Genetic Diversity and Drug Susceptibility of Mycobacterium tuberculosis Isolates in a Remote Mountain Area of China / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Analysis of genetic heterogeneity of Staphylococcus aureus strains isolated from food and clinical samples from northern Jordan using VNTR, toxin profiles and antibiograms

Aims: Staphylococcus aureus is a Gram positive pathogen distributed worldwide and represents a rising problem for both hospitals and community. The aims of the study were to examine the antibiograms, toxin profiles as well as the genetic diversity of a set of S. aureus isolates from clinical and food samples. Methodology and results: To get some insights on the genetic heterogeneity and test for the presence of certain virulence genes, all isolates were subjected to different PCR amplifications and antibiotic sensitivity analysis. The mecA gene was detected in both clinical and food isolates. Resistance to penicillin and amoxicillin was observed in both clinical and food isolates. About 88% of both food and clinical isolates harbored the toxin gene sea, while 70% and 29% of clinical and food isolates respectively, harbored sec. The seb gene was detected in 59% and 18% of clinical and food isolates, respectively. Dendrograms prepared from the VNTR, antibiograms and toxin profiles, revealed 89, 52 and 12 clusters, respectively. Thus, suggesting a very high heterogeneity among the isolates. Conclusion, significance and impact of study: Strains used in this study showed high heterogeneity when examined by VNTR or antibiograms, while appeared less heterogeneous when dendrogram was generated based on toxin profiles. This study highlights the fact that methicillin resistance in S. aureus might be generated within the health institutions or the community. Obtained results also might help health authorities understand the origin of methicillin resistant clones within the study area.