ABSTRACT
The ever-expanding role of extended-spectrum-ß-lactamase (ESBL)-harboring and carbapenem-resistant Enterobacteriaceae in causing serious infections poses a grave public health threat because these organisms also tend to be multidrug resistant, for which very few (if any) antibiotic options remain available. Rapid detection of such panresistant organisms offers one of the best solutions to improve patient screening and hospital infection control practices as well as curb inappropriate antibiotic use. This review discusses and compares primarily the current state-of-the-art culture-based and molecular methods that are commercially available for detection or screening of ESBL-harboring and carbapenem-resistant Enterobacteriaceae.
Subject(s)
Anti-Bacterial Agents/pharmacology , Carbapenems/pharmacology , Enterobacteriaceae Infections/diagnosis , Enterobacteriaceae/drug effects , beta-Lactam Resistance , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Culture Techniques , Enterobacteriaceae/enzymology , Enterobacteriaceae Infections/microbiology , Humans , Sensitivity and Specificity , beta-Lactamases/genetics , beta-Lactamases/metabolismABSTRACT
OBJECTIVES: To perform a multicentre study to evaluate the performance of the colorimetric redox indicator (CRI) assay and to establish the MICs and critical concentrations of rifampicin, isoniazid, ofloxacin, kanamycin and capreomycin. METHODS: The study was carried out in two phases. Phase I determined the MIC of each drug. Phase II established critical concentrations for the five drugs tested by the CRI assay compared with the conventional proportion method. RESULTS: Phase I: a strain was considered resistant by the CRI assay if the MIC was ≥0.5 mg/L for rifampicin, ≥0.25 mg/L for isoniazid, ≥4.0 mg/L for ofloxacin and ≥5.0 mg/L for kanamycin and capreomycin. Sensitivity was 99.1% for isoniazid and 100% for the other drugs and specificity was 97.9% for capreomycin and 100% for the other drugs. Phase II: the critical concentration was 0.5 mg/L for rifampicin, 0.25 mg/L for isoniazid, 2.0 mg/L for ofloxacin and 2.5 mg/L for kanamycin and capreomycin giving an overall accuracy of 98.4%, 96.6%, 96.7%, 98.3% and 90%, respectively. CONCLUSIONS: Results demonstrate that the CRI assay is an accurate method for the rapid detection of XDR Mycobacterium tuberculosis. The CRI assay is faster than the conventional drug susceptibility testing method using solid medium, has the same turnaround time as the BACTEC MGIT 960 system, but is less expensive, and could be an adequate method for low-income countries.
Subject(s)
Antitubercular Agents/pharmacology , Colorimetry/methods , Drug Resistance, Multiple, Bacterial , Extensively Drug-Resistant Tuberculosis/diagnosis , Mycobacterium tuberculosis/drug effects , Extensively Drug-Resistant Tuberculosis/microbiology , Humans , Indicators and Reagents/metabolism , Microbial Sensitivity Tests/methods , Mycobacterium tuberculosis/isolation & purification , Oxidation-ReductionABSTRACT
One of the greatest threats to global tuberculosis (TB) control is the growing prevalence of drug-resistant bacilli. Correctly diagnosing drug-resistant TB patients is more problematic in resource-limited settings as there is no or limited infrastructure for drug susceptibility testing (DST) of TB bacilli. The conventional phenotypic DST method for TB takes weeks before declaring the results and initiating proper anti-TB treatment. Molecular DST offers advantages over the phenotypic methods mainly because of the short turnaround time. This review summarizes the different molecular DST methods for TB and discusses challenges and opportunities in implementing them in resource-limited settings.
