Unique Class 1 Integron and Multiple Resistance Genes Co-located on IncHI2 Plasmid Is Associated with the Emerging Multidrug Resistance of Salmonella Indiana Isolated from Chicken in China (original) (raw)
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Microbial Drug Resistance, 2014
A total of 70 multidrug-resistant (MDR) Salmonella isolates (44 human and 26 poultry) were examined. The conserved segment-PCR, restriction fragment length polymorphism-PCR analysis, and DNA sequencing were used to determine the presence and cassette content of integrons. The genetic relatedness among the isolates was examined by pulsed-field gel electrophoresis (PFGE). The rate of integron carriage for MDR Salmonella isolates was 91.4% and integron-positive isolates belonged to six distinct serovars. Out of 64 integron-positive isolates, only four Salmonella Paratyphi C isolates could transfer integrons to Escherichia coli K12 by conjugation. Thirty-three PFGE types were detected in 52 integron-positive isolates, including 22, 4, 3, 2, 1, and 1 patterns among Salmonella serovars Enteritidis, Typhimurium, Paratyphi C, Paratyphi B, Paratyphi A, and Havana, respectively. The human and poultry Salmonella Enteritidis isolates from different regions with identical integrons had closely related PFGE patterns. Of the four integron-positive Salmonella Typhimurium isolates, the two poultry isolates with identical integron had very closely related PFGE patterns whereas the two human isolates with different integrons showed unrelated PFGE patterns. PFGE showed undistinguishable patterns in Salmonella Paratyphi C isolates with identical cassettes but revealed relatively unrelated patterns in those with different cassettes. Relatively unrelated and identical PFGE patterns were found in two Salmonella Paratyphi B and three Salmonella Paratyphi A isolates with the same integrons, respectively. In conclusion, PFGE patterns demonstrated more genetic relatedness among each Salmonella serovar with identical class 1 integrons than the same serovar with different class 1 integrons.
Antimicrobial agents and chemotherapy, 1998
The presence and genetic content of integrons were investigated for 37 epidemiologically unrelated multiple-drug-resistant strains of Salmonella enterica serotype Typhimurium from humans. All isolates were resistant to ampicillin, chloramphenicol, kanamycin, streptomycin, sulfonamides, and trimethoprim, as well as to tetracycline and/or nalidixic acid; 20% of them were also resistant to gentamicin and amikacin. Three different class 1 integrons (In-t1, In-t2, and In-t3) were identified by Southern blot hybridization, PCR, and DNA sequencing, and these integrons were found to carry the aadB, catB3, oxa1, aadA1a, aacA4, and aacC1 gene cassettes. Integrons In-t1 (aadB and catB3) and In-t2 (oxa1 and aadA1a) were both located on a conjugative IncFI plasmid of 140 kb. In-t3 (aacA4, aacC1, and aadAIa) was located on an IncL/M plasmid of 100 kb which was present, in association with the IncFI plasmid, in gentamicin- and amikacin-resistant isolates. Despite the extensive similarity at the le...
Veterinary World, 2019
Aim: The present study was conducted with the following aims: (i) To screen the Salmonella spp. isolates recovered from suspected cases of fowl typhoid for carriage of Class 1 integrons and analyze their association with antimicrobial resistance and (ii) to carry out molecular characterization and phylogenetic analysis of Class 1 integron-integrase (intI1) gene. Materials and Methods: A total of 43 Salmonella isolates were subjected to polymerase chain reaction (PCR) assay to determine the presence of Class1 intI1. Differences between different serotypes in relation to their carriage of integrons and the differences between strains containing or not containing an integron and being resistant to different antimicrobials were analyzed by Fisher exact test using STATA™ (StataCorp, College Station, TX). Phylogenetic analysis was carried out using MEGA6 software. Results: Out of 43 isolates, 40 (93.02%) were found positive for Class 1 integrons. 35/40 (87.5%) intI1-positive isolates were multidrug resistance (MDR) (resistant to ≥4 antibiotics), which support the hypothesis of an association between the presence of Class 1 integrons and emerging MDR in Salmonella. There was no significant difference among isolates resistant to different antimicrobials in Class 1 integron carrying isolates and the Class 1 integron negative isolates (p<0.05). Further, there was no significant difference among different serotypes in respect of their carriage of Class 1 integrons. Conclusion: It can be concluded that the high prevalence of Class 1 integrons indicates a high potential of Salmonella isolates for horizontal transmission of antimicrobial genes, especially among Gram-negative organisms.
