Blastocystis isolates from patients with irritable bowel syndrome and from asymptomatic carriers exhibit similar parasitological loads, but significantly different generation times and genetic variability across multiple subtypes
Por:
VargasSanchez, GB, Romero-Valdovinos M., Ramirez-Guerrero C., Vargas-Hernandez I., Ramirez-Miranda M.E., Martinez-Ocaña J., Valadez A., Ximenez C., Lopez-Escamilla E., Hernandez-Campos M.E., Villalobos G., Martinez-Hernandez F., Maravilla P.
Publicada:
29 abr 2015
Resumen:
Blastocystis spp is a common intestinal parasite of humans and animals that has been associated to the etiology of irritable bowel syndrome (IBS); however, some studies have not found this association. Furthermore, many biological features of Blastocystis are little known. The objective of present study was to assess the generation times of Blastocystis cultures, from IBS patients and from asymptomatic carriers. A total of 100 isolates were obtained from 50 IBS patients and from 50 asymptomatic carriers. Up to 50 mg of feces from each participant were cultured in Barret's and in Pavlova's media during 48 h. Initial and final parasitological load were measured by microscopy and by quantitative PCR. Amplicons were purified, sequenced and submitted to GenBank; sequences were analysed for genetic diversity and a Bayesian inference allowed identifying genetic subtypes (ST). Generation times for Blastocystis isolates in both media, based on microscopic measures and molecular assays, were calculated. The clinical symptoms of IBS patients and distribution of Blastocystis ST 1, 2 and 3 in both groups was comparable to previous reports. Interestingly, the group of cases showed scarce mean nucleotide diversity (p) as compared to the control group (0.011±0.016 and 0.118±0.177, respectively), whilst high gene flow and small genetic differentiation indexes between different ST were found. Besides, Tajima's D test showed negative values for ST1-ST3. No statistical differences regarding parasitological load between cases and controls in both media, as searched by microscopy and by qPCR, were detected except that parasites grew faster in Barret's than in Pavlova's medium. Interestingly, slow growth of isolates recovered from cases in comparison to those of controls was observed (p<0.05). We propose that generation times of Blastocystis might be easily affected by intestinal environmental changes due to IBS probably because virulent strains with slow growth may be selected, reducing their genetic variability. © 2015 Vargas-Sanchez et al.
Filiaciones:
Romero-Valdovinos M.:
Hospital General Dr. Manuel Gea Gonzalez, Calzada de Tlalpan 4800, Seccion XVI, Mexico City, DF 14080, Mexico
Ramirez-Guerrero C.:
Hospital Infantil de Mexico Federico Gomez, Dr. Marquez 162, Doctores, Mexico City, DF 06720, Mexico
Vargas-Hernandez I.:
Centro Especializado de Atención Primaria Melchor-Ocampo, Bicentenario, Secretaria de Salud del Estado Mexico, Estado de Mexico, 54880, Mexico
Ramirez-Miranda M.E.:
Hospital General Dr. Manuel Gea Gonzalez, Calzada de Tlalpan 4800, Seccion XVI, Mexico City, DF 14080, Mexico
Martinez-Ocaña J.:
Hospital General Dr. Manuel Gea Gonzalez, Calzada de Tlalpan 4800, Seccion XVI, Mexico City, DF 14080, Mexico
Valadez A.:
Univ Nacl Autonoma Mexico, Fac Med, Dept Expt Med, Mexico City 04510, DF, Mexico
Ximenez C.:
Univ Nacl Autonoma Mexico, Fac Med, Dept Expt Med, Mexico City 04510, DF, Mexico
Lopez-Escamilla E.:
Hospital General Dr. Manuel Gea Gonzalez, Calzada de Tlalpan 4800, Seccion XVI, Mexico City, DF 14080, Mexico
Hernandez-Campos M.E.:
Escuela Superior de Medicina, Instituto Politecnico Nacional, Plan de San Luis y Diaz Miron s/n, Casco de Santo Tomas, Mexico City, DF 11340, Mexico
Villalobos G.:
Univ Nacl Autonoma Mexico, Inst Ecol, Dept Ecol Evolut, Mexico City 04510, DF, Mexico
Martinez-Hernandez F.:
Hospital General Dr. Manuel Gea Gonzalez, Calzada de Tlalpan 4800, Seccion XVI, Mexico City, DF 14080, Mexico
Maravilla P.:
Hospital General Dr. Manuel Gea Gonzalez, Calzada de Tlalpan 4800, Seccion XVI, Mexico City, DF 14080, Mexico
Gold
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