title: Genetic analysis of Tn916-like elements conferring tetracycline resistance in clinical isolates of Clostridium difficile.
abstract: As an important clinically relevant pathogen, Clostridium difficile has a high multidrug resistance rate. Conjugative transposons play a vital role in its resistance phenotype. In the present study, 34 tetracycline-resistant clinical isolates of C. difficile were studied to detect tetracycline resistance genes and the presence of transposons. Thirty-two isolates were found to harbour Tn916-like elements carrying the tet(M) resistance gene, of which only one copy existed in the genome by Southern blot analysis. To characterise the genetic organisation of the Tn916-like elements, overlap PCR assays were performed with nine primer pairs, revealing three types of elements designated T1 to T3. The prevalent element T1 lacking PCRA (ORF23 to ORF21) and PCRB (ORF21 to ORF20) products, present in the epidemic ST37 clone, was further analysed by genome walking PCR in the left and right end sequences of the novel Tn916-like element. A gene coding for an FtsK/SpoIIIE family protein was found to replace the ORF24 to ORF21 region in Tn916. Moreover, the element could hardly conjugate between cells by filter mating experiments. These findings suggest that the dissemination of Tn916-like elements in epidemic ST37 strains in China was likely to have been conferred by clonal spread, signifying the importance of future surveillance and characterisation of conjugative transposons.
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197 Ruijin ER Road, Shanghai 200025, China.
authors.forename: Danfeng
authors.initials: D
authors.lastname: Dong
authors.affiliation: Department of Clinical Microbiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197 Ruijin ER Road, Shanghai 200025, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197 Ruijin ER Road, Shanghai 200025, China.
authors.forename: Cen
authors.initials: C
authors.lastname: Jiang
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197 Ruijin ER Road, Shanghai 200025, China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197 Ruijin ER Road, Shanghai 200025, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Cai
authors.affiliation: Department of Clinical Microbiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197 Ruijin ER Road, Shanghai 200025, China.
authors.forename: Lizhong
authors.initials: L
authors.lastname: Han
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197 Ruijin ER Road, Shanghai 200025, China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Emergency Intensive Care Unit, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197 Ruijin ER Road, Shanghai 200025, China.
authors.forename: Enqiang
authors.initials: E
authors.lastname: Mao
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197 Ruijin ER Road, Shanghai 200025, China. Electronic address: pyb9861@sohu.com.
authors.forename: Yibing
authors.initials: Y
authors.lastname: Peng
mesh_terms: D015139:Blotting, Southern; D002681:China / Q000453:epidemiology; D016360:Clostridioides difficile / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D003015:Clostridium Infections / Q000453:epidemiology / Q000382:microbiology; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D018628:Gene Dosage; D023061:Gene Order; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013753:Tetracycline Resistance
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial
keywords: Clostridium difficile; Tetracycline resistance; Tn916-like elements