利用结核分枝杆菌基因型分型技术研究外源性再感染在结核病复发中的作用

目的 研究外源性再感染在结核病复发中的作用。方法以上海地区1999年1月至2004年3月复发肺结核患者为对象，通过比较复发肺结核患者前后两次发病时结核分枝杆菌散在分布重复单位（mycobacterial interspersed repetitive units，MIRU）基因型的差异，判断结核病复发的原因。结果在37例符合要求的结核病复发患者中，25例患者两次发病时MIRU基因型发生了变化，提示68％的结核病患者复发是由于外源性再感染而引起的。随着年龄的增加，结核病复发患者中由外源性再感染所致的可能性逐步降低，≤30岁、31～60岁、≥61岁患者中外源性再感染的比例分别为3／3、73％（11／15）、58％（11／19）。随着复发间隔时间的延长，结核病复发患者中由外源性再感染所致的可能性逐步增加，6个月内复发的患者中58％（7／12）是由外源性再感染引起的，而1年以后这个比例达到79％（11／14）。结论外源性再感染是上海地区结核病复发的重要原因；MIRU分型方法是研究结核病复发原因的可行方法。

Study on the cause of tuberculosis recurrence by Mycobacterium tuberculosis genotyping method

Objective To study the contribution of exogenous reinfeciton to tuberculosis recurrence. Methods Mycobacterium tuberculosis isolates from patients who had experienced 2 successive tuberculosis episodes during the years from January 1999 to March 2004 were genotyped by mycobacterial interspersed repetitive units (MIRU) method. The cause of tuberculosis recurrence was determined by comparing the MIRU pattern of Mycobacterium tuberculosis isolates responsible for different tuberculosis episodes from patients. Results Of 37 qualified patients with recurrent tuberculosis, the isolates from 25 patients in their two tuberculosis episodes showed different MIRU patterns, indicating that 68% recurrent patients were due to exogenous reinfection. The exogenous reinfection rate decreased with the age from 3/3 (under 30 years) to 73% (11/15, 30 to 60 years) and 58% (11/19, over 60 years). The frequency of exogenous reinfection increased with the tuberculosis recurrent interval. Within 6 months, the exogenous reinfection accounted for 58% (7/12) of all the recurrentce, while for the time more than one year, the percentage increased to 79% (11/14). Conclusions Exogenous reinfection was a major cause of tuberculosis recurrence in Shanghai. MIRU genotyping method is useful to study the cause of tuberculosis recurrence.