title: Determining Clostridium difficile intra-taxa diversity by mining multilocus sequence typing databases.
abstract: Multilocus sequence typing (MLST) is a highly discriminatory typing strategy; it is reproducible and scalable. There is a MLST scheme for Clostridium difficile (CD), a gram positive bacillus causing different pathologies of the gastrointestinal tract. This work was aimed at describing the frequency of sequence types (STs) and Clades (C) reported and evalute the intra-taxa diversity in the CD MLST database (CD-MLST-db) using an MLSA approach.
  
  
  
  Analysis of 1778 available isolates showed that clade 1 (C1) was the most frequent worldwide (57.7%), followed by C2 (29.1%). Regarding sequence types (STs), it was found that ST-1, belonging to C2, was the most frequent. The isolates analysed came from 17 countries, mostly from the United Kingdom (UK) (1541 STs, 87.0%). The diversity of the seven housekeeping genes in the MLST scheme was evaluated, and alleles from the profiles (STs), for identifying CD population structure. It was found that adk and atpA are conserved genes allowing a limited amount of clusters to be discriminated; however, different genes such as drx, glyA and particularly sodA showed high diversity indexes and grouped CD populations in many clusters, suggesting that these genes' contribution to CD typing should be revised. It was identified that CD STs reported to date have a mostly clonal population structure with foreseen events of recombination; however, one group of STs was not assigned to a clade being highly different containing at least nine well-supported clusters, suggesting a greater amount of clades for CD.
  
  
  
  This study shows the usefulness of CD-MLST-db as a tool for studying CD distribution and population structure, identifying the need for reviewing the usefulness of sodA as housekeeping gene within the MLST scheme and suggesting the existence of a greater amount of CD clades. The study also shows the plausible exchange of genetic material between STs, contributing towards intra-taxa genetic diversity.
authors.affiliation: Grupo de Investigaciones Microbiológicas-UR (GIMUR), Programa de Biología, Facultad de Ciencias Naturales y Matemáticas, Universidad del Rosario, Carrera 24 # 63C - 69, Bogotá, Colombia.|Posgrado Interfacultades Doctorado en Biotecnología, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia.
authors.forename: Marina
authors.initials: M
authors.lastname: Muñoz
authors.affiliation: Grupo de Investigaciones Microbiológicas-UR (GIMUR), Programa de Biología, Facultad de Ciencias Naturales y Matemáticas, Universidad del Rosario, Carrera 24 # 63C - 69, Bogotá, Colombia.
authors.forename: Dora Inés
authors.initials: DI
authors.lastname: Ríos-Chaparro
authors.affiliation: Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia.|School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia.
authors.forename: Manuel Alfonso
authors.initials: MA
authors.lastname: Patarroyo
authors.affiliation: Grupo de Investigaciones Microbiológicas-UR (GIMUR), Programa de Biología, Facultad de Ciencias Naturales y Matemáticas, Universidad del Rosario, Carrera 24 # 63C - 69, Bogotá, Colombia. juand.ramirez@urosario.edu.co.
authors.forename: Juan David
authors.initials: JD
authors.lastname: Ramírez
mesh_terms: D000483:Alleles; D015373:Bacterial Typing Techniques / Q000379:methods*; D016360:Clostridioides difficile / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D019143:Evolution, Molecular; D005798:Genes, Bacterial / Q000235:genetics; D020043:Genes, Essential / Q000235:genetics; D014644:Genetic Variation; D058885:Multilocus Sequence Typing / Q000379:methods*; D010802:Phylogeny; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA
keywords: Clostridium difficile; Distribution pattern; Multilocus sequence typing (MLST); Population structure