Background Whole-genome sequencing has shown that the Mycobacterium tuberculosis infection proces... more Background Whole-genome sequencing has shown that the Mycobacterium tuberculosis infection process can be more heterogeneous than previously thought. Compartmentalized infections, exogenous reinfections, and microevolution are manifestations of this clonal complexity. The analysis of the mechanisms causing the microevolution —the genetic variability of M. tuberculosis at short time scales— of a parental strain into clonal variants with a patient is a relevant issue that has not been yet completely addressed. To our knowledge, a whole genome sequence microevolution analysis in a single patient with inadequate adherence to treatment has not been previously reported. Case presentation In this work, we applied whole genome sequencing analysis for a more in-depth analysis of the microevolution of a parental Mycobacterium tuberculosis strain into clonal variants within a patient with poor treatment compliance in Argentina. We analyzed the whole-genome sequence of 8 consecutive Mycobacteri...
The International Journal of Tuberculosis and Lung Disease
A multicentre evaluation was performed to assess two rapid low-cost methods, MTT (3-[4.5dimethylt... more A multicentre evaluation was performed to assess two rapid low-cost methods, MTT (3-[4.5dimethylthiazol-2-yl]-2.5-diphenyltetrazolium bromide) and resazurin assays, for testing the susceptibility of Mycobacterium tuberculosis to the first-line anti-tuberculosis drugs rifampicin (RMP), isoniazid (INH), ethambutol (EMB) and streptomycin (SM). M E T H O D S : Thirty coded M. tuberculosis strains were sent to seven laboratories located in Latin America, representing six countries. Each site performed the colorimetric assays, MTT and resazurin, blind for the first-line drugs RMP, INH, EMB and SM. The minimum inhibitory concentration results obtained were compared to the conventional proportion method on Löwenstein-Jensen medium. R E S U L T S : After establishing the breakpoint concentrations, excellent results were obtained for RMP, INH and EMB, with levels of specificity and sensitivity of between 96% and 99%. C O N C L U S I O N : MTT and resazurin assays are promising, accessible new alternative methods for middle-and low-resource countries that need low-cost methods to perform rapid susceptibility testing of M. tuberculosis to key anti-tuberculosis drugs.
The Journal of antimicrobial chemotherapy, Jan 25, 2018
To describe the distributions of bedaquiline and linezolid MIC values for the Mycobacterium tuber... more To describe the distributions of bedaquiline and linezolid MIC values for the Mycobacterium tuberculosis WT population and to define the corresponding epidemiological cut-offs (ECOFFs) in three Latin American countries. MICs of bedaquiline and linezolid were determined by the resazurin microtitre assay (REMA). In phase 1, interlaboratory reproducibility was assessed using a panel of 10 fully susceptible M. tuberculosis strains. Phase 2 involved MIC determination for 248 clinical isolates from Argentina (n = 58), Brazil (n = 100) and Peru (n = 90) from patients who were treatment-naive for bedaquiline and linezolid. We then determined the ECOFFs for bedaquiline and linezolid by the eyeball method and the ECOFFinder statistical calculator. Phase 1: REMA MIC values in the three sites were either identical to each other or differed by one 2-fold dilution from the consensus value with the exception of a single value. Phase 2: the bedaquiline MIC range was 0.0039-0.25 mg/L for pan-suscept...
The "Spanish" flu pandemic, which occurred a century ago, is considered the most devast... more The "Spanish" flu pandemic, which occurred a century ago, is considered the most devastating in human history. An estimated one third of world population fell ill with flu and more than 2.5% of them died. The course of the epidemic had two main waves (1918 and 1919) and showed an unusual W-shaped morbidity/mortality distribution. Death was not a direct outcome of flu itself but rather a consequence of secondary bacterial bronchopneumonia, for which antibiotics had not yet been discovered. Pre-existing pulmonary tuberculosis was also accountable for increased flu death rates during the pandemic. As it happened in Europe, in Argentina the epidemic had two main waves, with ample variation in mortality by region. Available treatment at the time included diet, throat antiseptic rinses, low doses of quinine valerianate, salicylates, codeine as a cough suppressant, and camphor oil. Primitive anti-pneumococcal vaccines and immune sera were also applied. Upon the disclosure of the ...
