scholarly journals SGI2, a Relative of Salmonella Genomic Island SGI1 with an Independent Origin

2008 ◽  
Vol 52 (7) ◽  
pp. 2529-2537 ◽  
Author(s):  
Renee S. Levings ◽  
Steven P. Djordjevic ◽  
Ruth M. Hall

ABSTRACT Multiply antibiotic-resistant Salmonella enterica serovar Emek strains isolated in Australia and the United Kingdom had similar features, suggesting that they all belong to a single clone. These strains all contain SGI2 (formerly SGI1-J), an independently formed relative of Salmonella genomic island SGI1. In SGI2, the complex class 1 integron which includes all of the resistance genes is not located between tnpR (S027) and S044 as in SGI1 and SGI1 variants. Instead, tnpR was found to be adjacent to S044, and the integron is located 6.9 kb away, within S023. In both SGI1 and SGI2, the 25-bp inverted repeats that mark the outer ends of class 1 integrons are flanked by a 5-bp duplication of the target, indicating that incorporation of the integron was by transposition. A small number of differences between the sequences of the backbones of SGI1 and SGI2 were also found. Hence, a class 1 integron has entered two different variants of the SGI backbone to generate two distinct lineages. Despite this, the integron in SGI2 has a complex structure that is very similar to that of In104 in SGI1. Differences are in the cassette arrays and in the gene which encodes the chloramphenicol and florfenicol efflux protein. The CmlA9 protein, encoded by InEmek, is only 92.8% identical to FloRc (also a CmlA family protein) from SGI1. A variant form of SGI2, SGI2-A, which has lost the tet(G) and cmlA9 resistance determinants, was found in one strain.

2006 ◽  
Vol 51 (1) ◽  
pp. 317-323 ◽  
Author(s):  
Renee S. Levings ◽  
Sally R. Partridge ◽  
Steven P. Djordjevic ◽  
Ruth M. Hall

ABSTRACT A multiple-antibiotic-resistant Salmonella enterica serovar Kentucky strain was found to contain SGI1-K, a variant form of the Salmonella genomic island 1 (SGI1) with an In4-type class 1 integron that contains only one cassette array, aacCA5-aadA7, and an adjacent mercury resistance module. Part of the 3′-conserved segment (3′-CS) of the integron, together with the inverted short segment from the right-hand end of the integron transposition module normally found between the 3′-CS and IS6100 in In4 family integrons, has been removed by an IS6100-mediated deletion. IRt, the right-hand inverted repeat found at the outer end of the integron, abuts a mercury resistance region instead of the usual SGI1 backbone segment. The mer module is a hybrid of those found in Tn501 and Tn21. This mer region and a further uncharacterized segment of at least 10 kb appear to have been incorporated between IRt and the SGI1 backbone. These findings demonstrate that the multidrug resistance region in SGI1 can incorporate new DNA segments in the same way as multiple antibiotic resistance regions in plasmids.


2020 ◽  
Vol 8 (2) ◽  
pp. 161 ◽  
Author(s):  
Max Laurence Cummins ◽  
Mohammad Hamidian ◽  
Steven Philip Djordjevic

Salmonella genomic island 1 (SGI1) is an integrative mobilisable element that plays an important role in the capture and spread of multiple drug resistance. To date, SGI1 has been found in clinical isolates of Salmonella enterica serovars, Proteus mirabilis, Morganella morganii, Acinetobacter baumannii, Providencia stuartii, Enterobacter spp, and recently in Escherichia coli. SGI1 preferentially targets the 3´-end of trmE, a conserved gene found in the Enterobacteriaceae and among members of the Gammaproteobacteria. It is, therefore, hypothesised that SGI1 and SGI1-related elements (SGI1-REs) may have been acquired by diverse bacterial genera. Here, Bitsliced Genomic Signature Indexes (BIGSI) was used to screen the NCBI Sequence Read Archive (SRA) for putative SGI1-REs in Gammaproteobacteria. Novel SGI-REs were identified in diverse genera including Cronobacter spp, Klebsiella spp, and Vibrio spp and in two additional isolates of Escherichia coli. An extensively drug-resistant human clonal lineage of Klebsiella pneumoniae carrying an SGI1-RE in the United Kingdom and an SGI1-RE that lacks a class 1 integron were also identified. These findings provide insight into the origins of this diverse family of clinically important genomic islands and expand the knowledge of the potential host range of SGI1-REs within the Gammaproteobacteria.


2005 ◽  
Vol 187 (13) ◽  
pp. 4401-4409 ◽  
Author(s):  
Renee S. Levings ◽  
Diane Lightfoot ◽  
Sally R. Partridge ◽  
Ruth M. Hall ◽  
Steven P. Djordjevic

ABSTRACT The global dissemination of the multiply-antibiotic-resistant Salmonella enterica serovar Typhimurium DT104 clone with the resistance genes located in a class 1 integron, here designated In104, within genomic island SGI1 is a significant public health issue. Here, we have shown that SGI1 and variants of it carrying different combinations of resistance genes are found in several Salmonella enterica serovars. These are serovars Cerro, Derby, Dusseldorf, Infantis, Kiambu, and Paratyphi B dT+ isolated from human infections and serovar Emek from sewage effluent. Two new variants, SGI1-I and SGI1-J, both of which include the dfrA1-orfC cassette array, were identified.


