小児一般病棟入院児の尿中サイトメガロウィルス排泄状況と外部環境下でのウィルスの生残率について

A Study Of the Cytomegalovirus Excretion Rate on the Children in a General Pediatric Ward and Its Inactivation Kinetics in Extracellular Environment

要旨

　本研究はサイトメガロウィルス(以下CMV)を尿中，咽頭より高濃度(50％ Tissueculture infectious dose 10^4.3以上)に排泄していた先天性CMV感染症の一症例が契機となって，小児科一般病棟におけるCMVの院内感染発生の可能性を考察することを目的に千葉大学病院小児科一般病棟の尿中CMV排泄患者の頻度と排泄量，およびCMVの外部環境下での不活化の経過を検討したものである．

　先の先天性CMV感染症と診断された児，及び彼の同室患児10名と，その隣室の11名の患児尿からCMVの分離を行なった結果，小児一般病棟において，28％(6/21)前後の患児が尿中にCMVを排泄しており，このうち3名は10³TCID₅₀/ml以上のCMVを排泄していた．

　またCMVの不活化実験では，室温における尿中でのCMVは5日を経てもまだその10％弱が生残し，ガラス面上に滴下した場合では24時間経過後にその90％以上が生残していた．

　以上の我々の得た感染源としてのCMV排泄患児の頻度と排泄量，およびCMVの外部環境下における不活化の結果から，小児一般病棟内において，CMVの水平感染は十分に起こりうることが示唆され，この点から排尿の処理方法や尿で汚染された器具の消毒医療従事者の手洗などに対する注意深い配慮が，院内における水平感染防止に必要であると考えられた．

Abstract

　We experienced a case of congenital cytomegalovirus (CMV) infection exhibiting excretion of CMV at quite high titer (more than 50% Tissus Culture Infectious Dose 10^4.3) in urine and throat.

　Following this experience, the present study investigated the CMV excretion rate of children in the general pediatric ward of Chiba University Hospital, and investigated the process by which CMV becomes inactive in extracellular environment, in order to check the possibility of a nosocomial CMV infection.

　10 children in the room where the case had been admitted and 11 children in the adjacent room were surveyed for excretion of the virus into their urine.

　6 of the 21 children, 3 from each room, excreted CMV into their urine, and 3 of the 6 children excreted at more than 10³ TCID₅₀/ml

　Tests for the stability of CMV in urine, contrary to our expectations, showed that the stability of CMV was comparatively stable, i. e. the residual infectious CMV was about 10% of the starting material in urine after being kept for five days at room temperature. Similarly 90% of CMV in urine exposed to the atmosphere was still active after 24 hours.

　These findings do suggest that CMV could be a possible candidate as agent of nosocomial infection in general pediatric wards, and so it seems that careful nursing practices, such as effective methods of urine disposal, sterilization of all materials contaminated with urine, and careful hand washing by all the personnel who come into contact with urine, to prevent nosocomial CMV infection are required.