RESUMEN

Antiemetic treatment compliance is important to prevent chemotherapy-induced nausea and vomiting, a feared chemotherapy side effect. NEPA, a new oral fixed combination of netupitant, a highly selective NK1 receptor antagonist (RA), and palonosetron, a second-generation 5-HT3 RA, targets dual antiemetic pathways with a single dose. This study investigated the effect of food intake and age on NEPA pharmacokinetics (PK) and safety. In this open-label, single-center, randomized, phase 1 study, 24 adults (18-45 years) received NEPA in a fed or fasted state during the first treatment period and in the alternative state in the next treatment period. Twelve elderly subjects (≥65 years) received NEPA in a fasted state. Blood samples were taken for netupitant and palonosetron PK analysis. In the fed condition, netupitant plasma exposure increased, whereas palonosetron PK parameters were not affected. Furthermore, elderly subjects showed increased netupitant and palonosetron exposure compared with adults. All adverse events were mild/moderate, with constipation and headache the most common. Although food intake and age altered NEPA PK, dose adjustments were not needed, as netupitant and palonosetron exposure increases did not lead to safety concerns in healthy subjects.

Asunto(s)

Antieméticos/administración & dosificación , Antieméticos/farmacocinética , Interacciones Alimento-Droga , Isoquinolinas/administración & dosificación , Isoquinolinas/farmacocinética , Piridinas/administración & dosificación , Piridinas/farmacocinética , Quinuclidinas/administración & dosificación , Quinuclidinas/farmacocinética , Administración Oral , Adulto , Factores de Edad , Anciano , Antieméticos/efectos adversos , Antieméticos/sangre , Estudios Cruzados , Combinación de Medicamentos , Ayuno/sangre , Femenino , Alemania , Voluntarios Sanos , Humanos , Isoquinolinas/efectos adversos , Isoquinolinas/sangre , Masculino , Persona de Mediana Edad , Periodo Posprandial , Piridinas/efectos adversos , Piridinas/sangre , Quinuclidinas/efectos adversos , Quinuclidinas/sangre , Adulto Joven

RESUMEN

Bacteria exchange genetic material by horizontal gene transfer (HGT). To evaluate the impact of HGT on Escherichia coli genome plasticity, 19 commensal strains collected from the intestinal floras of humans and animals were analyzed by microarrays. Strains were hybridized against an oligoarray containing 2700 E. coli K12 chromosomal genes. A core (genes shared among compared genomes) and a flexible gene pool (genes unique for each genome) have been identified. Analysis of hybridization signals evidenced 1015 divergent genes among the 19 strains and each strain showed a specific genomic variability pattern. Four hundred and fifty-eight genes were characterized by higher rates of interstrain variation and were considered hyperdivergent. These genes are not randomly distributed onto the chromosome but are clustered in precise regions. Hyperdivergent genes belong to the flexible gene pool and show a specific GC content, differing from that of the chromosome, indicating acquisition by HGT. Among these genes, those involved in defense mechanisms and cell motility as well as intracellular trafficking and secretion were far more represented than others. The observed genome plasticity contributes to the maintenance of genetic diversity and may therefore be a source of evolutionary adaptation and survival.

Asunto(s)

ADN Bacteriano/genética , Escherichia coli/genética , Transferencia de Gen Horizontal , Análisis por Micromatrices , Animales , Composición de Base , Cromosomas Bacterianos , Escherichia coli/aislamiento & purificación , Escherichia coli/fisiología , Genes Bacterianos , Humanos , Familia de Multigenes , Polimorfismo Genético , Sintenía

RESUMEN

BACKGROUND: Chlamydophila pneumoniae is an obligate intracellular bacterium that replicates in a biphasic life cycle within eukaryotic host cells. Four published genomes revealed an identity of > 99 %. This remarkable finding raised questions about the existence of distinguishable genotypes in correlation with geographical and anatomical origin. RESULTS: We studied the genetic diversity of C. pneumoniae by analysing synonymous single nucleotide polymorphisms (sSNPs) that are under reduced selection pressure. We conducted an in silico analysis of the four sequenced genomes, chose 232 representative sSNPs and analysed the loci in 38 C. pneumoniae isolates. We identified 15 different genotypes that were separated in four major clusters. Clusters were not associated with anatomical or geographical origin. However, animal lineages are basal on the C. pneumomiae phylogeny, suggesting a recent transmission to humans through successive bottlenecks some 150,000 years ago. A lack of detectable variation in 17 isolates emphasizes the extraordinary genetic conservation of this species and the high clonality of the population. Moreover, the largest cluster, which encompasses 80% of all analysed strains, is an extremely young clade, that went through an important population expansion some 3,300 years ago. CONCLUSION: sSNPs have proven useful as a sensitive marker to gain new insights into genetic diversity, population structure and evolutionary history of C. pneumoniae.

