海南省一例糖尿病患者足趾感染非产毒白喉棒状杆菌的鉴定与溯源分析

Analysis on identification and traceability of one non-toxigenic Corynebacterium diphtheriae from a patient with diabetic foot in Hainan province

为探讨糖尿病患者足趾感染的病因,采用微生物形态学结合分子生物学方法对2021年9月海南省人民医院的1例老年糖尿病患者足趾伤口分泌物培养分离出的白喉棒状杆菌溯源分析,为临床感染诊断提供参考。通过革兰染色、Albert法染色镜检、VITEK 2 Compat鉴定仪和MALDI-TOF MS质谱仪鉴定结合16S rRNA基因序列溯源分析,同时开展tox毒力基因检测。结果显示分离菌株镜检为革兰阳性杆菌,有异染颗粒,可发酵大多数糖类,符合白喉棒状杆菌生物学特性;16S rRNA序列与白喉棒状杆菌标准菌株Corynebacterium diphtheriae NCTC 11397T(GenBank登记号:MW682323.1)同源性为100%;tox毒力基因阴性。本研究结果为临床微生物实验室准确鉴定非产毒白喉棒状杆菌奠定了基础,同时为临床认识非产毒白喉棒状杆菌的感染风险提供依据。

There is a rare case of an elderly diabetic with diabetic foot infection at Hainan General Hospital in September 2021,which was diagnosed as Corynebacterium diphtheriae infection incidentally on routine culture with conventional methods and molecular biological approaches,to aid in diagnosis in clinical practice.Owing to smear staining,Albert staining and VITEK 2 system,automated identification systems viz matrix-assisted laser desorption ionization-time of flight(MALDI-TOF)confirmed combing with 16S ribosomal RNA(16S rRNA)gene has been used for the taxonomic classification of bacteria.Otherwise,toxin gene tox was done for diphtheria toxin synthesis.The isolate was Gram-stain-positive,rod-like arrangement with irregular thickness,with characteristic metachromatic granules,ferment most sugars and homology of 16S rRNA analyses with C.diphtheriae NCTC11397T(MW682323.1)was greater than a 100%possibility,toxin gene tox was negative.The findings lay the foundation to clinical identify and trace of non-toxigenic C.diphtheriae.Moreover,this work provides insights into the non-toxigenic C.diphtheriae that contribute to recognized risk of non-toxigenic C.diphtheriae infections.