Dissemination of Sulfonamide Resistance Genes (sul1, sul2, and sul3) in Portuguese Salmonella enterica Strains and Relation with Integrons

Faculdade de Ciências da Nutrição e Alimentação, Universidade do Porto, Rua Aníbal Cunha, n(o)164, 4050-047 Porto, Portugal.
Antimicrobial Agents and Chemotherapy (Impact Factor: 4.48). 03/2005; 49(2):836-9. DOI: 10.1128/AAC.49.2.836-839.2005
Source: PubMed


In 200 sulfonamide-resistant Portuguese Salmonella isolates, 152 sul1, 74 sul2, and 14 sul3 genes were detected. Class 1 integrons were always associated with sul genes, including sul3 alone in some isolates. The sul3 gene has been identified in isolates from different sources and serotypes, which also carried a class 1 integron with aadA and dfrA gene cassettes.

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Available from: Luísa Peixe
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    • "However, 44 % of the sul3-positive isolates did not carry integrons, and this gene was thus likely inserted into plasmids (Han et al. 2012). In contrast, sul2 showed a lower association with integrons, which is in accordance with its integron-independent plasmid origin (Antunes et al. 2005). Aminoglycosides and tetracyclines have been widely used in veterinary medicine (Schwarz et al. 2001), which likely led to the selection of resistant isolates to these antimicrobials. "
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    ABSTRACT: Antimicrobial resistance profiles and presence of resistance determinants and integrons were evaluated in Salmonella enterica strains from Brazilian poultry. The analysis of 203 isolates showed that those from the poultry environment (88 isolates) were significantly more resistant to antimicrobials than isolates from other sources, particularly those isolated from poultry by-product meal (106 isolates). Thirty-seven isolates were resistant to at least three antimicrobial classes. Class 1 integrons were detected in 26 isolates, and the analysis of the variable region between the 5' conserved segment (CS) and 3' CS of each class 1 integron-positive isolate showed that 13 contained a typical 3' CS and 14 contained an atypical 3' CS. One Salmonella Senftenberg isolate harbored two class 1 integrons, showing both typical and atypical 3' CSs. The highest percentage of resistance was found to sulfonamides, and sul genes were detected in the majority of the resistant isolates. Aminoglycoside resistance was detected in 50 isolates, and aadA and aadB were present in 28 and 32 isolates, respectively. In addition, strA and strB were detected in 78.1 and 65.6 % isolates resistant to streptomycin, respectively. Twenty-one isolates presented reduced susceptibility to β-lactams and harbored bla TEM, bla CMY, and/or bla CTX-M. Forty isolates showed reduced susceptibility to tetracycline, and most presented tet genes. These results highlight the importance of the environment as a reservoir of resistant Salmonella, which may enable the persistence of resistance determinants in the poultry production chain, contributing, therefore, to the debate regarding the impacts that antimicrobial use in animal production may exert in human health.
    Full-text · Article · Sep 2015 · Antonie van Leeuwenhoek
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    • "was found in cattle , pig , and poultry isolates ( Guerra et al . , 2003 ) . These studies suggest that sul3 is spreading widely amongst animals but not amongst humans , possibly due to the use of sulfonamide for animal husbandry but not in humans in developed countries , and that sul3 is transferred by a different gene cassette to sul1 and sul2 ( Antunes et al . , 2005 ) . Although recent advances in metagenomics can detect total resistome , quantitative estimation of ARGs in the microbial community is not yet possible ."
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    ABSTRACT: Antibiotic resistant bacteria are ubiquitous in the natural environment. The introduction of effluent derived antibiotic resistance genes (ARGs) into aquatic environments is of concern in the spreading of genetic risk. This study showed the prevalence of sulfonamide and tetracycline resistance genes, sul1, sul2, sul3, and tet(M), in the total bacterial assemblage and colony forming bacterial assemblage in river and estuarine water and sewage treatment plants (STP) in South Africa. There was no correlation between antibiotic concentrations and ARGs, suggesting the targeted ARGs are spread in a wide area without connection to selection pressure. Among sul genes, sul1 and sul2 were major genes in the total (over 10(-2) copies/16S) and colony forming bacteria assemblages (∼10(-1) copies/16S). In urban waters, the sul3 gene was mostly not detectable in total and culturable assemblages, suggesting sul3 is not abundant. tet(M) was found in natural assemblages with 10(-3) copies/16S level in STP, but was not detected in colony forming bacteria, suggesting the non-culturable (yet-to-be cultured) bacterial community in urban surface waters and STP effluent possess the tet(M) gene. Sulfamethoxazole (SMX) resistant (SMX(r)) and oxytetracycline (OTC) resistant (OTC(r)) bacterial communities in urban waters possessed not only sul1 and sul2 but also sul3 and tet(M) genes. These genes are widely distributed in SMX(r) and OTC(r) bacteria. In conclusion, urban river and estuarine water and STP effluent in the Durban area were highly contaminated with ARGs, and the yet-to-be cultured bacterial community may act as a non-visible ARG reservoir in certain situations.
    Full-text · Article · Aug 2015 · Frontiers in Microbiology
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    • "The sul2 gene is frequently associated with the small, multi-copy, non-conjugative IncQ plasmid group. The sulfamethoxazole resistance gene sul3 is also often found in horizontally transferable elements that are transposons and plasmids (Antunes et al., 2005; Blahna et al., 2006). As such, any study that is concerned with the detection of sulfonamid-resistance bacteria in wastewaters should focus on these three common sul genes (Gao et al., 2012). "
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    ABSTRACT: Biological treatment processes offer the ideal conditions in which a high diversity of microorganisms can grow and develop. The wastewater produced during these processes is contaminated with antibiotics and, as such, they provide the ideal setting for the acquisition and proliferation of antibiotic resistance genes (ARGs). This research investigated the occurrence and variation in the ARGs found during the one-year operation of the anaerobic sequencing batch reactors (SBRs) used to treat pharmaceutical wastewater that contained combinations of sulfamethoxazole-tetracycline-erythromycin (STE) and sulfamethoxazole-tetracycline (ST). The existence of eighteen ARGs encoding resistance to sulfamethoxazole (sul1, sul2, sul3), erythromycin (ermA, ermF, ermB, msrA, ereA), tetracycline (tetA, tetB, tetC, tetD, tetE, tetM, tetS, tetQ, tetW, tetX) and class Ι integron gene (intΙ 1) in the STE and ST reactors was investigated by quantitative real-time PCR. Due to the limited availability of primers to detect ARGs, Illumina sequencing was also performed on the sludge and effluent of the STE and ST reactors. Although there was good reactor performance in the SBRs, which corresponds to min 80% COD removal efficiency, tetA, tetB, sul1, sul2 and ermB genes were among those ARGs detected in the effluent from STE and ST reactors. A comparison of the ARGs acquired from the STE and ST reactors revealed that the effluent from the STE reactor had a higher number of ARGs than that from the ST reactor; this could be due to the synergistic effects of erythromycin. According to the expression of genes results, microorganisms achieve tetracycline and erythromycin resistance through a combination of three mechanisms: efflux pumping protein, modification of the antibiotic target and modifying enzymes. There was also a significant association between the presence of the class 1 integron and sulfamethoxazole resistance genes. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Full-text · Article · Jul 2015 · Water Research
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