Transferable multiresistance plasmids carrying cfr in Enterococcus spp. from swine and farm environment.
Seventy-seven porcine Enterococcus isolates with florfenicol MICs of ≥16 μg of were/ml screened for the presence of the multiresistance gene cfr, its location on plasmids, and its genetic environment. Three isolates-Enterococcus thailandicus 3-38 (from a porcine rectal swab collected at a pig farm), Enterococcus thailandicus W3, and Enterococcus faecalis W9-2 (the latter two from sewage at a different farm), carried the cfr gene. The SmaI pulsed-field gel electrophoresis patterns of the three isolates differed distinctly. In addition, E. faecalis W9-2 was assigned to a new multilocus sequence type ST469. Mating experiments and Southern blot analysis indicated that cfr is located on conjugative plasmids pW3 (∼75 kb) from E. thailandicus W3, p3-38 (∼72 kb) from E. thailandicus 3-38, and pW9-2 (∼55 kb) from E. faecalis W9-2; these plasmids differed in their sizes, additional resistance genes, and the analysis of the segments encompassing the cfr gene. Sequence analysis revealed that all plasmids harbored a 4,447-bp central region, in which cfr was bracketed by two copies of the novel insertion sequence ISEnfa4 located in the same orientation. The sequences flanking the central regions of these plasmids, including the partial tra gene regions and a ω-ε-ζ toxin-antitoxin module, exhibited >95% nucleotide sequence identity to the conjugative plasmid pAMβ1 from E. faecalis. Conjugative plasmids carrying cfr appear to play an important role in the dissemination and maintenance of the multiresistance gene cfr among enterococcal isolates and possibly other species of Gram-positive bacteria.
Key Laboratory of Development and Evaluation of Chemical and Herbal Drugs for Animal Use, College of Veterinary Medicine, China Agricultural University, Beijing, People's Republic of China.
Yang
Y
Liu
Yang
Y
Wang
Stefan
S
Schwarz
Yun
Y
Li
Zhangqi
Z
Shen
Qijing
Q
Zhang
Congming
C
Wu
Jianzhong
J
Shen
D000818:Animals; D000829:Animals, Domestic; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D001426:Bacterial Proteins / Q000235:genetics*; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016983:Enterococcus / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D008780:Methyltransferases / Q000235:genetics; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D010957:Plasmids; D017422:Sequence Analysis, DNA; D013552:Swine; D013553:Swine Diseases / Q000188:drug therapy / Q000382:microbiology*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D008780:Methyltransferases