Author(s):  
Jinru Chen ◽  
Joycelyn Quansah

Fresh produce-borne enteric bacterial pathogens with resistance to antibiotics have posed serious challenges to food safety and public health worldwide.  This study examined the antibiotic resistance profile of Salmonella enterica (n=33), previously isolated from exotic and indigenous leafy green vegetable samples (n=328) collected from 50 vegetable farms in 12 farming areas and 37 vegetable sellers in 4 market centers in Accra, Ghana during the period of March 2016 to March 2017, and determined the distribution of integrons among antibiotic-resistant isolates.  The susceptibility of the Salmonella isolates to 12 antibiotics was assayed using the standard disc diffusion assay.  The minimum inhibitory concentrations (MICs) of the five most resisted antibiotics were determined using the twofold macro dilution method.  PCR assay was used to detect the presence of integrons in Salmonella cells, and PCR product with amplified integron gene cassette was purified and sequenced using the Sanger sequencing technology.  The Salmonella isolates used in the study resisted at least one tested antibiotic, and multi-drug resistant (MDR) isolates were 30.3% (10/33).  Most isolates (81.8%) were resistant to sulfisoxazole.  The MICs of tetracycline, cefoxitin, streptomycin, ampicillin, and sulfisoxazole were 16, 32, 64, 64, and > 1,024 µg/ml, respectively.  A total of five different patterns of MDR were observed among the Salmonella isolates, and the common MDR patterns were AAuFox (30.3%) and AAuFoxSSu (18.1%).  One out of the 33 (3.0%) Salmonella isolates tested positive for class 1 integron with a gene cassette of about 800 bp.  Nucleotide sequencing revealed the class 1 integron carried a single gene dfrA7 .  Future studies are needed to confirm whether the consumption of contaminated leafy green vegetables is a route of acquiring antibiotic-resistant Salmonella by consumers in Accra, Ghana.


2011 ◽  
Vol 5 (23) ◽  
pp. 3907-3912
Author(s):  
Chang Yi Chih ◽  
Chuang Hsiao Li ◽  
Chiu Chien Chao ◽  
Yeh Kuang Sheng ◽  
Chang Chao Chin ◽  
...  

2001 ◽  
Vol 67 (12) ◽  
pp. 5675-5682 ◽  
Author(s):  
Anja S. Schmidt ◽  
Morten S. Bruun ◽  
Inger Dalsgaard ◽  
Jens L. Larsen

ABSTRACT A collection of 313 motile aeromonads isolated at Danish rainbow trout farms was analyzed to identify some of the genes involved in high levels of antimicrobial resistance found in a previous field trial (A. S. Schmidt, M. S. Bruun, I. Dalsgaard, K. Pedersen, and J. L. Larsen, Appl. Environ. Microbiol. 66:4908–4915, 2000), the predominant resistance phenotype (37%) being a combined oxytetracycline (OTC) and sulphadiazine/trimethoprim resistance. Combined sulphonamide/trimethoprim resistance (135 isolates) appeared closely related to the presence of a class 1 integron (141 strains). Among the isolates containing integrons, four different combinations of integrated resistance gene cassettes occurred, in all cases including a dihydrofolate reductase gene and a downstream aminoglycoside resistance insert (87 isolates) and occasionally an additional chloramphenicol resistance gene cassette (31 isolates). In addition, 23 isolates had “empty” integrons without inserted gene cassettes. As far as OTC resistance was concerned, only 66 (30%) out of 216 resistant aeromonads could be assigned to resistance determinant class A (19 isolates), D (n = 6), or E (n = 39); three isolates contained two tetracycline resistance determinants (AD, AE, and DE). Forty OTC-resistant isolates containing large plasmids were selected as donors in a conjugation assay, 27 of which also contained a class 1 integron. Out of 17 successful R-plasmid transfers to Escherichia coli recipients, the respective integrons were cotransferred along with the tetracycline resistance determinants in 15 matings. Transconjugants were predominantly tetApositive (10 of 17) and contained class 1 integrons with two or more inserted antibiotic resistance genes. While there appeared to be a positive correlation between conjugative R-plasmids andtetA among the OTC-resistant aeromonads, tetEand the unclassified OTC resistance genes as well as class 1 integrons were equally distributed among isolates with and without plasmids. These findings indicate the implication of other mechanisms of gene transfer besides plasmid transfer in the dissemination of antibiotic resistance among environmental motile aeromonads.


2008 ◽  
Vol 53 (2) ◽  
pp. 824-827 ◽  
Author(s):  
Benoît Doublet ◽  
Chishih Chu ◽  
Cheng-Hsun Chiu ◽  
Yi-Chin Fan ◽  
Axel Cloeckaert

ABSTRACT Salmonella genomic island 1 was identified for the first time in Salmonella enterica serovar Virchow isolated from humans in Taiwan. The complex class 1 integron conferring multidrug resistance was shown to be inserted within open reading frame (ORF) S023 and contains for the first time a partial transpositional module. The 5-bp target duplication flanking the complex integron suggests that its insertion in ORF S023 was by transposition.


