title: Molecular diversity of class 2 integrons in antibiotic-resistant gram-negative bacteria found in wastewater environments in China.
abstract: The molecular architecture of class 2 integrons among gram-negative bacteria from wastewater environments was investigated in Jinan, China. Out of the 391 antibiotic-resistant bacteria found, 38 isolates harboring class 2 integrons encoding potentially transferrable genes that could confer antibiotic resistance were found. These isolates were classified into 19 REP-PCR types. These strains were identified using 16S rRNA gene sequencing and found to be as follows: Proteus mirabilis (16), Escherichia coli (7), Providencia spp. (7), Proteus spp. (2), P. vulgaris (3), Shigella sp. (1), Citrobacter freundii (1), and Acinetobacter sp. (1). Their class 2 integron cassette arrays were amplified and then either analyzed using PCR-RFLP or sequenced. The typical array dfrA1-sat2-aadA1 was detected in 27 isolates. Six atypical arrays were observed, including three kinds of novel arrangements (linF2(∆attC1)-dfrA1(∆attC2)-aadA1-orf441 or linF2(∆attC1)-dfrA1(∆attC2)-aadA1, dfrA1-catB2-sat2-aadA1, and estX(Vr)-sat2-aadA1) and a hybrid with the 3'CS of class 1 integrons (dfrA1-sat2-aadA1-qacH), and dfrA1-sat1. Twenty-four isolates were also found to carry class 1 integrons with 10 types of gene cassette arrays. Several non-integron-associated antibiotic resistance genes were found, and their transferability was investigated. Results showed that water sources in the Jinan region harbored a diverse community of both typical and atypical class 2 integrons, raising concerns about the overuse of antibiotics and their careless disposal into the environment.
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Ruirui
authors.initials: R
authors.lastname: Xia
authors.forename: Ye
authors.initials: Y
authors.lastname: Ren
authors.forename: Xianhu
authors.initials: X
authors.lastname: Guo
authors.forename: Hai
authors.initials: H
authors.lastname: Xu
mesh_terms: D000900:Anti-Bacterial Agents / Q000633:toxicity*; D002681:China; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D014644:Genetic Variation; D006090:Gram-Negative Bacteria / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000254:growth & development; D032023:Integrons; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D021521:Ribotyping; D017422:Sequence Analysis, DNA; D062065:Wastewater / Q000382:microbiology*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000900:Anti-Bacterial Agents; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D062065:Wastewater; D014874:Water Pollutants, Chemical