Résumé
In this study we evaluated the crystal violet decolorization assay (CVDA) for detection of minimum inhibitory concentration (MIC) of antituberculosis drugs. 53 isolates were tested in this study and 13 of them were multidrug resistant (MDR) isolates. The antibiotics concentrations were 2-0.06 mg/L for isoniazid (INH) and rifampicin (RIF) and were 16-0.25 mg/L for streptomycin (STM) and ethambutol (EMB). Crystal violet (CV-25 mg/L) was added into the microwells on the seventh day of incubation and incubation was continued until decolorization. Decolorization of CV was the predictor of bacterial growth. Overall agreements for four drugs were detected as 98.1%, and the average time was detected as 9.5 ± 0.89 day after inoculation. One isolate for INH and two isolates for STM were determined resistant in the reference method, but susceptible by the CVDA. One isolate was susceptible to EMB by the reference method, but resistant by the CVDA. All results were concordant for RIF. This study shows that CVDA is a rapid, reliable and suitable for determination of MIC values of Mycobacterium tuberculosis. And it can be used easily especially in countries with limited-sources.
Sujets)
Humains , Antituberculeux/pharmacologie , Mycobacterium tuberculosis/effets des médicaments et des substances chimiques , Antituberculeux/administration et posologie , Dosage biologique , Multirésistance bactérienne aux médicaments/effets des médicaments et des substances chimiques , Éthambutol/administration et posologie , Éthambutol/pharmacologie , Chlorure de méthylrosanilinium/composition chimique , Indicateurs et réactifs/composition chimique , Isoniazide/administration et posologie , Isoniazide/pharmacologie , Tests de sensibilité microbienne/méthodes , Mycobacterium tuberculosis/croissance et développement , Rifampicine/administration et posologie , Rifampicine/pharmacologie , Streptomycine/administration et posologie , Streptomycine/pharmacologie , Tuberculose multirésistante/microbiologieRésumé
The purpose of this study is to evaluate four rapid colourimetric methods, including the resazurin microtitre assay (REMA), malachite green decolourisation assay (MGDA), microplate nitrate reductase assay (MNRA) and crystal violet decolourisation assay (CVDA), for the rapid detection of multidrug-resistant (MDR) tuberculosis. Fifty
Sujets)
Humains , Antituberculeux/pharmacologie , Multirésistance bactérienne aux médicaments/effets des médicaments et des substances chimiques , Tests de sensibilité microbienne/méthodes , Mycobacterium tuberculosis/effets des médicaments et des substances chimiques , Agents colorants , Indicateurs et réactifs , Sensibilité et spécificitéRésumé
The microplate nitrate reductase assay (MNRA) and the rezasurin microtitre assay (REMA) were used for the susceptibility testing of 73 clinical isolates and the results were compared with those that were obtained using the Bactec 460 TB and Bactec MGIT 960 systems. The REMA and the MNRA were performed in 96-well plates. For the REMA, the concentrations of isoniazid (INH) and rifampicin (RIF) ranged from 1.0-0.01 µg/mL and 2.0-0.03 µg/mL, respectively. For the MNRA, the INH concentration was between 1.0-0.03 µg/mL and the RIF concentration was between 2.0-0.06 µg/mL. For the MNRA, the sensitivity, specificity, positive predictive value, negative predictive value and INH/RIF agreement were 100/95.6, 97.6/100, 96.8/100, 100/98 and 98.6/98.6, respectively, and for the REMA, they were 100/91.3, 90.4/100, 88.5/100, 100/96.1 and 94.5/97.2, respectively. Our data suggest that these two rapid, low-cost methods may be inexpensive, alternative assays for the rapid detection of multidrug resistant tuberculosis in low-income countries.
Sujets)
Humains , Antituberculeux/pharmacologie , Multirésistance bactérienne aux médicaments/effets des médicaments et des substances chimiques , Isoniazide/pharmacologie , Tests de sensibilité microbienne/méthodes , Mycobacterium tuberculosis/effets des médicaments et des substances chimiques , Rifampicine/pharmacologie , Mycobacterium tuberculosis/isolement et purification , Nitrate reductase/métabolisme , Oxazines/métabolisme , Valeur prédictive des tests , Trousses de réactifs pour diagnostic , Sensibilité et spécificité , Tuberculose multirésistante/microbiologie , Xanthènes/métabolismeRésumé
The susceptibility of 49 Mycobacterium tuberculosis clinical isolates to isoniazid (INH) and rifampisin (RIF) (28 multi-drug resistant-tuberculosis samples) was determined by a nitrate reductase assay (NRA) on blood agar. Agreement between the NRA and other testing methods was found to be 93.8 percent for both INH and RIF. The sensitivity, specificity, positive predictive value and negative predictive value for INH were 92.8 percent, 94.2 percent, 86.6 percent and 97 percent, respectively. The sensitivity, specificity, positive predictive value and negative predictive value for RIF were 90.4 percent, 96.4 percent, 95 percent and 93.1 percent. In conclusion, we show here that blood agar can be used effectively for the NRA test.
Sujets)
Humains , Antituberculeux , Multirésistance bactérienne aux médicaments , Isoniazide , Mycobacterium tuberculosis , Rifampicine , Agar-agar , Tests de sensibilité microbienne , Nitrate reductase , Valeur prédictive des tests , Sensibilité et spécificité , Tuberculose multirésistanteRésumé
In this study, we have evaluated the broth microdilution method (BMM) for susceptibility testing of Mycobacterium tuberculosis. A total of 43 clinical isolates of M. tuberculosis and H37Rv as a control strain were studied. All isolates were tested by the proportion method and the BMM for isoniazid (INH), rifampicin (RIF), streptomycin (STR), and ethambutol (ETM). The proportion method was carried out according to the National Committee for Clinical Laboratory Standards (NCCLS) on Lõwenstein-Jensen (LJ) medium. The BMM was carried out using 7H9 broth with 96 well-plates. All strains were tested at 3.2-0.05 µg/ml, 16-0.25 µg/ml, 32-0.5 µg/ml, and 32-0.5 µg/ml concentrations for INH, RIF, STR, and ETM, respectively. When the BMM was compared with the proportion method, sensitivity was 100, 100, 96.9, and 90.2 percent, while specificity was 100, 85.7, 90.9, and 100 percent for INH, RIF, STR, and ETM, respectively. The plates were examined 7, 10, 14, and 21 days after incubation. The majority of the result were obtained at 14th days after incubation, while the proportion method result were ended in 21-28 days. According to our results, it may be suggested that the BMM is suitable for early determining of multidrug-resistance-M. tuberculosis strains in developed or developing countries.
Sujets)
Humains , Antituberculeux , Mycobacterium tuberculosis , Résistance microbienne aux médicaments , Éthambutol , Isoniazide , Tests de sensibilité microbienne , Rifampicine , Sensibilité et spécificité , StreptomycineRésumé
OBJECTIVES: Outcome after acute hepatitis B virus (HBV) infection may be determined by the host immune system. We studied the distribution of major histocompatibility (MHC) antigens in patients who developed natural immunity against HBV and those with chronic hepatitis B. METHODS: Thirty patients positive for IgG anti-HBs and anti-HBc ('naturally immune'), 30 patients with HBsAg-positive chronic hepatitis and 30 subjects with no serological markers of HBV infection (controls) were studied. MHC class-I antigens were detected by the standard Terasaki microlymphocytotoxicity test and the MHC class-II antigens by a polymerase chain reaction using sequence-specific primers. RESULTS: In the naturally immune group, A11, B73, CW3, DRB1*16 and DQB1*05 antigens were significantly more frequent than in the control group, and B73, DRB1*04 and DRB1*13 antigens were more frequent than in the chronic hepatitis group. In the chronic hepatitis group, CW6, DRB5 and DQB1*05 antigens were significantly more frequent than in the control group, and B8, CW7, DRB1*03 and DQB1*02 antigens were more frequent than in the naturally immune group. CONCLUSIONS: Differences in alleleic frequencies of HLA among persons with natural immunity against HBV and those with chronic hepatitis B may suggest a genetic basis for persistence of HBV infection and occurrence of chronic liver disease.
Sujets)
Adulte , Études cas-témoins , Femelle , Antigènes HLA/immunologie , Hépatite B chronique/immunologie , Humains , Complexe majeur d'histocompatibilité/immunologie , Mâle , Pronostic , Facteurs de risqueRésumé
The aim of this study was to investigate the correlation between proportion method with mycobacteria growth indicator tube (MGIT) and E-test for Mycobacterium tuberculosis. Forty clinical isolates were tested. MGIT and E-test with the first line antituberculous drugs correlated with the proportion method. Our results suggested that MGIT and E-test methods can be routinely used instead of the proportion method