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Journal of Clinical Microbiology, February 1998, p. 362-366, Vol. 36, No. 2
GWL Hansen's Disease Center, Baton Rouge,
Louisiana1;
Johns Hopkins University
School of Public Health, Baltimore, Maryland2;
Universidad Peruana Cayetano Heredia, Lima,
Peru4; and
University of New
Mexico Health Science Center3 and
Scientific Laboratory Division, New Mexico State Department of
Health,5 Albuquerque, New Mexico
Received 3 June 1997/Returned for modification 14 July
1997/Accepted 26 September 1997
A colorimetric, microplate-based Alamar Blue assay (MABA) method
was used to determine the MICs of isoniazid (INH), rifampin, streptomycin (SM), and ethambutol (EMB) for 34 Peruvian
Mycobacterium tuberculosis isolates (including both
pansensitive and multidrug-resistant strains) and the H37Rv
strain by using bacterial suspensions prepared directly from solid
media. Results for all isolates were available within 8 days.
Discordant results were observed on initial tests for 3 of 16 INH-susceptible isolates, 5 of 31 EMB-susceptible isolates, and 2 of 4 SM-resistant isolates (by the BACTEC 460 system). The overall
agreements between the MICs obtained by MABA and the results obtained
with the BACTEC 460 system were 87.9% for initial results and 93.6%
after retesting 12 of 17 samples with discrepant results.
Interpretation of MABA endpoints improved with technical experience.
The MABA is a simple, rapid, low-cost, appropriate technology which
does not require expensive instrumentation and which makes use of a
nontoxic, temperature-stable reagent.
Tuberculosis is estimated to have
caused the deaths of 1 billion people in the last 200 years
(10). Both the current human immunodeficiency virus pandemic
and multidrug-resistant Mycobacterium tuberculosis have
emerged as major obstacles to treatment and public health control of
tuberculosis (5). Many developing countries have difficulty
obtaining drug susceptibility information for M. tuberculosis isolates for financial or technical reasons. Treatment of tuberculosis without the benefit of susceptibility information increases the risk of treatment failure and the spread of
resistant strains, as well as the development of resistance to
additional drugs. Global surveillance of the drug resistance of
M. tuberculosis isolates has been proposed as a means of
augmenting databases of drug-resistant M. tuberculosis
isolates to help with the development of future program policy
recommendations (1).
The agar proportion susceptibility method (4) is
labor-intensive, and results may take up to 2 months, often making the result clinically irrelevant. Commercially available systems such as
the BACTEC system (7) and the newer Mycobacteria Growth Indicator Tubes (9, 15) and the Etest (14) are
simple and rapid but expensive, making them impractical for use in
developing countries.
Oxidation-reduction dyes, e.g., tetrazoliums, have been used to obtain
drug susceptibility measurements for bacteria (12) including
mycobacteria (3, 16). Yajko et al. (16) reported as a result of tests with clinical isolates a good correlation between
the proportion technique and a broth method with Alamar Blue, a novel
proprietary, resazurin-based (11) oxidation-reduction indicator which delivered colorimetric MICs for M. tuberculosis isolates in 14 days. A microplate version of the
Alamar Blue assay (MABA) with modified medium composition, reaction
time and temperature, and inoculum preparation was evaluated as a
high-throughput screen by comparing the MICs of 30 antimicrobial agents
for M. tuberculosis H37Ra and H37Rv
obtained by MABA to the MICs obtained with the BACTEC 460 system
(2).
This study evaluated the performance of MABA with 34 clinical M. tuberculosis isolates and M. tuberculosis
H37Rv. MABA was performed in a university laboratory in
Peru, a country that has a high incidence of tuberculosis and
multidrug-resistant M. tuberculosis isolates (8,
13), in order to determine the feasibility of using the assay
under conditions resembling those existing in areas of the world with a
high prevalence of tuberculosis and minimal financial resources. The
results were compared with those obtained in the United States at the
New Mexico State Department of Health with the BACTEC 460 system.
(This study was presented in part at the 45th Annual Meeting of the
American Society of Tropical Medicine and Hygiene, Baltimore, Md., 1996 [2a].)
Isolates and drug preparation.
