MPT抗原阴性的结核分枝杆菌复合群临床分离株mpt64突变特征分析

目的 分析MPT抗原阴性的结核分枝杆菌复合群临床分离株mpt64突变特征。 方法 收集湖南省胸科医院2017年1—6月BACTEC MGIT 960法(MGIT 960)培养分离的菌株,通过生化和分子生物学方法进行菌种鉴定,然后将结核分枝杆菌复合群随机抽取部分MPT抗原阳性株及全部MPT抗原阴性菌株进行DNA提取、mpt64基因扩增测序和序列比对,并对结核分枝杆菌复合群MPT抗原呈阴性的临床分离株mpt64突变特征进行分析。 结果 2017年1—6月湖南省胸科医院就诊的结核病患者的痰液或支气管肺泡灌洗液等标本共分离出2 560株结核分枝杆菌,其中MPT抗原检测阳性有2 458株,MPT抗原检测阴性有102株,MPT抗原阴性占比3.98% (102/2 560)。随机抽取的20株MPT抗原阳性株的mpt64基因无突变。测序成功的85株MPT抗原阴性的临床分离株中,有81株mpt64基因存在 63 bp碱基的缺失突变,有4株存在单碱基突变,2株402位G→A,2株613和614位间加了碱基C。 结论 湖南省胸科医院MPT抗原呈阴性的结核分枝杆菌复合群临床分离株mpt64基因突变主要类型为63bp碱基的缺失。

Characteristics of mpt64 gene mutation of MPT64-negative clinical isolates ofMycobacterium tuberculosis complex

Objective To explore the characteristics of mpt64 gene mutation of MPT64-negative clinical isolates of Mycobacterium tuberculosis complex (MTC). Methods MTC clinical isolates cultured by BACTEC MGIT 960 in Hunan Chest Hospital from January and June in 2017 were collected. All the isolates were identified by biochemical and molecular biological methods. DNA extraction, mpt64 gene amplification sequencing and sequence alignment analysis were performed in some MPT64-positive isolates and all MPT64-negative isolates randomly selected from MTC, and the characteristics ofmpt64 gene mutation of MPT64-negativeclinical isolates of MTC were analyzed. Results A total of 2,560 Mycobacterium tuberculosis isolates were recovered from sputa, bronchoalveolar lavage fluid or other samples from tuberculosis patients hospitalized in Hunan Chest Hospital from January to June in 2017. Among the 2,560 isolates, 102 (3.98%) isolates were MPT64-negative. No mutation was foundin mpt64 genein 20 randomly selected MPT64-positive isolates. Among 85 successfully sequenced MPT64-negative clinical isolates, 81 isolates had a 63-bp deletion, and 4 isolates had a single base mutation, including 2 isolates with G→A at 402 and 2 isolates with a 1-bp (C) insertion between 613 and 614. Conclusion The 63-bp deletion was the dominant mutation type for mpt64 gene in MPT64-negative clinical isolatesof MTCin Hunan Chest Hospital.