Comparison of IncL/M Plasmids Using the Neighbor-Joining Method on Basis repA and excA Genes

Touati Abdelaziz,Mairi Assia

doi:10.3844/ajbsp.2019.14.17

Abstract

The aim of this study is to make comparison of IncL/M groups on basis of two genes candidates’ repA and excA genes. The sequences of 27 plasmids were compared using the neighbor-joining method. This method was used to construct a phylogenetic tree for the nucleotide sequences of two genes (repA and excA), using the program MEGA X software. The evolutionary distances were computed using the maximum composite likelihood method. The neighbor-joining method analysis showed different results based on the gene used for comparison. The repA gene was more accurate than excA gene to distinguish between different incL/M plasmids. This study suggested that IncL/M plasmids harboring different antibiotic resistance genes have evolved differently.

Highlights

The dissemination of antimicrobial resistance in Gram-negative bacteria has been largely attributed to the horizontal transfer of plasmid-located resistance genes (Carattoli, 2013)
OXA-48-type carbapenem-hydrolyzing class D β-lactamases are widely distributed among Enterobacteriaceae, with significant geographical differences (Mairi et al, 2018)
The sequences of 14 plasmids carrying the blaOXA-48 gene were already published (Mairi et al, 2019) and served as a matrix for bioinformatics comparison. These plasmids were originated from different species of Enterobacterales strains obtained from different ecological niches in Algeria

Summary

Introduction

The dissemination of antimicrobial resistance in Gram-negative bacteria has been largely attributed to the horizontal transfer of plasmid-located resistance genes (Carattoli, 2013). Plasmids do not carry genes essential for the growth of host cells under no stressed conditions (Carattoli, 2009). The production of carbapenemases is the major mechanism underlying carbapenem resistance in CRE throughout the world (Cui et al, 2019). Carbapenemases belong to Ambler class A (i.e., KPC types), class B (i.e., MBLs: VIM, IMP and NDM types) and class D (i.e., OXA48). The KPC, NDM, IMP, VIM and OXA-type enzymes are the most common global carbapenemases among Gramnegative bacteria (Pitout et al, 2019). OXA-48-type carbapenem-hydrolyzing class D β-lactamases are widely distributed among Enterobacteriaceae, with significant geographical differences (Mairi et al, 2018)

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Results