Characterisation of clinical meticillin-resistant Staphylococcus epidermidis demonstrating high levels of linezolid resistance (>256 μg/ml) resulting from transmissible and mutational mechanisms.
Staphylococcus epidermidis (S. epidermidis), one of the leading etiological agents of nosocomial infections poses a significant economic burden globally. Introduced in 2000, linezolid (LZD) has become an important antibiotic, used in nearly seventy countries worldwide to treat infections caused by Gram-positive pathogens such as meticillin-resistant Staphylococcus and Streptococcus species along with vancomycin-resistant enterococci. Resistance to LZD in clinical settings remains rare. Here, we report the emergence of meticillin resistant S. epidermidis (MRSE) clinical isolates from two voluntary general acute hospitals exhibiting higher than typically reported levels of LZD resistance (MIC>256 μg/ml). The MRSE ST-2 clone isolated from eight patients (2010-2011) not only possessed resistance-conferring mutations such as G2576T in domain V of 23S rRNA gene (as determined by HRM-PCR analysis) and R172C substitution in the ribosomal protein L3, but also carried the cfr gene (the only known transmissible mechanism of LZD resistance). All isolates possessed several key biofilm-associated genes (such as icaA, icaD, aap and atlE) and resistance to multiple clinically significant antibiotics was recorded. This study reports the earliest incidence (2010) of clinical MRSE in the Republic of Ireland demonstrating multiple LZD resistance mechanisms both mutational and potentially transmissible, and characterises this emerging resistance from a molecular perspective.
Department of Biological Sciences, Cork Institute of Technology, Cork, Ireland.
Emma M
EM
Gabriel
Department of Microbiology, Mercy University Hospital, Cork, Ireland.
Siobhan
S
Fitzgibbon
Department of Microbiology, Mercy University Hospital, Cork, Ireland.
James
J
Clair
Department of Biological Sciences, Cork Institute of Technology, Cork, Ireland.
Aidan
A
Coffey
Department of Biological Sciences, Cork Institute of Technology, Cork, Ireland. Electronic address: jim.omahony@cit.ie.
Jim M
JM
O'Mahony
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D000069349:Linezolid / Q000494:pharmacology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D017354:Point Mutation; D000090822:Ribosomal Protein L3; D013203:Staphylococcal Infections / Q000382:microbiology*
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; C000716547:RPL3 protein, human; D000090822:Ribosomal Protein L3; D000069349:Linezolid
Biofilm; Cfr; Emerging linezolid resistance; G2576T mutation; L3 L4 and L22 ribosomal proteins; Meticillin-resistant Staphylococcus epidermidis