Asunto(s)

Chlamydophila pneumoniae/genética , Genoma Bacteriano , Polimorfismo de Nucleótido Simple , Chlamydophila pneumoniae/clasificación , Filogenia , Reacción en Cadena de la Polimerasa

RESUMEN

One hundred and twenty clinical and commensal Escherichia coli strains isolated in Switzerland from humans and from companion and farm animals were analysed for the prevalence of integrons of classes 1, 2, and 3 and for the characterization of their gene cassettes. The relationships between integron carriage and host category, and between integron carriage and phylogenetic E. coli lineage were also analysed. Integrons were detected in 48 (40%) of the isolates and were thus widely disseminated in the human and animal E. coli strains considered. Moreover, the association between integron carriage and certain animal categories (farm animals) suggests that animals that are raised for economic purposes might be exposed to a major antibiotic pressure. Finally, our data confirm that E. coli commensal strains represent a significant source of antibiotic-resistant determinants.

Asunto(s)

Enfermedades de los Animales/microbiología , Infecciones por Escherichia coli/microbiología , Infecciones por Escherichia coli/veterinaria , Escherichia coli/genética , Integrones/genética , Animales , Secuencia de Bases , Gatos , Bovinos , Perros , Escherichia coli/aislamiento & purificación , Humanos , Datos de Secuencia Molecular , Filogenia , Aves de Corral , Regiones Promotoras Genéticas/genética , Porcinos

RESUMEN

Due to its mostly isolated living environment, Mycobacterium tuberculosis is generally believed to be highly clonal, and thus recombination between different strains must be rare and is not critical for the survival of the species. To investigate the roles recombination could have possibly played in the evolution of M. tuberculosis, an analysis was conducted on previously determined genotypes of 36 synonymous single nucleotide polymorphisms (SNPs) in 3,320 M. tuberculosis isolates. The results confirmed the predominant clonal structure of the M. tuberculosis population. However, recombination between different strains was also suggested. To further resolve the issue, 175 intergenic SNPs and 234 synonymous SNPs were genotyped in 37 selected representative strains. A clear mosaic polymorphic pattern ahead of the MT0105 locus encoding a PPE (Pro-Pro-Glu) protein was obtained, which is most likely a result of recombination hot spot. Given that PPE proteins are thought to be critical in host-pathogen interactions, we hypothesize that recombination has been influential in the history of M. tuberculosis and possibly a major contributor to the diversity observed ahead of the MT0105 locus.

Asunto(s)

Mycobacterium tuberculosis/genética , Recombinación Genética , Antígenos Bacterianos/genética , Humanos , Polimorfismo de Nucleótido Simple , Tuberculosis/microbiología

RESUMEN

We studied genetic relationships among 5069 Mycobacterium tuberculosis strains recovered from patients enrolled in 4 population-based studies in the United States and Europe, by analysis of 36 synonymous single-nucleotide polymorphisms (SNPs). All strains were assigned to 1 of 9 major genetic clusters based on sSNP profile. The same 9 genetic clusters were revealed by analysis of 227 nonsynonymous SNPs, 121 intergenic SNPs, and concatenated profiles of 578 SNPs available for a subset of 48 representative strains. IS6110 profiles, spoligotypes, and mycobacterial interspersed repetitive unit patterns were nonrandomly associated with SNP-based phylogenetic lineages, together indicating a strongly clonal population structure. Isolates of the 9 genetic clusters were not distributed with equal frequency in all localities, reflecting geographic subdivision. The SNP-based phylogenetic framework provides new insight into the worldwide evolution of M. tuberculosis and a gateway for investigating genotype-disease phenotype relationships in large samples of strains.

