title: Phenotypic and genotypic evaluation of 18 Nocardia isolates from human clinical samples in Mexico.
abstract: BACKGROUND
  Mexico has the largest number of clinical cases of actinomycetoma in North and South America. Species originally identified by less specific methods have been recently reclassified as other known species or as new species.
  
  
  OBJECTIVE
  To assess, by 16S rRNA gene sequencing and phenotypic methods, the species distribution of 18 human clinical isolates originally identified as N. brasiliensis, some of them isolated between 1947 and 1959 in Mexico City.
  
  
  METHODS
  Clinical isolates came from the Hospital General, "Dr. Manuel Gea Gonzalez", and Instituto Nacional de Diagnóstico y Referencia Epidemiológica (INDRE) in Mexico, D.F. The strains used in this study included 15 clinical strains isolated between 1947 and 1959 that were originally identified as N. brasiliensis and three more strains obtained in 2007 identified as Nocardia spp. The isolates were identified genotypically by sequencing the 16S rRNA gene, and their phenotypic profiles were obtained with the API Coryne(®) system. Antibiotic susceptibility patterns were tested according to the protocol of the Comité de l'antibiogramme de la Société française de microbiologie[4].
  
  
  RESULTS
  According to 16S rRNA gene, sequencing were identified among 18 human clinical isolates as Nocardia farcinica (n=11) and Nocardia brasiliensis (n=7). A high number of the strains were susceptible to the majority of the antibiotics tested. The phenotypic profiles of the strains were quite uniform for N. farcinica and some variability was observed for N. brasiliensis strains.
  
  
  CONCLUSIONS
  N. farcinica was the most prevalent species identified. Modern methodologies should be applied in clinical laboratories to accurately identify etiological agents.
authors.affiliation: Departamento de Sistemas Biológicos, Universidad Autónoma Metropolitana-Xochimilco, Calz. del Hueso 1100, Col. Villa Quietud Del. Coyoacán, DF 04960, México. karinash@yahoo.com
authors.forename: K
authors.initials: K
authors.lastname: Sánchez-Herrera
authors.forename: H
authors.initials: H
authors.lastname: Sandoval
authors.forename: A
authors.initials: A
authors.lastname: Couble
authors.forename: D
authors.initials: D
authors.lastname: Mouniee
authors.forename: N
authors.initials: N
authors.lastname: Ramírez-Durán
authors.forename: M
authors.initials: M
authors.lastname: Uzcategui de Morillo
authors.forename: J A
authors.initials: JA
authors.lastname: Serrano
authors.forename: E
authors.initials: E
authors.lastname: Bergeron
authors.forename: P
authors.initials: P
authors.lastname: Boiron
authors.forename: V
authors.initials: V
authors.lastname: Rodríguez-Nava
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D005838:Genotype; D006801:Humans; D008800:Mexico / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D009615:Nocardia / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D009617:Nocardia Infections / Q000453:epidemiology / Q000382:microbiology*; D010641:Phenotype; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D012336:RNA, Ribosomal, 16S