Characterization of antibiotic resistance genes linked to class 1 and 2 integrons in strains of Salmonella spp. isolated from swine

2008 ◽  
Vol 54 (7) ◽  
pp. 569-576 ◽  
Author(s):  
Betty San Martín ◽  
Lisette Lapierre ◽  
Javiera Cornejo ◽  
Sergio Bucarey

The aim of this study was to characterize the antibiotic resistance profiles, the integron-associated resistance determinants, and the potential ability of transferring these determinants by conjugation in Salmonella enterica isolated from swine. Fifty-four strains of Salmonella spp. were isolated from healthy swine. The percentages of resistance, determined by the plate dilution method were as follows: oxytetracycline (41%), streptomycin (39%), sulphamethoxazol+trimethoprim (19%), enrofloxacin–ciprofloxacin (13%), and amoxicillin (0%). The most important resistance serovars were Salmonella Branderburg, Salmonella Derby, Salmonella Typhimurium, and Salmonella Heidelberg. The oxytetracycline-resistant strains amplified the genes tetA (36%), tetB (64%); and the strains resistant to streptomycin and trimethoprim amplified the genes aadA1 (100%) and dfrA1 (100%), respectively. None of the fluoroquinolone-resistant strains amplified the gene qnr. Ten strains amplified the class 1 integron harboring the cassette aadA1. Six strains amplified the class 2 integron harboring the cassettes dfrA1, sat1, and aadA1. The conjugation assays showed that 2 strains transferred the tetA and aadA1 genes and the class 1 integron to a recipient strain. Taken together, the results obtained in this study show a high percentage of resistance in and the presence of integrons in strains of S. enterica isolated from swine. This information should support the implementation of regulations for the prudent use of antimicrobial agents in food-producing animals.

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.


2000 ◽  
Vol 44 (6) ◽  
pp. 1568-1574 ◽  
Author(s):  
Didier Mazel ◽  
Broderick Dychinco ◽  
Vera A. Webb ◽  
Julian Davies

ABSTRACT The 72 Escherichia coli strains of the ECOR collection were examined for resistance to 10 different antimicrobial agents including ampicillin, tetracycline, mercury, trimethoprim, and sulfonamides. Eighteen strains were resistant to at least one of the antibiotics tested, and nearly 20% (14 of 72) were resistant to two or more. Several of the resistance determinants were shown to be carried on conjugative elements. The collection was screened for the presence of the three classes of integrons and for the sul1 gene, which is generally associated with class 1 integrons. The four strains found to carry a class 1 integron also had Tn21-encoded mercury resistance. One of the integrons encoded a novel streptomycin resistance gene, aadA7, with an attC site (or 59-base element) nearly identical to the attC site associated with the qacF gene cassette found in In40 (M.-C. Ploy, P. Courvalin, and T. Lambert, Antimicrob. Agents Chemother. 42:2557–2563, 1998). The conservation of associated attCsites among unrelated resistance cassettes is similar to arrangements found in the Vibrio cholerae superintegrons (D. Mazel, B. Dychinco, V. A. Webb, and J. Davies, Science 280:605–608, 1998) and supports the hypothesis that resistance cassettes are picked up from superintegron pools and independently assembled from unrelated genes and related attC sites.


2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
King-Ting Lim ◽  
Rohani Yasin ◽  
Chew-Chieng Yeo ◽  
Savithri Puthucheary ◽  
Kwai-Lin Thong

The emergence ofEscherichia colithat produce extended spectrumβ-lactamases (ESBLs) and are multidrug resistant (MDR) poses antibiotic management problems. Forty-sevenE. coliisolates from various public hospitals in Malaysia were studied. All isolates were sensitive to imipenem whereas 36 were MDR (resistant to 2 or more classes of antibiotics). PCR detection using gene-specific primers showed that 87.5% of the ESBL-producingE. coliharbored theblaTEMgene. Other ESBL-encoding genes detected wereblaOXA,blaSHV, andblaCTX-M. Integron-encoded integrases were detected in 55.3% of isolates, with class 1 integron-encodedintI1integrase being the majority. Amplification and sequence analysis of the5′CS region of the integrons showed known antibiotic resistance-encoding gene cassettes of various sizes that were inserted within the respective integrons. Conjugation and transformation experiments indicated that some of the antibiotic resistance genes were likely plasmid-encoded and transmissible. All 47 isolates were subtyped by PFGE and PCR-based fingerprinting using random amplified polymorphic DNA (RAPD), repetitive extragenic palindromes (REPs), and enterobacterial repetitive intergenic consensus (ERIC). These isolates were very diverse and heterogeneous. PFGE, ERIC, and REP-PCR methods were more discriminative than RAPD in subtyping theE. coliisolates.


