An Association Between Blastocystis Subtypes and Colorectal Cancer Patients: A Significant Different Profile from Non-cancer Individuals

Abstract

Purpose Blastocystis is a common enteric human parasite of non-conclusive pathogenicity which may be determined by subtype (ST) variation. Colorectal cancer (CRC) is considered one of the primary causes of cancer mortality. Blastocystis ST7 has been shown to reduce beneficial intestinal microbiota and may exacerbate CRC. This study assessed the possible association between Blastocystis STs and CRC in comparison to non-cancer patients. Material and Methods A total of 200 fecal samples were obtained from CRC (100) and non-CRC (100) individuals attending Beni-Suef University Hospital, Egypt. Blastocystis was searched for in all samples using microscopy and culturing. Positive subculture samples were genetically sequenced and subtyped using conventional polymerase chain reaction (PCR). Blastocystis STs were determined by sequencing and a phylogenetic tree was created. Related patient characteristics and tumor stages were analyzed for association with presence of Blastocystis . Results Blastocystis was identified in 52% and 42% of CRC and non-cancer individuals, respectively. ST1, 2, and 3 were isolated from both cancer and non-cancer individuals; however, for the first time, ST7 was only isolated from CRC stool samples with significant association. Associated patient characteristics were evaluated as predictors. Conclusion Blastocystosis is highly prevalent in CRC patients, predominantly in the latest CRC grades and stages. To the best of our knowledge, this is the first study to report the identification of Blastocystis ST7 in CRC patients. To determine whether certain STs of Blastocystis are associated with CRC would require further research, including the role played by gut microbiota.

Subtypes and phylogenetic analysis of Blastocystis sp. isolates from West Ismailia, Egypt

“… Country/Region Group of study and associated comorbidity Associated GIT symptoms 2 Molecular methods Species/STs Most prevalent subtype/allele Reference Egypt/Ismailia West Ismailia subjects Asymptomatic Symptomatic PCR Sequencing Blastocystis sp./ ST1, ST2 and ST3 ST3/ Allele no. 34 The current study Egypt/Beni-Suef Patients with colorectal cancer and non-cancer individuals NR PCR Sequencing Blastocystis sp./ ST1, ST2, ST3 and ST7 ST3 41 Egypt/Cairo Patients with urticaria unresponsive to urticarial TTT Asymptomatic 1 Symptomatic PCR RFLP Blastocystis sp./ ST3 ST3 26 Egypt/Beni-Suef Patients with IBS Symptomatic PCR Sequencing Blastocystis sp./ ST3 & ST1 ST3 27 Egypt/Cairo Anaemic and non-anaemic individuals NR PCR Blastocystis sp. / ST1 & ST3 ST1 28 Egypt/Cairo Symptomatic patients Diarrhoea, abdominal pain nPCR Sequencing Blastocystis sp./ ST1, ST2 & ST3 ST3 50 Egypt/Ismailia …”

“…Notably, humans in direct contact with animals were found to have the same Blastocystis STs in two studies conducted in Northern and Eastern Egypt (ST1, ST2, ST3, and ST4) 37 , 39 . Additionally, poultry can harbor the human-transmissible Blastocystis ST6 and ST7 40 , although this has only been reported in a recent Egyptian study of colorectal cancer patients 41 .…”

“…Several Egyptian studies have subtyped and sequenced Blastocystis sp. 39 , 41 , 50 , with five STs (ST1, ST2, ST3, ST4 and ST7) identified at varying frequencies in distinct Egyptian groups using PCR sequenced-tagged sites, PCR restriction fragment length polymorphisms, and PCR sequencing (barcoding) (Table 6 ). The high prevalence of Blastocystis sp.…”

Commensal Intestinal Protozoa—Underestimated Members of the Gut Microbial Community

“…For instance, ST2 was suggested to be a non-pathogenic type [ 66 ], while ST3 has frequently been identified as a major subtype among patients with gastrointestinal disorders [ 67 , 68 ]. A study by Ali et al showed a significant association between Blastocystis subtypes and colorectal cancer (CRC) [ 69 ]. Although a similar prevalence of Blastocystis ST1, 2, and 3 were observed between CRC and non-cancer individuals, a rare ST7 was identified in CRC patients [ 69 ].…”

“…A study by Ali et al showed a significant association between Blastocystis subtypes and colorectal cancer (CRC) [ 69 ]. Although a similar prevalence of Blastocystis ST1, 2, and 3 were observed between CRC and non-cancer individuals, a rare ST7 was identified in CRC patients [ 69 ].…”