BACKGROUND: We used 2 in vitro experimental systems to compare phenotypic and genotypic changes that accompany selection of mutants of methicillin-resistant Staphylococcus aureus (MRSA) strain JH1 with low-level vancomycin resistance similar to the type found in vancomycin-intermediate S. aureus (VISA). METHODS: The previously described MRSA strain JH1 and its vancomycin-intermediate mutant derivative JH2, both of which were recovered from a patient undergoing vancomycin chemotherapy, were used in this study. Mutants of JH1 were selected in vitro by means of a pharmacokinetic/pharmacodynamic (PK/PD) model of simulated endocardial vegetations (SEVs) and by exposure to vancomycin in laboratory growth medium. Phenotypic abnormalities of JH1 mutants generated by each in vitro experimental system were compared to those of JH2, and whole genomes of 2 in vitro JH1 mutants were sequenced to identify mutations that may be associated with an increased vancomycin minimum inhibitory concentration. RESULTS: JH1R1 was selected from the PK/PD model, and JH1R2 was selected in laboratory growth medium. Both mutants displayed reduced vancomycin and daptomycin susceptibility and phenotypic alterations (eg, thicker cell walls and abnormal autolysis) that are typical of in vivo VISA mutants. Genome sequencing of JH1R1 identified point mutations in 4 genes, all of which were different from the mutations described in JH2, including 1 mutation in yycG, a component of the WalKR sensory regulatory system. Sequencing of the JH1R2 genome identified mutations in 7 genes, including 2 in rpoB. CONCLUSION: Our findings indicate that JH1 is able to develop VISA-type resistance through several alternative genetic pathways.
BACKGROUND: We used 2 in vitro experimental systems to compare phenotypic and genotypic changes that accompany selection of mutants of methicillin-resistant Staphylococcus aureus (MRSA) strain JH1 with low-level vancomycin resistance similar to the type found in vancomycin-intermediate S. aureus (VISA). METHODS: The previously described MRSA strain JH1 and its vancomycin-intermediate mutant derivative JH2, both of which were recovered from a patient undergoing vancomycin chemotherapy, were used in this study. Mutants of JH1 were selected in vitro by means of a pharmacokinetic/pharmacodynamic (PK/PD) model of simulated endocardial vegetations (SEVs) and by exposure to vancomycin in laboratory growth medium. Phenotypic abnormalities of JH1 mutants generated by each in vitro experimental system were compared to those of JH2, and whole genomes of 2 in vitro JH1 mutants were sequenced to identify mutations that may be associated with an increased vancomycin minimum inhibitory concentration. RESULTS: JH1R1 was selected from the PK/PD model, and JH1R2 was selected in laboratory growth medium. Both mutants displayed reduced vancomycin and daptomycin susceptibility and phenotypic alterations (eg, thicker cell walls and abnormal autolysis) that are typical of in vivo VISA mutants. Genome sequencing of JH1R1 identified point mutations in 4 genes, all of which were different from the mutations described in JH2, including 1 mutation in yycG, a component of the WalKR sensory regulatory system. Sequencing of the JH1R2 genome identified mutations in 7 genes, including 2 in rpoB. CONCLUSION: Our findings indicate that JH1 is able to develop VISA-type resistance through several alternative genetic pathways.
Authors: A S Bayer; L I Kupferwasser; M H Brown; R A Skurray; S Grkovic; T Jones; K Mukhopadhay; M R Yeaman Journal: Antimicrob Agents Chemother Date: 2006-07 Impact factor: 5.191
Authors: Benjamin P Howden; John K Davies; Paul D R Johnson; Timothy P Stinear; M Lindsay Grayson Journal: Clin Microbiol Rev Date: 2010-01 Impact factor: 26.132
Authors: Michael M Mwangi; Shang Wei Wu; Yanjiao Zhou; Krzysztof Sieradzki; Herminia de Lencastre; Paul Richardson; David Bruce; Edward Rubin; Eugene Myers; Eric D Siggia; Alexander Tomasz Journal: Proc Natl Acad Sci U S A Date: 2007-05-21 Impact factor: 11.205
Authors: Michael A Quail; Iwanka Kozarewa; Frances Smith; Aylwyn Scally; Philip J Stephens; Richard Durbin; Harold Swerdlow; Daniel J Turner Journal: Nat Methods Date: 2008-12 Impact factor: 28.547
Authors: Benjamin P Howden; Danielle J Smith; Ashley Mansell; Paul D R Johnson; Peter B Ward; Timothy P Stinear; John K Davies Journal: BMC Microbiol Date: 2008-02-27 Impact factor: 3.605
Authors: Justin R Lenhard; Tanya Brown; Michael J Rybak; Calvin J Meaney; Nicholas B Norgard; Zackery P Bulman; Daniel A Brazeau; Steven R Gill; Brian T Tsuji Journal: Antimicrob Agents Chemother Date: 2015-12-28 Impact factor: 5.191
Authors: Kristoffer T Bæk; Louise Thøgersen; René G Mogenssen; Maiken Mellergaard; Line E Thomsen; Andreas Petersen; Søren Skov; David R Cameron; Anton Y Peleg; Dorte Frees Journal: Antimicrob Agents Chemother Date: 2015-08-31 Impact factor: 5.191
Authors: N C Gordon; J R Price; K Cole; R Everitt; M Morgan; J Finney; A M Kearns; B Pichon; B Young; D J Wilson; M J Llewelyn; J Paul; T E A Peto; D W Crook; A S Walker; T Golubchik Journal: J Clin Microbiol Date: 2014-02-05 Impact factor: 5.948
Authors: Md Tauqeer Alam; Robert A Petit; Emily K Crispell; Timothy A Thornton; Karen N Conneely; Yunxuan Jiang; Sarah W Satola; Timothy D Read Journal: Genome Biol Evol Date: 2014-04-30 Impact factor: 3.416
Authors: Henrique Machado; Yara Seif; George Sakoulas; Connor A Olson; Ying Hefner; Amitesh Anand; Ying Z Jones; Richard Szubin; Bernhard O Palsson; Victor Nizet; Adam M Feist Journal: Commun Biol Date: 2021-06-25
Authors: Olivier Poupel; Mati Moyat; Julie Groizeleau; Luísa C S Antunes; Simonetta Gribaldo; Tarek Msadek; Sarah Dubrac Journal: PLoS One Date: 2016-03-21 Impact factor: 3.240