Acute renal failure after rifampicin

A patient with miliary tuberculosis and a chronic urogenital focus is described, who had a borderline renal function at diagnosis and developed overt renal failure upon daily treatment with rifampin (RMP), isoniazid (INH) and ethambutol (EMB). This is the first Brazilian report of BMP induced renal damage. A renal biopsy taken on the third day of oliguria showed recent tubular necrosis with acute interstitial inflammation and granuloma formation. The aspect of the granulomatous lesion hightly suggested drug etiology because of the lack of palisading, high incidence of neutrophils and absence of facid-fast bacilli. This is the first presentation of an acute granulomatous interstitial nephritis probably due to RMP. Furthermore the pathogenesis of the renal damage caused by tuberculosis and RMP are discussed.

Radiometric studies of mycobacterium tuberculosis

An in vitro assay system that included automated radiometric quantification of 14CO2 released as a result of oxidation of 14C- substrates was applied for studying the metabolic activity of M. tuberculosis under various experimental conditions. These experiments included the study of a) mtabolic pathways, b) detection times for various inoculum sizes, c) effect of filtration on reproducibility of results, d) influence of stress environment e) minimal inhibitory concentrations for isoniazid, streptomycin, ethambutol and rifampin, and f) generation times of M. tuberculosis and M. bovis. These organisms were found to metabolize 14C-for-mate, (U-14C) acetate, (U-14C) glycerol, (1-14C) palmitic acid, 1-14C) lauric acid, (U-14C) L-malic acid, (U-14C) D-glucose, and (U-14C) D-glucose, but not (1-14C) L-glucose, (U-14C) glycine, or (U-14C) pyruvate to 14CO2. By using either 14C-for-mate, (1-14C) palmitic acid, or (1-14C) lauric acid, 10(7) organisms/vial could be detected within 24 48 hours and as few as 10 organisms/vial within 16-20 days. Reproducible results could be obtained without filtering the bacterial suspension, provided that the organisms were grown in liquid 7H9 medium with 0.05% polysorbate 80 and homogenized prior to the study. Drugs that block protein synthesis were found to have lower minimal inhibitory concentrations with the radiometric method when compared to the conventional agar dilution method. The mean generation time obtained for M. bovis and different strains of M. tuberculosis with various substrates was 9 ± 1 hours.

Tuberculosis in patients with chronic renal failure

Nine cases of tuberculosis (TB) were diagnosed among 800 uremic patients, followed-up during 11 years, a prevalence of 1125%, 2.5 times higher than that in the general population. Six patients (66.7%) had lymph node involvement (4 cervical and 2 mediastinal). Three patients (33.3%) had pulmonary involvement (2 pleuro-pulmonary and 1 bilateral apical pulmonary). Eight patients were undergoing dialysis and 1 was pre-dialytic. The duration of dialysis ranged from 1 to 60 months. Three patients had previously received immunosuppressive drugs for unsuccessful renal transplantation. Daily fever was present in all but one patient; he was asymptomatic and TB was suspected after routine chest radiography. Biopsy was the diagnostic procedure in 7 patients (77.8%), four by direct cervical lymph node biopsy, 2 by mediastinal, performed by mediastinoscopy and 1 by pleural biopsy. In 2 other patients TB was confirmed by the presence of tubercle bacilli; in sputum (1 patient) and in a bronchial flushing specimen (the other patient). Triple therapy was used in all patients (isoniazid and ethambutol in all), plus rifampicin in 8 and streptomycin in 1. One patient had jaundice and another had optical neuritis. Five patients were cured. The other four died during treatment of causes unrelated to TB or its treatment.

Optochiasmatic tuberculoma as the sole manifestation of late recurrent tuberculosis

Brain tuberculomas account for 10-20% of space occupying brain lesions in developing countries. Most lesions are observed at time of tuberculosis diagnosis or soon after starting treatment. We herein describe a 32 year-old patient with a 14-month history of headache and progressive visual loss. Her past medical history revealed pulmonary tuberculosis treated eight years before. A brain MRI showed a T1- and T2-weighted isointense contrast-enhancing lesion in the optic chiasm. A presumptive diagnosis of optochiasmatic tuberculoma was made and isoniazid, rifampin, pyrazinamide, and ethambutol were started. Despite treatment, the patient evolved to blindness. The prompt recognition of this condition is extremely important since the presence of optochiasmal enhancement is associated with blindness in patients with tuberculosis.

