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San Fernando del Valle de Catamarca, Argentina

Imperiale B.R.,Reference Laboratory of Tuberculosis Control Program | Di Giulio A.B.,Mycobacteria Laboratory | Cataldi A.A.,Instituto Nacional de Tecnologia Agropecuaria | Morcillo N.S.,Reference Laboratory of Tuberculosis Control Program
Journal of Antibiotics

The emergence of drug-resistant, multidrug-resistant and extensively drug-resistant tuberculosis (TB) is of major public health concern in several countries. In this study, the pharmacodynamic relationships among the structural analogs of antibiotics belonging to the same family were taken into consideration. The aim of this study was to compare the susceptibility of Mycobacterium tuberculosis to isoniazid (INH), rifampicin and levofloxacin (LX) to their respective structural analogs, which are frequently used as second-line agents. The microplate colorimetric method was used to determine the MIC to INH, ethionamide (ETH), rifampicin, rifabutin, LX and moxifloxacin (MOX) in clinical isolates previously shown to be drug resistant. Mutations conferring drug resistance were detected by GenoType MTBDR plus and DNA sequencing. INH and ETH cross-resistance was found in 95.12% (39/41) of the INH-resistant isolates harboring a mutation in inhAP or inhA open reading frame, but rifabutin cross-resistance was observed in 90.0% (63/70) of the clinical isolates originally shown to be resistant to rifampicin. Isolates with high LX-resistance levels also showed high MIC to MOX. Fluoroquinolone cross-resistance was verified in isolates containing the gyrA94 and the gyrA90 mutation. In general, isolates with high INH, rifampicin and LX-resistance levels also displayed high MIC values for their structural analogs. These findings suggest the need to test in vitro the second-line drugs before their incorporation in the therapeutic schemes. © 2014 Japan Antibiotics Research Association All rights reserved 0021-8820/14. Source

Morcillo N.S.,Reference Laboratory of Tuberculosis Control Program of Buenos Aires Province | Imperiale B.R.,Reference Laboratory of Tuberculosis Control Program of Buenos Aires Province | Di Giulio A.,Mycobacteria Laboratory | Zumarraga M.J.,Instituto Nacional de Tecnologia Agropecuaria | And 2 more authors.

There has been an on-going debate on whether the development of drug resistance in Mycobacterium tuberculosis reduces its relative fitness and its ability to cause disease. The aim of this study was to explore this relationship. For this purpose, we evaluated the in vitro growth of clinical isolates and the transmission of the strains within the patients' households. Clinical and epidemiological data from patients in households, drug-susceptibility and genetic patterns of the isolates were collected. BACTEC MGIT 960™ system with the Epicenter™ software was used to perform fitness experiments and calculate the relative fitness (RF) comparing with the H73Rv reference strain. From 39 households, 124 patients and 388 contacts were included. Concerning transmission, 20 Multi drug-resistant (MDR) and 16 drug sensitive (DS) index cases generated 23 and 28 secondary cases, respectively. An average RF drop of 16.7% was found for MDR strains, but only mutations in rpoB codons 531 were associated with reduced fitness. When the strains were transmitted, their RF tended to decrease, and strains with low RF were less frequently transmitted. Within the limitations of this study, the results showed that the decrease in RF was associated to a limited transmission among the households' contacts. © 2014 Elsevier Ltd. Source

Verma R.,Indian Veterinary Research Institute | Verma R.,Mycobacteria Laboratory | Sena D.S.,National Research Center on Camel | Sharma N.,National Research Center on Camel | And 4 more authors.
Indian Journal of Animal Sciences

An adult male camel was diagnosed with tuberculosis (TB). It exhibited typical TB lesions in the lungs, liver and spleen. The histopathological examination of sections of tissues revealed presence of acid-fast bacilli. Mycobacteria were isolated from the camel's lung and were identified as the member of Mycobacterium tuberculosis complex (MTBC) subsequently confirmed as M. bovis by biochemical tests and multiplex PCR where 445 bp band indicative of MTBC and 823 bp band indicative of M. bovis was observed. Source

Imperiale B.R.,Reference Laboratory of Tuberculosis Control Program of Buenos Aires Province | Zumarraga M.J.,BioTechnology Institute | Di Giulio A.B.,Mycobacteria Laboratory | Cataldi A.A.,BioTechnology Institute | Morcillo N.S.,Reference Laboratory of Tuberculosis Control Program of Buenos Aires Province
International Journal of Tuberculosis and Lung Disease

SETTING: Dr Cetrángolo Hospital, Buenos Aires, Argentina. OBJECTIVES: To characterise drug-resistant (DR), multidrug-resistant (MDR-) and extensively drug-resistant (XDR-) Mycobacterium tuberculosis isolates, and identify their genetic profiles, drug resistance levels and resistance- conferring mutations. DESIGN: Phenotypic drug susceptibility testing methods were used to determine drug resistance profiles. Minimal inhibitory concentrations (MICs) of isoniazid (INH), rifampicin (RMP) and levofloxacin (LVX) from 169 DR tuberculosis (TB) isolates, 78 of them monoresistant to INH, 13 to RMP, 7 to LVX, and 71 MDR-TB, were determined. Multiplex allele-specific polymerase chain reaction and DNA sequencing were used to detect mutations in katG, rpoB and gyrA/B genes. Genotyping was performed using spoligotyping and insertion sequence 6110 restriction fragment length polymorphism. RESULTS: In total, 38.9% of the INH-resistant (INHR) isolates had an MIC ≥ 32 μg/ml; 61.3% of the RMP-resistant (RMPR) isolates had an MIC ≥ 64 μg/ml and 55.6% of the LVX-r esistant (LVXR) isolates had an MIC 4-≥16 μg/ml. The main mutations found in INHR isolates were katG315 (53.7%) and inhAP-15 (25.5%), whereas in RMPR isolates the main mutations were rpoB531 (61.9%), followed by rpoB526 (16.7%). LVX R isolates showed mutations in gyrA94/90. Haarlem, LAM and T were the main spoligotyping families found. katG315 was mainly associated with Haarlem and LAM, whereas inhAP-15 was associated with T. CONCLUSIONS: Several isolates showed an association between high INHR levels and katG mutation; others from the Haarlem family were prone to becoming MDR-TB and continue to circulate in the community. © 2013 The Union. Source

Kidangan A.,Indian Veterinary Research Institute | Verma R.,Indian Veterinary Research Institute | Verma R.,Mycobacteria Laboratory
Indian Journal of Animal Sciences

The usefulness of polymerase chain reaction-single stranded confirmation polymorphism (PCR-SSCP) for determination of rifampicin and isoniazid resistance in Mycobacterium tuberculosis and M. bovis cultures from human and animal origin was investigated. Mycobacteria (81) in the study included, viz. 12 MDR-TB samples, 35 sputum samples, 3 lung and lymphnode tissues from bovines and 11 M. tuberculosis and 18 M. bovis culture, M. tuberculosis H37Rv and M. bovis BCG strain). All the mycobacterial cultures were characterized on growth characteristics, biochemical test pattern, MTB complex specific IS6110 PCR and species specific 12.7 kb multiplex PCR. PCR-SSCP was used to determine resistance against rifiampin by targeting rpoB gene (305 bp) and isoniazid by targeting katG (237 bp) and inhA (261 bp). Rifampicin resistance was detected by PCR-SSCP in 1 out of 12 MDR-TB samples (8.3%), while isoniazid resistance was detected in 66.7% of MDR-TB samples using PCR-SSCP of katG and 75% of MDR-TB samples using inhA SSCP analysis. Source

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