Liow Y L, Rohaidah H, Fairuz A, Hazwani H, Nurul Ain D, Norazah A
Bacteriology Unit, Infectious Diseases Research Centre, Institute for Medical Research, 50588 Kuala Lumpur, Malaysia.
Trop Biomed. 2018 Sep 1;35(3):775-780.
Diphtheria is an infectious but vaccine preventable disease caused by Corynebacterium diphtheriae and humans are the only reservoir. While toxigenic strains most frequently cause pharyngeal diphtheria, non-toxigenic strains commonly cause cutaneous infections. In 2016, there was a sudden increase in cases of C. diphtheriae reported in Malaysia. The toxigenic strains are currently determined using Elek's test and are carried out only in the reference laboratory. With the sudden increase in diphtheria cases in Malaysia, it is important for local laboratories in state hospitals to be able to perform a rapid, reliable diagnostic test for the detection of the exotoxin. In this study, we aimed to evaluate the application of conventional PCR method to detect toxigenic strains of C. diphtheriae compared to the Elek's test. Forty-eight C. diphtheriae strains were subjected to PCR detection of toxin gene A and B subunits, and also Elek's test. The A and B subunits of the toxin gene were detected in all C. diphtheriae strains except for one strain which was isolated from a foot ulcer. Elek's test was also positive for all the PCR positive strains. This study showed 100% corelation between the results of PCR and Elek's test assay. The conventional PCR can be used at the state laboratories for rapid detection of toxin genes in toxigenic C. diphtheriae cultures, thus early treatment can be given to the patients while waiting for Elek's test results.
白喉是一种由白喉棒状杆菌引起的传染性疾病，但可通过疫苗预防，人类是唯一的宿主。产毒株最常引起咽白喉，而非产毒株通常引起皮肤感染。2016年，马来西亚报告的白喉棒状杆菌病例突然增加。目前产毒株通过埃利克试验确定，且仅在参考实验室进行。随着马来西亚白喉病例的突然增加，州立医院的当地实验室能够进行快速、可靠的外毒素检测诊断试验非常重要。在本研究中，我们旨在评估与埃利克试验相比，常规PCR方法检测白喉棒状杆菌产毒株的应用。48株白喉棒状杆菌菌株接受了毒素基因A和B亚基的PCR检测以及埃利克试验。除了从足部溃疡分离出的一株菌株外，所有白喉棒状杆菌菌株均检测到毒素基因的A和B亚基。所有PCR阳性菌株的埃利克试验也呈阳性。本研究表明PCR结果与埃利克试验检测结果之间存在100%的相关性。常规PCR可用于州立实验室快速检测产毒白喉棒状杆菌培养物中的毒素基因，从而在等待埃利克试验结果时可为患者提供早期治疗。
