Characterization of class I integrons in clinical strains of Salmonella enterica subsp. enterica serovars Typhimurium and Enteritidis from Norwegian hospitals

Lindstedt, Bjørn-Arne; Heir, Even; Nygård, Irene; Kapperud, Georg

doi:10.1099/jmm.0.04958-0

Cited by 67 publications

(45 citation statements)

References 43 publications

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“…Previous studies concerning clinical environments identified a high predominance of weak PcW variants in Salmonella (6,14), and PcW and PcH1 variants also prevailed in Escherichia coli strains from human and animal origins (2), although the authors did not discriminate between PcW and PcW . In this study, the control of gene cassette expression was also associated with weak PcW and PcH1 variants in both wastewaters, suggesting the existence of a dynamic gene cassette pool in these environments that is similar to what has been described for clinical settings (2,6,14).…”

mentioning

confidence: 78%

Diversity of Gene Cassette Promoters in Class 1 Integrons from Wastewater Environments

Moura

Jové

Ploy

et al. 2012

Appl Environ Microbiol

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mentioning

confidence: 78%

Diversity of Gene Cassette Promoters in Class 1 Integrons from Wastewater Environments

Moura

Jové

Ploy

et al. 2012

Appl Environ Microbiol

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“…In contrast, integron-mediated antibiotic resistance was common among E. coli isolates, where more than 50% of the isolates were shown to contain integrons, with some containing two integrons. Various gene cassettes detected in Salmonella and E. coli isolates in this study, including aadA1, aadA2, aadA5, aacA4, dhfrXII, dfrA1, dhfrA17, bla PSE1 , and catB3, have been detected in clinical and nonclinical isolates in reports from many countries (6,20,29,31,32,34,35,43,49,51,52,62,64). The gene cassette array aacA4-catB3-dfrA1, which has been reported recently in Japan (31) and China (34), was also detected in E. coli isolates in this study, indicating that this resistance cassette is widespread in Asia.…”

Section: Discussionmentioning

confidence: 99%

Antibiotic Resistance in Food-Borne Bacterial Contaminants in Vietnam

Van

Moutafis

Tran

et al. 2007

Appl Environ Microbiol

111

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This study was conducted to examine the rate of contamination and the molecular characteristics of enteric bacteria isolated from a selection of food sources in Vietnam. One hundred eighty raw food samples were tested; 60.8% of meat samples and 18.0% of shellfish samples were contaminated with Salmonella spp., and more than 90% of all food sources contained Escherichia coli. The isolates were screened for antibiotic resistance against 15 antibiotics, and 50.5% of Salmonella isolates and 83.8% of E. coli isolates were resistant to at least one antibiotic. Isolates were examined for the presence of mobile genetic elements conferring antibiotic resistance. Fifty-seven percent of E. coli and 13% of Salmonella isolates were found to contain integrons, and some isolates contained two integrons. Sequencing results revealed that the integrons harbored various gene cassettes, including aadA1, aadA2, and aadA5 (resistance to streptomycin and spectinomycin), aacA4 (resistance to aminoglycosides), the dihydrofolate reductase gene cassettes dhfrXII, dfrA1, and dhfrA17 (trimethoprim resistance), the beta-lactamase gene bla PSE1 (ampicillin resistance), and catB3 (chloramphenicol resistance). Plasmids were also detected in all 23 antibiotic-resistant Salmonella isolates and in 33 E. coli isolates. Thirty-five percent of the Salmonella isolates and 76% of the E. coli isolates contained plasmids of more than 95 kb, and some of the isolates contained two large plasmids. Conjugation experiments showed the successful transfer of all or part of the antibiotic resistance phenotypes among the Salmonella and E. coli food isolates. Our results show that enteric bacteria in raw food samples from Vietnam contain a pool of mobile genetic elements and that the transfer of antibiotic resistance can readily occur between similar bacteria.

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“…However, only 10% of class 1 integrons harbor a P2 promoter, as shown by both in silico (11) and epidemiological studies (13,19). This indicates that constitutive intI1 expression in the PcW-P2 configuration may have a deleterious effect and a fitness cost for bacteria.…”

Section: Vol 193 2011mentioning

confidence: 99%

High-Level Gene Cassette Transcription Prevents Integrase Expression in Class 1 Integrons

Guérin

Jové

Tabesse

et al. 2011

Journal of Bacteriology

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Class 1 integrons are widespread genetic elements responsible for dissemination of antibiotic resistance among Gram-negative bacteria. Integrons allow bacteria to capture and express gene cassettes (GCs) via an integrase (IntI1) and a promoter (Pc) contained in the integron functional platform. GCs are transcribed from Pc, of which 13 variants of different strengths have been described, or, occasionally, from both Pc and a second promoter (P2). The intI1 promoter (PintI1) is repressed by LexA, which is the transcriptional repressor of the global regulatory SOS response network. Moreover, PintI1 lies face to face with Pc and overlaps P2, both configurations being propitious to transcriptional interference (TI). In this study, we analyzed possible transcriptional interference by quantifying transcripts produced from Pc, P2, and PintI1. We found that the Pc promoter interferes with the level of intI1 transcription but that this effect depends on the Pc variant: the strong Pc variant prevents intI1 expression, in contrast to the other variants. Although P2 formation results in LexA binding site disruption and thus prevents SOS regulation of intI1 expression, P2 does not interfere with PintI1. These findings reveal a tight relationship between GC and integrase expression.

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Characterization of class I integrons in clinical strains of Salmonella enterica subsp. enterica serovars Typhimurium and Enteritidis from Norwegian hospitals

Cited by 67 publications

References 43 publications

Diversity of Gene Cassette Promoters in Class 1 Integrons from Wastewater Environments

Diversity of Gene Cassette Promoters in Class 1 Integrons from Wastewater Environments

Antibiotic Resistance in Food-Borne Bacterial Contaminants in Vietnam

High-Level Gene Cassette Transcription Prevents Integrase Expression in Class 1 Integrons

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