Possibilities of practical application of different culture mediums for laboratory diagnostic of diphtheria.

The purpose of the work is to evaluate the cultural and morphological properties of colonies of clinically significant corynebacteria on culture mediums for the isolation of corynebacteria. The study used 9 culture mediums for the isolation of corynebacteria: a culture medium for the isolation of corynebacteria (Corynebacagar); Tellurite-containing blood agars on base - Culture medium № 1 GRM, Culture agar for the cultivation of microorganisms (GRM agar), Culture medium for determining the sensitivity of microorganisms to antibacterial preparations - AGV, culture agar for the cultivation of dry microorganisms (SPA), Clauberg medium II, Hoyle Medium agar (Oxoid), Blood agar base (Conda), Columbia Agar Base (Conda). The work used 7 test strains of microorganisms from the State collections of pathogenic microorganisms - C. diphtheriae biovars gravis, mitis, intermedius, belfanti and subspecies lausannense, C. ulcerans and C.pseudotuberculosis. Studies were carried out in accordance with MUK 4.2.3065-13 «Laboratory diagnosis of diphtheria infection¼. We describe culture-morphological properties of strains on all tested culture mediums the isolation of corynebacteria after 24 and 48 hours of incubation. Analysis of the results on the growth properties of culture mediums showed that all culture mediums had high sensitivity - from dilution 10-7 for all test strains. Colonies of corynebacteria were visually detected on culture mediums after 19-20 hours of cultivation. When cultivating a suspension of corynebacteria from breeding 10-6 on culture mediums, the number of colonies ranged from 95±5 to 120±10. Conclusion. All culture mediums had differential diagnostic properties that ensure the growth of corynebacteria after the day of incubation.

Clinical trials of new culture media for staphylococcus isolation.

A comparative analysis of the quality of the developed nutrient media, Baird-Parker dry agar base and Vogel-Johnson dry agar Base and foreign analogues, was done based on results of clinical trials. The tested media were qualified by the main biological parameters, such as sensitivity, growth rate, and differentiating and inhibiting properties. The evaluation of statistical reliability of the results of trials of clinical samples was evaluated taking into account the number of parallel studies and the number of matches of the results of studies conducted by different performers. 116 clinical samples of received by a laboratory of the testing laboratory center for research from hospital no.164 over the period of clinical trials were analyzed. 46 cultures of potential pathogens were isolated when culturing on test and control media: S. aureus -35; S. epidermidis-6; S. saprophyticus - 5. Lecithinase activity on the medium "Baird-Parker dry agar Base" and mannitol fermentation on the medium "Vogel-Johnson dry agar Base" in the preliminary phenotypic test allow the isolation and differentiation of clinical isolates of S. aureus from S. epidermidis, and S. saprophyticus.

[Comparison of hemolytic activity and hemolytic toxin genes of Staphylococcus aureus clinical strains, isolated in Russia.]

Clinical strains of Staphylococcus aureus were tested for hemolytic activity on blood agar, in the PCR test and by analyzing the gene alleles of hemolytic toxins. The study analyzed the information content of the phenotypic determination of hemolytic activity to assess the pathogenic properties of S. aureus isolates.

[Clinical trials of salmonella enrichment medium.]

Salmonella infections continue to be a serious problem in modern medicine. Being intestinal infections-associated pathogens, representatives of the genus Salmonella manifest themselves as pathogenic bacteria, especially in developing nosocomial infections. Given the polymorphism of clinical symptoms of salmonellosis, laboratory studies using bacteriological and serological methods are an important link in the diagnosis. In addition, the general prevention of salmonellosis includes measures to identify bacteria carriers, to ensure control over the incidence in farm animals and birds, food safety, etc. The list of nutrient media to isolate and identify Salmonella is lengthy and steadily extending, and the choice of specific media is largely relies on the nature of the material under study as well as on the idea of the potential availability of Salmonella bacteria in it, with research, diagnosis or epidemic situation being taken into account. The SRCAMB (Rospotrebnadzor) has designed two nutrient media allowing the enrichment and isolation Salmonella from various clinical samples. These are "Nutrient Medium for Enrichment of Salmonella, Dry (Magnesium medium) and "Nutrient Agar with Brilliant Green, Phenolic Red, Lactose and Sucrose, Dry (BPLS-FMH agar)." Growth and inhibitory properties of the new culture media produced by the SRCAMB and commercial domestic and foreign counterparts have been compared by using clinical material. Domestic nutrient media such as Magnesium medium and BPLS-FMH agar were proved to correspond to their commercial analogues when being used for enrichment, isolating and counting Salmonella bacteria in clinical specimens to have bacteriological control real data.

[The clinical trials of agar and Mossel EE broth.]

The cultural diagnostic of acute intestinal infections is based on application of growth medium for selective cumulation of enterobacteria. The development of composition and technology of production of national import-substituting growth medium is an important task for supporting laboratories with high quality medical products. In the state research center of applied microbiology and biotechnology are developed and registered in established procedure a dry growth medium for selective cumulation of enterobacteria (Mossel EE broth) and dry growth medium for selective isolation and counting of enterobacteria (Mossel agar). Both media are intended for selective cumulation, isolation and counting of enterobacteria of family Enterobacteriaceae in clinical material and other objects. The comparative evaluation was applied concerning growth and inhibiting characteristics of new growth media produced by the state research center of applied microbiology and biotechnology against foreign analogues using clinical material. The total correspondence of national Mossel broth and Mossel agar to foreign analogues in case of using these media with the purpose of selective cumulation, isolation and counting of enterobacteria of family Enterobacteriaceae in clinical material and obtaining objective results of bacteriolog.

