Endoscopy procedure

This single‐center, retrospective study included and assessed endoscopy procedures performed at the Division of Endoscopy, Hirosaki University Hospital, between March 15 and October 28, 2021. This study consisted of a survey of bacterial contamination in the endoscopy room and a retrospective analysis of clinical information. The study was approved by the ethics committee of Hirosaki University Graduate School of Medicine (No. 2022–076) and conducted in accordance with the Declaration of Helsinki. Each patient was informed that the endoscopy room would use 222‐nm far UV‐C for infection control, and only after obtaining their consent to participate, did the patient undergo an EGD. We retrospectively analyzed the clinical information with approval from the ethics committee.

The surveyed EGD were performed on Wednesdays or Fridays in an endoscopy room (No. 1 or 2 out of No. 1–4) which was randomly allocated by a medical clerk. Endoscopy rooms No. 1 and No. 2 were separated by a curtain. The endoscopists performed EGD wearing a gown with a petri dish containing tryptic soy agar medium (TSA) attached to their epigastric region at a height of about 110 cm above the floor (Figure 1a). The EGD was divided into two groups according to the endoscopy room used: 222‐nm far UV‐C irradiation group (UV group) in endoscopy room No. 2 and the non‐UV irradiation group (non‐UV group) in endoscopy room No. 1.

Endoscopy procedure. (a) The endoscopists performed esophagogastroduodenoscopy while wearing a gown with a tryptic soy agar medium plate attached to their epigastric region. The tryptic soy agar medium plate was approximately 110 cm above the floor. (b): The patients wore a mask cut in the center to allow the endoscope to pass during esophagogastroduodenoscopy.

This study categorized EGD into two types: diagnostic endoscopy (DE) and therapeutic endoscopy (TE). DE included standard diagnostic procedures, such as magnifying endoscopy, chromoendoscopy, digital image enhanced endoscopy, forceps biopsy, pre‐operation marking, and endoscopic ultrasonography. TE included endoscopic submucosal dissection (ESD), hemostasis, and foreign matter removal. Generally, TE needs a longer examination time than DE. To accurately evaluate the effect of 222‐nm far UV‐C regardless of irradiation time, each TE procedure was surveyed for up to 10 min.

In addition, as a control group (C group), environmental bacteria in the endoscopy rooms were evaluated by placing a TSA plate at a height of approximately 110 cm above the floor for 10 min during non‐endoscopic procedures. This height was used because the epigastric regions of endoscopists were almost 110 cm high. The bacteria were collected from the same height in the UV, non‐UV, and C groups.