Research

Genomic analysis of an emerging multiresistant Staphylococcus aureus strain rapidly spreading in cystic fibrosis patients revealed the presence of an antibiotic inducible bacteriophage

Jean-Marc Rolain¹ , Patrice François² , David Hernandez² , Fadi Bittar¹ , Hervé Richet¹ , Ghislain Fournous¹ , Yves Mattenberger² , Emmanuelle Bosdure³ , Nathalie Stremler³ , Jean-Christophe Dubus³ , Jacques Sarles³ , Martine Reynaud-Gaubert⁴ , Stephanie Boniface⁴ , Jacques Schrenzel² and Didier Raoult¹

¹  URMITE CNRS-IRD UMR 6236, Faculté de Médecine et de Pharmacie, Université de la Méditerranée, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 05, France

²  Geneva University Hospitals and University of Geneva, Central Lab of Bacteriology, and Genomic Research Lab, 24 rue Micheli-du-Crest, CH-1211 Geneva 14, Switzerland

³  Département des Maladies Respiratoires, Centre de Ressources et de Compétences pour la Mucoviscidose Enfants (CRCM), Hôpital Timone, Marseille, France

⁴  Département des Maladies Respiratoires, Centre de Ressources et de Compétences pour la Mucoviscidose Adultes (CRCM), Hôpital Sainte Marguerite, Marseille, France

author email corresponding author email

Biology Direct 2009, 4:1doi:10.1186/1745-6150-4-1

Published:	13 January 2009

Abstract

Background

Staphylococcus 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.

Results

CF-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.

Conclusion

In 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.

Reviewers

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