Thirty-four clinical isolates
of M. tuberculosis obtained from Cayetano Heredia University
Hospital and M. tuberculosis H37Rv ATCC 27294 (American Type Culture Collection, Rockville, Md.) were subcultured on
Middlebrook 7H11 agar (Becton Dickinson Microbiology Systems,
Cockeysville, Md.). Suspensions were prepared in 0.04% (vol/vol) Tween
80-0.2% bovine serum albumin (Sigma Chemical Co., St. Louis, Mo.) so
that their turbidities matched that of a McFarland no. 1 turbidity
standard (6). Suspensions were further diluted 1:25 in 7H9GC
broth (4.7 g of Middlebrook 7H9 broth base [Difco, Detroit, Mich.],
20 ml of 10% [vol/vol] glycerol, 1 g of Bacto Casitone
[Difco], 880 ml of distilled water, 100 ml of oleic acid, albumin,
dextrose, and catalase [Remel, Lenexa, Kans.]).
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Rapid, Low-Technology MIC Determination with
Clinical Mycobacterium tuberculosis Isolates by Using
the Microplate Alamar Blue Assay
ABSTRACT
Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
INTRODUCTION
Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
MABA. Two hundred microliters of sterile deionized water was added to all outer-perimeter wells of sterile 96-well plates (Falcon 3072; Becton Dickinson, Lincoln Park, N.J.) to minimize evaporation of the medium in the test wells during incubation. The wells in rows B to G in columns 3 to 11 received 100 µl of 7H9GC broth. One hundred microliters of 2× drug solutions were added to the wells in rows B to G in columns 2 and 3. By using a multichannel pipette, 100 µl was transferred from column 3 to column 4, and the contents of the wells were mixed well. Identical serial 1:2 dilutions were continued through column 10, and 100 µl of excess medium was discarded from the wells in column 10. Final drug concentration ranges were as follows: for INH, 0.031 to 8.0 µg/ml; for RMP, 0.0156 to 4 µg/ml in initial tests and 0.062 to 16 µg/ml on repeat testing; for SM, 0.125 to 32 µg/ml; and for EMB, 0.5 to 128 µg/ml.
One hundred microliters of M. tuberculosis inoculum was added to the wells in rows B to G in columns 2 to 11 by using an Eppendorf repeating pipette (yielding a final volume of 200 µl per well). Thus, the wells in column 11 served as drug-free (inoculum-only) controls. The plates were sealed with Parafilm and were incubated at 37°C for 5 days. Fifty microliters of a freshly prepared 1:1 mixture of 10× Alamar Blue (Accumed International, Westlake, Ohio) reagent and 10% Tween 80 was added to well B11. The plates were reincubated at 37°C for 24 h. If well B11 turned pink, the reagent mixture was added to all wells in the microplate (if the well remained blue, the reagent mixture would be added to another control well and the result would be read on the following day). The microplates were resealed with Parafilm and were incubated for an additional 24 h at 37°C, and the colors of all wells were recorded. A blue color in the well was interpreted as no growth, and a pink color was scored as growth. A few wells appeared violet after 24 h of incubation, but they invariably changed to pink after another day of incubation and thus were scored as growth (while the adjacent blue wells remained blue). The MIC was defined as the lowest drug concentration which prevented a color change from blue to pink.BACTEC assay. Drug susceptibility was determined in the BACTEC 460 instrument (Becton Dickinson, Sparks, Md.) by standard procedures (7) but using the following critical concentrations: INH, 0.1 and 0.4 µg/ml; RMP, 1 µg/ml; SM, 2 and 6 µg/ml; and EMB, 2.5 and 5 µg/ml. Isolates which were susceptible to the higher concentration of drug but resistant to the lower concentration were termed partially resistant.
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RESULTS |
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Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
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Colorimetric MIC test results for all 34 of the clinical M. tuberculosis isolates and the H37Rv strain were available by the 8th day of incubation. After 5 days of incubation, the Alamar Blue reagent was added to the control wells. Following incubation at 37°C for 24 h, most control wells became pink. For those that remained blue, Alamar Blue was added to the next control well and the plates were reincubated for another 24 h until all control wells were pink (indicating sufficient growth to determine drug susceptibility). Alamar Blue was then added to all remaining wells, and the results were determined on the following day (day 7 or 8). The correlations between MIC results obtained by MABA and the results obtained by the BACTEC 460 system are illustrated in Fig. 1 to 4. Although we intended to retest all isolates for which discordant results were obtained, for logistical reasons this was not possible in all cases.
INH susceptibility tests.