Asunto(s)

Mycobacterium tuberculosis/clasificación , Mycobacterium tuberculosis/genética , Polimorfismo de Nucleótido Simple/genética , Tuberculosis Pulmonar/epidemiología , Técnicas de Tipificación Bacteriana , Elementos Transponibles de ADN , Europa (Continente)/epidemiología , Humanos , Oligonucleótidos/análisis , Filogenia , Polimorfismo de Longitud del Fragmento de Restricción , Tuberculosis Pulmonar/microbiología , Estados Unidos/epidemiología

RESUMEN

Genetic relationships among 62 Vibrio vulnificus strains of different geographical and host origins were analyzed by multilocus enzyme electrophoresis (MLEE), random amplification of polymorphic DNA (RAPD), and sequence analyses of the recA and glnA genes. Out of 15 genetic loci analyzed by MLEE, 11 were polymorphic. Cluster analysis identified 43 distinct electrophoretic types (ETs) separating the V. vulnificus population into two divisions (divisions I and II). One ET (ET 35) included all indole-negative isolates from diseased eels worldwide (biotype 2). A second ET (ET 2) marked all of the strains from Israel isolated from patients who handled St. Peter's fish (biotype 3). RAPD analysis of the 62 V. vulnificus isolates identified 26 different profiles separated into two divisions as well. In general, this subdivision was comparable (but not identical) to that observed by MLEE. Phylogenetic analysis of 543 bp of the recA gene and of 402 bp of the glnA gene also separated the V. vulnificus population into two major divisions in a manner similar to that by MLEE and RAPD. Sequence data again indicated the overall subdivision of the V. vulnificus population into different biotypes. In particular, indole-negative eel-pathogenic isolates (biotype 2) on one hand and the Israeli isolates (biotype 3) on the other tended to cluster together in both gene trees. None of the methods showed an association between distinct clones and human clinical manifestations. Furthermore, except for the Israeli strains, only minor clusters comprising geographically related isolates were observed. In conclusion, all three approaches (MLEE, RAPD, and DNA sequencing) generated comparable but not always equivalent results. The significance of the two divisions (divisions I and II) still remains to be clarified, and a reevaluation of the definition of the biotypes is also needed.

Asunto(s)

Anguilas/microbiología , Vibriosis/microbiología , Vibrio vulnificus/clasificación , Vibrio vulnificus/genética , Animales , Técnicas de Tipificación Bacteriana , Electroforesis/métodos , Enfermedades de los Peces/microbiología , Variación Genética , Genética de Población , Glutamato-Amoníaco Ligasa/genética , Humanos , Datos de Secuencia Molecular , Filogenia , Técnica del ADN Polimorfo Amplificado Aleatorio , Rec A Recombinasas/genética , Análisis de Secuencia de ADN , Vibriosis/veterinaria , Vibrio vulnificus/patogenicidad

RESUMEN

The sequences of part of the glutamine synthetase-encoding gene (glnA) and of the RecA-encoding gene (recA) were determined and aligned for 45 Bacteroides fragilis isolates from different clinical and geographical origin. The patterns of sequence divergence of glnA and recA were very similar. The sequences of a 303-bp fraction of recA showed 45 nucleotide substitutions, 40 of which allowed the separation of B. fragilis into two major divisions, which were not found when the deduced amino acid sequences were considered. The 687-bp sequences analysed for the glnA gene showed 112 nucleotide substitutions, 96 of which separated the population into the same two divisions as those described for recA. In this case, the deduced amino acid sequences showed this subdivision as well: three of the six observed amino acid substitutions were division-specific. Within the two divisions, both genes presented a high degree of sequence conservation. Each B. fragilis division was associated with the presence of a different antibiotic resistance gene: cepA encoding a serine-beta-lactamase (division I) and cfiA encoding a metallo-beta-lactamase (division II). No particular clusters associated with geographical or clinical origin, or with the production of an enterotoxin were observed. Sequencing of the cfiA gene allowed identification of two different alleles in division II. However, no association of these different cfiA alleles with the expression of imipenem resistance was observed. In conclusion, the phylogenetic patterns observed by sequencing recA and glnA are in agreement with those obtained previously by MLEE (multilocus enzyme electrophoresis). Thus, it appears that the evolution of recA and glnA genes is similar to that of the whole chromosome of B. fragilis. Horizontal gene transfer between divisions I and II seems to be low, at best. However, the results of the present study could not clarify definitively whether divisions I and II should be considered as two different B. fragilis genospecies.

