Evaluation of methods in detecting vancomycin MIC among MRSA isolates and the changes in accuracy related to different MIC values.

January 17, 2015 at 5:21 pm

Rev Inst Med Trop Sao Paulo. 2014 Nov-Dec;56(6):469-72.

Rossatto FC1, Proença LA1, Becker AP1, Silveira AC1, Caierão J1, D’Azevedo PA1.

1Department of Microbiology, Federal University of Health Science of Porto Alegre, Porto Alegre, RS, Brazil.

Abstract

INTRODUCTION:

Methicillin-Resistant Staphylococcus aureus (MRSA) presenting reduced susceptibility to vancomycin has been associated to therapeutic failure. Some methods used by clinical laboratories may not be sufficiently accurate to detect this phenotype, compromising results and the outcome of the patient.

OBJECTIVES:

To evaluate the performance of methods in the detection of vancomycin MIC values among clinical isolates of MRSA.

MATERIAL AND METHODS:

The Vancomycin Minimal Inhibitory Concentration was determined for 75 MRSA isolates from inpatients of Mãe de Deus Hospital, Porto Alegre, Brazil. The broth microdilution (BM) was used as the gold-standard technique, as well as the following methods: E-test® strips (BioMérieux), M.I.C.E® strips (Oxoid), PROBAC® commercial panel and the automated system MicroScan® (Siemens). Besides, the agar screening test was carried out with 3 µg/mL of vancomycin.

RESULTS:

All isolates presented MIC ≤ 2 µg/mL for BM. E-test® had higher concordance (40%) in terms of global agreement with the gold standard, and there was not statistical difference among E-test® and broth microdilution results. PROBAC® panels presented MICs, in general, lower than the gold-standard panels (58.66% major errors), while M.I.C.E.® MICs were higher (67.99% minor errors).

CONCLUSIONS:

For the population of MRSA in question, E-test® presented the best performance, although with a heterogeneous accuracy, depending on MIC values.

PDF

http://www.scielo.br/pdf/rimtsp/v56n6/0036-4665-rimtsp-56-06-469.pdf

 

Entry filed under: Antimicrobianos, Bacterias, Bacteriemias, Metodos diagnosticos, Resistencia bacteriana. Tags: .

Vancomycin intermediate-Resistant Staphylococcus aureus (VISA) Isolated from a patient never received Vancomycin treatment. Characterization of methicillin-resistant Staphylococcus aureus isolates from patients with persistent or recurrent bacteremia.


Calendar

January 2015
M T W T F S S
« Dec   Feb »
 1234
567891011
12131415161718
19202122232425
262728293031  

Most Recent Posts


%d bloggers like this: