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The aim of this study was to perform an in silico analysis of the available whole-genome sequencing data to detect syntenic genomic islands (GIs) having homology to Salmonella genomic island 1 (SGI1), analyze the genetic variations of their backbone, and determine their relatedness. Eighty-nine non-redundant SGI1-related elements (SGI1-REs) were identified among gamma-proteobacteria. With the inclusion of the thirty-seven backbones characterized to date, seven clusters were identified based on integrase homology: SGI1, PGI1, PGI2, AGI1 clusters, and clusters 5, 6, and 7 composed of GIs mainly harbored by waterborne or marine bacteria, such as Vibrio , Shewanella , Halomonas , Idiomarina , Marinobacter , and Pseudohongiella. The integrase genes and the backbones of SGI1-REs from clusters 6 and 7, and from PGI1, PGI2, and AGI1 clusters differed significantly from those of the SGI1 cluster, suggesting a different ancestor. All backbones consisted of two parts: the part from attL to the origin of transfer (oriT) harbored the DNA recombination, transfer, and mobilization genes, and the part from oriT to attR differed among the clusters. The diversity of SGI1-REs resulted from the recombination events between GIs of the same or other families. The oriT appeared to be a high recombination site. The multi-drug resistant (MDR) region was located upstream of the resolvase gene. However, most SGI1-REs in Vibrio , Shewanella , and marine bacteria did not harbor any MDR region. These strains could constitute a reservoir of SGI1-REs that could be potential ancestors of SGI1-REs encountered in pathogenic bacteria. Furthermore, four SGI1-REs did not harbor a resolvase gene and therefore could not acquire an integron. The presence of mobilization genes and AcaCD binding sites indicated that their conjugative transfer could occur with helper plasmids. The plasticity of SGI1-REs contributes to bacterial adaptation and evolution. We propose a more relevant classification to categorize SGI1-REs into different clusters based on their integrase gene similarity. [ABSTRACT FROM AUTHOR]

The aim of this study was to perform an in silico analysis of the available whole-genome sequencing data to detect syntenic genomic islands (GIs) having homology to Salmonella genomic island 1 (SGI1), analyze the genetic variations of their backbone, and determine their relatedness. Eighty-nine non-redundant SGI1-related elements (SGI1-REs) were identified among gamma-proteobacteria. With the inclusion of the thirty-seven backbones characterized to date, seven clusters were identified based on integrase homology: SGI1, PGI1, PGI2, AGI1 clusters, and clusters 5, 6, and 7 composed of GIs mainly harbored by waterborne or marine bacteria, such as Vibrio, Shewanella, Halomonas, Idiomarina, Marinobacter, and Pseudohongiella. The integrase genes and the backbones of SGI1-REs from clusters 6 and 7, and from PGI1, PGI2, and AGI1 clusters differed significantly from those of the SGI1 cluster, suggesting a different ancestor. All backbones consisted of two parts: the part from attL to the origin of transfer (oriT) harbored the DNA recombination, transfer, and mobilization genes, and the part from oriT to attR differed among the clusters. The diversity of SGI1-REs resulted from the recombination events between GIs of the same or other families. The oriT appeared to be a high recombination site. The multi-drug resistant (MDR) region was located upstream of the resolvase gene. However, most SGI1-REs in Vibrio, Shewanella, and marine bacteria did not harbor any MDR region. These strains could constitute a reservoir of SGI1-REs that could be potential ancestors of SGI1-REs encountered in pathogenic bacteria. Furthermore, four SGI1-REs did not harbor a resolvase gene and therefore could not acquire an integron. The presence of mobilization genes and AcaCD binding sites indicated that their conjugative transfer could occur with helper plasmids. The plasticity of SGI1-REs contributes to bacterial adaptation and evolution. We propose a more relevant classification to categorize SGI1-REs into different clusters based on their integrase gene similarity.

NDM-1-producing multidrug-resistant Proteus mirabilis brings formidable clinical challenges. We report a nosocomial outbreak of carbapenem-resistant P. mirabilis in China. Six P. mirabilis strains collected in the same ward showed close phylogenetic relatedness, indicating clonal expansion. Illumina and MinION sequencing revealed that three isolates harbored a novel Salmonella genomic island 1 carrying a blaNDM–1 gene (SGI1-1NDM), while three other isolates showed elevated carbapenem resistance and carried a similar SGI1 but with two blaNDM–1 gene copies (SGI1-2NDM). Four new single nucleotide mutations were present in the genomes of the two-blaNDM–1-harboring isolates, indicating later emergence of the SGI1-2NDM structure. Passage experiments indicated that both SGI variants were stably persistent in this clone without blaNDM–1 copy number changes. This study characterizes two novel blaNDM–1-harboring SGI1 variants in P. mirabilis and provides a new insight into resistance gene copy number variation in bacteria.

NDM-1-producing multidrug-resistant Proteus mirabilis brings formidable clinical challenges. We report a nosocomial outbreak of carbapenem-resistant P. mirabilis in China. Six P. mirabilis strains collected in the same ward showed close phylogenetic relatedness, indicating clonal expansion. Illumina and MinION sequencing revealed that three isolates harbored a novel Salmonella genomic island 1 carrying a bla NDM–1 gene (SGI1-1NDM), while three other isolates showed elevated carbapenem resistance and carried a similar SGI1 but with two bla NDM–1 gene copies (SGI1-2NDM). Four new single nucleotide mutations were present in the genomes of the two- bla NDM–1-harboring isolates, indicating later emergence of the SGI1-2NDM structure. Passage experiments indicated that both SGI variants were stably persistent in this clone without bla NDM–1 copy number changes. This study characterizes two novel bla NDM–1-harboring SGI1 variants in P. mirabilis and provides a new insight into resistance gene copy number variation in bacteria. [ABSTRACT FROM AUTHOR]

ABSTRACT Integrative mobilizable elements belonging to the SGI1-H, -K, and -L Salmonella genomic island 1 (SGI1) variant groups are distinguished by the presence of an alteration in the backbone (IS1359 replaces 2.8 kb of the backbone extending from within traN [S005] to within S009). Members of this SGI1-HKL group have been found in Salmonella enterica serovars and in Proteus mirabilis. Two novel variants from this group, designated SGI1-LK1 and SGI1-LK2, were found in the draft genomes of antibiotic-resistant P. mirabilis isolates from two French hospitals. Both variants can be derived from SGI1-PmGUE, a configuration found previously in another P. mirabilis isolate from France. SGI1-LK1 could arise via an IS26-mediated inversion in the complex class 1 integron that duplicated the IS26 element and the target site in IS6100. SGI1-LK1 also has a larger 8.59-kb backbone deletion extending from traN to within S013 and removing traG and traH. However, SGI1-LK1 was mobilized by an IncC plasmid. SGI1-LK2 can be derived from a hypothetical progenitor, SGI1-LK0, that is related to SGI1-PmGUE but lacks the aphA1 gene and one copy of IS26. The integron of SGI1-LK2 could arise via deletion of DNA adjacent to an IS26 and a deletion occurring via homologous recombination between duplicated copies of part of the integron 3′-conserved segment. SGI1-K can also be derived from SGI1-LK0. This would involve an IS26-mediated deletion and an inversion via homologous recombination of a segment between inversely oriented IS26s. Similar events can explain the configuration of the integrons in other SGI1-LK variants. IMPORTANCE Members of the SGI1-HKL subgroup of SGI1-type integrative mobilizable elements have a characteristic alteration in their backbone. They are widely distributed among multiply antibiotic-resistant Salmonella enterica serovars and Proteus mirabilis isolates. The SGI1-K type, found in the globally disseminated multiply antibiotic-resistant Salmonella enterica serovar Kentucky clone ST198 (sequence type 198), and various configurations in the original SGI1-LK group, found in other multiresistant S. enterica serovars and Proteus mirabilis isolates, have complex and highly plastic resistance regions due to the presence of IS26. However, how these complex forms arose and the relationships between them had not been analyzed. Here, a hypothetical progenitor, SGI1-LK0, that can be formed from the simpler SGI1-H is proposed, and the pathways to the formation of new variants, SGI1-LK1 and SGI1-LK2, found in P. mirabilis and other reported configurations via homologous recombination and IS26-mediated events are proposed. This led to a better understanding of the evolution of the SGI1-HKL group.

ABSTRACT Salmonella genomic island 1 (SGI1) is an integrative genetic island first described in Salmonella enterica serovars Typhimurium DT104 and Agona in 2000. Variants of it have since been described in multiple serovars of S. enterica, as well as in Proteus mirabilis, Acinetobacter baumannii, Morganella morganii, and several other genera. The island typically confers resistance to older, first-generation antimicrobials; however, some variants carry blaNDM-1, blaVEB-6, and blaCTX-M15 genes that encode resistance to frontline, clinically important antibiotics, including third-generation cephalosporins. Genome sequencing studies of avian pathogenic Escherichia coli (APEC) identified a sequence type 117 (ST117) isolate (AVC96) with genetic features found in SGI1. The complete genome sequence of AVC96 was assembled from a combination of Illumina and single-molecule real-time (SMRT) sequence data. Analysis of the AVC96 chromosome identified a variant of SGI1-B located 18 bp from the 3′ end of trmE, also known as the attB site, a known hot spot for the integration of genomic islands. This is the first report of SGI1 in wild-type E. coli. The variant, here named SGI1-B-Ec1, was otherwise unremarkable, apart from the identification of ISEc43 in open reading frame (ORF) S023. IMPORTANCE SGI1 and variants of it carry a variety of antimicrobial resistance genes, including those conferring resistance to extended-spectrum β-lactams and carbapenems, and have been found in diverse S. enterica serovars, Acinetobacter baumannii, and other members of the Enterobacteriaceae. SGI1 integrates into Gram-negative pathogenic bacteria by targeting a conserved site 18 bp from the 3′ end of trmE. For the first time, we describe a novel variant of SGI1 in an avian pathogenic Escherichia coli isolate. The presence of SGI1 in E. coli is significant because it represents yet another lateral gene transfer mechanism to enhancing the capacity of E. coli to acquire and propagate antimicrobial resistance and putative virulence genes. This finding underscores the importance of whole-genome sequencing (WGS) to microbial genomic epidemiology, particularly within a One Health context. Further studies are needed to determine how widespread SGI1 and variants of it may be in Australia.

The integrative mobilizable elements of SGI1-family considerably contribute to the spread of resistance to critically important antibiotics among enteric bacteria. Even though many aspects of SGI1 mobilization by IncA and IncC plasmids have been explored, the basic transfer elements such as oriT and self-encoded mobilization proteins remain undiscovered. Here we describe the mobilization region of SGI1 that is well conserved throughout the family and carries the oriTSGI1 and two genes, mpsA and mpsB (originally annotated as S020 and S019, respectively) that are essential for the conjugative transfer of SGI1. OriTSGI1, which is located in the vicinity of the two mobilization genes proved to be a 125-bp GC-rich sequence with several important inverted repeat motifs. The mobilization proteins MpsA and MpsB are expressed from a bicistronic mRNA, although MpsB can be produced from its own mRNA as well. The protein structure predictions imply that MpsA belongs to the lambda tyrosine recombinase family, while MpsB resembles the N-terminal core DNA binding domains of these enzymes. The results suggest that MpsA may act as an atypical relaxase, which needs MpsB for SGI1 transfer. Although the helper plasmid-encoded relaxase proved not to be essential for SGI1 transfer, it appeared to be important to achieve the high transfer rate of the island observed with the IncA/IncC-SGI1 system.

Objectives: The aim of this study was to characterise the draft genome sequence of a multidrug-resistant (MDR) Salmonella enterica serotype Kentucky strain (XJ9S) isolated from a poultry slaughterhouse in China. Methods: The genome was sequenced using an Illumina HiSeq platform and was assembled using SPAdes_3.12.0. The CGE Bacterial Analysis Pipeline was used to identify the sequence type (ST) as well as the presence of antimicrobial resistance genes (ARGs) and plasmids in strain XJ9S. Gaps among contigs that carried MDR Salmonella genomic island 1 (SGI1) fragments were filled in by PCR linkage and sequencing. Results: The draft genome of strain XJ9S was assembled into 54 contigs with a total assembly size of 4 785 059 bp. XJ9S belonged to ST198 and harboured five acquired ARGs [blaCTX-M-14b, sul1, tetA(A), aacCA5 and aadA7]. The blaCTX-M-14b gene was located on a 2849-bp ISEcp1-mediated translocatable unit inserted in the chromosome. The other four acquired ARGs were carried by a new variant of SGI1 (SGI1-XJ9S; 38 593 bp) belonging to the SGI1-K group. Moreover, point mutations in the quinolone resistance-determining region (QRDR) were found at positions 83 (Ser83Phe) and 87 (Asp87Gly) of GyrA and at position 80 (Ser80Ile) of ParC. Conclusion: In this study, a new SGI1 variant (SGI1-XJ9S) was characterised for the first time. The draft genome sequence of S. Kentucky ST198 strain XJ9S isolated from a poultry slaughterhouse provides valuable information for tracing the potential spread of this MDR clone from poultry product processing to consumption, and even to humans.

