In this study, metagenomic sequencing (10G) results of stool samples from health care workers in ICU and non-medical professionals were compared to observe whether there are significant differences in community diversity, structure and function of intestinal microbiota and whether there are drug resistance genes carried by intestinal microbes, so as to determine whether long-term exposure to multi-pathogen environment in ICU has an impact on intestinal microbiota.

The infection rate of multidrug-resistant bacteria in critically ill patients in intensive care unit (ICU) is high, resulting in high mortality, prolonged hospitalization, and becoming a source of pathogen transmission. The front-line medical staff engaged in ICU are constantly in contact with patients and exposed to the intensive care unit (ICU) environment, and this high-risk contact and exposure makes many pathogenic microorganisms and their drug-resistance genes become part of the intestinal microbiota of ICU medical staff and are carried. So far, there have been no previous reports on the characteristics of intestinal microbiome and the drug resistance genes carried by ICU staff. Therefore, in this study, metagenomic sequencing (10G) results of stool samples from medical staff and non-medical professionals in ICU were compared to observe whether there are significant differences in community diversity, structure and function of intestinal microbiota and whether there are drug resistance genes carried by intestinal microbes, so as to determine whether long-term exposure to multi-pathogen environment in ICU has an impact on intestinal microbiota.

Inclusion Criteria:

1. Inclusion criteria for ICU health care workers: 25≤ age ≤40 years old, regardless of ethnicity or gender; Doctors and nurses who provide direct treatment and care for ICU patients, who have been working in ICU for ≥5 years, and who have been absent from frontline work continuously for < 1 month; Agree to sign informed consent.
2. Inclusion criteria for non-medical professionals: 25≤ age ≤40 years old, regardless of ethnicity or gender; Age, sex, and body mass index matched with ICU medical staff; No hospitalization within the last year; Not an ICU health care worker or does not live with an ICU health care worker; Agree to sign informed consent.

Exclusion Criteria:

1. Active gastrointestinal infection or chronic gastrointestinal disease;
2. Significant dietary changes or significant weight fluctuations (gain or loss > 5 kg) within 3 months;
3. Antibiotics, proton pump inhibitors or prebiotics, probiotics , including yogurt, have been used in the past 4 weeks;
4. Drinking within the past week;
5. Those who have recently been treated with high-risk immunosuppressive or cytotoxic drugs, such as medium-high dose steroid hormones (20 mg/day or higher) for more than 4 weeks;
6. History of major gastrointestinal surgery;
7. Chronic diseases that may affect the gut microbiota;
8. Congenital or acquired immunodeficiency disease;
9. Do not agree to provide information about their diet, exercise and other lifestyle factors that may affect the composition of their microbiome;
10. Pregnant or lactating women;
11. Participate in other clinical studies at the time of enrollment or within 3 months before enrollment;
12. Do not agree to sign a written informed consent.

Participants were enrolled according to strict inclusion and exclusion criteria and divided into ICU health care workers or non-medical professionals according to exposed factors.