Abstract：
The human gut microbiota represents a complex ecosystem that is composed of bacteria, fungi, viruses, and archaea. It affects many physiological functions including metabolism, inflammation, and the immune response. The gut microbiota also plays a role in preventing infection. Chemotherapy disrupts an organism\'s microbiome, increasing the risk of microbial invasive infection; therefore, restoring the gut microbiota composition is one potential strategy to reduce this risk. The gut microbiome can develop colonization resistance, in which pathogenic bacteria and other competing microorganisms are destroyed through attacks on bacterial cell walls by bacteriocins, antimicrobial peptides, and other proteins produced by symbiotic bacteria. There is also a direct way. For example, Escherichia coli colonized in the human body competes with pathogenic Escherichia coli 0157 for proline, which shows that symbiotic bacteria compete with pathogens for resources and niches, thus improving the host\'s ability to resist pathogenic bacteria. Increased attention has been given to the impact of microecological changes in the digestive tract on tumor treatment. After 2019, the global pandemic of novel coronavirus disease 2019 (COVID-19), the development of novel tumor-targeting drugs, immune checkpoint inhibitors, and the increased prevalence of antimicrobial resistance have posed serious challenges and threats to public health. Currently, it is becoming increasingly important to manage the adverse effects and complications after chemotherapy. Gastrointestinal reactions are a common clinical presentation in patients with solid and hematologic tumors after chemotherapy, which increases the treatment risks of patients and affects treatment efficacy and prognosis. Gastrointestinal symptoms after chemotherapy range from nausea, vomiting, and anorexia to severe oral and intestinal mucositis, abdominal pain, diarrhea, and constipation, which are often closely associated with the dose and toxicity of chemotherapeutic drugs. It is particularly important to profile the gastrointestinal microecological flora and monitor the impact of antibiotics in older patients, low immune function, neutropenia, and bone marrow suppression, especially in complex clinical situations involving special pathogenic microbial infections (such as clostridioides difficile, multidrug-resistant Escherichia coli, carbapenem-resistant bacteria, and norovirus).
摘要：
人类肠道微生物群代表了一个由细菌组成的复杂生态系统，真菌,病毒,和古细菌。它影响许多生理功能，包括新陈代谢，炎症,和免疫反应。肠道微生物群也在预防感染中发挥作用。化疗会破坏生物体的微生物组，增加微生物侵袭性感染的风险；因此，恢复肠道菌群组成是降低这种风险的一个潜在策略.肠道微生物组可以产生定植抗性，其中病原菌和其他竞争性微生物通过细菌素攻击细菌细胞壁而被破坏，抗菌肽，和共生细菌产生的其他蛋白质。也有直接的方式。例如,在人体内定植的大肠杆菌与致病性大肠杆菌0157竞争脯氨酸，这表明共生细菌与病原体竞争资源和生态位，从而提高宿主抵抗病原菌的能力。消化道微生态变化对肿瘤治疗的影响日益受到重视。2019年后，2019年新型冠状病毒病全球大流行(COVID-19)，新型肿瘤靶向药物的开发，免疫检查点抑制剂，抗生素耐药性的增加对公共卫生构成了严峻的挑战和威胁。目前,治疗化疗后的不良反应和并发症变得越来越重要.胃肠道反应是实体肿瘤和血液肿瘤患者化疗后常见的临床表现，增加患者的治疗风险,影响治疗效果和预后。化疗后的胃肠道症状包括恶心，呕吐,厌食症和严重的口腔和肠道粘膜炎，腹痛,腹泻,便秘，这通常与化疗药物的剂量和毒性密切相关。尤其重要的是对老年患者的胃肠道微生态菌群进行分析和监测抗生素的影响。免疫功能低下，中性粒细胞减少症,和骨髓抑制，特别是在涉及特殊病原微生物感染的复杂临床情况下（如艰难梭菌，多重耐药大肠杆菌，耐碳青霉烯类细菌，和诺如病毒）。
