First Report of the Multiresistance Gene cfr in Streptococcus suis

Abstract

The multiresistance gene cfr was identified for the first time in streptococci, namely, in porcine Streptococcus suis isolate S10. The cfr gene was detected on the ϳ100-kb plasmid pStrcfr, where it was bracketed by two copies of the novel insertion sequence ISEnfa5, located in the same orientation. The detection of a cfr-and ISEnfa5-containing amplicon by inverse PCR suggests that ISEnfa5 may play a role in the dissemination of cfr.T he cfr gene, encoding a 23S rRNA methyltransferase, confers resistance to five chemically unrelated antimicrobial classes, including phenicols, lincosamides, oxazolidinones, pleuromutilins, and streptogramin A (1), as well as decreased susceptibility to the 16-membered macrolides spiramycin and josamycin (2). Since its first identification in a Staphylococcus sciuri isolate of bovine origin (3), this multiresistance gene has been detected in isolates of the genera Staphylococcus, Bacillus, Enterococcus, Macrococcus, Jeotgalicoccus, Proteus, and Escherichia (4). Although florfenicol and lincosamides are used for the control of Streptococcus suis infections, the gene cfr has not yet been reported in streptococci. In a routine surveillance study of antimicrobial resistance of bacteria from farm animals in 2012, a hemolytic, florfenicolresistant (MIC Ն 16 g/ml) streptococcal isolate, S10, was obtained from the nasal swab of an apparently healthy pig at a conventional farm in the Beijing, China, area. Gram staining, colony morphology, and ATB Rapid ID 32 Strep analysis (bioMérieux, Craponne, France) identified isolate S10 as Streptococcus suis. Moreover, 16S rRNA gene sequences, obtained using both universal prokaryotic primers (3) and S. suis-specific primers (5), showed 100% identity to the 16S rRNA gene sequence of S. suis strain NYFC (GenBank accession no. FJ660465.1).S. suis is a global pathogen that causes a wide variety of diseases in swine, such as meningitis, pneumonia, endocarditis, septicemia, and arthritis (6). Of the 35 official serotypes described to date for S. suis, S. suis serotype 2 (SS2) is the most virulent and frequently isolated from diseased animals (7). A PCR assay (5) to detect virulence genes in SS2 isolates, including capsular polysaccharide (cps2J), muramidase-released protein (mrp), extracellular factor (ef), and suilysin (sly), yielded negative results for isolate S10. Rapid serotype-specific PCR screening to detect 15 serotypes of S. suis using previously described primers (8, 9) revealed that S. suis S10 does not belong to any of these serotypes.S. suis S10 was investigated for the presence of the genes cfr, fexA, and fexB, all of which confer florfenicol resistance in Grampositive bacteria, using previously described primers (3). Both cfr and fexA were detected in S. suis S10, and the nucleotide sequence of cfr in isolate S10 showed 100% identity to that of the cfr gene on plasmid pSCFS1 of S. sciuri (GenBank accession no. NC_005076). To the best of our knowledge, this is the first report of either the cfr or the fexA gene in a Streptococcus isolate. Isol...

Identification of the Novel Lincosamide Resistance Gene lnu (E) Truncated by ISEnfa5-cfr-IS Enfa5 Insertion in Streptococcus suis: De Novo Synthesis and Confirmation of Functional Activity in Staphylococcus aureus

“…Since this gene was nonfunctional in the original por- cine S. suis isolate due to the insertion of an ISEnfa5-cfr-ISEnfa5 segment, de novo synthesis was employed to confirm its functionality. Although we could not detect a naturally occurring, functionally active lnu(E) gene in our strain collections, it is nevertheless most likely that such a gene exists since its inactivated version was present on a naturally occurring S. suis plasmid (13). Routine surveillance for lnu(E) in bacteria of human and animal origin is warranted and might help to clarify whether S. suis is the original host, in which bacteria this gene is present, and how widespread it is.…”

“…In this plasmid, cfr was bracketed by two copies of insertion sequence ISEnfa5, located in the same orientation, and direct target site duplications of 3 bp (GAT) were found immediately upstream and downstream of this segment (13). Further analysis identified a 522-bp open reading frame into which this ISEnfa5-cfr-ISEnfa5 segment was inserted (Fig.…”

“…In a previous study, we identified the cfr-carrying plasmid pStrcfr, isolated from porcine Streptococcus suis S10 in Beijing, China (13). In this plasmid, cfr was bracketed by two copies of insertion sequence ISEnfa5, located in the same orientation, and direct target site duplications of 3 bp (GAT) were found immediately upstream and downstream of this segment (13).…”

The Plasmidome of Firmicutes: Impact on the Emergence and the Spread of Resistance to Antimicrobials

“…Streptococcus suis, a particularly virulent emerging zoonotic pathogen that remains an outlier to the mitis, sanguinis, and anginosus groups is known to carry plasmids, although they have been scarcely characterized (189,190). Relevant AbR genes coding for chloramphenicol (cfr and fexA) and lincosamides (lnu) embedded in composite regions similar to those present in plasmids of E. faecalis have been located in streptococcal plasmids of approximately 100 kb (191). Smaller plasmids carrying tetB associated with Gram-negative species have been described (192).…”

Mutations within the rplD Gene of Linezolid-Nonsusceptible Streptococcus pneumoniae Strains Isolated in the United States

“…This affects binding of linezolid to the 50S subunit (11,18,19). While carried by Staphylococcus aureus strains (20,21) and recently described in Streptococcus suis (22), this mobile element has not been described in S. pneumoniae.…”