Dataset Information

A novel integron in Salmonella enterica serovar Enteritidis, carrying the bla(DHA-1) gene and its regulator gene ampR, originated from Morganella morganii.

ABSTRACT: The genetic organization of the gene coding for DHA-1 and the corresponding ampR gene was determined by PCR mapping. These genes have been mobilized from the Morganella morganii chromosome and inserted into a complex sulI-type integron, similar to In6 and In7. However, they are not themselves mobile cassettes. This integron probably includes a specific site for recombination allowing the mobilization of diverse resistance genes, as observed for bla(CMY-1) and bla(MOX-1).

SUBMITTER: Verdet C

PROVIDER: S-EPMC89661 | biostudies-literature | 2000 Jan

REPOSITORIES: biostudies-literature

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A novel integron in Salmonella enterica serovar Enteritidis, carrying the bla(DHA-1) gene and its regulator gene ampR, originated from Morganella morganii.

Verdet C C Arlet G G Barnaud G G Lagrange P H PH Philippon A A

Antimicrobial agents and chemotherapy 20000101 1

The genetic organization of the gene coding for DHA-1 and the corresponding ampR gene was determined by PCR mapping. These genes have been mobilized from the Morganella morganii chromosome and inserted into a complex sulI-type integron, similar to In6 and In7. However, they are not themselves mobile cassettes. This integron probably includes a specific site for recombination allowing the mobilization of diverse resistance genes, as observed for bla(CMY-1) and bla(MOX-1). ...[more]

PMID: 10602756

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Project description:Shotgun cloning experiments with restriction enzyme-digested genomic DNA from Morganella morganii 1, which expresses high levels of cephalosporinase, into the pBKCMV cloning vector gave a recombinant plasmid, pPON-1, which encoded four entire genes: ampC, ampR, an hybF family gene, and orf-1 of unknown function. The deduced AmpC beta-lactamase of pI 7.6 shared structural and functional homologies with AmpC from Citrobacter freundii, Escherichia coli, Yersinia enterocolitica, Enterobacter cloacae, and Serratia marcescens. The overlapping promoter organization of ampC and ampR, although much shorter in M. morganii than in the other enterobacterial species, suggested similar AmpR regulatory properties. The MICs of beta-lactams for E. coli MC4100 (ampC mutant) harboring recombinant plasmid pACYC184 containing either ampC and ampR (pAC-1) or ampC (pAC-2) and induction experiments showed that the ampC gene of M. morganii 1 was repressed in the presence of ampR and was activated when a beta-lactam inducer was added. Moreover, transformation of M. morganii 1 or of E. coli JRG582 (delta ampDE) harboring ampC and ampR with a recombinant plasmid containing ampD from E. cloacae resulted in a decrease in the beta-lactam MICs and an inducible phenotype for M. morganii 1, thus underlining the role of an AmpD-like protein in the regulation of the M. morganii cephalosporinase. Fifteen other M. morganii clinical isolates with phenotypes of either low-level inducible cephalosporinase expression or high-level constitutive cephalosporinase expression harbored the same ampC-ampR organization, with the hybF and orf-1 genes surrounding them; the organization of these genes thus differed from those of ampC-ampR genes in C. freundii and E. cloacae, which are located downstream from the fumarate operon. Finally, an identical AmpC beta-lactamase (DHA-1) was recently identified as being plasmid encoded in Salmonella enteritidis, and this is confirmatory evidence of a chromosomal origin of the plasmid-mediated cephalosporinases.

Project description:Salmonella genomic island 1 (SGI1) is a multidrug resistance integrative mobilizable element that harbors a great diversity of antimicrobial resistance gene clusters described in numerous Salmonella enterica serovars and also in Proteus mirabilis. A serious threat to public health was revealed in the recent description in P. mirabilis of a SGI1-derivative multidrug resistance island named PGI1 (Proteus genomic island 1) carrying extended-spectrum-?-lactamase (ESBL) and metallo-?-lactamase resistance genes, blaVEB-6 and blaNDM-1, respectively. Here, we report the first description of Salmonella genomic island 1 (SGI1) in a multidrug-resistant clinical Morganella morganii subsp. morganii strain isolated from a patient in France in 2013. Complete-genome sequencing of the strain revealed SGI1 variant SGI1-L carrying resistance genes dfrA15, floR, tetA(G), blaPSE-1 (now referred to as blaCARB-2), and sul1, conferring resistance to trimethoprim, phenicols, tetracyclines, amoxicillin, and sulfonamides, respectively. The SGI1-L variant was integrated into the usual chromosome-specific integration site at the 3' end of the trmE gene. Beyond Salmonella enterica and Proteus mirabilis, the SGI1 integrative mobilizable element may thus also disseminate its multidrug resistance phenotype in another genus belonging to the Proteae tribe of the family Enterobacteriaceae. IMPORTANCE Since its initial identification in epidemic multidrug-resistant Salmonella enterica serovar Typhimurium DT104 strains, several SGI1 variants, SGI1 lineages, and SGI1-related elements (SGI2, PGI1, and AGI1) have been described in many bacterial genera (Salmonella, Proteus, Morganella, Vibrio, Shewanella, etc.). They constitute a family of multidrug resistance site-specific integrative elements acquired by horizontal gene transfer, SGI1 being the best-characterized element. The horizontal transfer of SGI1/PGI1 elements into other genera is of public health concern, notably with regard to the spread of critically important resistance genes such as ESBL and carbapenemase genes. The identification of SGI1 in Morganella morganii raises the issue of (i) the potential for SGI1 to emerge in other human pathogens and (ii) its bacterial host range. Further surveillance and research are needed to understand the epidemiology, the spread, and the importance of the members of this SGI1 family of integrative elements in contributing to antibiotic resistance development.

Dataset Information

A novel integron in Salmonella enterica serovar Enteritidis, carrying the bla(DHA-1) gene and its regulator gene ampR, originated from Morganella morganii.

Publications

A novel integron in Salmonella enterica serovar Enteritidis, carrying the bla(DHA-1) gene and its regulator gene ampR, originated from Morganella morganii.

Similar Datasets

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