For 16 of the 19 isolates that were
susceptible to 0.1 µg of INH per ml in the BACTEC 460 system, the MIC
by MABA was 
0.25 µg/ml (Fig. 1). Of
the three isolates with discordant results, the MIC for one isolate was
0.5 µg/ml (one dilution off, which was interpreted as partial
resistance) and the MICs for two isolates were 8 µg/ml (one of the
two isolates was retested and the MIC was 0.125 µg/ml, which was
classified as susceptible; the other isolate was retested five times,
with all results indicating resistance). Of five isolates that were
partially resistant in tests with the BACTEC system (resistant at 0.1 µg/ml and susceptible at 0.4 µg/ml), the MICs by MABA for one
isolate were in agreement with those of the BACTEC system (0.5 µg/ml); the MICs for the other four isolates were discordant between
the two systems (MICs, 0.125, 0.125, 4, and 8 µg/ml, respectively;
(two isolates were retested by MABA, and the MICs were in agreement
with those obtained with the BACTEC system [0.5 µg/ml]). For all 12 isolates which appeared to be resistant to 0.4 µg/ml, in the BACTEC
system, MICs by MABA were 
1 µg/ml.
|
, isolates for which results were concordant
(and isolates for which discordant results were confirmed upon repeat
testing by MABA); 
, isolates for which results were discordant and
for which MICs by MABA were not redetermined; 
, isolates for which
results were discordant but for which results were concordant upon
repeat MABA testing by MABA. The vertical lines in the figures separate
the standard breakpoints for the BACTEC 460 system. PR, partially
resistant. The horizontal lines separate the interpretive breakpoints
for colorimetric MICs, which were selected on the basis of the best fit
of the MABA results with the BACTEC 460 system results.
RMP susceptibility tests.
For all 26 isolates susceptible to
RMP at 1 µg/ml in the BACTEC system, the MIC by MABA was 0.25
µg/ml (Fig. 2). For the nine isolates
resistant to RMP at 1 µg/ml in the BACTEC system, the MICs by MABA
for five isolates were >4 µg/ml on initial testing and >16 µg/ml
on repeat testing (when the concentration range was extended). The
other four isolates were initially tested at the higher concentration
range, and the RMP MICs for all four isolates were >16 µg/ml.
|
EMB susceptibility tests.
For 26 of the 31 isolates
susceptible to EMB at 5 µg/ml in the BACTEC system, the MIC by MABA
was 2 µg/ml (Fig. 3). For five isolates with discordant results between the two systems, the MICs by
MABA were 4, 4, 8, 64, and 128 µg/ml, respectively. The MICs by MABA
were redetermined for three of the isolates, and all repeat MICs were
2 µg/ml, putting them into agreement with those obtained with the
BACTEC system. The other two isolates were not retested. For two of the
three isolates resistant to EMB at 5 µg/ml but susceptible to EMB at
10 µg/ml in the BACTEC system, the MIC by MABA was 4 µg/ml. The MIC
for the third isolate was originally 64 µg/ml, but on retesting the
MIC by MABA was 4 µg/ml. For the one isolate completely resistant to
EMB at 10 µg/ml in the BACTEC system, the MIC by MABA was 16 µg/ml.
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SM susceptibility tests.
For all 18 isolates susceptible to SM
at 2 µg/ml in the BACTEC system, the MIC by MABA was 1 µg/ml
(Fig. 4). For 11 of the 13 isolates
resistant to SM at 2 µg/ml but susceptible to SM at 6 µg/ml in the
BACTEC system (partial resistance), the MIC by MABA was 2 to 8 µg/ml.
For the two isolates with discordant results, the MICs by MABA were 1 µg/ml. For two of the four isolates resistant to SM at 6 µg/ml in
the BACTEC system, the MIC by MABA was 32 µg/ml. The MIC for one
isolate with discordant results was 4 µg/ml, but upon retesting by
MABA the MIC was 16 µg/ml.
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isolates for
which results were discordant and for which MICs by MABA were not
redetermined; | |
DISCUSSION |
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Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
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The overall agreements between the results obtained with the BACTEC system and by MABA were 87.9% upon initial testing and 93.6% after retesting 12 of the 17 isolates with discordant results (Table 1). Although initial concordance was relatively low for INH-susceptible, EMB-susceptible, and SM-resistant (by the BACTEC system) isolates, these values improved upon retesting, especially for EMB-susceptible isolates. For INH, RMP, and SM, the breakpoints were sharp (the wells were either blue or pink), while with EMB testing with some isolates, violet wells were observed, but on extended incubation these became pink. In general the repeat test results were considered to be more accurate as a result of the additional experience obtained by the technicians, for whom this study represented the first attempt at performing susceptibility studies in a microplate format.
