bacteriological diagnosis of diphtheria infection in the Russian Federation

The purpose of the work was to assess the state of bacteriological diagnosis of diphtheria infection in Russia in order to establish possible reasons for the decrease in the release of C. diphtheriae. The Reference Center for Monitoring the Pathogens of Measles, Rubella, Mumps, Pertussis and Diphtheria in 2018 in 85 subjects of Russia conducted a questionnaire of laboratories of medical organizations and the Centers for Hygiene and Epidemiology of Rospotrebnadzor, carrying out bacteriological studies for diphtheria infection. It was found that the number of studies conducted over the five-year period decreased by 1.2 times. The tendency to decrease the number of bacteriological studies for diphtheria is observed in the territories of almost all federal districts. In 99% and 29% of cases, the institutions of the FBUZ Centers for Hygiene and Epidemiology and medical organizations (MO) and use in their work documents regulating bacteriological studies for diphtheria infection. In a number of territories, the list of documents used includes documents that are invalid or do not define such studies. Most organizations use dry tampons when examining for diphtheria, however, 13.1% and 53.4% of FBUZ Centers for Hygiene and Epidemiology and medical organizations (respectively) use commercial transport environments, which does not comply with regulatory documentation. Analysis of the quality of work of bacteriological laboratories showed shortcomings at the stage of preparation of media (use of donor blood, or absence of addition of blood and potassium tellurite), Elek tests (addition of horse serum or absence of serum to the medium), setting of incomplete biochemical series (absence of tests for urease and nitrate reductase), absence of standard control strains, incomplete volume of internal laboratory quality control. Given the continuing circulation of the pathogen in various countries of the world and in our country, as well as the possibility of imported cases of infection from endemic regions, the analysis was aimed at drawing the attention of specialists to the problem of improving the quality of laboratory diagnosis of diphtheria in Russia.

Silver Antibacterial Synergism Activities with Eight Other Metal(loid)-Based Antimicrobials against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus

The present study surveys potential antibacterial synergism effects of silver nitrate with eight other metal or metalloid-based antimicrobials (MBAs), including silver nitrate, copper (II) sulfate, gallium (III) nitrate, nickel sulfate, hydrogen tetrachloroaurate (III) trihydrate (gold), aluminum sulfate, sodium selenite, potassium tellurite, and zinc sulfate. Bacteriostatic and bactericidal susceptibility testing explored antibacterial synergism potency of 5760 combinations of MBAs against three bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus) in three different media. Silver nitrate in combination with potassium tellurite, zinc sulfate, and tetrachloroaurate trihydrate had remarkable bactericidal and bacteriostatic synergism effects. Synergism properties of MBAs decreased effective antibacterial concentrations remarkably and bacterial cell count decreased by 8.72 log10 colony-forming units (CFU)/mL in E. coli, 9.8 log10 CFU/mL in S. aureus, and 12.3 log10 CFU/mL in P. aeruginosa, compared to each MBA alone. Furthermore, most of the MBA combinations inhibited the recovery of bacteria; for instance, the combination of silver nitrate–tetrachloroaurate against P. aeruginosa inhibited the recovery of bacteria, while three-fold higher concentration of silver nitrate and two-fold higher concentration of tetrachloroaurate were required for inhibition of recovery when used individually. Overall, higher synergism was typically obtained in simulated wound fluid (SWF) rather than laboratory media. Unexpectedly, the combination of A silver nitrate–potassium tellurite had antagonistic bacteriostatic effects in Luria broth (LB) media for all three strains, while the combination of silver nitrate–potassium tellurite had the highest bacteriostatic and bactericidal synergism in SWF. Here, we identify the most effective antibacterial MBAs formulated against each of the Gram-positive and Gram-negative pathogen indicator strains.

Identification and Biochemical Characterization of some Strains of Clavibacter michiganensis subsp. Michiganensis, in Romania

Clavibacter michiganensis subsp. michiganensis is responsible for the ʻbacterial canker of tomato’. The study aimed to identify and characterize biochemically some strains of the bacteria. Five strains were used for biochemical identification and characterization and two reference strains were used as positive controls. The biochemical characterization was performed with Biolog Microbial Identification System. All the strains used many carbon sources and were positive for growth in the presence of: 1%NaCl, Nalidixic Acid, Aztreonam, Potassium Tellurite and pH 6, but negative for growth and sensitivite to: Troleandomycin, Lincomycin, Vancomycin, Fusidic Acid, Eimfamycin SV, Guanidine HCl, D-Serine, Minocycline and Niaproof 4. The differences between the Biolog system database and the studied strains did not change their classification at the level of genus and species, but modifed or did not allow the classification at the subspecies level. Furthermore, the analyzed strains had metabolic diversity.

Study of the sensitivity of bacteria of the species Pseudomonas stutzeri and their associates to various inhibitors

Currently, the development of methods for isolation, indication and identification of Pseudomonas stutzeri bacteria from environmental objects and pathological material is an urgent problem. At the same time, there are no data in the scientific literature on the sensitivity of Ps.stutzeri bacteria to various inhibitors, which are necessary for the development of a selective and differential nutrient medium for them. The article presents the results of studying the sensitivity of Ps. stutzeri and their associates to inhibitors such as sodium benzoate, SDS, nalidixic acid, potassium tellurite and sodium azide, which will be used to develop a selective and differential culture medium for Ps.stutzeri bacteria.