Limits...
Resazurin tube method: rapid, simple, and inexpensive method for detection of drug resistance in the clinical isolates of mycobacterium tuberculosis.

Patil SS, Mohite ST, Kulkarni SA, Udgaonkar US - J Glob Infect Dis (2014)

Bottom Line: Rapid detection is critical for the effective treatment of patients.The results obtained were compared with the gold standard proportion method.Kappa is the measure of agreement between the RTM and proportion method (PM) for RIF and INH, which was found to be 0.972 and 0.935 for RIF and INH, respectively.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Bharati Vidyapeeth Deemed University, Medical College and Hospital, Sangli, Maharashtra, India.

ABSTRACT

Background: Tuberculosis (TB) remains a serious public health problem worldwide. The emergence of drug resistance and multidrug resistance (MDR) has become the main threat to TB treatment and control programs. Rapid detection is critical for the effective treatment of patients. In recent times, a new method using the colorimetric indicator resazurin has been proposed for drug susceptibility of Mycobacterium tuberculosis.

Materials and methods: In this study, the resazurin reduction assay was adapted to screw cap tubes. Using the Resazurin Tube Method (RTM), a total of 100 clinical isolates were tested against Rifampicin (RIF) and Isoniazide (INH). By visual reading, the minimum inhibitory concentrations (MICs) were obtained after eight days. The results obtained were compared with the gold standard proportion method.

Results: Excellent results were obtained for RTM with a sensitivity of 100% for both RIF and INH, with a specificity of 98.7 and 95.3%, respectively. Kappa is the measure of agreement between the RTM and proportion method (PM) for RIF and INH, which was found to be 0.972 and 0.935 for RIF and INH, respectively.

Conclusion: The RTM appears to be a reliable method for the rapid and simultaneous detection of MDR-TB and drug susceptibility testing (DST) of M. tuberculosis. It is simple, inexpensive, and with no biohazard risk involved.

No MeSH data available.


Related in: MedlinePlus

Drug sensitivity testing of Mycobacterium tuberculosis H37RV strain by RTM for INH and RIF, showing susceptibility for both. (PC: Positive control; NC: Negative control)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4265830&req=5

Figure 1: Drug sensitivity testing of Mycobacterium tuberculosis H37RV strain by RTM for INH and RIF, showing susceptibility for both. (PC: Positive control; NC: Negative control)

Mentions: The results of the RTM were obtained after eight days of incubation. Complete color change from blue to pink was observed in all growth control tubes, whereas, color change was not observed in the sterility control tubes. The reference strain M. tuberculosis H37Rv, tested by RTM, showed no color change in all the drug-containing tubes, indicating no growth and confirming its sensitivity to both the drugs [Figure 1]. The MIC of RIF and INH for 100 M. tuberculosis clinical isolates was determined by visual reading of the assay tubes. For RIF, out of 77 susceptible isolates by PM, 76 had an MIC of ≤ 0.25 μg/ml in the RTM. One isolate showed an intermediate resistance with an MIC at 0.5 μg/ml. This was retested by both the methods and the same results were obtained. The MICs of RIF for the remaining 23 resistant isolates by PM were > 2.0 μg/ml. For INH, of the 65 isolates found to be susceptible by PM, 62 had an MIC of ≤ 0.125 μg/ml. Two isolates showed an intermediate MIC of 0.25 μg/ml in the RTM. However, one isolate, susceptible by PM, was found to be resistant by RTM giving a discordant result, with an MIC of >1.0μg/ml. These three isolates were retested by both the methods, with the same results. The MICs of INH for the remaining 35 resistant isolates by PM were >1.0 μg/ml [Table 1].


Resazurin tube method: rapid, simple, and inexpensive method for detection of drug resistance in the clinical isolates of mycobacterium tuberculosis.

Patil SS, Mohite ST, Kulkarni SA, Udgaonkar US - J Glob Infect Dis (2014)

Drug sensitivity testing of Mycobacterium tuberculosis H37RV strain by RTM for INH and RIF, showing susceptibility for both. (PC: Positive control; NC: Negative control)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4265830&req=5

Figure 1: Drug sensitivity testing of Mycobacterium tuberculosis H37RV strain by RTM for INH and RIF, showing susceptibility for both. (PC: Positive control; NC: Negative control)
Mentions: The results of the RTM were obtained after eight days of incubation. Complete color change from blue to pink was observed in all growth control tubes, whereas, color change was not observed in the sterility control tubes. The reference strain M. tuberculosis H37Rv, tested by RTM, showed no color change in all the drug-containing tubes, indicating no growth and confirming its sensitivity to both the drugs [Figure 1]. The MIC of RIF and INH for 100 M. tuberculosis clinical isolates was determined by visual reading of the assay tubes. For RIF, out of 77 susceptible isolates by PM, 76 had an MIC of ≤ 0.25 μg/ml in the RTM. One isolate showed an intermediate resistance with an MIC at 0.5 μg/ml. This was retested by both the methods and the same results were obtained. The MICs of RIF for the remaining 23 resistant isolates by PM were > 2.0 μg/ml. For INH, of the 65 isolates found to be susceptible by PM, 62 had an MIC of ≤ 0.125 μg/ml. Two isolates showed an intermediate MIC of 0.25 μg/ml in the RTM. However, one isolate, susceptible by PM, was found to be resistant by RTM giving a discordant result, with an MIC of >1.0μg/ml. These three isolates were retested by both the methods, with the same results. The MICs of INH for the remaining 35 resistant isolates by PM were >1.0 μg/ml [Table 1].

Bottom Line: Rapid detection is critical for the effective treatment of patients.The results obtained were compared with the gold standard proportion method.Kappa is the measure of agreement between the RTM and proportion method (PM) for RIF and INH, which was found to be 0.972 and 0.935 for RIF and INH, respectively.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Bharati Vidyapeeth Deemed University, Medical College and Hospital, Sangli, Maharashtra, India.

ABSTRACT

Background: Tuberculosis (TB) remains a serious public health problem worldwide. The emergence of drug resistance and multidrug resistance (MDR) has become the main threat to TB treatment and control programs. Rapid detection is critical for the effective treatment of patients. In recent times, a new method using the colorimetric indicator resazurin has been proposed for drug susceptibility of Mycobacterium tuberculosis.

Materials and methods: In this study, the resazurin reduction assay was adapted to screw cap tubes. Using the Resazurin Tube Method (RTM), a total of 100 clinical isolates were tested against Rifampicin (RIF) and Isoniazide (INH). By visual reading, the minimum inhibitory concentrations (MICs) were obtained after eight days. The results obtained were compared with the gold standard proportion method.

Results: Excellent results were obtained for RTM with a sensitivity of 100% for both RIF and INH, with a specificity of 98.7 and 95.3%, respectively. Kappa is the measure of agreement between the RTM and proportion method (PM) for RIF and INH, which was found to be 0.972 and 0.935 for RIF and INH, respectively.

Conclusion: The RTM appears to be a reliable method for the rapid and simultaneous detection of MDR-TB and drug susceptibility testing (DST) of M. tuberculosis. It is simple, inexpensive, and with no biohazard risk involved.

No MeSH data available.


Related in: MedlinePlus