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The tube microdilution format used by Yajko et al. (16) offers a rapid Alamar Blue reaction by incubating the tubes at 50°C and providing results in 2 h (versus overnight when incubation is at 37°C). A tube format may also have an advantage over microplates with respect to biosafety, although sealing of the microplates with Parafilm should minimize the biohazard potential in the event that a plate is mishandled. On the other hand, the MABA used in the present study facilitates liquid handling and should be economical, especially when (as anticipated for routine clinical testing) only two critical concentrations of each drug are used. This would allow at least three specimens to be tested per plate. Contamination was not found to be a problem. Our use of a 37°C reaction temperature obviates the need for a second incubator or water bath or the use of separate vessels for control samples, factors advantageous to a scheme that can be set up at minimum cost.
The fact that 100% of results were available within 8 days in this study, compared to 58% of results in 7 days in the study of Yajko et al. (16), was somewhat surprising considering that our use of 37°C for the Alamar Blue reaction lengthens the total assay time by 2 days, whereas the use of 50°C shortens the Alamar Blue reaction time to 2 h. Moreover, our use of an inoculum prepared from solid medium (in order to simulate the use of a primary culture and to reduce the overall turnaround time) would not be expected to shorten the lag phase of growth in the susceptibility test. This is more likely due to the use of glycerol in the culture medium in the present study.
Existing methods for drug susceptibility testing of clinical M. tuberculosis isolates are either inexpensive with long turnaround times or rapid but too expensive for all but the most affluent institutions. We have also successfully used the Mycobacteria Growth Indicator Tube and Etest (unpublished data) in Peru to determine drug susceptibilities, but the cost of materials is substantially higher than the cost of materials for the MABA. The MABA or the Alamar Blue tube microdilution version of Yajko et al. (16) offer a superior combination of rapidity and affordability. Results from this study, that of Yajko et al. (16), and others to be performed may allow the selection of one or two critical concentrations of each drug for use in differentiating susceptible, partially resistant, and fully resistant strains. This would further reduce the cost of the assay by allowing the drug susceptibilities of up to three isolates to be determined on a single 96-well plate. The minimum major equipment needed to perform MABA consists of a biosafety cabinet, an autoclave, and a 37°C incubator.
Preliminary results (1a) suggest that the less expensive nonproprietary oxidation-reduction indicator dimethylthiazoldiphenyltetrazolium bromide (MTT) in a microplate assay would give results similar to those obtained by MABA and thus could further reduce the costs of such assays (1a). MTT has already been shown to be of value in susceptibility testing of Mycobacterium avium-Mycobacterium intracellulare (3). Another nonproprietary oxidation-reduction indicator, 2,3-diphenyl-5-thienyl-(2)-tetrazolium chloride, has shown promise for use in drug susceptibility testing of M. tuberculosis isolates (17).
Considering their rapidity, their use of low technology, and their low cost, microplate assays that use Alamar Blue or tetrazolium-type compounds have the potential of becoming the methods of choice for drug susceptibility testing of M. tuberculosis isolates for much of the world where tuberculosis is a major problem.
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ACKNOWLEDGMENTS |
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We thank Lisa Collins for help in assay design and Patricia Fuentes, Melissa McGuire, and Patricia Sheen for technical assistance.
This study was supported by the Division of AIDS, National Institute of Allergy and Infectious Diseases (interagency agreement Y1-AI-50016).
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FOOTNOTES |
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* Corresponding author. Mailing address: Laboratory Research Branch, GWL Hansen's Disease Center, P.O. Box 25072, Baton Rouge, LA 70894. Phone: (504) 346-5773. Fax: (504) 346-5786. E-mail: franzblau{at}vt8200.vetmed.lsu.edu.
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REFERENCES |
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Abstract
Introduction
Materials & Methods
Results
Discussion
References
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| 1. | Cohn, D. L., F. Bustreo, and M. C. Raviglione. 1997. Drug-resistant tuberculosis: review of the worldwide situation and the WHO/IUATLD global surveillance project. Clin. Infect. Dis. 24(Suppl. 1):S121-S130. |
| 1a. | Collins, L., and S. Franzblau. Unpublished data. |
| 2. | Collins, L. S., and S. G. Franzblau. 1997. Microplate Alamar Blue assay versus BACTEC 460 system for high-throughput screening of compounds against Mycobacterium tuberculosis and Mycobacterium avium. Antimicrob. Agents Chemother. 41:1004-1009[Abstract]. |
| 2a. | Franzblau, S. G., R. S. Witzig, R. H. Gilman, G. Madico, J. McLaughlin, M. B. Cook, P. Torres, P. Fuentes, and M. S. McGuire. 1996. Rapid drug susceptibility assay for developing countries using Alamar Blue, abstr. 335, p. 210. In Abstracts of the 45th Annual Meeting of the American Society of Tropical Medicine and Hygiene. |
| 3. | Gomez-Flores, R., S. Gupta, R. Tamez-Guerra, and R. T. Mehta. 1995. Determination of MICs for Mycobacterium avium-M. intracellulare complex in liquid medium by a colorimetric method. J. Clin. Microbiol. 33:1842-1846[Abstract]. |
| 4. | Hacek, D. 1992. Modified proportion agar dilution test for slowly growing mycobacteria, p. 5.13.1-5.13.15. In H. D. Isenberg (ed.), Clinical microbiology procedures handbook, vol. 1. American Society for Microbiology, Washington, D.C. |
| 5. |
Hart, C. A.,
N. J. Beeching, and B. I. Duerden.
1996.
