Evaluation of a Colorimetric Broth Microdilution Method for Antimicrobial Susceptibility Testing Using 2,3,5-Triphenyltetrazolium Chloride.
- Author:
Dae Dong LEE
1
;
Eun Yup LEE
;
Seok Hoon JEONG
;
Chulhun L CHANG
Author Information
1. Department of Laboratory Medicine, Pusan National University School of Medicine, Korea. cchl@pusan.ac.kr
- Publication Type:Original Article
- Keywords:
Susceptibility tests;
Colorimetric assay;
2,3,5-triphenyltetrazolium chloride;
Escherichia coli;
Staphylococcus aureus;
Enterobacter cloacae;
Acinetobacter baumannii
- MeSH:
Acinetobacter baumannii;
Agar;
Bacteria;
Enterobacter cloacae;
Escherichia coli;
Microbial Sensitivity Tests;
Oxidation-Reduction;
Staphylococcus aureus
- From:Korean Journal of Clinical Microbiology
2007;10(1):49-53
- CountryRepublic of Korea
- Language:English
-
Abstract:
BACKGROUND: The broth microdilution susceptibility testing method is considered a standard for determining minimum inhibitory concentrations, and the addition of the redox indicator 2,3,5-triphenyltetrazolium chloride (TTC) to the broth microdilution method simplifies and increases its objectivity. The current study evaluated the usefulness of a TTC-modified broth microdilution method for antimicrobial susceptibility test of frequently encountered clinical isolates. METHODS: The minimal inhibitory concentrations (MICs) of 10 antimicrobials for 111 clinical isolates of four bacterial species, Staphylococcus aureus, Escherichia coli, Enterobacter cloacae, and Acinetobacter baumannii, were investigated by a modification of the Clinical and Laboratory Standards Institute (CLSI)-recommended broth microdilution method with the addition of 2,3,5-triphenyltetrazolium chloride (TTC). The inhibitory effects of TTC against 192 strains of 22 bacterial species isolated from clinical specimens were also evaluated. RESULTS: The number of colonies of all 192 strains of 22 bacterial species grown on TTC-containing Mueller-Hinton agar did not differ from those grown on Mueller-Hinton agar only. The MICs with TTC were within 2 dilutions of those obtained by the CLSI method in 569 (97.6%) of 583 organism-antimicrobial agent combinations. CONCLUSIONS: The colorimetric MIC method using TTC may be a useful surrogate of antimicrobial susceptibility testing for most of the frequently isolated bacteria.
