Antibiotic Adjuvant 4-Hexylresorcinol Enhances the Efficiency of Antituberculosis Drugs.

We studied the possibility of using 4-hexylresorcinol to increase the efficiency of anti-mycobacterial chemotherapy. In an in vitro experiment, 4-hexylresorcinol increased the efficiency of rifampicin, kanamycin, and isoniazid against Mycobacterium smegmatis by 3-5 times. Experiments in sanitation of BALB/c mice infected with M. smegmatis showed the best efficacy of the isoniazid and 4-hexylresorcinol combination in comparison with isoniazid monotherapy. The growth-inhibiting activity of the combination of antibiotic rifabutin with 4-hexylresorcinol was shown on 6 strains of M. tuberculosis. A 2-fold decrease in the minimum inhibitory concentration of this antibiotic in the presence of half-minimum inhibitory concentration of 4-hexylresorcinol was demonstrated for monoresistant strain M. tuberculosis 5360/42Hr. On the mouse model of experimental tuberculosis caused by M. tuberculosis H37Rv, a 5-fold decrease in lung contamination and more rapid complete cure were achieved in animals treated with the combination of rifabutin and 4-hexylresorcinol in comparison with rifabutin monotherapy.

Stress-Tolerant Dormant Bacterial Forms: Biological and Ultrastructural Properties of Moraxella catarrhalis and Kocuria rhizophila.

Dormant forms of causative agents of healthcare-acquired infections Moraxella catarrhalis and Kocuria rhizophila have been obtained. Dormant forms cells retained viability during long-term storage (≈107 CFU/ml after 2 months) under provocative conditions (lack of nutrient sources; temperature 20°C, oxygen access) were characterized by heat resistance, and acquired special ultrastructural organization typical of dormant forms (compacted nucleoid, thickened cell wall). They were also capable of forming alternative phenotypes (dominant and small colony variants) in a new cycle of germination in a fresh medium. These results demonstrate that the dormant forms can be responsible both for survival in the environment and persistence in the host organism.

[Characterization of oligonucleotides with LNA-monomers for PCR detection of point mutations in mycobacteria tuberculosis genome].

Point mutations associated with isoniazid resistance in Mycobacterium tuberculosis (MTB) have been analyzed in codon 315 of the katG gene by conventional polymerase chain reaction (PCR) using primers containing locked nucleic acid (LNA) modified nucleotides. Purity and structure of primers containing 5 LNA monomers of 17 nucleotides in length were characterized by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) and a 17-mer duplex formed by two complementary oligonucleotides was characterized by the method of thermal denaturation. The duplex containing five LNA monomers per each strand was characterized by a higher melting temperature than it was expected using extrapolation of theoretical calculation for nucleotide modification of one strand of the duplex. Detection of any of six possible mutations in katG codon 315 (i.e. discrimination between sensitive and resistant MTB) requires just one PCR employing a set of two primers with one LNA-modified primer; this is an important advantage of oligonucleotides containing LNA over unmodified nucleotides: employment of multiplex PCR would require up to 12 primers. Problems of control of oligonucleotide modification by LNA monomers are discussed.

[Vibrio cholerae strains certification].

AIM: Certification of V. cholerae strains stored at State collection of pathogenic microorganisms and cell cultures SCPM - Obolensk. MATERIALS AND METHODS: 50 V. cholerae strains were studied. Real-time PCR with primers to genes ctxA, ctxB, ace, zot, tcpA, toxR, hlyA, rtxC, rfbO1, ompU, ompW was used. RESULTS: Membership of the studied strains in V. cholerae species was confirmed by molecular-biological methods. 46 strains belong to O1 serogroup, 42 of those - E1 Tor toxigenic, having all the virulence genes and 4 non-toxigenic strains. A strain had ace, zot, tcpA, toxR, rtxC, hlyA, ompU genes. 2 strains had ace, toxR, rtxC, hlyA genes, a strain had only toxR gene which is a global regulatory gene. 2 of the 4 serogroup O1 strains were non-toxigenic and had all the virulence genes (ctxA, ctxB, ace, zot, tcpA, toxR, rtxC, hlyA, ompU). 1 non-toxigenic strain has ace, zot, toxR, hlyA, ompUgenes, and the other - toxR, hlyAgenes. CONCLUSION: Genome certificates of all the V. cholerae strains stored in State collection of pathogenic microorganisms and cell cultures SCPM - Obolensk were created. Markers of epidemic threat - ctxA, ctxB, tcpA, toxR and additional virulence genes were determined.

[Detection of wild type isolates and point mutations in genome of isoniazid-resistant Mycobacteria tuberculosis].

The isoniazid resistance of mycobacteria tuberculosis (MBT) is associated with point mutations in the codon 315 of katG gene of MBT. The two PCR-techniques for detection of point mutations in codon 315 have been developed. A use of two sets of primers comprising the additional competitive blocking primer with 3'-terminal phosphate group (in order to eliminate unspecific amplification) allowed to identify most frequent point mutations AGC-->ACC and AGC-->AGA in the codon 315. PCR with a set of two primers one of which contained 5 LNA-monomers allowed to discriminate between wild type and isoniazid-resistant MBT isolates; any of 6 known mutations in codon 315 of kafG gene being detected. A structure and purity of the LNA-containing oligonucleotides (length of 17 nucleotides) was characterized by MALDI-TOF mass spectrometry; the duplex formed by two LNA-containing complementary oligonucleotides (length of 17 b.p.) was anlyzed by thermal denaturation.

[Development of a comprehensive approach to detecting the antituberculous activity of low molecular-weight chemical compounds].

The optimal parameters of the Alamar Blue test have been determined to detect the antituberculous activity of the chemical compounds under study. The duration of mycobacterial cell incubation before addition of Alamar Blue is 24 hours; that is 17 hours for both H37Ra and H37Rv M. tuberculosis. A method has been devised to evaluate the bactericidal/bacteriostatic activity of the chemical compounds. A thoroughly characterized collection of clinical M. tuberculosis strains that differ in drug sensitivity has been created. A procedure has been developed to reveal the activity of the chemical compounds, by applying mono and multiresistant M. tuberculosis strains. Variability in the growth rate for the clinical strains of mycobacterial cultures is shown. A method has been devised to evaluate the toxicity of the chemical compounds for eukaryotic cells.

[Determination of critical kanamycin concentration for Mycobacterium tuberculosis in the MGIT Bactec 960 system].

The critical concentration of canamycin for the MGIT Bactec 960 system, which has been determined on a panel of the tho--roughly characterized genetically heterogeneous clinical Mycobacterium tuberculosis isolated in the Central Region of Russia, is equal to 1.25 microg/ml.

[Enzyme complex celloconingine P10x]. / Issledovanie fermentativnogo kompleksa tsellokoningina p10x.

The composition and properties of the enzyme preparation celloconingine P10x were studied. The preparation contained a number of citolytic enzymes and showed proteolytic and amylolytic activities. Optimal conditions for the enzyme action were found to be: for total citolytic and hemicellulase activities pH 5.2-6.2 and 45-55 degrees, for endo-beta-glucanase activity pH 4.2-5.2 and 58-62 degrees, for proteolytic activity pH 4.0-4.8 and 64-68 degrees, and for amylolytic activity pH 3.6-4.2 and 60-66 degrees C.