Applied and Environmental Microbiology, 2009
A total of 210 Salmonella isolates, representing 64 different serovars, were isolated from imported seafood samples, and 55/210 isolates were found to be resistant to at least one antibiotic. Class 1 integrons from three multidrug-resistant Salmonella enterica strains (Salmonella enterica serovars Newport [strain 62], Typhimurium var. Copenhagen [strain 629], and Lansing [strain 803], originating from Hong Kong, the Philippines, and Taiwan, respectively) were characterized. Southern hybridization of plasmids isolated from these strains, using a class 1 integron probe, showed that trimethoprim-sulfamethoxazole and streptomycin resistance genes were located on a megaplasmid in strain 629. Our study indicates that imported seafood could be a reservoir for Salmonella isolates resistant to multiple antibiotics.
Integron-Associated Antibiotic Resistance in Salmonella enterica Serovar Typhi from Asia
Antimicrobial Agents and Chemotherapy, 2003
Eighteen of 25 isolates of Salmonella enterica serovar Typhi were multidrug resistant and contained class 1 integrons with a single cassette, dfrVII or aadA1. The dfrVII-containing integron was likely borne on an IncHI1 plasmid. Salmonella serovar Typhi could become resistant to broad-spectrum cephalosporins by integrating cassettes, such as veb-1, a common cassette in Asia.
High prevalence of integron-mediated resistance in clinical isolates of Salmonella enterica
Japanese journal of infectious diseases, 2010
Salmonella enterica has become progressively resistant to antimicrobial agents worldwide as a result of genes carried on different classes of integrons. The aim of the current study was to investigate the molecular diversity of these integrons and their association with antimicrobial resistance in clinical S. enterica isolates from Tehran, Iran. Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute. The presence of integrons was investigated by PCR using specific primers. Integrons were detected in 65 (47.1%) strains, with classes 1 and 2 being observed in 54 (39%) and 11 (8%) strains, respectively. Integron-positive isolates belonged to seven different S. enterica serovars, and all showed a multidrug-resistant (MDR) phenotype. Our findings show that integrons are widely disseminated among S. enterica strains from Tehran. Furthermore, the results that class 1 integrons were more prevalent than class 2 in Salmonella isolates, ...
British Microbiology Research Journal, 2014
This study was carried out to detect the distribution of antibiotic-resistant genes in Escherichia coli isolates from slaughtered commercial chickens in Iran by PCR. The investigated genes included aadA1, tet(A), tet(B), dfrA1, qnrA, aac(3)-IV, sul1, bla SHV , bla CMY , ere(A), catA1 and cmlA. According to biochemical experiments, 57 isolates from 360 chicken meat samples were recognized as E. coli. The distribution of antibiotic-resistance genes in the E. coli isolates included tet(A) and tet(B) (52.63%), dfrA1, qnrA, catA1 and cmlA (36.84%) and sul1 and ere(A) (47.36%), respectively. Nine strains (15.78%) were resistant to a single antimicrobial agent and 11 strains (19.29%) showed resistance to two antimicrobial agents. Multi-resistance which was defined as resistance to three or more tested agents was found in 64.91% of E. coli strains. The results indicate that all isolates harbour one or more of antibiotic resistance genes and that the PCR technique is a fast, practical and appropriate method for determining the presence of antibiotic-resistance genes.
Antimicrobial Resistance and Spread of Class 1 Integrons among Salmonella Serotypes
Antimicrobial Agents and Chemotherapy, 2000
The resistance profiles, for 15 antimicrobial agents, of 333 Salmonella strains representing the most frequent nontyphoidal serotypes, isolated between 1989 and 1998 in a Spanish region, and 9 reference strains were analyzed. All strains were susceptible to amikacin, ceftazidime, ciprofloxacin, and imipenem, and 31% were susceptible to all antimicrobials tested. The most frequent types of resistance were to sulfadiazine, tetracycline, streptomycin, spectinomycin, ampicillin, and chloramphenicol (ranging from 46 to 22%); 13% were resistant to these six drugs. This multidrug resistance pattern was found alone or together with other resistance types within serotypes Typhimurium (45%), Panama (23%), and Virchow (4%). Each isolate was also screened for the presence of class 1 integrons and selected resistance genes therein; seven variable regions which carried one (aadA1a, aadA2, or pse-1) or two (dfrA14-aadA1a, dfrA1-aadA1a, oxa1-aadA1a, or sat1-aadA1a) resistance genes were found in integrons.