Changes in antimicrobial susceptibility in a population of Salmonella enterica serovar Dublin isolated from cattle in Japan from 1976 to 2005

Akiba, Masato; Nakaoka, Yuji; Kida, Muneyoshi; Ishioka, Yukiko; Sameshima, Toshiya; Yoshii, Noriyo; Nakazawa, Muneo; Uchida, Ikuo; Terakado, Nobuaki

doi:10.1093/jac/dkm402

Cited by 13 publications

(8 citation statements)

References 29 publications

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“…The ArcAB-TolC efflux pumps are important for triclosan resistance [ 11 ] and these pumps have also been shown to directly contribute to flouroquinolone (e.g. ENR) resistance in Salmonella [ 40 , 41 ]. The efflux systems EmrAB and ArcEF have been shown to be important for both triclosan resistance [ 10 ] and trimethoprim resistance [ 42 ].…”

Section: Discussionmentioning

confidence: 99%

Importance of sigma factor mutations in increased triclosan resistance in Salmonella Typhimurium

2015

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BackgroundSalmonella enterica is the second most common foodborne pathogen. The use of biocides is crucial to prevent spread of foodborne pathogens, and it would be devastating for food safety if Salmonella would become resistant to the disinfectants used. Another concern is that exposure to disinfectants might lead to decreased susceptibility to antibiotics.The current study aimed to identify genetic changes causing high level triclosan resistance in S. enterica serovar Typhimurium and evaluate how these affected antibiotic resistance and efflux pump activity.ResultsWild type strains S. Typhimurium 4/74 and DTU3 were adapted to increasing concentrations of the biocide triclosan by serial passage. High level triclosan resistant isolates (MIC > 1000 μg/ml) were obtained. Strains were genome sequenced, and SNPs in fabI, rpoS and rpoD were found to be associated with high level resistance. However, work with defined mutants revealed that a SNP in fabI was not sufficient to obtain high level resistance. This required additional mutations in the sigma factors rpoS or rpoD. The adapted strains showed triclosan-dependent increased efflux, increased fabI expression and reduced susceptibility towards the antibiotics enrofloxacin and sulphamethoxazole/trimethoprim.ConclusionsMedium level triclosan resistance could be obtained by fabI mutations in S. Typhimurium, however, high level resistance was found to require sigma factor mutations in addition to a fabI mutation. Reduced antibiotic sensitivity was observed for the adapted strains, which could be associated with increased efflux.

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Section: Discussionmentioning

confidence: 99%

Importance of sigma factor mutations in increased triclosan resistance in Salmonella Typhimurium

2015

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“…Construction of gene replacement vectors and generation of deletion mutants. To generate deletion mutants of SGI3, the pco gene cluster, and the cus gene cluster, gene replacement was performed as described previously (52) with slight modifications. Detailed methods for the construction of gene replacement vectors can be found in the supplemental material.…”

Section: Methodsmentioning

confidence: 99%

Salmonella Genomic Island 3 Is an Integrative and Conjugative Element and Contributes to Copper and Arsenic Tolerance of Salmonella enterica

Arai

Sekizuka

Tamamura

et al. 2019

Antimicrob Agents Chemother

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Salmonella genomic island 3 (SGI3) was first described as a chromosomal island in Salmonella 4,[5],12:i:–, a monophasic variant of Salmonella enterica subsp. enterica serovar Typhimurium. The SGI3 DNA sequence detected from Salmonella 4,[5],12:i:– isolated in Japan was identical to that of a previously reported one across entire length of 81 kb. SGI3 consists of 86 open reading frames, including a copper homeostasis and silver resistance island (CHASRI) and an arsenic tolerance operon, in addition to genes related to conjugative transfer and DNA replication or partitioning, suggesting that the island is a mobile genetic element. We successfully selected transconjugants that acquired SGI3 after filter-mating experiments using the S. enterica serovars Typhimurium, Heidelberg, Hadar, Newport, Cerro, and Thompson as recipients. Southern blot analysis using I-CeuI-digested genomic DNA demonstrated that SGI3 was integrated into a chromosomal fragment of the transconjugants. PCR and sequencing analysis demonstrated that SGI3 was inserted into the 3′ end of the tRNA genes pheV or pheR. The length of the target site was 52 or 55 bp, and a 55-bp attI sequence indicating generation of the circular form of SGI3 was also detected. The transconjugants had a higher MIC against CuSO4 compared to the recipient strains under anaerobic conditions. Tolerance was defined by the cus gene cluster in the CHASRI. The transconjugants also had distinctly higher MICs against Na2HAsO4 compared to recipient strains under aerobic conditions. These findings clearly demonstrate that SGI3 is an integrative and conjugative element and contributes to the copper and arsenic tolerance of S. enterica.

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“…To generate deletion mutants of SGI3, pco gene cluster, and cus gene cluster, gene replacement was performed as described previously (40) with slight modifications. For SGI3, upstream and downstream regions of SGI3 were amplified and connected by three continuous PCRs for the insert fragment as described below to construct a gene replacement vector.…”

Section: Methodsmentioning

confidence: 99%

Salmonellagenomic island 3 is an integrative and conjugative element and contributes to copper and arsenic resistance ofSalmonella enterica

Arai

Sekizuka

Tamamura

et al. 2019

Preprint

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Changes in antimicrobial susceptibility in a population of Salmonella enterica serovar Dublin isolated from cattle in Japan from 1976 to 2005

Cited by 13 publications

References 29 publications

Importance of sigma factor mutations in increased triclosan resistance in Salmonella Typhimurium

Importance of sigma factor mutations in increased triclosan resistance in Salmonella Typhimurium

Salmonella Genomic Island 3 Is an Integrative and Conjugative Element and Contributes to Copper and Arsenic Tolerance of Salmonella enterica

Salmonellagenomic island 3 is an integrative and conjugative element and contributes to copper and arsenic resistance ofSalmonella enterica

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