14th ICID - Poster Abstracts - International Society for Infectious ...

When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.
Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1
is available electronically on http://www.sciencedirect.com
Final Abstract Number: 74.015
Session: Antibiotic Resistance: Gram-Positive
Date: Friday, March 12, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation
Trends in Methicillin resistant staphylococcus aureus (MRSA) minimal inhibitory concentration
(MIC) to Vancomycin over a 2 year period in a community based hospital
J. Murillo 1 , C. Garcia 2 , F. Ordieres 3
1 Miami, USA, 2 South Miami hospital, Miami, Fl, USA, 3 South Miami hospital, 33143, Fl, USA
Background: Clinical and laboratory standards institute (CLSI) susceptible range for MRSA
isolates to Vancomycin is established at MIC of 2mcg/ml or less, however MRSA isolates with
higher MIC within the susceptible range are being reported more frequently. It has been reported
that the clinical response to therapy with vancomycin for patients infected with MRSA isolates
with MIC’s 1.5 to 2mcg/ml is decreased.
The objectives of the present study were to determine the MIC to Vancomycin of MRSA blood
isolates over a 2 year period in a Community based hospital in Miami, Florida.
Methods: All blood cultures that were found to have MRSA isolates, from patients treated at our
institution during the years 2008 and 2009 were evaluated. Minimum inhibitory concentrations
(MIC’s) were initially obtained by the Vitek system, however by the last quarter of 2008 and all of
2009 the MIC's were confirmed by Etest strips and results were then reported.
Results: 64.7% of the strains tested in 2008 had an MIC between 1.5 and 2.0mcg/ml, whereas
87.9% of the strains had MIC's within the same range in 2009.
MRSA vancomycin MIC 2008-09
Conclusion: There seems to be a trend to higher MIC’s of MRSA blood isolates to vancomycin,
although still within susceptible range. The findings suggest that monitoring of MRSA
susceptibility to vancomycin should continued in our institution.