The possibility of using BCG-a Mycobacterium bovis strain of attenuated virulence-for PPD product... more The possibility of using BCG-a Mycobacterium bovis strain of attenuated virulence-for PPD production instead of a virulent strain of M. bovis has been considered to avoid the biological risks involved in the procedure. The potency and specificity of a PPD tuberculin prepared from BCG was compared in guinea pigs with that of PPD produced from strain AN5 (two batches), a virulent strain of M. bovis: the European Communities Standard (ECS), and a reference batch prepared at the Pan American Zoonoses Center (CPZ). The potency of the BCG-PPD was also assessed in cows naturally infected with M. bovis in comparison with the other two PPD and a third (WS) produced at the Central Veterinary Laboratory, Weybridge, United Kingdom. Finally, the antigenic value of BCG-PPD was compared with that of CPZ and ECS in an ELISA against sera from tuberculous and healthy cattle. In the above assays, BCG-PPD showed a lower sensitivity and specificity than PPD produced from virulent M. bovis. Therefore its use either for tuberculin testing of cattle or as antigen in the ELISA test for detecting bovine IgG anti-M. bovis antibodies would not seem advisable.
C5a anaphylatoxin is a component of the complement system involved in the modulation of T-cell po... more C5a anaphylatoxin is a component of the complement system involved in the modulation of T-cell polarization. Herein we investigated whether C5a receptors, C5aR and C5L2, modulate the cytokine profiles induced by Mycobacterium tuberculosis (Mtb). We analyzed the impact of both receptors on T helper cell polarization induced by the multidrug resistant outbreak strain named M, which is a poor IFN-γ inducer compared with the laboratory strain H37Rv. To this aim, we first blocked C5aR or C5L2 of peripheral blood monocytes (Mo) from patients with tuberculosis and healthy donors, then we stimulated the Mo either with H37Rv or the M strain, and finally we analyzed cytokine profiles of Mo/macrophages (MΦ) and CD4(+) T-cells. We found that: (i) Mtb modulated the expression of both C5a receptors, (ii) C5aR inhibited the expansion of CD4(+)IFN-γ(+) lymphocytes stimulated by the M strain but not by H37Rv, (iii) both receptors modulated the Mo/MΦ cytokine expression induced by Mtb. We conclude that C5aR, but not C5L2, plays a role in T helper cell polarization induced by Mtb and that this effect is strain- and donor-dependent. We speculate that the epidemiologically successful M strain takes advantage of this C5aR-mediated inhibition of Th1 polarization to survive within the host.
The tuberculosis (TB) epidemic is fueled by a parallel Human Immunodeficiency Virus (HIV) epidemi... more The tuberculosis (TB) epidemic is fueled by a parallel Human Immunodeficiency Virus (HIV) epidemic, but it remains unclear to what extent the HIV epidemic has been a driver for drug resistance inMycobacterium tuberculosis (Mtb). Here we assess the impact of HIV co-infection on the emergence of resistance and transmission ofMtbin the largest outbreak of multidrug-resistant TB in South America to date. By combining Bayesian evolutionary analyses and the reconstruction of transmission networks utilizing a new model optimized for TB, we find that HIV co-infection does not significantly affect the transmissibility or the mutation rate ofMtbwithin patients and was not associated with increased emergence of resistance within patients. Our results indicate that the HIV epidemic serves as an amplifier of TB outbreaks by providing a reservoir of susceptible hosts, but that HIV co-infection is not a direct driver for the emergence and transmission of resistant strains.
Background The Mtb strain (LAM3/SIT33 genotype) named Ra was first detected in 1994 as causing an... more Background The Mtb strain (LAM3/SIT33 genotype) named Ra was first detected in 1994 as causing an HIVrelated MDR-TB outbreak in a referral hospital, Rosario, Argentina, 1994-96 [1]. Although hospital transmission has long been contained, the Ra strain is still circulating in the community and occasionally appears in sites distant from the outbreak hotspot [2]. Purpose This study aims to gain insight into strain evolution and transmission dynamics of the Ra strain.
