Genomic analysis of an emerging multiresistant Staphylococcus aureusstrain rapidly spreading in cystic fibrosis patients revealed the presence of an antibiotic inducible bacteriophageReportar como inadecuado

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Biology Direct

, 4:1

First Online: 13 January 2009Received: 08 January 2009Accepted: 13 January 2009


BackgroundStaphylococcus aureus is a major human pathogen responsible for a variety of nosocomial and community-acquired infections. Recent reports show that the prevalence of Methicillin-Resistant S. aureus MRSA infections in cystic fibrosis CF patients is increasing. In 2006 in Marseille, France, we have detected an atypical MRSA strain with a specific antibiotic susceptibility profile and a unique growth phenotype. Because of the clinical importance of the spread of such strain among CF patients we decided to sequence the genome of one representative isolate strain CF-Marseille to compare this to the published genome sequences. We also conducted a retrospective epidemiological analysis on all S. aureus isolated from 2002 to 2007 in CF patients from our institution.

ResultsCF-Marseille is multidrug resistant, has a hetero-Glycopeptide-Intermediate resistance S. aureus phenotype, grows on Cepacia agar with intense orange pigmentation and has a thickened cell wall. Phylogenetic analyses using Complete Genome Hybridization and Multi Locus VNTR Assay showed that CF-Marseille was closely related to strain Mu50, representing vancomycin-resistant S. aureus. Analysis of CF-Marseille shows a similar core genome to that of previously sequenced MRSA strains but with a different genomic organization due to the presence of specific mobile genetic elements i.e. a new SCCmec type IV mosaic cassette that has integrated the pUB110 plasmid, and a new phage closely related to phiETA3. Moreover this phage could be seen by electron microscopy when mobilized with several antibiotics commonly used in CF patients including, tobramycin, ciprofloxacin, cotrimoxazole, or imipenem. Phylogenetic analysis of phenotypically similar h-GISA in our study also suggests that CF patients are colonized by polyclonal populations of MRSA that represents an incredible reservoir for lateral gene transfer.

ConclusionIn conclusion, we demonstrated the emergence and spreading of a new isolate of MRSA in CF patients in Marseille, France, that has probably been selected in the airways by antibiotic pressure. Antibiotic-mediated phage induction may result in high-frequency transfer and the unintended consequence of promoting the spread of virulence and-or antibiotic resistance determinants. The emergence of well-adapted MRSA is worrying in such population chronically colonized and receiving many antibiotics and represents a model for emergence of uncontrollable super bugs in a specific niche.

ReviewersThis article was reviewed by Eric Bapteste, Pierre Pontarotti, and Igor Zhulin. For the full reviews, please go to the Reviewers- comments section.

AbbreviationsCA-MRSACommunity-Acquired Methicillin-Resistant Staphylococcus aureus

CDSCoDing Sequence

CFCystic Fibrosis

CGHComplete Genome Hybridization

GISAGlycopeptide-Intermediate Staphylococcus aureus

ORFOpen Reading Frame

GS-MRSAGentamicin Susceptible Methicillin-Resistant Staphylococcus aureus

MLSTMulti Locus Sequence Typing

MLVAMulti Locus VNTR Assay

MRSAMethicillin-Resistant Staphylococcus aureus

PVLPanton Valentine Leukocidin

MSSAMethicillin-Susceptible Staphylococcus aureus

TSSTToxic Shock Syndrome Toxin

SCCmecStaphylococcal Chromosomal Cassette mec

VSSAVancomycin-Susceptible Staphylococcus aureus.

Electronic supplementary materialThe online version of this article doi:10.1186-1745-6150-4-1 contains supplementary material, which is available to authorized users.

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Autor: Jean-Marc Rolain - Patrice François - David Hernandez - Fadi Bittar - Hervé Richet - Ghislain Fournous - Yves Mattenberge


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