Evaluation of the genetic relatedness of Bacteroides fragilis isolates by TRs analysis

Document Type: Original Article


1 Microbial Biotechnology Research Center, Iran University of Medical Science, Tehran, Iran

2 Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran

3 Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran

4 Department of Medical Microbiology, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, Iran

5 Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Tehran, Iran



Objective(s): Human gastrointestinal tract harbors a variety of bacteria with vital roles in human health. Bacteroides fragilis is considered one of the dominant constituents of gut microflora which can act as an opportunistic pathogen leading to various diseases, including colon cancer, diarrhea, uterine and intrathecal abscesses, septicemia, and pelvic inflammation. In this study, multiple locus variable number of tandem repeats analysis (MLVA) was performed to genetically differentiate 50 B. fragilis isolates.
Materials and Methods: Eight suitable tandem repeats (TRs) were selected by bioinformatics tools and were then subjected to PCR amplification using specific primers. Finally, MLVA profiles were clustered using BioNumerics 7.6 software package.
Results: All VNTR loci were detected in all isolates using the PCR method. Overall, B. fragilis isolates were differentiated into 27 distinct MLVA types. The highest diversity index was allocated to TR1, TR2, TR5, TR6, and TR8; with this taken into account, strain type 14 was the most prevalent with 12 strains belonging to this type. Clustering revealed three major clusters of A, B, and C. With regards to the pathogenicity of B. fragilis and the outcomes of infections related to this microorganism, it is imperative to study this microorganism isolated from both patients and healthy individuals.
Conclusion: This study aimed at evaluating the efficiency of MLVA for the genetic differentiation of B. fragilis. The results of this study indicate the promising efficiency of MLVA typing for cluster detection of this bacterium.


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