Genomic Characterization of Multidrug-Resistant Escherichia coli BH100 Sub-strains

Abstract

The rapid emergence of multidrug-resistant (MDR) bacteria is a global health problem. Mobile genetic elements like conjugative plasmids, transposons, and integrons are the major players in spreading resistance genes in uropathogenic Escherichia coli (UPEC) pathotype. The E. coli BH100 strain was isolated from the urinary tract of a Brazilian woman in 1974. This strain presents two plasmids carrying MDR cassettes, pBH100, and pAp, with conjugative and mobilization properties, respectively. However, its transposable elements have not been characterized. In this study, we attempted to unravel the factors involved in the mobilization of virulence and drug-resistance genes by assessing genomic rearrangements in four BH100 sub-strains (BH100 MG2014, BH100 MG2017, BH100L MG2017, and BH100N MG2017). Therefore, the complete genomes of the BH100 sub-strains were achieved through Next Generation Sequencing and submitted to comparative genomic analyses. Our data shows recombination events between the two plasmids in the sub-strain BH100 MG2017 and between pBH100 and the chromosome in BH100L MG2017. In both cases, IS3 and IS21 elements were detected upstream of Tn21 family transposons associated with MDR genes at the recombined region. These results integrated with Genomic island analysis suggest pBH100 might be involved in the spreading of drug resistance through the formation of resistance islands. Regarding pathogenicity, our results reveal that BH100 strain is closely related to UPEC strains and contains many IS3 and IS21-transposase-enriched genomic islands associated with virulence. This study concludes that those IS elements are vital for the evolution and adaptation of BH100 strain.

Characterization of virulence and antimicrobial resistance genes of Aeromonas media strain SD/21–15 from marine sediments in comparison with other Aeromonas spp.

“…Although the plasmid of strain SD/21-15 had no AMR-genes in its genome, other A. media isolates had plasmids having various AMR genes that included bla KPC-1 , bla OXA-427 , sul1, bla OXA-1 , and qnr genes. In additions, the detected plasmids had several transposases, such as Tn3, ISAs1, IS1595, and IS4 known to carry various AMR-gene cassettes (Dziewit et al, 2012;Baquero et al, 2013;Carvalho et al, 2021). The plasmids also encoded various efflux pump proteins, such as tet(E), merD, mexC, OprJ, mph(E), (Chopra, 2002), and mph(A) known to play significant roles in drug trafficking across cell membranes (Dayao et al, 2016;Kim et al, 2017;Yang et al, 2021).…”

Molecular Factors and Mechanisms Driving Multidrug Resistance in Uropathogenic Escherichia coli—An Update

“…This strain was obtained from the urinary tract of a Brazilian woman in 1974, but was not fully described until now. The usage of the Next Generation Sequencing (NGS) technique allowed assessing the entire sequence of the genome of the strain and it was found that the bacterium harbors two plasmids carrying MDR cassettes: pBH100 and pAp, presenting conjugative and mobilization properties, respectively [ 80 ]. The authors indicated transposon Tn 21 as the one likely responsible for the mobilization of the streptomycin resistance gene— aadA (encoding for streptomycin 3′-adenylyltransferase).…”

“…Carvalho et al [ 80 ] also described the Tn 3 transposon, associated with the bla TEM gene, which encodes the β-lactamase TEM-1 type enzyme. Members of the Tn 3 transposon family form a widespread and homogeneous group of bacterial TEs that play a major role in disseminating antibiotic resistance.…”

“…Moreover, they also stated that some Tn 3 members encode a type II toxin-antitoxin (TA) system, which improves plasmid maintenance within a bacterial cell. The TA system usually consists of a stable toxin and a labile antitoxin that binds the toxin, therefore preventing it from being lethal for the bacteria [ 80 , 82 , 83 , 84 ].…”

IS21 family transposase cleaved donor complex traps two right-handed superhelical crossings

“…IS elements are usually formed by one or two genes delimited by two TIRs. Interestingly, many ISs contain promoter sequences that can modify the expression of neighboring genes 22 – 24 , and several families have been associated with the dissemination of antibiotic resistance and the spread of multidrug-resistance 9 , 25 , 26 .…”