2020 ◽  
Vol 20 (2) ◽  
pp. 160-166
Author(s):  
Seyedeh Hanieh Eshaghi Zadeh ◽  
Hossein Fahimi ◽  
Fatemeh Fardsanei ◽  
Mohammad Mehdi Soltan Dallal

Background: Salmonellosis is a major food-borne disease worldwide. The increasing prevalence of antimicrobial resistance among food-borne pathogens such as Salmonella spp. is concerning. Objective: The main objective of this study is to identify class 1 integron genes and to determine antibiotic resistance patterns among Salmonella isolates from children with diarrhea. Methods: A total of 30 Salmonella isolates were recovered from children with diarrhea. The isolates were characterized for antimicrobial susceptibility and screened for the presence of class 1 integron genes (i.e. intI1, sulI1, and qacEΔ1). Results: The most prevalent serotype was Enteritidis 36.7%, followed by Paratyphi C (30%), and Typhimurium (16.7%). The highest rates of antibiotic resistance were obtained for nalidixic acid (53.3%), followed by streptomycin (40%), and tetracycline (36.7%). Regarding class 1 integrons, 36.7%, 26.7%, and 33.3% of the isolates carried intI1, SulI, and qacEΔ1, respectively, most of which (81.8%) were multidrug-resistant (MDR). Statistical analysis revealed that the presence of class 1 integron was significantly associated with resistance to streptomycin and tetracycline (p = 0.042). However, there was no association between class 1 integron and other antibiotics used in this study (p > 0.05). Conclusion: The high frequency of integron class 1 gene in MDR Salmonella strains indicates that these mobile genetic elements are versatile among different Salmonella serotypes, and associated with reduced susceptibility to many antimicrobials.


2007 ◽  
Vol 73 (20) ◽  
pp. 6566-6576 ◽  
Author(s):  
Moussa S. Diarra ◽  
Fred G. Silversides ◽  
Fatoumata Diarrassouba ◽  
Jane Pritchard ◽  
Luke Masson ◽  
...  

ABSTRACT The effects of feed supplementation with the approved antimicrobial agents bambermycin, penicillin, salinomycin, and bacitracin or a combination of salinomycin plus bacitracin were evaluated for the incidence and distribution of antibiotic resistance in 197 commensal Escherichia coli isolates from broiler chickens over 35 days. All isolates showed some degree of multiple antibiotic resistance. Resistance to tetracycline (68.5%), amoxicillin (61.4%), ceftiofur (51.3%), spectinomycin (47.2%), and sulfonamides (42%) was most frequent. The levels of resistance to streptomycin, chloramphenicol, and gentamicin were 33.5, 35.5, and 25.3%, respectively. The overall resistance levels decreased from day 7 to day 35 (P < 0.001). Comparing treatments, the levels of resistance to ceftiofur, spectinomycin, and gentamicin (except for resistance to bacitracin treatment) were significantly higher in isolates from chickens receiving feed supplemented with salinomycin than from the other feeds (P < 0.001). Using a DNA microarray analysis capable of detecting commonly found antimicrobial resistance genes, we characterized 104 tetracycline-resistant E. coli isolates from 7- to 28-day-old chickens fed different growth promoters. Results showed a decrease in the incidence of isolates harboring tet(B), bla TEM, sulI, and aadA and class 1 integron from days 7 to 35 (P < 0.01). Of the 84 tetracycline-ceftiofur-resistant E. coli isolates, 76 (90.5%) were positive for bla CMY-2. The proportions of isolates positive for sulI, aadA, and integron class 1 were significantly higher in salinomycin-treated chickens than in the control or other treatment groups (P < 0.05). These data demonstrate that multiantibiotic-resistant E. coli isolates can be found in broiler chickens regardless of the antimicrobial growth promoters used. However, the phenotype and the distribution of resistance determinants in E. coli can be modulated by feed supplementation with some of the antimicrobial agents used in broiler chicken production.