Salmonella genomic island 1 (SGI1) is a resistance-conferring chromosomal genomic island that contains an antibiotic resistance gene cluster. The international spread of SGI1-containing strains drew attention to the role of genomic islands in the dissemination of antibiotic resistance genes in Salmonella and other Gram-negative bacteria. In this study, five SGI1 variants conferring multidrug and heavy metal resistance were identified and characterized in Proteus mirabilis strains: SGI1-PmCAU, SGI1-PmABB, SGI1-PmJN16, SGI1-PmJN40, and SGI1-PmJN48. The genetic structures of SGI1-PmCAU and SGI1-PmABB were identical to previously reported SGI1s, while structural analysis showed that SGI1-PmJN16, SGI1-PmJN40, and SGI1-PmJN48 are new SGI1 variants. SGI1-PmJN16 is derived from SGI1-Z with the MDR region containing a new gene cassette array dfrA12-orfF-aadA2-qacEΔ1-sul1-chrA-orf1. SGI1-PmJN40 has an unprecedented structure that contains two right direct repeat sequences separated by a transcriptional regulator-rich DNA fragment, and is predicted to form two different extrachromosomal mobilizable DNA circles for dissemination. SGI1-PmJN48 lacks a common ORF S044, and its right junction region exhibits a unique genetic organization due to the reverse integration of a P. mirabilis chromosomal gene cluster and the insertion of part of a P. mirabilis plasmid, making it the largest known SGI1 to date (189.1 kb). Further mobility functional analysis suggested that these SGIs can be excised from the chromosome for transfer between bacteria, which promotes the horizontal transfer of antibiotic and heavy metal resistance genes. The identification and characterization of the new SGI1 variants in this work suggested the diversity of SGI1 structures and their significant roles in the evolution of bacteria.

The integrative mobilizable elements of SGI1-family considerably contribute to the spread of resistance to critically important antibiotics among enteric bacteria. Even though many aspects of SGI1 mobilization by IncA and IncC plasmids have been explored, the basic transfer elements such as oriT and self-encoded mobilization proteins remain undiscovered. Here we describe the mobilization region of SGI1 that is well conserved throughout the family and carries the oriT SGI1 and two genes, mpsA and mpsB (originally annotated as S020 and S019, respectively) that are essential for the conjugative transfer of SGI1. OriT SGI1, which is located in the vicinity of the two mobilization genes proved to be a 125-bp GC-rich sequence with several important inverted repeat motifs. The mobilization proteins MpsA and MpsB are expressed from a bicistronic mRNA, although MpsB can be produced from its own mRNA as well. The protein structure predictions imply that MpsA belongs to the lambda tyrosine recombinase family, while MpsB resembles the N-terminal core DNA binding domains of these enzymes. The results suggest that MpsA may act as an atypical relaxase, which needs MpsB for SGI1 transfer. Although the helper plasmid-encoded relaxase proved not to be essential for SGI1 transfer, it appeared to be important to achieve the high transfer rate of the island observed with the IncA/IncC-SGI1 system. [ABSTRACT FROM AUTHOR]

ABSTRACT 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-β-lactamase (ESBL) and metallo-β-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.