Tuberculosis into the next century.
J. Med Microbiol.
44:1-34 |
| 6. | Hindler, J., L. Hochstein, and A. Howell. 1992. Preparation of routine media and reagents used in antimicrobial susceptibility testing. Part 1. McFarland standards, p. 5.19.1-5.19.6. In H. D. Isenberg (ed.), Clinical microbiology procedures handbook, vol. 1. American Society for Microbiology, Washington, D.C. |
| 7. | Inderlied, C. B., and M. Salfinger. 1995. Antimicrobial agents and susceptibility tests: mycobacteria, p. 1385-1404. In P. R. Murray, E. J. Barron, M. A. Pfaller, F. C. Tenover, and R. H. Yolken (ed.), Manual of clinical microbiology, 6th ed. ASM Press, Washington, D.C. |
| 8. | Laszlo, A., and I. N. de Kantor. 1994. A random sample survey of initial drug resistance among tuberculosis cases in Latin America. Bull. W. H. O. 72:603-610[Medline]. |
| 9. | Palaci, M., S. Y. M. Ueki, D. N. Sato, M. A. Da Silva Telles, M. Curcio, and E. A. M. Silva. 1996. Evaluation of Mycobacteria Growth Indicator Tube for recovery and drug susceptibility testing of Mycobacterium tuberculosis isolates from respiratory specimens. J. Clin. Microbiol. 34:762-764[Abstract]. |
| 10. |
Ryan, F.
1992.
The forgotten plague: how the battle against tuberculosis was won and lost, p. 3.
Little, Brown & Co., Boston, Mass.
|
| 11. | Shiloh, M. U., J. Ruan, and C. Nathan. 1997. Evaluation of bacterial survival and phagocyte function with a fluorescence-based microplate assay. Infect. Immun. 65:3193-3198[Abstract]. |
| 12. | Vasquez, A., Y. Valdez, R. H. Gilman, J. J. McDonald, T. U. Westblom, D. Berg, H. Mayta, and V. Gutierrez. 1996. Metronidazole and clarithromycin resistance in Helicobacter pylori determined by measuring MICs of antimicrobial agents in color indicator egg yolk agar in a miniwell format. J. Clin. Microbiol. 34:1232-1234[Abstract]. |
| 13. | Vivar, A., G. Madico, P. Torres, C. Chang, A. Mayta, A. Hernandez, M. T. Degnan, M. B. Cook, V. K. Quenzer, R. B. Ferguson, J. C. McLaughlin, and R. H. Gilman. 1996. Multi-drug resistant Mycobacterium tuberculosis in an urban hospital, Lima, Peru, abstr. 334, p. 210. In Abstracts of the 45th Annual Meeting of the American Society of Tropical Medicine and Hygiene. |
| 14. | Wagner, A., and K. Mills. 1996. Testing of Mycobacterium tuberculosis susceptibility to ethambutol, isoniazid, rifampin, and streptomycin by using Etest. J. Clin. Microbiol. 34:1672-1676[Abstract]. |
| 15. | Walters, S. B., and B. A. Hanna. 1996. Testing of susceptibility of Mycobacterium tuberculosis to isoniazid and rifampin by Mycobacterium Growth Indicator Tube method. J. Clin. Microbiol. 34:1565-1567[Abstract]. |
| 16. | Yajko, D. M., J. J. Madej, M. V. Lancaster, C. A. Sanders, V. L. Cawthon, B. Gee, A. Babst, and W. K. Hadley. 1995. Colorimetric method for determining MICs of antimicrobial agents for Mycobacterium tuberculosis. J. Clin. Microbiol. 33:2324-2327[Abstract]. |
| 17. | Yamane, N., T. Oiwa, T. Kiyota, H. Saitoh, T. Sonoda, M. Tosaka, M. Nakashima, H. Fukunaga, T. Masaki, K. Miyagawa, M. Miyagoe, and Y. Okazawa. 1996. Multicenter evaluation of a colorimetric microplate antimycobacterial susceptibility test: comparative study with the NCCLS M24-P. Rinsho Byori 44:456-464[Medline]. |
Journal of Clinical Microbiology, February 1998, p. 362-366, Vol. 36, No. 2
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
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[Abstract] [Full Text] -
KAWAI, V., SOTO, G., GILMAN, R. H., BAUTISTA, C. T., CAVIEDES, L., HUAROTO, L., TICONA, E., ORTIZ, J., TOVAR, M., CHAVEZ, V., RODRIGUEZ, R., ESCOMBE, A. R., EVANS, C. A.