Asunto(s)

Proteínas Bacterianas , Bacteroides fragilis/clasificación , Farmacorresistencia Bacteriana/genética , Glutamato-Amoníaco Ligasa/genética , Rec A Recombinasas/genética , beta-Lactamasas/genética , Bacteroides fragilis/efectos de los fármacos , Bacteroides fragilis/genética , Secuencia de Bases , Variación Genética , Genotipo , Datos de Secuencia Molecular , Filogenia

RESUMEN

Several human pathogens (e.g., Bacillus anthracis, Yersinia pestis, Bordetella pertussis, Plasmodium falciparum, and Mycobacterium tuberculosis) have very restricted unselected allelic variation in structural genes, which hinders study of the genetic relationships among strains and strain-trait correlations. To address this problem in a representative pathogen, 432 M. tuberculosis complex strains from global sources were genotyped on the basis of 230 synonymous (silent) single nucleotide polymorphisms (sSNPs) identified by comparison of four genome sequences. Eight major clusters of related genotypes were identified in M. tuberculosis sensu stricto, including a single cluster representing organisms responsible for several large outbreaks in the United States and Asia. All M. tuberculosis sensu stricto isolates of previously unknown phylogenetic position could be rapidly and unambiguously assigned to one of the eight major clusters, thus providing a facile strategy for identifying organisms that are clonally related by descent. Common clones of M. tuberculosis sensu stricto and M. bovis are distinct, deeply branching genotypic complexes whose extant members did not emerge directly from one another in the recent past. sSNP genotyping rapidly delineates relationships among closely related strains of pathogenic microbes and allows construction of genetic frameworks for examining the distribution of biomedically relevant traits such as virulence, transmissibility, and host range.

Asunto(s)

Mycobacterium tuberculosis/genética , Alelos , Animales , Variación Genética , Genoma Bacteriano , Genotipo , Humanos , Epidemiología Molecular , Mycobacterium bovis/genética , Mycobacterium bovis/aislamiento & purificación , Mycobacterium tuberculosis/clasificación , Mycobacterium tuberculosis/aislamiento & purificación , Mycobacterium tuberculosis/patogenicidad , Filogenia , Polimorfismo de Longitud del Fragmento de Restricción , Polimorfismo de Nucleótido Simple , Especificidad de la Especie , Virulencia/genética

RESUMEN

Ninety-three Bacteroides fragilis strains of different origin were analysed by multilocus enzyme electrophoresis (MLEE). Fourteen of the 15 genetic loci analysed were polymorphic, whilst nucleoside phosphorylase was monomorphic. There was a mean of six alleles per locus and a mean genetic diversity of 0.393. Cluster analysis identified 90 electrophoretic types (ETs) separated into two major phylogenetic divisions at a genetic distance of 0.70. Division I consisted of 81 ETs carrying the endogenous class A beta-lactamase gene cepA, whereas division II comprised 9 ETs carrying the class B beta-lactamase gene cfiA, but not cepA. The presence of these two genes was assessed by PCR and the expression of the cfiA gene was investigated by determining the level of resistance to the antibiotic imipenem. MLEE showed a smaller genetic distance among the genotypes of the imipenem-resistant than among the imipenem-susceptible strains. No other particular cluster was observed. The enterotoxin gene (bft) was detected by PCR: DNA sequencing of the products obtained showed that the different bft alleles (bft-1, bft-2 and bft-3) were scattered randomly troughout the phylogenetic tree. No association between distinct clones and clinical manifestations (sepsis, abscesses, diarrhoea), geographical origin or host origin (human or animal) could be found.

Asunto(s)

Proteínas Bacterianas , Bacteroides fragilis/genética , beta-Lactamasas/genética , Alelos , Animales , Toxinas Bacterianas/genética , Bacteroides fragilis/efectos de los fármacos , Bacteroides fragilis/enzimología , Análisis por Conglomerados , ADN Bacteriano/análisis , ADN Ribosómico/análisis , Farmacorresistencia Microbiana/genética , Electroforesis en Gel de Almidón , Humanos , Imipenem/farmacología , Metaloendopeptidasas/genética , Pruebas de Sensibilidad Microbiana , Datos de Secuencia Molecular , Pentosiltransferasa/análisis , Pentosiltransferasa/genética , Reacción en Cadena de la Polimerasa , Polimorfismo Genético , ARN Ribosómico 16S/genética , Tienamicinas/farmacología