Publikationsdatenbank

A novel small tet(T)–tet(L)–aadD-carrying plasmid from MRSA and MSSA ST9 isolates of swine origin (2019)

Art

Zeitschriftenartikel / wissenschaftlicher Beitrag

Autoren

Jiang, Nansong

Li, Jun

Feßler, Andrea T (WE 7)

Wang, Yang

Schwarz, Stefan (WE 7)

Wu, Congming

Quelle

The journal of antimicrobial chemotherapy : JAC

Bandzählung: 74

Heftzählung: 8

Seiten: 2462 – 2464

ISSN: 0305-7453

Sprache

Englisch

Verweise

URL (Volltext): https://academic.oup.com/jac/article/74/8/2462/5485290

DOI: 10.1093/jac/dkz177

Pubmed: 31050760

Kontakt

Institut für Mikrobiologie und Tierseuchen

Robert-von-Ostertag-Str. 7-13
14163 Berlin
+49 30 838 51843 / 66949
mikrobiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Sir,

Staphylococcus aureus, especially methicillin-resistant isolates, are major pathogens of humans and animals.1 Plasmids play a key role in the dissemination of antimicrobial resistance genes within the gene pool to which staphylococci and other Firmicutes have access.2 Tetracycline is one of the most commonly used antimicrobial agents in veterinary medicine and food animal production. The tetracycline resistance gene tet(L) was often identified on plasmids of S. aureus, particularly among those of livestock-associated MRSA (LA-MRSA) of ST398.3 In contrast, the tetracycline resistance gene tet(T) has only been reported in a few streptococcal and enterococcal strains.4 As such, there are no available sequence data for staphylococcal tet(T) genes. The genes tet(L) and tet(T) code for proteins of 458 and 576 amino acids, respectively. Unlike tet(T), which encodes a ribosome-protecting protein,4,tet(L) encodes a membrane-associated efflux system that prevents tetracycline accumulation within the bacterial cell.4 In this study, we identified a novel small plasmid that harboured the resistance genes tet(T), tet(L) and aadD in single MRSA and MSSA isolates.

The MSSA isolate GD-G33 and the MRSA isolate GD-G38, both of which belong to ST9 and spa type t899, were obtained from nasal swabs of two healthy pigs from different swine farms in Guangdong province during our previous surveillance study.5 Genomic libraries of the two isolates were prepared and then sequenced as previously described.6 Draft assemblies of the sequences were generated using CLC Genomics Workbench 9 (CLC bio). Genomic analyses were conducted using PlasmidFinder (https://cge.cbs.dtu.dk/services/PlasmidFinder/), BLAST analysis (https://www.ncbi.nlm.nih.gov/BLAST/) and ORF Finder (https://www.ncbi.nlm.nih.gov/orffinder/). Each predicted ORF was subjected to BLAST analysis against the NCBI GenBank database. The results showed that both isolates contained a single novel tet(T)–tet(L)–aadD-carrying plasmid of 9274 bp, designated pG38.

Sequence analysis revealed that pG38 plasmids obtained from each of the two isolates were identical. This plasmid harboured seven ORFs, including three resistance genes, i.e. the kanamycin/neomycin resistance gene aadD and the two tetracycline resistance genes tet(T) and tet(L). A schematic representation of plasmid pG38 is shown in Figure 1. The initial 1956 bp ORF showed 100% nucleotide sequence identity to tet(T) from Streptococcus pyogenes strain A498.4 The 510 bp repU gene and an adjacent 5185 bp fragment of the pG38 sequence showed 99.9% identity to the corresponding regions of plasmid pSTE1. This 5185 bp fragment comprised the resistance gene tet(L), the gene pre/mob coding for a 436 amino acid plasmid recombination/mobilization protein and the gene rep coding for a 454 amino acid plasmid replication protein.