Evaluation of Microsphere-based xMAP Test for gyrA Mutation Identification in Mycobacterium Tuberculosis

Drug-resistant(DR) tuberculosis(TB) is a growing threat to public health[1]. Fluoroquinolone(FQ) antibiotics have long been used as anti-tuberculosis drugs, and their widespread application has led to the development of resistance in clinical isolates of Mycobacterium tuberculosis complex(MTBC).

Genetic Diversity and Drug Susceptibility of Mycobacterium tuberculosis Isolates in a Remote Mountain Area of China

Objective We determined the genetic diversity of Mycobacterium tuberculosis（MTB） in a remote mountainous area of southwest China and evaluated the resolving ability of single nucleotide polymorphism（SNP） genotyping combined with variable number tandem repeat（VNTR） genotyping for Beijing family strains in association with drug resistance status.Methods Three hundred thirty-one MTB strains were isolated from patients living in mountainous regions of southwest China,and 8-loci SNP,VNTR-15 genotyping assays,and drug susceptibility testing of 9 drugs were performed.Results A total of 183 [55.29%（183/331）] strains were classified into the Beijing family.Of the 183 strains,111（60.66%） were defined as modern Beijing strains.The most predominant modern Beijing sub-lineage and ancient Beijing sub-lineage were Bmyc10 [39.34%（72/183）] and Bmyc25 [20.77%（38/183）],respectively.Of the isolates,19.64%（65/331） were resistant to at least 1 of the 9 anti-TB drugs and 17 [4.98%（17/331）] MTB isolates were multi-drug resistant tuberculosis（MDR-TB）.Two hundred sixty-one isolates showed a clustering rate of 14.18%（37/261） and a discriminatory index of 0.9990.The Beijing lineage exhibited a significantly higher prevalence of MDR-TB,as well as resistance to isoniazid（INH）,rifampin（RIF）,and para-aminosalicylic acid（PAS） when analyzed independently（P = 0.005,P = 0.017,P = 0.014,and P = 0.006 respectively）.The Beijing lineage was not associated with genetic clustering or resistance to any drug.In addition,genetic clustering was not associated with drug resistance.Conclusion MTB strains demonstrate high genetic diversity in remote mountainous areas of southwest China.Beijing strains,especially modern Beijing strains,are predominant in remote mountainous area of China.The combination of 8-loci SNPs and VNTR-15 genotyping is a useful tool to study the molecular epidemiology of MTB strains in this area.

Comparison of Xpert MTB/RIF, Real Amp, and CPA Tests in Detecting Mycobacterium tuberculosis

Today, tuberculosis (TB) remains a global public health threat associated with significantly high rates of morbidity and mortality. The World Health Organization's (WHO) Global Tuberculosis Report 2018[1] has reported that in 2017, 10.0 million people across the world had developed TB diseases that resulted in an estimated 1.6 million deaths, and 889, 000 people developed TB in China that led to 39, 000 TB-related deaths. Therefore, rapid and accurate detection of Mycobacterium tuberculosis (MTB) is important for initiating early treatment and reducing mortality. Traditional diagnostic methods for pulmonary TB incorporate chest radiography and sputum smear microscopy;however, several cases of tuberculosis go undiagnosed because of the low sensitivity of smear microscopy[2].

Prevalence and Risk Factors of Primary Drug-Resistant Tuberculosis in China

Objective To investigate the prevalence of primary drug-resistant tuberculosis（TB） and associated risk factors in China. We also explored factors contributing to the transmission of multidrug-resistant tuberculosis（MDR-TB）. Methods A total of 2794 representative, Mycobacterium tuberculosis isolates from treatment-naive patients were subjected to drug susceptibility testing, and risk factors for drug-resistant TB were analyzed. We also analyzed MDR-TB strain sublineages, drug-resistance-conferring mutations, and risk factors associated with clustered primary MDR strains. Results Among 2794 Mycobacterium tuberculosis isolates from treatment-naive patients, the prevalence of any resistance to first-line drugs was 33.2% and the prevalence of MDR-TB was 5.7%. We did not find any risk factors significantly associated with resistance to first-line drugs. The 93 primary MDR-TB isolates were classified into six sublineages, of which, 75（80.6%） isolates were the RD105-deleted Beijing lineage. The largest sublineage included 65（69.9%） isolates with concurrent deletions of RD105, RD207, and RD181. Twenty-nine（31.2%） primary MDR strains grouped in clusters; MDR isolates in clusters were more likely to have S531 L rpoB mutation. Conclusion This study indicates that primary drug-resistant TB and MDR-TB strains are prevalent in China, and multiple measures should be taken to address drug-resistant TB.