胃肠道癌症患者肠道原虫共感染的分子流行病学调查

MOLECULAR EPIDEMIOLOGICAL INVESTIGATION ON CO-INFECTION OF INTESTINAL PROTOZOA IN GASTROINTESTINAL CANCER PATIENTS

目的寄生虫感染与癌症的关系已成为研究热点之一。目前胃肠癌患者肠道单一原虫感染已有报道,但共感染报道较少见。本研究旨在明确胃肠癌患者肠道原虫共感染情况。方法根据人五毛滴虫、十二指肠贾第虫、微小隐孢子虫、人芽囊原虫、脆弱双核阿米巴和毕氏肠微孢子虫特异的基因序列设计引物进行巢氏PCR扩增,检测195例临床胃肠癌患者肠道原虫共感染情况。结果巢氏PCR检测结果显示胃肠癌患者肠道原虫总感染率为48.72%(95/195)。其中2种原虫共感染23例(8例:人五毛滴虫+人芽囊原虫;11例:人五毛滴虫+微小隐孢子虫;3例:人五毛滴虫+十二指肠贾第虫;1例:十二指肠贾第虫+微小隐孢子虫),占肠道原虫感染的24.21%。3种原虫共感染为3例(1例:人五毛滴虫+微小隐孢子虫+人芽囊原虫;2例:人五毛滴虫+十二指肠贾第虫+微小隐孢子虫),占原虫感染的3.16%。1种原虫感染67例(56例:人五毛滴虫;9例:微小隐孢子虫;1例:人芽囊原虫;1例:脆弱双核阿米巴),占原虫感染的70.52%,未检测到毕氏肠微孢子虫感染。结论胃肠癌患者存在肠道原虫共感染且感染率较高。单因素方差分析发现人五毛滴虫单独感染病例显著高于含人五毛滴虫的2种原虫共感染(P=0.0022)以及3种原虫共感染病例(P=0.0019),而2种和3种原虫共感染病例的感染率间无明显差异(P=0.2775),表明胃肠道癌症患者中人五毛滴虫单独感染病例高于2种或以上原虫共感染病例。BLAST和单核苷酸多态性分析发现,不同感染原虫的基因序列除个别与GenBank参考序列同源性为100%外,其他基因序列在不同位点出现不同程度的碱基突变、插入或丢失现象。该研究结果为今后胃肠癌患者病因学以及诊断和防治提供了重要参考。

Objective The relationship between parasitic infections and cancer has become a research hotpot.Although reports of single intestinal protozoan infection in gastrointestinal cancer patients,co-infections are rare.To investigate co-infections of intestinal protozoa in gastrointestinal cancer patients.Methods The DNA of 195 fecal specimens was amplified using nested PCR and sequenced for the presence of Pentatrichomonas hominis,Giardia duodenalis,Cryptosporidium parvum,Blastocystis hominis,Dientamoeba fragilis,and Enterocytozoon bieneusi.Results An overall infection rate of 48.72%(95/195),with 23 cases(24.21%)co-infected with two parasites,three cases(3.16%)co-infected with three parasites.Additionally,67 cases(70.52%)were infected with one protozoa,including 56 cases with Pentatrichomonas hominis,one with Blastocystis hominis,nine with Cryptosporidium parvum,and one case with Dientamoeba fragilis.No infection with Enterocytozoon bieneusi was detected.Conclusion The results indicated a high rate of intestinal protozoan co-infection among gastrointestinal cancer patients.Through one-way ANOVA analysis,it was observed that cases of individual infection with P.hominis were significantly higher compared to those of co-infection with two or three types of protozoa containing P.hominis(P=0.0022)and cases of co-infection with three types of protozoa(P=0.0019).However,no significant difference in the infection rates was observed between two and three types of protozoa(P=0.2775),suggesting that cases of single infection with P.hominis were higher than cases of co-infection with two or more types of protozoa in gastrointestinal cancer patients.BLAST and single nucleotide polymorphism analysis revealed that gene sequences of different infected protozoa,except for a few with 100%homology to the GenBank reference sequence,exhibited varying degrees of base mutations,insertions,or loss at different loci.This study offers crucial insights for understanding the etiology,diagnosis,and prevention of gastrointestinal cancer.