(2006). TUBERCULOSIS MORTALITY, DRUG RESISTANCE, AND INFECTIOUSNESS IN PATIENTS WITH AND WITHOUT HIV INFECTION IN PERU. Am J Trop Med Hyg
75: 1027-1033
[Abstract] [Full Text] -
Mohammadzadeh, A., Farnia, P., Ghazvini, K., Behdani, M., Rashed, T., Ghanaat, J.
(2006). Rapid and low-cost colorimetric method using 2,3,5-triphenyltetrazolium chloride for detection of multidrug-resistant Mycobacterium tuberculosis.. J Med Microbiol
55: 1657-1659
[Abstract] [Full Text] -
Barco, P., Cardoso, R. F., Hirata, R. D. C., Leite, C. Q. F., Pandolfi, J. R., Sato, D. N., Shikama, M. L., de Melo, F. F., Mamizuka, E. M., Campanerut, P. A. Z., Hirata, M. H.
(2006). pncA mutations in pyrazinamide-resistant Mycobacterium tuberculosis clinical isolates from the southeast region of Brazil. J Antimicrob Chemother
58: 930-935
[Abstract] [Full Text] -
Teo, J. W. P., Thayalan, P., Beer, D., Yap, A. S. L., Nanjundappa, M., Ngew, X., Duraiswamy, J., Liung, S., Dartois, V., Schreiber, M., Hasan, S., Cynamon, M., Ryder, N. S., Yang, X., Weidmann, B., Bracken, K., Dick, T., Mukherjee, K.
(2006). Peptide Deformylase Inhibitors as Potent Antimycobacterial Agents. Antimicrob. Agents Chemother.
50: 3665-3673
[Abstract] [Full Text] -
Moore, D. A.J., Evans, C. A.W., Gilman, R. H., Caviedes, L., Coronel, J., Vivar, A., Sanchez, E., Pinedo, Y., Saravia, J. C., Salazar, C., Oberhelman, R., Hollm-Delgado, M.-G., LaChira, D., Escombe, A. R., Friedland, J. S.
(2006). Microscopic-Observation Drug-Susceptibility Assay for the Diagnosis of TB.. NEJM
355: 1539-1550
[Abstract] [Full Text] -
Vera-Cabrera, L., Castro-Garza, J., Rendon, A., Ocampo-Candiani, J., Welsh, O., Choi, S. H., Blackwood, K., Molina-Torres, C.
(2005). In Vitro Susceptibility of Mycobacterium tuberculosis Clinical Isolates to Garenoxacin and DA-7867. Antimicrob. Agents Chemother.
49: 4351-4353
[Abstract] [Full Text] -
Hazbon, M. H., Bobadilla del Valle, M., Guerrero, M. I., Varma-Basil, M., Filliol, I., Cavatore, M., Colangeli, R., Safi, H., Billman-Jacobe, H., Lavender, C., Fyfe, J., Garcia-Garcia, L., Davidow, A., Brimacombe, M., Leon, C. I., Porras, T., Bose, M., Chaves, F., Eisenach, K. D., Sifuentes-Osornio, J., Ponce de Leon, A., Cave, M. D., Alland, D.
(2005). Role of embB Codon 306 Mutations in Mycobacterium tuberculosis Revisited: a Novel Association with Broad Drug Resistance and IS6110 Clustering Rather than Ethambutol Resistance. Antimicrob. Agents Chemother.
49: 3794-3802
[Abstract] [Full Text] -
Guna, R., Munoz, C., Dominguez, V., Garcia-Garcia, A., Galvez, J., de Julian-Ortiz, J.-V., Borras, R.
(2005). In vitro activity of linezolid, clarithromycin and moxifloxacin against clinical isolates of Mycobacterium kansasii. J Antimicrob Chemother
55: 950-953
[Abstract] [Full Text] -
Falzari, K., Zhu, Z., Pan, D., Liu, H., Hongmanee, P., Franzblau, S. G.
(2005). In Vitro and In Vivo Activities of Macrolide Derivatives against Mycobacterium tuberculosis. Antimicrob. Agents Chemother.
