Identification and characterization of class 1 integron resistance gene cassettes among Salmonella strains isolated from healthy humans in China

Hongmei Zhang, Lei Shi, Lin Li, Siyuan Guo, Ximei Zhang, Shinji Yamasaki, Shin Ichi Miyoshi, Sumio Shinoda

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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.

Original languageEnglish
Pages (from-to)639-645
Number of pages7
Issue number9
Publication statusPublished - Jan 1 2004



  • Antibiotic resistance gene cassette
  • Integron

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Virology

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