2017 ◽  
Vol 62 (No. 3) ◽  
pp. 169-177 ◽  
Author(s):  
TH Chung ◽  
SW Yi ◽  
BS Kim ◽  
WI Kim ◽  
GW Shin

The present study sought to identify pathogens associated with septicaemia in the Chinese soft-shelled turtle (Pelodiscus sinensis) and to characterise antibiotic resistance in these pathogens. Twenty-three isolates recovered from the livers of diseased soft-shelled turtles were genetically identified as Aeromonas hydrophila (n = 8), A. veronii (n = 3), Citrobacter freundii (n = 4), Morganella morganii (n = 3), Edwardsiella tarda (n = 2), Wohlfahrtiimonas chitiniclastica (n = 1), Chryseobacterium sp. (n = 1), and Comamonas sp. (n = 1). Most isolates (n = 21) were resistant to ampicillin whereas a low percentage of isolates was susceptible to aminoglycosides (amikacin, gentamicin, and tobramycin). PCR assays and sequence analysis revealed the presence of the qnrS2 and bla<sub>TEM</sub> antibiotic resistance genes in all isolates. The bla<sub>DHA-1</sub>, bla<sub>CTX-M-14</sub> and bla<sub>CMY-2</sub> genes were harboured by 17.4% (n = 4), 13.5% (n = 3) and 8.7% (n = 2) of the strains, respectively. One or more tetracycline resistance genes were detected in 60.9% (n = 14) of the isolates. Four isolates (17.4%) harboured single or multiple class 1 integron cassettes. Collectively, a variety of bacterial pathogens were involved in the occurrence of septicaemia in Chinese soft-shelled turtles and most of the isolates had multi-antibiotic resistant phenotypes. To our knowledge, the present report is the first to identify W. chitiniclastica and Comamonas sp. as causes of septicaemia in soft-shelled turtles and the first to identify Aeromonas spp. with bla<sub>CTX-M-14</sub> and bla<sub>DHA-1</sub> resistance genes.


1999 ◽  
Vol 43 (12) ◽  
pp. 2925-2929 ◽  
Author(s):  
Lydia Bass ◽  
Cynthia A. Liebert ◽  
Margie D. Lee ◽  
Anne O. Summers ◽  
David G. White ◽  
...  

ABSTRACT Antibiotic resistance among avian bacterial isolates is common and is of great concern to the poultry industry. Approximately 36% (n = 100) of avian, pathogenic Escherichia coli isolates obtained from diseased poultry exhibited multiple-antibiotic resistance to tetracycline, oxytetracycline, streptomycin, sulfonamides, and gentamicin. Clinical avian E. coli isolates were further screened for the presence of markers for class 1 integrons, the integron recombinase intI1 and the quaternary ammonium resistance gene qacEΔ1, in order to determine the contribution of integrons to the observed multiple-antibiotic resistance phenotypes. Sixty-three percent of the clinical isolates were positive for the class 1 integron markersintI1 and qacEΔ1. PCR analysis with the conserved class 1 integron primers yielded amplicons of approximately 1 kb from E. coli isolates positive for intI1 andqacEΔ1. These PCR amplicons contained the spectinomycin-streptomycin resistance gene aadA1. Further characterization of the identified integrons revealed that many were part of the transposon Tn21, a genetic element that encodes both antibiotic resistance and heavy-metal resistance to mercuric compounds. Fifty percent of the clinical isolates positive for the integron marker gene intI1 as well as for theqacEΔ1 and aadA1 cassettes also contained the mercury reductase gene merA. The correlation between the presence of the merA gene with that of the integrase and antibiotic resistance genes suggests that these integrons are located in Tn21. The presence of these elements among avianE. coli isolates of diverse genetic makeup as well as inSalmonella suggests the mobility of Tn21 among pathogens in humans as well as poultry.