Standartization of broth microdilution method for Mycobacterium tuberculosis

Indirect drug susceptibility tests of Mycobacterium tuberculosis was done to investigate the accuracy and feasibility of a broth microdilution method (BMM) for determining minimal inhibitory concentrations of conventional drugs against M. tuberculosis. Test drugs included isoniazid (H), rifampicin (R), ethambutol (E), streptomycin (S) and pyrazinamide (Z). Fifty isolates of M. tuberculosis from patients who had never received drug therapy, and H37Rv strain for control, were evaluated in the system. When comparing this method with the gold standard proportional method in Lowenstein-Jensen medium, sensitivity of 100% for all drugs and specifities of 91, 100, 96, 98 and 85% were observed respectively for H, R, E, S and Z. The BMM was read faster (14-20 days) than the proportional method (20-28 days). The microdilution method evaluated allows the testing of multiple drugs in multiple concentrations. It is easy to perform and does not require special equipment or expensive supplies. In contrast to radiometric method it does not use radioactive material.

Direct Sensitivity Test of the MB/BacT System

In order to evaluate the direct-method test of sensitivity to drugs used in the principal tuberculosis treatment regimes, in the Organon Teknika MB/BacT system, we tested 50 sputum samples positive to microscopy taken from patients with pulmonary tuberculosis and with clinical indications for an antibiogram, admitted sequentially for examination during the routine of the reference laboratory. The material was treated v/v with 23% trisodium phosphate solution, incubated for 24 h at 35°C, and neutralized v/v with 20% monosodium phosphate solution. The material was then centrifuged and the sediment inoculated into flasks containing Rifampin - 2 µg/ml, Isoniazid - 0.2 µg/ml, Pyrazinamide - 100 µg/ml, Ethambutol - 2.5 µg/ml, Ethionamide - 1.25 µg/ml, and Streptomycin - 2 µg/ml. The tests were evaluated using the indirect method in the BACTEC 460 TB (Becton Dickinson) system as the gold standard. The results showed that the Rifampin test performed best, i.e., 100% sensitivity at 95% Confidence Interval (82.2-100) and 100% specificity at 95% Confidence Interval (84.5-100), followed by Isoniazid and Pyrazinamide. In this experiment, 92% of the materials showed a final reading in 30 days; this period represents the time for primary isolation as well as the results of the sensitivity profile, and is within Centers for Disease Control and Prevention recommendations regarding time for performance of the antibiogram. The inoculated flasks showed no contamination during the experiment. The MB/BacT is shown to be a reliable, rapid, fully automated nonradiometric system for the tuberculosis antibiogram.

Evaluation of indirect susceptibility testing of Mycobacterium tuberculosis to the first- and second-line, and alternative drugs by the newer MB/BacT system

In order to evaluate the Organon Teknika MB/BacT system used for testing indirect susceptibility to the alternative drugs ofloxacin (OFLO), amikacin (AMI), and rifabutin (RIF), and to the usual drugs of standard treatment regimes such as rifampin (RMP), isoniazid (INH), pyrazinamide (PZA), streptomycin (SM), ethambutol (EMB), and ethionamide (ETH), cultures of clinical specimens from 117 patients with pulmonary tuberculosis under multidrug-resistant investigation, admitted sequentially for examination from 2001 to 2002, were studied. Fifty of the Mycobacterium tuberculosis cultures were inoculated into the gold-standard BACTEC 460 TB (Becton Dickinson) for studying resistance to AMI, RIF, and OFLO, and the remaining 67 were inoculated into Lowenstein Jensen (LJ) medium (the gold standard currently used in Brazil) for studying resistance to RMP, INH, PZA, SM, EMB, and ETH. We observed 100% sensitivity for AMI (80.8-100), RIF (80.8-100), and OFLO (78.1-100); and 100% specificity for AMI (85.4-100), RIF (85.4-100), and OFLO (86.7-100) compared to the BACTEC system. Comparing the results obtained in LJ we observed 100% sensitivity for RMP (80-100), followed by INH - 95% (81.8-99.1), EMB - 94.7% (71.9-99.7), and 100% specificity for all drugs tested except for PZA - 98.3 (89.5-99.9) at 95% confidence interval. The results showed a high level of accuracy and demonstrated that the fully automated, non-radiometric MB/BacT system is indicated for routine use in susceptibility testing in public health laboratories.

Drug susceptibility testing of Mycobacterium tuberculosis by the broth microdilution method with 7H9 broth

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 Löwenstein-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%, while specificity was 100, 85.7, 90.9, and 100% 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.

