Genotyping of B. pertussis strains isolated from pertussis patients in Moscow.
53 strains of B. pertussis isolated from pertussis patients in Moscow in 2007 - 2010 as well as 3 vaccine strains ...currently used in Russia for the production of DTP vaccine were studied by multilocus sequencing (MLST) based on allele combinations of ptxA, ptxC and tcfA genes.
A genetic characteristic of B. pertussis strains isolated from pertussis patients in Moscow by using MLST is presented. Allele profile analysis of the studied B. pertussis strains was performed, 4 sequence types (ST) were identified--ST1, ST2, ST3 and ST5, most of the circulating strains (86.7%) were shown to belong to ST5, equal percentage of cases (5.7%)--to ST2 and ST3, and 1.9%--to ST1, while 2 vaccine production strains belong to ST2 and 1 - to ST1.
Clonal structure of contemporary Moscow strains was shown to be different from strain structure used for the production of DTP vaccine.
Comparative analysis of structure of tcfA gene coding tracheal colonization factor of Bordetella pertussis strans isolated in Moscow from patients with pertussis.
Ninety-seven strains of B. pertussis ...isolated in different periods of pertussis infection epidemic process (1948 - 1989--from collection of Gabrichevsky Moscow Research Institute of Epidemiology and Microbiology; 1990 - 2007--isolated in Moscow from patients with pertussis) were studied. Primers for amplification of tcfA gene region with size 945 n.p. were used. Amplicons obtained in PCR were used for sequencing. Nucleotide sequences of tcfA gene types of B. pertussis strains were matched to EMBL/GenBank database.
Sequencing of tcfA gene fragments revealed two sequence variants. Ninety-six of 97 studied B. pertussis strains had the same sequence variant--variant 1. The one strain was characterized by other nucleotide sequence--variant 2, which differed from variant 1 by presence of insertion g in position 396 that led to reading frame shift.
The structure of tcfA gene circulating population of B. pertussis strains is homogenous and is characterized by presence of "vaccine" allele dominating in majority of countries in the world.
The article deals with the results of studying the growth characteristics of nine nutrient mediums for primary plating of pathologic material. It is demonstrated that for successful and proper ...functioning of bacteriologic laboratory providing bacterial analysis for diphtheria the permanent quality control is needed to monitor the nutrient mediums for primary plating. The quality control is applied to evaluate the growth characteristics on such criteria as germination of isolated culture, intensity of its growth in 24 and 48 hours, optimal size of colonies characterized by their cultural characteristics, inhibiting activity concerning concurrent microflora.
Features of structure of different B. pertussis genes are studied in many countries of the world, and, first of all, ptxA gene, which encodes main protective antigen of the microbe--pertussis toxin. ...Starting from 1980s, B. pertussis strains with new "non-vaccine" allele ptxA1 gradually displaced strains with old "vaccine" alleles--ptxA2 and ptxA4, and now the formers dominate in circulating bacterial population. Molecular genetic method of rapid identification of B. pertussis strains, based on the differences in ptxA gene structure, was developed. The method using phenomenon of endonuclease restriction can be applied for differentiation of B. pertussis from B. parapertussis strains in diagnostic purposes.
To study pathogenic characteristics of B. pertussis strains isolated from patients during different periods of pertussis infection epidemic process.
Strains of B. pertussis isolated in Moscow during ...1967 - 1971, 1980 - 1985, and 2001 - 2005 were studied. Nutrient media: Bordet-Gengou blood agar, casein-charcoal agar.
mice - F1 hybrids (CBA x C57BL6). Pathogenic characteristics of strains were studied by assessment of virulence (LD50), leukocytosis-stimulating (LS units) and histamine-sensitizing (HSD50) activities of cultures. Genotyping was performed using standard equipment and reagents for DNA isolation, amplification, sequencing and detection of results.
On the sample of 164 strains, pathogenic and genotypic characteristics of B. pertussis populations circulated during 1967 - 1971, 1980 - 1985, and 2001 - 2005. Majority of B. pertussis strains isolated in 1967 - 1971 and strains circulated during current phase of epidemic process were virulent (80.75% and 81.8% respectively) and had significant leukocytosis-stimulating and histamine-sensitizing activity, whereas strains isolated from patients with pertussis in 1980 - 1985 characterized by lower virulence and toxicity. Genotyping showed strains carrying "non-vaccine" allele ptxA1, which emerged in the middle of 1970s, totally displaced strains with "vaccine" alleles ptxA2 and ptxA4.
Adaptive changes of B. pertussis driven by increased vaccination coverage involve both ptxA gene and pathogenic characteristics of infectious agent in the range of genotypically homogenous population with domination of strains, which have high levels of virulence and toxicity.
The developed direct method for the laboratory diagnosis of pertussis, which is based on isothermal amplification technologies, has a high (100%) specificity and sensitivity (102 m.cl.), can detect ...the pathogen of the disease just in the clinical sample from a patient within 7-8 hours after start of the study. The clinical trials conducted at Infectious Diseases Hospital One (Moscow) on examination of 103 patients (63 patients with the clinical diagnosis of pertussis and 40 with other respiratory tract diseases) provided evidence its high specificity and diagnostic efficiency as compared with a bacteriological test, the efficiency in different clinical types of the disease and during examinations of patients in different periods after the onset of the disease, as well as during examinations of patients with suspected pertussis and pertussis-like diseases.
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