TY - JOUR
T1 - Virulence of Vancomycin-resistant enterococcus faecium according to linezolid resistance and clinical outbreak status
AU - McLaughlin, Milena
AU - Malczynski, Michael
AU - Qi, Chao
AU - Barajas, Grace
AU - Radetski, Jordan
AU - Zembower, Teresa
AU - Scheetz, Marc H.
PY - 2013/8
Y1 - 2013/8
N2 - Assessing clinical virulence differences between vancomycin-resistant Enterococcus faecium (VREF) strains resistant to linezolid (LRVRE) and linezolid-susceptible VRE (LSVRE) strains is difficult due to confounding patient variables. Galleria mellonella is a validated host interaction model allowing straightforward organism virulence assessment. The objective of this study was to assess the virulence of VREF in G. mellonella according to linezolid resistance and clinical outbreak status. A genetically related pair of VREF strains with and without genotypically confirmed linezolid resistance was selected for analysis. Additionally, six strains of LSVRE and two strains of LRVRE were selected according to epidemiologic outbreak status. Mortality of G. mellonella was assessed daily over a 5-day period and analyzed using Kaplan-Meier survival curves and log rank tests. Linezolid resistance did not have a significant effect on G. mellonella mortality in the genetically related pair (P 0.93). There was no significant difference in mortality over time between strains (non-outbreak [i.e., no patient transmissions were recorded] [n2] versus outbreak [i.e., transmission occurred between 3 or more patients in a period of 30 days] [n6], P 0.84; extensive transmission [i.e., the isolate was transmitted between at least 80 patients] [n2] versus limited transmission [i.e., the isolate was transmitted between fewer than 10 patients] [n4], P 0.78). These results suggest that patients infected with LRVRE or outbreak strains of VREF are at no greater risk of poor outcomes mediated by organism virulence than those infected with LSVRE or non-outbreak strains.
AB - Assessing clinical virulence differences between vancomycin-resistant Enterococcus faecium (VREF) strains resistant to linezolid (LRVRE) and linezolid-susceptible VRE (LSVRE) strains is difficult due to confounding patient variables. Galleria mellonella is a validated host interaction model allowing straightforward organism virulence assessment. The objective of this study was to assess the virulence of VREF in G. mellonella according to linezolid resistance and clinical outbreak status. A genetically related pair of VREF strains with and without genotypically confirmed linezolid resistance was selected for analysis. Additionally, six strains of LSVRE and two strains of LRVRE were selected according to epidemiologic outbreak status. Mortality of G. mellonella was assessed daily over a 5-day period and analyzed using Kaplan-Meier survival curves and log rank tests. Linezolid resistance did not have a significant effect on G. mellonella mortality in the genetically related pair (P 0.93). There was no significant difference in mortality over time between strains (non-outbreak [i.e., no patient transmissions were recorded] [n2] versus outbreak [i.e., transmission occurred between 3 or more patients in a period of 30 days] [n6], P 0.84; extensive transmission [i.e., the isolate was transmitted between at least 80 patients] [n2] versus limited transmission [i.e., the isolate was transmitted between fewer than 10 patients] [n4], P 0.78). These results suggest that patients infected with LRVRE or outbreak strains of VREF are at no greater risk of poor outcomes mediated by organism virulence than those infected with LSVRE or non-outbreak strains.
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U2 - 10.1128/AAC.00192-13
DO - 10.1128/AAC.00192-13
M3 - Article
C2 - 23733458
AN - SCOPUS:84880300555
SN - 0066-4804
VL - 57
SP - 3923
EP - 3927
JO - Antimicrobial Agents and Chemotherapy
JF - Antimicrobial Agents and Chemotherapy
IS - 8
ER -
