Long-lasting successful dissemination of resistance to oxazolidinones in MDR Staphylococcus epidermidis clinical isolates in a tertiary care hospital in France

Laurent Dortet (1, 2, 3, 4) , Philippe Glaser (3) , Najiby Kassis-Chikhani (5, 6, 7) , Delphine Girlich (3, 1, 8, 2) , Philippe Ichai (9) , Marc Boudon (9) , Didier Samuel (10, 11) , Elodie Creton (1, 8, 2, 3) , Dilek Imanci (12) , Rémy Bonnin (8, 1, 2, 3) , Nicolas Fortineau (1, 8, 2, 3, 4) , Thierry Naas (1, 8, 2, 3, 4)

1 Hôpital Bicêtre [AP-HP, Le Kremlin-Bicêtre]
2 CNRARA/Service de Microbiologie - Centre National de Référence Associé de la Résistance aux Antibiotiques [Hôpital Bicêtre AP-HP]
3 EERA - Ecologie et Evolution de la Résistance aux Antibiotiques / Ecology and Evolution of Antibiotics Resistance
4 Service de Bactériologie-Virologie-Hygiène
5 CHU Saint-Antoine [AP-HP]
6 Centre Hospitalier Universitaire Paul Brousse, Villejuif, France
7 Hôpital Paul Brousse
8 Structure, Dynamique, Fonction Et Expression Des Beta-Lactamases À Large Spectre
9 CHB - Centre Hépato-Biliaire [Hôpital Paul Brousse]
10 Physiopathologie et traitement des maladies du foie
11 Hôpital Paul Brousse
12 Service de Génétique Moléculaire Pharmacogénétique et Hormonologie [CHU Bicêtre]

Objectives: Patient-and procedure-related changes in modern medicine have turned CoNS into one of the major nosocomial pathogens. Treatments of CoNS infections are challenging owing to the large proportion of MDR strains and oxazolidinones often remain the last active antimicrobial molecules. Here, we have investigated a long-lasting outbreak (2010-13) due to methicillin-and linezolid-resistant (LR) CoNS (n " 168), involving 72 carriers and 49 infected patients. Methods: Antimicrobial susceptibilities were tested by the disc diffusion method and MICs were determined by broth microdilution or Etest. The clonal relationship of LR Staphylococcus epidermidis (LRSE) was first determined using a semi-automated repetitive element palindromic PCR (rep-PCR) method. Then, WGS was performed on all cfr-positive LRSE (n " 30) and LRSE isolates representative of each rep-PCR-defined clone (n " 17). Self-transferability of cfr-carrying plasmids was analysed by filter-mating experiments. Results: This outbreak was caused by the dissemination of three clones (ST2, ST5 and ST22) of LRSE. In these clones, linezolid resistance was caused by (i) mutations in the chromosome-located genes encoding the 23S RNA and L3 and L4 ribosomal proteins, but also by (ii) the dissemination of two different self-conjugative plasmids carrying the cfr gene encoding a 23S RNA methylase. By monitoring linezolid prescriptions in two neighbouring hospitals, we highlighted that the spread of LR-CoNS was strongly associated with linezolid use. Conclusions: Physicians should be aware that plasmid-encoded linezolid resistance has started to disseminate among CoNS and that rational use of oxazolidinones is critical to preserve these molecules as efficient treatment options for MDR Gram-positive pathogens.

Domaines: Maladies infectieuses; Biologie moléculaire

Laurent Dortet, Philippe Glaser, Najiby Kassis-Chikhani, Delphine Girlich, Philippe Ichai, et al.. Long-lasting successful dissemination of resistance to oxazolidinones in MDR Staphylococcus epidermidis clinical isolates in a tertiary care hospital in France. Journal of Antimicrobial Chemotherapy, 2018, 73 (1), pp.41-51. ⟨10.1093/jac/dkx370⟩. ⟨pasteur-02565669⟩