In order to investigate the prevalence of fosfomycin-resistance (fos) determinants in Enterococcus faecium, clinical strains were collected from hospitals throughout China between January 2008 and December 2009. Antimicrobial susceptibility testing was performed, after which the fos genes in all isolates and van genes in vancomycin-resistant isolates were characterized by PCR and sequencing. Conjugation experiments were carried out with fosB-positive E. faecium, DNA fragments flanking the fosB3 gene were sequenced and the genetic environment of fosB3 was analysed. Fosfomycin-resistant E. faecium (FREF) strains were characterized further by multilocus sequence typing (MLST) and PFGE. Among 145 E. faecium clinical isolates, 10 were resistant to fosfomycin with MICs >1024 mg l−1 including six vancomycin-resistant strains of which five were vanA-positive and the sixth vanM-positive. All ten FREF strains harboured the fosB3 gene. Fosfomycin resistance and fosB3 could be transferred by conjugation from nine isolates. The fosB3 and tnpA genes were located in a circular DNA intermediate in all FREF strains and reversely inserted into vanA transposon Tn1546 in four vanA-positive FREF isolates. Ten different PFGE types and seven MLST types were found among the ten fosB3-positive isolates, while all strains belonged to the common clonal complex CC17. In conclusion, the transferable fosfomycin-resistance determinant fosB3 plays an important role in E. faecium resistance to fosfomycin in China.
BarbierN., SaulnierP., ChachatyE., DumontierS., AndremontA.1996; Random amplified polymorphic DNA typing versus pulsed-field gel electrophoresis for epidemiological typing of vancomycin-resistant enterococci. J Clin Microbiol 34:1096–1099[PubMed]
ButcuM., AkcayS. S., AksarayS., CalisiciG., InanA. S., EnginD. O.2011; In vitro susceptibility of enterococci strains isolated from urine samples to fosfomycin and other antibiotics. J Infect Chemother 17:575–578 [View Article][PubMed]
CaoM., BernatB. A., WangZ., ArmstrongR. N., HelmannJ. D.2001; FosB, a cysteine-dependent fosfomycin resistance protein under the control of sigma(W), an extracytoplasmic-function sigma factor in Bacillus subtilis.. J Bacteriol 183:2380–2383 [View Article][PubMed]
CarriçoJ. A., PintoF. R., SimasC., NunesS., SousaN. G., FrazãoN., de LencastreH., AlmeidaJ. S.2005; Assessment of band-based similarity coefficients for automatic type and subtype classification of microbial isolates analyzed by pulsed-field gel electrophoresis. J Clin Microbiol 43:5483–5490 [View Article][PubMed]
d’AzevedoP. A., DiasC. A., TeixeiraL. M.2006; Genetic diversity and antimicrobial resistance of enterococcal isolates from Southern region of Brazil. Rev Inst Med Trop Sao Paulo 48:11–16 [View Article][PubMed]
FrankeA. E., ClewellD. B.1981; Evidence for a chromosome-borne resistance transposon (Tn916) in Streptococcus faecalis that is capable of “conjugal” transfer in the absence of a conjugative plasmid. J Bacteriol 145:494–502[PubMed]
KahanF. M., KahanJ. S., CassidyP. J., KroppH.1974; The mechanism of action of fosfomycin (phosphonomycin). Ann N Y Acad Sci 235:364–386 [View Article][PubMed]
LamersA. P., KeithlyM. E., KimK., CookP. D., StecD. F., HinesK. M., SulikowskiG. A., ArmstrongR. N.2012; Synthesis of bacillithiol and the catalytic selectivity of FosB-type fosfomycin resistance proteins. Org Lett 14:5207–5209 [View Article][PubMed]
RigsbyR. E., FillgroveK. L., BeihofferL. A., ArmstrongR. N.2005; Fosfomycin resistance proteins: a nexus of glutathione transferases and epoxide hydrolases in a metalloenzyme superfamily. Methods Enzymol 401:367–379 [View Article][PubMed]
SahniR. D., BalajiV., VargheseR., JohnJ., TansarliG. S., FalagasM. E.2013; Evaluation of fosfomycin activity against uropathogens in a fosfomycin-naive population in South India: a prospective study. Future Microbiol 8:675–680 [View Article][PubMed]
WangF., ZhuD., HuF., RuanF., NiY., SunJ., XuY., SunH., HuY.other authors2008; CHINET 2007 surveillance of bacterial resistance in China. Chinese Journal of Infection and Chemotherapy 8:325–332 (in Chinese)
WillemsR. J., TopJ., van SantenM., RobinsonD. A., CoqueT. M., BaqueroF., GrundmannH., BontenM. J.2005; Global spread of vancomycin-resistant Enterococcus faecium from distinct nosocomial genetic complex. Emerg Infect Dis 11:821–828 [View Article][PubMed]
XuX., ChenC., LinD., GuoQ., HuF., ZhuD., LiG., WangM.2013; The fosfomycin resistance gene fosB3 is located on a transferable, extrachromosomal circular intermediate in clinical Enterococcus faecium isolates. PLoS ONE 8:e78106 [View Article][PubMed]
ZilhaoR., CourvalinP.1990; Nucleotide sequence of the fosB gene conferring fosfomycin resistance in Staphylococcus epidermidis.. FEMS Microbiol Lett 56:267–272[PubMed]