Two Proteus mirabilis strains, designated Pm TAN59 and Pm KAF126, were isolated from two different Egyptian cities in 2014 and 2015, respectively. Pm TAN59 was isolated from a sputum swab from a pneumonia patient in Tanta University Teaching Hospital. Pm KAF126 was isolated from a patient with a diabetic foot infection in a hospital in the city of Kafr El-Sheikh. The two isolates were identified with bacterial small ribosomal RNA (16S rRNA) gene amplification and sequencing and tested for antimicrobial sensitivity with a Kirby–Bauer disk diffusion assay. The two strains were resistant to amoxicillin/clavulante, ampicillin, cefotaxime, cefoxitin, ceftriaxone, chloramphenicol, ciprofloxacin, colistin, gentamicin, kanamycin, nalidixic acid, spectinomycin, streptomycin, sulfamethoxazole/trimethoprime, and tetracycline, but sensitive to aztreonam, imipenem, and meropenem. Molecular characterization was used to map the entire backbone, including the multiple antibiotic resistance (MDR) region, of Salmonella genomic island 1 (SGI1). Both isolates carried a structure similar to SGI1, with two different MDR regions corresponding to SGI1- Pm ABB in Pm TAN59 and SGI1-W in Pm KAF126. SGI1- Pm ABB carried an integron of ~ 1.5 kb with a two-gene cassette, aacCA5–aadA7 , which confers resistance to gentamicin, streptomycin, and spectinomycin, whereas SGI1-W carried an integron of ~ 1.9 kb containing aadA2–lnuF , which confers resistance to spectinomycin, streptomycin, and lincosamides. Pm KAF126 carried the entire SGI1 sequence, however Pm TAN59 carried a SGI1 structure with a deletion in the region from ORF S005 to ORF S009 and accompanied by insertion of IS1359 (1258 bp). Furthermore, Pm TAN59 carried class 2 integron of ~ 2.2 kb containing dfrA1-sat2 - aadA1 . An ERIC-PCR analysis detected no clonal relationship between the two strains. Molecular screening for other antimicrobial resistance genes and a plasmid analysis indicated that Pm TAN59 carried an IncFIB plasmid type. This strain also carried bla TEM-1 and the plasmid-mediated quinolone-resistance gene qnrA1 . However, Pm KAF126 carried no plasmids and no resistance gene other than that contained in the MDR region of SGI1 and floR gene conferring resistance to florfenicol. To the best of our knowledge, this is the first report of an SGI1-positive P . mirabilis strain in Egypt or on the entire African continent. [ABSTRACT FROM AUTHOR]

The prevalence of different antimicrobial resistance profiles and variants of the Salmonella genomic island 1 (SGI1) was reported for Salmonella enterica serovar Typhimurium DT104 strains isolated from patients in Denmark. Variation in antimicrobial resistance and corresponding changes of SGI1 were shown among isolates from a foodborne outbreak.

Though IncC and IncA plasmids are compatible, they exert high level exclusion on one another. Here, the question of whether the presence of an SGI1 family element in the donor can overcome the exclusion of an IncC plasmid exerted by an IncC or IncA plasmid in the recipient was investigated. The transfer of the integrative mobilizable element SGI1 and its many variant forms into a new host is dependent on transfer machinery supplied by IncC or IncA plasmids. SGI1 elements include the determinants of a mobilization system and three genes that encode homologues of transfer proteins including TraG. Exclusion of a complete IncC plasmid by a complete IncA or IncC plasmid in the recipient was not ameliorated by an SGI1 element in the donor. However, transfer of the SGI was unaffected indicating that a functional mating apparatus was formed. The presence of only the plasmid-derived eexC or eexA gene in the recipient exerted high level exclusion on an incoming IncC plasmid and this was overcome by an SGI1 variant in the donor. Hence, the SGI affects only entry exclusion and additional plasmid features must influence other routes to plasmid exclusion. • SGI1 variants are not excluded by an IncC or IncA plasmid or EexC in the recipient. • SGI1 variant in a donor doesn't affect exclusion of IncC plasmids by IncC plasmids. • SGI1 variant in a donor doesn't affect exclusion of IncC plasmids by IncA plasmids. • An SGI1 variant in a donor overcomes entry exclusion of IncC plasmids by EexC. • Multiple factors contribute to exclusion of IncC plasmids by IncA or IncC plasmids. [ABSTRACT FROM AUTHOR]

Abstract: A Salmonella genomic island 1 (SGI1) isogenic strain pair was constructed using Salmonella enterica serovar Typhimurium LT2 (ST LT2). Real-time quantitative reverse transcriptase PCR revealed detectable mRNA transcripts for all 44 putative ORFs encoded within the SGI1. The highest levels of transcripts observed in SGI1 encoded ORFs were found in genes conferring antibiotic resistance to ampicillin, streptomycin/spectinomycin, and sulphonamides. Abundant mRNA transcripts, relative to gapA, were also noted for one putative regulatory ORF and seven ORFs of unknown function encoded within SGI1, whose products could represent factors contributing to increases in virulence and/or fitness of the organism. DNA microarray analysis revealed the differential expression of known factors that contribute to virulence in many pathogens. Twenty-two chromosomal genes were significantly upregulated in ST LT2 harboring SGI1, which included increased expression of iron and sialic acid utilization genes. Decreased expression was noted for 15 genes in ST LT2 harboring SGI1, including genes involved in chemotaxis and motility. This is the first report examining gene expression within the SGI1, as well as its potential effect on global gene expression, and sets the foundation for future studies involving the effect of SGI1 in other Salmonella spp. [Copyright &y& Elsevier]