2009 ◽  
Vol 15 (3) ◽  
pp. 167-172 ◽  
Author(s):  
Ysanne B. Long ◽  
Joan Faoagali ◽  
Janice Bodman ◽  
Narelle George ◽  
David McKay ◽  
...  

2019 ◽  
Author(s):  
Ishmael Festus Jaja ◽  
James Oguttu ◽  
Ezekiel Green ◽  
Voster Muchenje

AbstractObjectiveThis study aimed to characterise antibiotics resistance ofEscherichia coliisolates from the formal meat sector (FMS) and informal meat sectors (INMS).MethodA total of 162 and 102E. coliisolates from the FMS, and INMS respectively were isolated by standard culture-based, and biochemical reactions. The isolates were further confirmed by polymerase chain reaction (PCR). The disc diffusion method was used to screen for antimicrobial susceptibility against 19 different antibiotics. The presence of class 1-2 integrons in eachE. coliisolates was assessed usingandregions specific primers.ResultAmong the 19 antimicrobials, resistance to tetracyclines, aminoglycosides, cephalosporins, and nitrofurans were found to be more frequent than carbapenems and phenicol with a noticeable increase in the number of multi-drug resistance ranging from three to ten antimicrobials. A total of 20 resistance determinants were assessed with their prevalence and distributions obtained as follows for FMS and INMS respectively; [aminoglycosides:aadA(40.6%; 31.9%),aacC2(21.4%; 31%),aphA1(20.8%; 15.1%),aphA2(37.7%; 18.9%) andstrA(6.5%; 9.4%)], [β-lactams:ampC(20%; 45%),blaTEM, (4.4%; 13.3), andblaZ(8.9%; 2.2%)], [Chloramphenicol:catI(1.7%; 1.7%), andcmIA1(1.7%; 1.7%)] and [tetracyclines:tetA(7.7%; 15.4%),tetB(11.5%; 24%), andtetM, (1.9%; 8.7%)], and [sulfonamides: sul1 (22.2%; 26.7%), sul2 (17.8%; 6.7%)].ConclusionMultiple antibiotic resistance (MAR) indexes ranged from 0.2 - 0.5. The results reveal a high prevalence of multidrug-resistantE. coliisolates and resistance determinants suggesting that consumers and handlers of such meat are at risk of contracting antibiotic resistantE. coli-related foodborne disease.


2012 ◽  
Vol 56 (10) ◽  
pp. 5096-5102 ◽  
Author(s):  
Simon Le Hello ◽  
François-Xavier Weill ◽  
Véronique Guibert ◽  
Karine Praud ◽  
Axel Cloeckaert ◽  
...  

ABSTRACTSalmonellagenomic island 1 (SGI1) is a 43-kb integrative mobilizable element that harbors a great diversity of multidrug resistance gene clusters described in numerousSalmonella entericaserovars and also inProteus mirabilis. The majority of SGI1 variants contain an In104-derivative complex class 1 integron inserted between resolvase generesand open reading frame (ORF) S044 in SGI1. Recently, the international spread of ciprofloxacin-resistantS. entericaserovar Kentucky sequence type 198 (ST198) containing SGI1-K variants has been reported. A retrospective study was undertaken to characterize ST198S. Kentucky strains isolated before the spread of the epidemic ST198-SGI1-K population in Africa and the Middle East. Here, we characterized 12 ST198S. Kentucky strains isolated between 1969 and 1999, mainly from humans returning from Southeast Asia (n= 10 strains) or Israel (n= 1 strain) or from meat in Egypt (n= 1 strain). All these ST198S. Kentucky strains did not belong to the XbaI pulsotype X1 associated with the African epidemic clone but to pulsotype X2. SGI1-J subgroup variants containing different complex integrons with a partial transposition module and inserted within ORF S023 of SGI1 were detected in six strains. The SGI1-J4 variant containing a partially deleted class 1 integron and thus showing a narrow resistance phenotype to sulfonamides was identified in two epidemiologically unrelated strains from Indonesia. The four remaining strains harbored a novel SGI1-J variant, named SGI1-J6, which containedaadA2,floR2,tetR(G)-tetA(G), andsul1resistance genes within its complex integron. Moreover, in all theseS. Kentucky isolates, a novel insertion sequence related to the IS630family and named ISSen5was found inserted upstream of the SGI1 complex integron in ORF S023. Thus, two subpopulations ofS. Kentucky ST198 independently and exclusively acquired the SGI1 during the 1980s and 1990s. Unlike the ST198-X1 African epidemic subpopulation, the ST198-X2 subpopulation mainly from Asia harbors variants of the SGI1-J subgroup that are encountered mainly in the Far East, as previously described forS. entericaserovars Emek and Virchow.


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