Abstract
BackgroundBlastocystis, a genetically diverse intestinal parasite with controversial pathogenic potential, has increasingly been incriminated for diarrheal illness in immunocompromised individuals including colorectal cancer (CRC) patients. The aim of the current study was to assess the possible association between Blastocystis infection and CRC condition in Makkah, Saudi Arabia (KSA).MethodsStool samples were collected from 80 non-cancer (NC) and 138 cancer subjects including 74 CRC patients and 64 patients with other cancers outside gastrointestinal tract (COGT). Molecularly confirmed Blastocystis isolates were genetically grouped and subtyped using multiplex polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP) and sequence-tagged site primers-based PCR (PCR-STS), respectively.ResultsBlastocystis hominis were confirmed in 29.7, 25 and 15% among CRC, COGT and NC patients, respectively. Obtained Blastocystis isolates were initially categorized into 2 groups (A and C), which were subsequently subtyped into 3 different subtypes; subtype-I (38%), subtype-II (44%) and subtype-V (22%). Interestingly, subtype-I was the most predominantly detected subtype (54.5%) among CRC patients with a significant association risk (COR 7.548; 95% CI: 1.629–34.987; P = 0.004).ConclusionTo the best of our knowledge, the current study is the first to provide genetic insights on the prevalence of Blastocystis hominis among CRC patients in Makkah, KSA. Moreover, the study suggests for a possible association between subtype-I of Blastocystis hominis and CRC, which could indicate a potential influence of Blastocystis on CRC condition. Further studies are required to confirm this association risk and to investigate the possible underlying mechanism of postulated carcinogenic influence of Blastocystis hominis subtype-I.
Highlights
Blastocystis, a genetically diverse intestinal parasite with controversial pathogenic potential, has increasingly been incriminated for diarrheal illness in immunocompromised individuals including colorectal cancer (CRC) patients
A significant difference (P < 0.05) of Blastocystis infection frequency was evident between Cancer patients (CP) group and Non cancer (NC) groups as well as between CRC and NC groups
Dissimilar to previous studies, which usually reveal the predominance of one subtype among investigated local population [22, 24, 40], the current study revealed the presence of 3 different subtypes (I, II and V) among investigated patients
Summary
Blastocystis, a genetically diverse intestinal parasite with controversial pathogenic potential, has increasingly been incriminated for diarrheal illness in immunocompromised individuals including colorectal cancer (CRC) patients. Blastocystis species remains one of the most common intestinal parasites in humans with a prevalence of up to 10% in developed countries, rising to 50–60% in developing countries [1, 2] It is considered one of the most commonly encountered non-fungal eukaryotic organisms in human fecal samples [3]. Only ST1 to ST9 are considered to colonize in humans [7, 17] This genetic diversity has supported the hypothesis that the variability in symptoms in patients positive for Blastocystis could be due to different pathogenic potential among the subtypes [18,19,20,21]
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