[Comparative Genotyping of Staphylococcus aureus Strains Isolated from Skin Lesions, Nasal Cavities, and Feces of Children with Atopic Dermatitis].

Background: The lesion of skin of the majority atopic dermatitis patients is chronically colonized by bacteria belonging to the species Staphylococcus aureus. Topical antibacterial and anti-inflammatory therapy treatment are often ineffective due to fast recolonization by S. aureus and exacerbation of allergic process. Aims: Our aim was to determine a frequency of S. aureus colonization in skin lesions, mucous membranes of the nasal cavity and intestine of children with atopic dermatitis, to compare the genotypes of Staphylococcus aureus strains isolated from different biotopes of atopic dermatitis patients, and to clarify whether the intestinal and nasal cavities microbiota may act as a source of S. aureus recolonization of skin lesions. Materials and Methods: Bacteriological examination of fecal samples, skin, and nasal swabs was conducted in 38 atopic dermatitis patients. The pure bacterial cultures of S. aureus were identified using API Staph (Biomerieux, France) and Vitek 2 MS (Biomerieux, France). Isolates of S. aureus were subjected to genotyping by analysis of rRNA internal 16S-23S rRNA spacer regions and high resolution melting analysis (HMR) of polymorphic spa X-regions. Results: 99% S. aureus strains were successfully identified using MALDI-TOF mass-spectrometry. S. aureus cultures were isolated from all biotopes in 31,6% of children, from skin and nasal cavities ­ in 42% of cases, from skin and feces ­ in 2,6% of cases, only from skin ­ in 10,5%, from nasal cavities and feces ­ in 2,6%, and only from nasal cavities ­ in 2,6% of cases. In 8% of children, S. aureus was not detected in any of the biotopes. Genotyping of the isolates enabled the detection of 17 different genotypes. A match between the genotypes of skin and nasal strains, and skin and fecal strains was observed in 88% and 61% of the cases respectively. Conclusions: The observed a high-frequency matching genotypes suggests the possibility of migration of S. aureus strains inside biotopes in humans and the absence of specialization to colonization of any of the niches.

[Analysis of genetic determinants of multidrug and extensively drug-resistant Mycobacterium tuberculosis using oligonucleotide microchip].

Steadily growing resistance of the tuberculosis causative agent towards a broad spectrum of anti-tuberculosis drugs calls for rapid and reliable methods for identifying the genetic determinants responsible for this resistance. In this study, we present a biochip-based method for simultaneous identification of mutations within rpoB gene associated with rifampin resistance, mutations in katG, inhA, ahpC genes responsible for isoniazid resistance, mutations within the regions of gyrA and gyrB genes leading to fluoroquinolones resistance, and mutations in the rrs gene and the eis promoter region associated with the resistance to kanamycin, capreomycin and amikacin. The oligonucleotide microchip, as the core element of this assay, provides simultaneous identification of 99 mutations in the format "one sample--one PCR--one microchip", and it makes it possible to complete analysis of multi-drug-resistant and extensively drug-resistant tuberculosis within a single day. The tests on 63 Mycobacterium tuberculosis clinical isolates with different resistance profiles using the developed approach allows us to reveal the spectrum of drug-resistance associated mutations, and to estimate the significance of the inclusion of extra genetic loci in the determination of M. tuberculosis drug resistance.

Molecular genetic study of species and strain variability in bifidobacteria population in intestinal microflora of breast-fed infants and their mothers.

Qualitative and quantitative composition of enteric bifidoflora was studied in a group of 13 mother-infant pairs. Pure cultures of Bifidobacterium strains were isolated from feces and their species were identified by PCR with species-specific primers or by partial sequencing of 16S rDNA. The strains were compared by REP-PCR. The most incident Bifidobacterium species in mothers were B. longum and B. adolescentis. The infants were mainly colonized by B. bifidum and B. longum. The mother and her baby were colonized by the same Bifidobacterium species in 9 of 13 cases. In 5 (38.5%) of these cases, these pairs of strains were identical by their REP-PCR profiles. These strains belonged to B. longum in one case, B. bifidum in 3 cases, and B. adolescentis in 1 case. Our results support the hypothesis on early colonization of infants with maternal bifidobacterium strains.

[Bifidobacterial plasmids and their application to genetic engineering].

Representatives of Bifidobacterium genus are considered to play many important roles in intestinal homeostasis. On the other hand, their molecular biology and genetics have been poorly studied. In order to broaden our understanding of their health-promoting mechanisms, it is extremely important to possess tools to manipulate them genetically. Another challenging task is to take advantage of genetic engineering technology for designing new probiotic bifidobacteria with unique therapeutic properties. An important step in such work is to isolate and characterize small bifidobacterial plasmids, which can be applied to the construction of cloning vectors. This article presents a review of several pioneering studied devoted to bifidobacterial plasmids and genetic engineering with bifidobacteria. Trends in and prospects of molecular genetics of bifidobacteria are discussed as well.