Plasmids of Shigella flexneri serotype 1c strain Y394 provide advantages to bacteria in the host

Abstract

Background Shigella flexneri has an extremely complex genome with a significant number of virulence traits acquired by mobile genetic elements including bacteriophages and plasmids. S. flexneri serotype 1c is an emerging etiological agent of bacillary dysentery in developing countries. In this study, the complete nucleotide sequence of two plasmids of S. flexneri serotype 1c strain Y394 was determined and analysed. Results The plasmid pINV-Y394 is an invasive or virulence plasmid of size 221,293 bp composed of a large number of insertion sequences (IS), virulence genes, regulatory and maintenance genes. Three hundred and twenty-eight open reading frames (ORFs) were identified in pINV-Y394, of which about a half (159 ORFs) were identified as IS elements. Ninety-seven ORFs were related to characterized genes (majority of which are associated with virulence and their regulons), and 72 ORFs were uncharacterized or hypothetical genes. The second plasmid pNV-Y394 is of size 10,866 bp and encodes genes conferring resistance against multiple antibiotics of clinical importance. The multidrug resistance gene cassette consists of tetracycline resistance gene tetA , streptomycin resistance gene strA-strB and sulfonamide-resistant dihydropteroate synthase gene sul2 . Conclusions These two plasmids together play a key role in the fitness of Y394 in the host environment. The findings from this study indicate that the pathogenic S. flexneri is a highly niche adaptive pathogen which is able to co-evolve with its host and respond to the selection pressure in its environment. Electronic supplementary material The online version of this article (10.1186/s12866-019-1455-1) contains supplementary material, which is available to authorized users.

<p><em>Shigella</em>: Antibiotic-Resistance Mechanisms And New Horizons For Treatment</p>

“…According to the study by Roberts101 and nomenclature for tetracycline resistance genes(https://faculty.washington.edu/marilynr), five tetracycline-efflux genes — tet (A), tet (B), tet (C), tet (D), and tet (G) — and one ribosomal protection protein encoded by tet (M) have been identified among Shigella isolates, most of which are encoded in transmittable elements, with extensive dissemination in different groups of bacteria. In a study, a 20.4 kb genomic island was identified encoding MDR genes, such as a wide variety of tet genes flanked by transposases 102. This identical MDR cassette was first identified in S. flexneri serotype 2a strain YSH6000 and was referred to as Shigella resistance locus–pathogenicity island 103 Interestingly, these MDR genes have recently been found in an E. coli plasmid, pRSB225, with a similar arrangement.104 The IncB/O/K/Z-type plasmid, termed p866, carrying resistance genes tet (A) and tet(B) have been identified in S. sonnei strains.105 These findings suggest that tet genes might be dispersed among other species by horizontal gene transfer…”

Microbial sulfate reduction by Desulfovibrio is an important source of hydrogen sulfide from a large swine finishing facility

“…Plasmid pDsulf-L4 harboured genes mobA and mobC associated with plasmid transfer and replication genes repA and repC . Like pNV-Y394 24 , plasmid pDsulf-L4 contained a multidrug-resistance cassette consisting of tetracycline resistance gene tetA (MFS family exporter), streptomycin resistance genes strA-strB (aminoglycoside phosphotransferases), and sulfonamide-resistance dihydropteroate synthase gene sul2 .…”

“…so far. Interestingly, nearly identical plasmids were found in several clinical isolates of Enterobacteriaceae , particularly in Shigella flexneri 1c strain Y394 (plasmid pNV-Y394) 24 . Therefore, horizontal acquisition of this plasmid by Desulfovibrio sp.…”

Proteomic Analysis of Virulence Profiles in Clinical Strains of Shigella flexneri in Manaus – Amazon State

“…A recent study identi ed the MobC gene present in a plasmid of virulence in Shigella exneri, such plasmid confers resistance to antibiotics of clinical importance, however, the study did not determine the ability of this plasmid to be transferred by conjugating (35). Studies relating MobC to virulence mechanisms are still scarce, especially in bacteria that cause damage to the intestinal microbiota, since little research is directed to the identi cation and characterization of conjugative systems, as well as the low frequency of the MobC family in relation to other components of the MOB family (36).…”