title: Identification and characterization of class 1 integron resistance gene cassettes among Salmonella strains isolated from healthy humans in China.
abstract: Twenty-three strains of Salmonella spp. isolated from healthy humans in Guangdong, China, were examined for their susceptibility to ten common antibiotics and the presence of antibiotic resistance integrons. All the strains were resistant to at least one antibiotic, and 4 strains were positive for the intI1 gene. Polymerase chain reaction using in-F and in-B primers showed the existence of amplicons of 1,009 bp in two, 1,664 bp in one, and 1,009 bp and 1,664 bp in one of the intI1 -positive isolates, respectively. Sequence analysis revealed that the 1,009-bp amplicon harbored gene cassette aadA2, conferring resistance to spectinomycin, and the 1,664-bp amplicon harbored genes aadA5 and dfr17, conferring resistance to spectinomycin, streptomycin and trimethoprim. Meanwhile the experiments of plasmid conjugation and Southern hybridization with intI1 as the DNA probe indicated that all the integrons found in these strains were chromosomal. Because the strains carrying class 1 integrons were isolated from healthy humans, it suggests the need for all-round surveillance of the antibiotic resistance of pathogens.
authors.affiliation: College of Food and Biological Engineering, South China University of Technology, Guangzhou 510640, China.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Zhang
authors.forename: Lei
authors.initials: L
authors.lastname: Shi
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.forename: Siyuan
authors.initials: S
authors.lastname: Guo
authors.forename: Ximei
authors.initials: X
authors.lastname: Zhang
authors.forename: Shinji
authors.initials: S
authors.lastname: Yamasaki
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Miyoshi
authors.forename: Sumio
authors.initials: S
authors.lastname: Shinoda
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002353:Carrier State / Q000382:microbiology*; D002681:China; D003227:Conjugation, Genetic; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D019426:Integrases / Q000235:genetics*; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids; D016133:Polymerase Chain Reaction; D012480:Salmonella Infections / Q000382:microbiology; D019779:Salmonella enterica / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D017422:Sequence Analysis, DNA
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D019426:Integrases; C115006:integron integrase IntI1