Drug susceptibility of Brazilian strains of Mycobacterium bovis using traditional and molecular techniques

Transmission of Mycobacterium bovis from cattle to humans has been reported and can cause tuberculosis (Tb) and a problem in certain risk populations. Therefore, knowledge of resistance of M. bovis towards antibiotics used for therapy of human Tb could help avoiding cure delay and treatment cost increase when dealing with drug resistant organisms. We therefore evaluated the susceptibility of M. bovis isolates towards streptomycin, isoniazide, rifampicin, ethambutol, and ethionamide, the first line antibiotics for human Tb. Therefore, 185 clinical samples from cattle with clinical signs of tuberculosis were processed and submitted to culturing and bacterial isolates to identification and drug susceptibility testing using the proportion method. Among 89 mycobacterial strains, 65 were identified as M. bovis and none were resistant to any of the antibiotics used. Confirmation of present results by future studies, enrolling a large number of isolates and designed to properly represent Brazilian regions, may favor the idea of using isoniazide preventive therapy as part of a Tb control strategy in special situations. Also, nucleic acids from bacterial isolates were submitted to rifoligotyping, a recently described reverse hybridization assay for detection of mutations causing resistance towards rifampicin. Concordance between the conventional and the molecular test was 100%, demonstrating the use of such methodology for rapid evaluation of drug susceptibility in M. bovis.

Evaluation of rapid alternative methods for drug susceptibility testing in clinical isolates of Mycobacterium tuberculosis

A study was carried out to compare the performance of a commercial method (MGIT) and four inexpensive drug susceptibility methods: nitrate reductase assay (NRA), microscopic observation drug susceptibility (MODS) assay, MTT test, and broth microdilution method (BMM). A total of 64 clinical isolates of Mycobacterium tuberculosis were studied. The Lowenstein-Jensen proportion method (PM) was used as gold standard. MGIT, NRA, MODS, and MTT results were available on an average of less than 10 days, whereas BMM results could be reported in about 20 days. Most of the evaluated tests showed excellent performance for isoniazid and rifampicin, with sensitivity and specificity values > 90%. With most of the assays, sensitivity for ethambutol was low (62-87%) whereas for streptomycin, sensitivity values ranged from 84 to 100%; NRA-discrepancies were associated with cultures with a low proportion of EMB-resistant organisms while most discrepancies with quantitative tests (MMT and BMM) were seen with isolates whose minimal inhibitory concentrations fell close the cutoff. MGIT is reliable but still expensive. NRA is the most inexpensive and easiest method to perform without changing the organization of the routine PM laboratory performance. While MODS, MTT, and BMM, have the disadvantage from the point of view of biosafety, they offer the possibility of detecting partial resistant strains. This study shows a very good level of agreement of the four low-cost methods compared to the PM for rapid detection of isoniazid, rifampicin and streptomycin resistance (Kappa values > 0.8); more standardization is needed for ethambutol.

Susceptibility of Mycobacterium tuberculosis to first-line antimycobacterial agents in a Brazilian hospital: assessing the utility of the tetrazolium (MTT) microplate assay

We conducted a cross-sectional, hospital-based study between January 2006-March 2008 to estimate the resistance of Mycobacterium tuberculosis to first-line drugs in patients with tuberculosis at a Brazilian hospital. We evaluated the performance of the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide] (MTT) microplate assay compared with the Bactec-MGIT 960™ system for mycobacteria testing. The prevalence of resistance in M. tuberculosis was 6.7%. Multidrug-resistance [resistance to rifampicin (RMP) and isoniazid (INH)], INH-resistance and streptomycin (SM)-resistance accounted for 1%, 3.8% and 3.8% of all resistance, respectively, and all isolates were susceptible to ethambutol (EM). The resistance was primary in four cases and acquired in three cases and previous treatment was associated with resistance (p = 0.0129). Among the 119 M. tuberculosis isolates, complete concordance of the results for INH and EM was observed between the MTT microplate and Bactec-MGIT 960TM methods. The observed agreement for RMP was 99% (sensitivity: 90%) and 95.8% for SM (sensitivity 90.9%), lower than those for other drugs. The MTT colourimetric method is an accurate, simple and low-cost alternative in settings with limited resources.