49: 1447-1454
[Abstract] [Full Text] -
McBride, J., Ingram, P. R., Henriquez, F. L., Roberts, C. W.
(2005). Development of Colorimetric Microtiter Plate Assay for Assessment of Antimicrobials against Acanthamoeba. J. Clin. Microbiol.
43: 629-634
[Abstract] [Full Text] -
Ma, G., Khan, S. I., Jacob, M. R., Tekwani, B. L., Li, Z., Pasco, D. S., Walker, L. A., Khan, I. A.
(2004). Antimicrobial and Antileishmanial Activities of Hypocrellins A and B. Antimicrob. Agents Chemother.
48: 4450-4452
[Abstract] [Full Text] -
Moore, D. A. J., Mendoza, D., Gilman, R. H, Evans, C. A. W., Hollm Delgado, M.-G., Guerra, J., Caviedes, L., Vargas, D., Ticona, E., Ortiz, J., Soto, G., Serpa, J., the Tuberculosis Working Group in Peru,
(2004). Microscopic Observation Drug Susceptibility Assay, a Rapid, Reliable Diagnostic Test for Multidrug-Resistant Tuberculosis Suitable for Use in Resource-Poor Settings. J. Clin. Microbiol.
42: 4432-4437
[Abstract] [Full Text] -
Cardoso, R. F., Cooksey, R. C., Morlock, G. P., Barco, P., Cecon, L., Forestiero, F., Leite, C. Q. F., Sato, D. N., Shikama, M. d. L., Mamizuka, E. M., Hirata, R. D. C., Hirata, M. H.
(2004). Screening and Characterization of Mutations in Isoniazid-Resistant Mycobacterium tuberculosis Isolates Obtained in Brazil. Antimicrob. Agents Chemother.
48: 3373-3381
[Abstract] [Full Text] -
Farnia, P., Mohammadi, F., Mirsaedi, M., Zarife, A. Z., Tabatabee, J., Bahadori, K., Bahadori, M., Masjedi, M. R., Velayati, A. A.
(2004). Application of Oxidation-Reduction Assay for Monitoring Treatment of Patients with Pulmonary Tuberculosis. J. Clin. Microbiol.
42: 3324-3325
[Abstract] [Full Text] -
Murray, C. K., Hospenthal, D. R.
(2004). Broth Microdilution Susceptibility Testing for Leptospira spp.. Antimicrob. Agents Chemother.
48: 1548-1552
[Abstract] [Full Text] -
Reis, R. S., Neves, I. Jr., Lourenco, S. L. S., Fonseca, L. S., Lourenco, M. C. S.
(2004). Comparison of Flow Cytometric and Alamar Blue Tests with the Proportional Method for Testing Susceptibility of Mycobacterium tuberculosis to Rifampin and Isoniazid. J. Clin. Microbiol.
42: 2247-2248
[Abstract] [Full Text] -
Huang, T.-S., Lee, S. S.-J., Tu, H.-Z., Huang, W.-K., Chen, Y.-S., Huang, C.-K., Wann, S.-R., Lin, H.-H., Liu, Y.-C.
(2004). Use of MGIT 960 for rapid quantitative measurement of the susceptibility of Mycobacterium tuberculosis complex to ciprofloxacin and ethionamide. J Antimicrob Chemother
53: 600-603
[Abstract] [Full Text] -
Garcia-Garcia, A., Galvez, J., de Julian-Ortiz, J.-V., Garcia-Domenech, R., Munoz, C., Guna, R., Borras, R.
(2004). New agents active against Mycobacterium avium complex selected by molecular topology: a virtual screening method. J Antimicrob Chemother
53: 65-73
[Abstract] [Full Text] -
Morlock, G. P., Metchock, B., Sikes, D., Crawford, J. T., Cooksey, R. C.
(2003). ethA, inhA, and katG Loci of Ethionamide-Resistant Clinical Mycobacterium tuberculosis Isolates. Antimicrob. Agents Chemother.
47: 3799-3805
[Abstract] [Full Text] -
Mayta, H., Gilman, R. H., Arenas, F., Valencia, T., Caviedes, L., Montenegro, S. H., Ticona, E., Ortiz, J., Chumpitaz, R., Evans, C. A., Williams, D. L.
(2003). Evaluation of a PCR-Based Universal Heteroduplex Generator Assay as a Tool for Rapid Detection of Multidrug-Resistant Mycobacterium tuberculosis in Peru. J. Clin. Microbiol.
41: 5774-5777
[Abstract] [Full Text] -
Martin, A., Camacho, M., Portaels, F., Palomino, J. C.