[TMOSKOVHE COMPARATIVE CHARACTERISTIC OF GROWTH MEDIUMS FOR SEPARATION OF CORYNEBACTERIA].

The comparative tests of growth mediums for isolation and accumulation of diphtheria bacteria were implemented. The testing consisted of six series of growth medium "Corynebacagar" produced by the state research center of applied microbiology and biotechnology and three series of blood tellurite agar. The concluding results of identification of biological indicators of all series of growth nutrient mediums are presented The "Corynebacagar" is recommended for application in health care practice for primary inoculation of pathological material during implementation of cultural analysis on diphtheria.

[Molecular-genetic characterization of shiga-toxin producing Escherichia coli isolated during a food-borne outbreak in St. Petersburg in 2013].

UNLABELLED: Shiga toxin-producing Escherichia coli (STEC) food-borne infections are reported worldwide and represent a serious problem for public healthcare. In the Russian Federation there is little information on epidemiology and etiology of STEC-infections as well as on molecular-genetic peculiarities of STEC pathogens. OBJECTIVE: Our aim was to describe a food-borne outbreak as hemorrhagic colitis (HC) along with hemolytic uremic syndrome (HUS), enterocolitis, and acute gastroenteritis in children in St. Petersburg in 2013. METHODS: Epidemiological, microbiological, molecular-genetic and bioinformatic methods were applied. RESULTS: Objects to study were clinical specimens, milk and food samples, as well as STEC strains isolated during the outbreak. The outbreak of food-borne infection was found to be caused by STEC-contaminated raw milk as confirmed by epidemiological analysis, detection of STEC DNA and isolation of relevant pathogens in milk and sick children fecal specimens. The whole-genome sequencing revealed two groups ofpathogens, E. coli O157:H7 and E. coli O101:H33 among collected strains. Group I strains were attributed to the previously known sequence type ST24, while group II strains belonged to the previously non-described sequence type ST145. In strain genomes of both groups there were identified nucleotide sequences of VT2-like prophage carrying stx2c gene, plasmid enterohemolysin gene, and gene of the STEC main adhesion factor intimin. Gene of intimin gamma was identified in E. coli O157:H7 strains and intimin iota 2 in E. coli O101:H33 strains. The latter previously was identified only in enteropathogenic E. coli (EPEC) strains. CONCLUSION: The additional knowledge of epidemiology and biology of STEC pathogens would assist clinicians and epidemiologists in diagnosing, treating and preventing hemorrhagic colitis.

[The comparative evaluation of differential diagnostic characteristics of Endo growth medium of different manufacturers].

The article deals with the results of comparative study of differential diagnostic characteristics of Endo growth medium of different foreign manufacturers permitted to be applied in the Russian Federation and the national Endo agar. The enhanced kit of museum test-strains and clinical material from patients were used. It is established that morphology, size and number of clumps of most enterobacteria growing in Tndo medium manufactured by Merck, Pronadisa, HiMedia and the state research center of applied microbiology and biotechnology have minor morphological differences and match the characteristics declared by manufacturers. The indicator of degree of detection (degree of inoculation) of pathogenic enterobacteria from clinical material onto Endo medium manufactured by the state research center of applied microbiology and biotechnology matched the indicators of media from foreign manufacturers. It is demonstrated that Endo growth medium manufactured by the state research center of applied microbiology and biotechnology not only is equal to import analogues but in particular cases even excels them.

[Development and use of a new growth medium for detection and identification of sanitary-indicative microorganisms].

Threat of emergence and spreading of dangerous intestinal infections determines the necessity to control for water quality in its sources in respect of sanitary-indicative microorganisms, thermo-tolerant coliforms and lactose-negative intestinal bacilli testifying fecal pollution. Standard techniques for isolation of enterobacteria are based on use of lactose-containing inhibitory and non-inhibitory growth media such as lactase-peptone and Kessler media. Development of standard, effective, and reliable for use in laboratory conditions accumulation medium for detection of enterobacteria aimed to increase reliability of sanitary-bacteriological monitoring of objects of aquatic environment. Two variants of Eikman medium with an added indicator were designed for differentiation of enterobacteria on the basis of lactose and glucose fermentation with application of a thermo-tolerance test at 44-46 degrees C. Maximal accumulation of coliforms on the developed media in static cultivation conditions and at sensitivity on the level of individual cells was observed after 16 +/- 2 hours, whereas in control inhibitory media--after 22 +/- 2 hours. Studies on sterilization of the developed media in disposable packages byy-irradiation were conducted to elucidate the possibility of their use in field conditions performing analysis in flasks for preservation of high growth properties. In order to reduce time for analysis on confirmation of detection of thermotolerant coliforms, addition of tryptophan in composition of the media was provided, which allows to perform an indole test and definitively confirm the detection of Escherichia coli. Pilot industrial samples of designed media were successively passed the approbation.