Biomedical subjects

Mamuka Kotetishvili

Publications and source records attributed to Mamuka Kotetishvili.

6 recordsLinked to original sources

PubMed2005

Multilocus sequence typing versus pulsed-field gel electrophoresis for characterization of extended-spectrum beta-lactamase-producing Escherichia coli isolates.

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains are emerging pathogens. Molecular typing of ESBL-producing E. coli is useful for surveillance purposes, to monitor outbreaks and track nosocomial spread. Although pulsed-field gel electrophoresis (PFGE) is the current "gold standard" for bacterial molecular typing, multilocus sequence typing (MLST) may offer advantages. Forty ESBL-producing E. coli isolates were selected at random from a cohort of intensive care unit patients who had active surveillance perirectal cultures done. PFGE identified 19 unique PFGE types (PT) among the 40 isolates; MLST identified 22 unique sequence types. MLST had greater discriminatory ability than PFGE for ESBL-producing E. coli. Simpson's indices of diversity for PFGE and MLST were 0.895 and 0.956, respectively. There were five clonal complexes (CCs) (isolates with differences of no more than two loci) that each contained multiple PT, but each PT was found in only one CC, indicating genetic consistency within a CC. MLST has clear utility in studies of ESBL-producing E. coli, based on a greater discriminatory ability and reproducibility than PFGE and the ability to a priori define genetically related bacterial strains.

Bacterial Typing Techniques↗

PubMed2005

Multilocus sequence typing for studying genetic relationships among Yersinia species.

The intra- and interspecies genetic relationships of 58 strains representing all currently known species of the genus Yersinia were examined by multilocus sequence typing (MLST), using sequence data from 16S RNA, glnA, gyrB, recA, and Y-HSP60 loci. Yersinia aldovae, Y. bercovieri, Y. intermedia, Y. pestis, Y. pseudotuberculosis, Y. rohdei, and Y. ruckeri were genetically more homogeneous than were Y. enterocolitica, Y. frederiksenii, Y. kristensenii, and Y. mollaretii. The MLST data concerning the genetic relatedness within and among various species of Yersinia support the idea that Y. pestis and Y. pseudotuberculosis are two lineages within the same species rather than two distinct species. Y. ruckeri is the genetically most distant species within the genus. There was evidence of O-antigen switching and genetic recombination within and among various species of Yersinia. The genetic relatedness data obtained by MLST of the four housekeeping genes and 16S RNA agreed in most, but not all, instances. MLST was better suited for determining genetic relatedness among yersiniae than was 16S RNA analysis. Some strains of Y. frederiksenii and Y. kristensenii are genetically less related to other strains within those species, compared to strains of all other species within the genus. The taxonomic standing of these strains should be further examined because they may represent currently unrecognized Yersinia species.

Animals↗

PubMed2004

Comparative analysis of multilocus sequence typing and pulsed-field gel electrophoresis for characterizing Listeria monocytogenes strains isolated from environmental and clinical sources.

One hundred seventy-five Listeria monocytogenes strains were characterized by serotyping, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST) based on loci in actA, betL, hlyA, gyrB, pgm, and recA. One hundred twenty-two sequence types (STs) were identified by MLST based on allelic profiles of the four housekeeping genes (betL, gyrB, pgm, and recA), and 34 and 38 alleles were identified for hlyA and actA, respectively. Several actA and hlyA alleles appeared to be predominantly associated with clinical isolates. MLST differentiated most of the L. monocytogenes strains better than did PFGE, and the discriminating ability of PFGE was better than that of serotyping. Several strains with different serotypes were found, by MLST and PFGE, to have very closely related genetic backgrounds, which suggested possible "antigen switching" among them. MLST can be a useful typing tool for differentiating L. monocytogenes strains (including strains undistinguishable by PFGE typing and serotyping), and it may be of value during investigations of food-borne outbreaks of listeriosis.

Bacterial Typing Techniques↗

PubMed2003

Comparative genomic analyses of the vibrio pathogenicity island and cholera toxin prophage regions in nonepidemic serogroup strains of Vibrio cholerae.

Two major virulence factors are associated with epidemic strains (O1 and O139 serogroups) of Vibrio cholerae: cholera toxin encoded by the ctxAB genes and toxin-coregulated pilus encoded by the tcpA gene. The ctx genes reside in the genome of a filamentous phage (CTXphi), and the tcpA gene resides in a vibrio pathogenicity island (VPI) which has also been proposed to be a filamentous phage designated VPIphi. In order to determine the prevalence of horizontal transfer of VPI and CTXphi among nonepidemic (non-O1 and non-O139 serogroups) V. cholerae, 300 strains of both clinical and environmental origin were screened for the presence of tcpA and ctxAB. In this paper, we present the comparative genetic analyses of 11 nonepidemic serogroup strains which carry the VPI cluster. Seven of the 11 VPI(+) strains have also acquired the CTXphi. Multilocus sequence typing and restriction fragment length polymorphism analyses of the VPI and CTXphi prophage regions revealed that the non-O1 and non-O139 strains were genetically diverse and clustered in lineages distinct from that of the epidemic strains. The left end of the VPI in the non-O1 and non-O139 strains exhibited extensive DNA rearrangements. In addition, several CTXphi prophage types characterized by novel repressor (rstR) and ctxAB genes and VPIs with novel tcpA genes were found in these strains. These data suggest that the potentially pathogenic, nonepidemic, non-O1 and non-O139 strains identified in our study most likely evolved by sequential horizontal acquisition of the VPI and CTXphi independently rather than by exchange of O-antigen biosynthesis regions in an existing epidemic strain.

Amino Acid Sequence↗

PubMed2003

Multilocus sequence typing has better discriminatory ability for typing Vibrio cholerae than does pulsed-field gel electrophoresis and provides a measure of phylogenetic relatedness.

Twenty-two Vibrio cholerae isolates, including some from "epidemic" (O1 and O139) and "nonepidemic" serogroups, were characterized by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) by using three housekeeping genes, gyrB, pgm, and recA; sequence data were also obtained for the virulence-associated genes tcpA, ctxA, and ctxB. Even with the small number of loci used, MLST had better discriminatory ability than did PFGE. On MLST analysis, there was clear clustering of epidemic serogroups; much greater diversity was seen among tcpA- and ctxAB-positive V. cholerae strains from other, nonepidemic serogroups, with a number of tcpA and ctxAB alleles identified.

Alleles↗

PubMed2002

Multilocus sequence typing for characterization of clinical and environmental salmonella strains.

Multilocus sequence typing (MLST) based on the 16S RNA, pduF, glnA, and manB genes was developed for Salmonella, and its discriminatory ability was compared to those of pulsed-field gel electrophoresis (PFGE) and serotyping. PFGE differentiated several strains undifferentiable by serotyping, and 78 distinct PFGE types were identified among 231 Salmonella isolates grouped into 22 serotypes and 12 strains of undetermined serotype. The strains of several PFGE types were further differentiated by MLST, which suggests that the discriminatory ability of MLST for the typing of Salmonella is better than that of serotyping and/or PFGE typing. manB-based sequence typing identified two distinct genetic clusters containing 32 of 54 (59%) clinical isolates whose manB gene sequences were analyzed. The G+C contents and Splitstree analysis of the manB, glnA, and pduF genes of Salmonella indicated that the genes differ in their evolutionary origins and that recombination played a significant role in their evolution.

Animals↗