A population-based study of first and second-line drug-resistant tuberculosis in a high-burden area of the Mexico/United States border

The resistance of 139 Mycobacterium tuberculosis (MTB) isolates from the city of Monterrey, Northeast Mexico, to first and second-line anti-TB drugs was analysed. A total of 73 isolates were susceptible and 66 were resistant to anti-TB drugs. Monoresistance to streptomycin, isoniazid (INH) and ethambutol was observed in 29 cases. Resistance to INH was found in 52 cases and in 29 cases INH resistance was combined with resistance to two or three drugs. A total of 24 isolates were multidrug-resistant (MDR) resistant to at least INH and rifampicin and 11 MDR cases were resistant to five drugs. The proportion of MDR-TB among new TB cases in our target population was 0.72% (1/139 cases). The proportion of MDR-TB among previously treated cases was 25.18% (35/139 cases). The 13 polyresistant and 24 MDR isolates were assayed against the following seven second-line drugs: amikacin (AMK), kanamycin (KAN), capreomycin (CAP), clofazimine (CLF), ethionamide (ETH), ofloxacin (OFL) and cycloserine (CLS). Resistance to CLF, OFL or CLS was not observed. Resistance was detected to ETH (10.80%) and to AMK (2.70%), KAN (2.70%) and CAP (2.70%). One isolate of MDR with primary resistance was also resistant to three second-line drugs. Monterrey has a high prevalence of MDR-TB among previously treated cases and extensively drug-resistant-MTB strains may soon appear.

BCG lymphadenopathy detected in a BCG-vaccinated infant

Large-scale vaccination with BCG, the live attenuated strain of Mycobacterium bovis, is being adopted around the world, although sporadic complications have occurred after the procedure. Lymphadenopathy is not uncommon especially in babies under one year (0.73% of vaccinated infants), but the swelling subsides within 2 months in most cases, with no medical or surgical treatment. Brazil adopted BCG vaccination program earlier in the seventies and by 1995 more than 96% of the infant population received this immunization. We report here the occurrence of lymphadenopathy in a two-year-old child vaccinated with the Brazilian BCG strain. The diagnosis was made using a lymph node biopsy and intestinal aspirates that yielded a positive mycobacterial culture. The isolate was resistant to isoniazid, rifampicin, pyrazinamide and thiophen-2-carbonic acid hydrazide, sensitive to streptomycin, ethambutol, and p-nitrobenzoic acid, and reacted positively to cyclo-serine and negatively to niacin. The pncA gene involved in bacterial activation of pyrazinamide contains in M. bovis a point mutation that renders pyrazinamidase unable to catalyze drug activation. Therefore, this polymorphism is a good option for developing methods to differentiate M. bovis and M. tuberculosis. Taking advantage of this difference we further analyzed the isolates by single-stranded conformation polymorphism electrophoresis of DNA following PCR of the pncA gene. The isolate identity was confirmed by RFLP electrophoretic analysis of the amplified fragment following Eco065I digestion, which selectively cleaves M. tuberculosis DNA. From this result it is proposed that RFLP of pncA gene represents an alternative for differential diagnosis of M. bovis.

Tuberculosis in renal transplant patients: The experience of a single center in Medellín-Colombia, 2005-2013

Introduction: Tuberculosis is a common opportunistic infection in renal transplant patients. Objective: To obtain a clinical and laboratory description of transplant patients diagnosed with tuberculosis and their response to treatment during a period ranging from 2005 to 2013 at the Pablo Tobón Uribe Hospital. Methods: Retrospective and descriptive study. Results: In 641 renal transplants, tuberculosis was confirmed in 12 cases. Of these, 25% had a history of acute rejection, and 50% had creatinine levels greater than 1.5 mg/dl prior to infection. The disease typically presented as pulmonary (50%) and disseminated (33.3%). The first phase of treatment consisted of 3 months of HZRE (isoniazid, pyrazinamide, rifampicin and ethambutol) in 75% of the cases and HZME (isoniazid, pyrazinamide, moxifloxacin and ethambutol) in 25% of the cases. During the second phase of the treatment, 75% of the cases received isoniazid and rifampicin, and 25% of the cases received isoniazid and ethambutol. The length of treatment varied between 6 and 18 months. In 41.7% of patients, hepatotoxicity was associated with the beginning of anti-tuberculosis therapy. During a year-long follow-up, renal function remained stable, and the mortality rate was 16.7%. Conclusion: Tuberculosis in the renal transplant population studied caused diverse nonspecific symptoms. Pulmonary and disseminated tuberculosis were the most frequent forms and required prolonged treatment. Antituberculosis medications had a high toxicity and mortality. This infection must be considered when patients present with a febrile syndrome of unknown origin, especially during the first year after renal transplant.