Abstract: The objective of this study was to investigate the antimicrobial resistance patterns, integron characteristics and gene cassettes as well as the presence of Salmonella genomic island 1 (SGI1) in non-typhoidal Salmonella (NTS) isolates from human and animal origin. Epidemiologically unrelated Dutch NTS strains (n =237) originating from food-producing animals and human cases of salmonellosis were tested for their susceptibility to 15 antimicrobial agents. Resistance to 14 of these antimicrobials, including the third-generation cephalosporins, was detected. Resistance to sulphonamides, ampicillin, tetracycline, streptomycin, trimethoprim and nalidixic acid was common (≥10% of the strains were resistant). Resistance against three or more antimicrobials was observed in 57 isolates. The same 237 strains were studied for the prevalence of class 1 integrons, their gene cassettes and the presence of SGI1. Thirty-six isolates (15.2%) carried class 1 integrons. These integrons had ten distinct profiles based on the size of the integron and restriction fragment length polymorphism analysis. Integrons were detected for the first time in serovars Indiana and Senftenberg. Multidrug resistance was strongly associated with the presence of class 1 integrons in which the aadA2, aadA1, bla PSE-1, dfrA1, dfrA5, dfrA14 or sat genes were present, as determined by nucleotide sequence determination. The presence of gene cassettes or combinations of gene cassettes not previously found in integrons in Salmonella was observed. SGI1 or its variants (SGI-B, -C and -F) were present in 16 isolates belonging to either serovar Typhimurium, Derby or Albany. Regardless of whether the isolate was of human or animal origin, the same resistance phenotype, integron profile and SGI1 structure could be observed. [Copyright &y& Elsevier]

Abstract: Molecular typing, the presence of Salmonella genomic island 1 (SGI1), and virulence factors were studied in 45 bla PSE-positive S. Typhimurium isolates from 3 hospitals. All isolates belonged to sequence type ST19, presented low clonal diversity, and harbored SGI1. The wide diversity of virulence factors was classified into 3 major virulotype groups. [Copyright &y& Elsevier]

The emergence and dissemination of Salmonella genomic island 1 (SGI1) are strongly associated with the occurrence of multidrug-resistant (MDR) enterobacteria in humans and animals. Diverse SGI1s have been reported among Salmonella enterica and Proteus mirabilis in several countries. We aimed to characterize SGI1 in P. mirabilis isolates from humans and chickens in Chungcheong Province, Korea. A total of 44 P. mirabilis isolates were recovered from humans ( n = 20) and chickens ( n = 24). Antimicrobial susceptibility was determined by disk diffusion assay. To detect and characterize SGI1s, PCR amplification and PCR mapping experiments were performed. Repetitive extragenic palindromic-PCR (REP-PCR) was performed to assess the clonality of the isolates. The four P. mirabilis strains (16.7%) from chicken harbored a SGI1, whereas none of the isolates from clinical specimens contained SGI1. The SGI1s detected in our study were all confirmed as SGI1- Pm ABB harboring aminoglycoside-resistant genes ( aac CA5 and aad A7). In P. mirabilis isolates, the presence of SGI1- Pm ABB was significantly correlated with high resistance rates of the isolates to antimicrobial agents, such as gentamicin, streptomycin, and spectinomycin. Moreover, the four SGI1-bearing isolates showed the same REP-PCR patterns and that suggested both horizontal and clonal spread of the isolates. This study is the first attempt to determine SGI1s in P. mirabilis isolates in Korea. We confirmed that P. mirabilis isolates carrying SGI1- Pm ABB were distributed at poultry farms in Korea. The present study emphasizes the need for continuous monitoring of SGI1s to prevent spreading of the MDR genomic islands among P. mirabilis isolates from humans and animals.