Maravilla 2012

Parasitol Res (2012) 110:1269–1275
DOI 10.1007/s00436-011-2626-7

ORIGINAL PAPER

Blastocystis infection is associated with irritable bowel
syndrome in a Mexican patient population
Diego Emiliano Jimenez-Gonzalez & Williams Arony Martinez-Flores &
Jesus Reyes-Gordillo & Maria Elena Ramirez-Miranda & Sara Arroyo-Escalante &
Mirza Romero-Valdovinos & Damien Stark & Valeria Souza-Saldivar &
FernandoMartinez-Hernandez & Ana Flisser & Angelica Olivo-Diaz & Pablo Maravilla

Received: 3 May 2011 / Accepted: 12 August 2011 / Published online: 26 August 2011
# Springer-Verlag 2011

Abstract In recent times, some common “non-pathogenic”
parasites, such as Blastocystis and Dientamoeba fragilis,
have been associated to the aetiology of irritable bowel
syndrome (IBS), while host pro-inflammatorycytokine
gene polymorphisms might have a role in the pathophysiology of the disease. Therefore, Blastocystis subtypes (ST),
D. fragilis and gene promoter single nucleotide polymorphisms of interleukin-6 (IL-6) and tumour necrosis
factor-alpha (TNF-α) in IBS patients and controls were
studied. After giving written consent, 45 patients with
symptoms of IBS according to the Rome III criteria and 45
D. E.Jimenez-Gonzalez : W. A. Martinez-Flores :
J. Reyes-Gordillo : M. E. Ramirez-Miranda :
M. Romero-V
aldovinos : F. Martinez-Hernandez : A. Olivo-Diaz :
P Maravilla (*)
.
Hospital General “Dr. Manuel Gea Gonzalez”,
Direccion de Investigacion,
Mexico, DF 14080, Mexico
e-mail: maravillap@yahoo.com
S. Arroyo-Escalante
Hospital General “Dr. Manuel Gea Gonzalez”,
Laboratorio Clinico,
Mexico, DF 14080,Mexico
D. Stark
Department of Microbiology, St.Vincent’s Hospital,
Darlinghurst 2010 NSW, Australia
V Souza-Saldivar
.
Instituto de Ecologia,
Universidad Nacional Autonoma de Mexico,
Mexico, DF 04510, Mexico
A. Flisser
Departamento de Microbiologia y Parasitologia,
Facultad de Medicina,
Universidad Nacional Autonoma de Mexico,
Mexico, DF 04536, Mexico

controls were enrolled. DNA was extracted fromperipheral
blood for SNP analysis at position -174 for IL-6 as well as 238 and -308 for TNF-α. Blastocystis was more common in
the IBS group (p =0.043). Interestingly, D. fragilis was
found more frequently in the control group (p =0.002);
Blastocystis ST1 and 3 were most frequent in both groups.
Haploview analysis revealed linkage disequilibrium in
TNF-α (p <0.0001); however, none of the SNPs forIL-6
and TNF-α were found to be significantly related with IBS.
The clinical and molecular approaches undertaken for the
first time in Latin American IBS patients demonstrated an
association with Blastocystis that supports a pathogenic role
of this parasite in IBS Furthermore, co-infections with ST1
and ST3 were frequent; thus, the genetic diversity proposed
within ST polymorphisms does not ruleout that particular
strains might be associated with disease. In addition, our
results do not support a major contribution of IL-6 and
TNF-α gene polymorphisms in the susceptibility to IBS.

Introduction
Irritable bowel syndrome (IBS) is a functional disorder in
which abdominal pain or discomfort is associated with a
change in bowel habits and disordered defecation (Longstreth
et al. 2006). Thepathophysiology of IBS remains poorly
understood, and no mechanism is unique to, or characteristic
of, IBS (Gasbarrini et al. 2008). Several factors occur in IBS
patients that account for clinical symptoms. These include
altered gut reactivity (colonic and/or small-bowel motility) in
response to luminal or psychological stimuli and visceral and
gut hypersensitivity, with enhanced visceral perceptionand
pain (Thompson et al. 2000; Stark et al. 2007).
The pathogenic role of Blastocystis is still controversial
because it is found not only in individuals with enteric

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symptoms but also in healthy and asymptomatic subjects
(Boorom et al. 2008; Tan 2008; Stensvold et al. 2009a; Stark
et al. 2010). In addition, Dientamoeba fragilis has been
reported to cause IBS-like symptoms and has a...