(2003). Resazurin Microtiter Assay Plate Testing of Mycobacterium tuberculosis Susceptibilities to Second-Line Drugs: Rapid, Simple, and Inexpensive Method. Antimicrob. Agents Chemother.
47: 3616-3619
[Abstract] [Full Text] -
Palomino, J.-C., Martin, A., Camacho, M., Guerra, H., Swings, J., Portaels, F.
(2002). Resazurin Microtiter Assay Plate: Simple and Inexpensive Method for Detection of Drug Resistance in Mycobacterium tuberculosis. Antimicrob. Agents Chemother.
46: 2720-2722
[Abstract] [Full Text] -
Brissette, C. A., Lukehart, S. A.
(2002). Treponema denticola Is Resistant to Human {beta}-Defensins. Infect. Immun.
70: 3982-3984
[Abstract] [Full Text] -
Freixo, I. M., Caldas, P. C. S., Martins, F., Brito, R. C., Ferreira, R. M. C., Fonseca, L. S., Saad, M. H. F.
(2002). Evaluation of Etest Strips for Rapid Susceptibility Testing of Mycobacterium tuberculosis. J. Clin. Microbiol.
40: 2282-2284
[Abstract] [Full Text] -
Caviedes, L., Delgado, J., Gilman, R. H.
(2002). Tetrazolium Microplate Assay as a Rapid and Inexpensive Colorimetric Method for Determination of Antibiotic Susceptibility of Mycobacterium tuberculosis. J. Clin. Microbiol.
40: 1873-1874
[Abstract] [Full Text] -
Maccari, R., Ottana, R., Monforte, F., Vigorita, M. G.
(2002). In Vitro Antimycobacterial Activities of 2'-Monosubstituted Isonicotinohydrazides and Their Cyanoborane Adducts. Antimicrob. Agents Chemother.
46: 294-299
[Abstract] [Full Text] -
Salazar, G. E., Schmitz, T. L., Cama, R., Sheen, P., Franchi, L. M., Centeno, G., Valera, C., Leyva, M., Montenegro-James, S., Oberhelman, R., Gilman, R. H., Thompson, M. J., the Working Group on TB in Peru,
(2001). Pulmonary Tuberculosis in Children in a Developing Country. Pediatrics
108: 448-453
[Abstract] [Full Text] -
Bastian, I., Rigouts, L., Palomino, J. C., Portaels, F.
(2001). Kanamycin Susceptibility Testing of Mycobacterium tuberculosis Using Mycobacterium Growth Indicator Tube and a Colorimetric Method. Antimicrob. Agents Chemother.
45: 1934-1936
[Abstract] [Full Text] -
Goloubeva, V., Lecocq, M., Lassowsky, P., Matthys, F., Portaels, F., Bastian, I.
(2001). Evaluation of Mycobacteria Growth Indicator Tube for Direct and Indirect Drug Susceptibility Testing of Mycobacterium tuberculosis from Respiratory Specimens in a Siberian Prison Hospital. J. Clin. Microbiol.
39: 1501-1505
[Abstract] [Full Text] -
Silva, P. E. A., Bigi, F., de la Paz Santangelo, M., Romano, M. I., Martín, C., Cataldi, A., Aínsa, J. A.
(2001). Characterization of P55, a Multidrug Efflux Pump in Mycobacterium bovis and Mycobacterium tuberculosis. Antimicrob. Agents Chemother.
45: 800-804
[Abstract] [Full Text] -
Lunde, C. S., Kubo, I.
(2000). Effect of Polygodial on the Mitochondrial ATPase of Saccharomyces cerevisiae. Antimicrob. Agents Chemother.
44: 1943-1953
[Abstract] [Full Text] -
Caviedes, L., Lee, T.-S., Gilman, R. H., Sheen, P., Spellman, E., Lee, E. H., Berg, D. E., Montenegro-James, S., The Tuberculosis Working Group in Peru,
(2000). Rapid, Efficient Detection and Drug Susceptibility Testing of Mycobacterium tuberculosis in Sputum by Microscopic Observation of Broth Cultures. J. Clin. Microbiol.
38: 1203-1208
[Abstract] [Full Text] -
Aínsa, J. A., Blokpoel, M. C. J., Otal, I., Young, D. B., De Smet, K. A. L., Martín, C.
(1998). Molecular Cloning and Characterization of Tap, a Putative Multidrug Efflux Pump Present in Mycobacterium fortuitum and Mycobacterium tuberculosis. J. Bacteriol.
180: 5836-5843
[Abstract] [Full Text]
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