2020 ◽  
Vol 28 (2) ◽  
pp. 81
Author(s):  
Raouia Ben Rhouma ◽  
Ahlem Jouini ◽  
Amira Klibi ◽  
Safa Hamrouni ◽  
Aziza Boubaker ◽  
...  

The purpose of this study was to identify <em>Escherichia coli</em> isolates in diarrhoeic and healthy rabbits in Tunisia and characterise their virulence and antibiotic resistance genes. In the 2014-2015 period, 60 faecal samples from diarrhoeic and healthy rabbits were collected from different breeding farms in Tunisia. Susceptibility to 14 antimicrobial agents was tested by disc diffusion method and the mechanisms of gene resistance were evaluated using polymerase chain reaction and sequencing methods. Forty <em>E. coli</em> isolates were recovered in selective media. High frequency of resistance to tetracycline (95%) was detected, followed by different levels of resistance to sulphonamide (72.5%), streptomycin (62.5%), trimethoprim-sulfamethoxazole (60%), nalidixic acid (32.5%), ampicillin (37.5%) and ticarcillin (35%). <em>E. coli</em> strains were susceptible to cefotaxime, ceftazidime and imipenem. Different variants of bla<sub>TEM</sub>, <em>tet</em>, <em>sul</em> genes were detected in most of the strains resistant to ampicillin, tetracycline and sulphonamide, respectively. The presence of class 1 integron was studied in 29 sulphonamide-resistant <em>E. coli</em> strains from which 15 harboured class 1 integron with four different arrangements of gene cassettes, <em>dfrA17</em>+<em>aadA5</em> (n=9), <em>dfrA1</em> + <em>aadA1</em> (n=4), <em>dfrA12</em> + <em>addA2</em> (n=1), <em>dfrA12</em>+<em>orf</em>+<em>addA2</em> (n=1). The <em>qnrB</em> gene was detected in six strains out of 13 quinolone-resistant <em>E. coli</em> strains. Seventeen <em>E. coli</em> isolates from diarrhoeic rabbits harboured the enteropathogenic eae genes associated with different virulence genes tested (<em>fimA</em>, <em>cnf1</em>, <em>aer</em>), and affiliated to B2 (n=8) and D (n=9) phylogroups. Isolated <em>E. coli</em> strains from healthy rabbit were harbouring <em>fim A</em> and/or <em>cnf1</em> genes and affiliated to A and B1 phylogroups. This study showed that <em>E. coli</em> strains from the intestinal tract of rabbits are resistant to the widely prescribed antibiotics in medicine. Therefore, they constitute a reservoir of antimicrobial-resistant genes, which may play a significant role in the spread of antimicrobial resistance. In addition, the eae virulence gene seemed to be implicated in diarrhoea in breeder rabbits in Tunisia.


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 &gt; 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.


Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 450 ◽  
Author(s):  
Ocean Thakali ◽  
Sarmila Tandukar ◽  
John Brooks ◽  
Samendra Sherchan ◽  
Jeevan Sherchand ◽  
...  

Urban rivers affected by anthropogenic activities can act as reservoirs of antibiotic resistance genes (ARGs). This study aimed to describe the occurrence of selected ARGs (blaTEM, ermF, mecA, and tetA) and a class 1 integron (intI1) in an urban river in Nepal. A total of 18 water samples were collected periodically from upstream, midstream, and downstream sites along the Bagmati River over a 1-year period. All ARGs except mecA and intI1 were consistently detected by a quantitative polymerase chain reaction in the midstream and downstream sites, with concentrations ranging from 3.1 to 7.8 log copies/mL. ARG abundance was significantly lower at the upstream site (p < 0.05), reflecting the impact of anthropogenic activities on increasing concentrations of ARGs at midstream and downstream sites. Our findings demonstrate the presence of clinically relevant ARGs in the urban river water of Nepal, suggesting a need for mitigating strategies to prevent the spread of antibiotic resistance in the environment.


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