Background. The growing international mobility of persons may hinder efforts made in low-resource... more Background. The growing international mobility of persons may hinder efforts made in low-resource countries to control tuberculosis (TB). During a study originally aimed to explore tuberculosis transmission among Paraguayan patients, evidence was found of across-border migration of a multidrug-resistant (MDR) Mycobacterium tuberculosis strain. Methods. The study population consisted of 166 patients with AFB smear positive pulmonary tuberculosis enrolled in the national survey of tuberculosis drug resistance in 2002-2003. M. tuberculosis drug susceptibility was determined by the proportion method on solid medium. IS6110 DNA fingerprinting and spoligotyping were performed according to internationally standardized methods. The software BioNumerics (Applied Maths, Belgium) was used for computer-assisted analysis and comparison with genotypes held in the Argentinean database. Results and Discussion. One of the isolates showed both IS6110 fingerprint and spoligopattern of a notorious mult...
A remarkable input to the epidemiology of tuberculosis was not the only benefit of the molecular ... more A remarkable input to the epidemiology of tuberculosis was not the only benefit of the molecular tools developed in the early nineties for Mycobacterium tuberculosis intra-species differentiation. These genotyping methods served also to unveil specimen cross-contamination, which was until then overlooked in laboratories culturing mycobacteria. This error consists in the accidental carry-over of bacilli from a specimen with high bacterial load to that, or those, processed subsequently. The ensuing detection of falsely positive cultures can result in a wrong diagnosis of tuberculosis and the initiation of a long-lasting treatment with potentially toxic drugs. This series of errors implies the mismanagement of patients, the distraction of public health system resources, and the distortion of epidemiological data. M. tuberculosis laboratory cross-contamination was detected wherever investigated systematically, with a median rate of 3% of all positive cultures. The confirmation of this e...
The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease, 2005
A multicentre evaluation was performed to assess two rapid low-cost methods, MTT (3-[4.5-dimethyl... more A multicentre evaluation was performed to assess two rapid low-cost methods, MTT (3-[4.5-dimethylthiazol-2-yl]-2.5-diphenyltetrazolium bromide) and resazurin assays, for testing the susceptibility of Mycobacterium tuberculosis to the first-line anti-tuberculosis drugs rifampicin (RMP), isoniazid (INH), ethambutol (EMB) and streptomycin (SM). Thirty coded M. tuberculosis strains were sent to seven laboratories located in Latin America, representing six countries. Each site performed the colorimetric assays, MTT and resazurin, blind for the first-line drugs RMP, INH, EMB and SM. The minimum inhibitory concentration results obtained were compared to the conventional proportion method on Lowenstein-Jensen medium. After establishing the breakpoint concentrations, excellent results were obtained for RMP, INH and EMB, with levels of specificity and sensitivity of between 96% and 99%. MTT and resazurin assays are promising, accessible new alternative methods for middle- and low-resource cou...
Polylactide-glycolide (PLGA) nanoparticles have been developed as pulmonary drug delivery carrier... more Polylactide-glycolide (PLGA) nanoparticles have been developed as pulmonary drug delivery carriers. To investigate their behavior, small-(d50 = 74 nm) and large-sized (d50 = 250 nm) FITC-conjugated PLGA nanoparticles were intratracheally administered to rats and were traced for 5, 30 and 60 minutes and 24 hours after administration (HAT). Immunohistochemically, a, FITCpositive reaction was observed in type-I alveolar epithelial cells (type-I AEC), endothelial cells and alveolar macrophages in the lungs from 5 minutes after treatment (MAT) to 24 HAT in both nanoparticle groups. In the kidneys, a positive reaction was observed in proximal tubular epithelial cells at 30 MAT; the reaction peaked at 60 MAT and was reduced at 24 HAT, while no positive reaction was seen in other sites. Ultrascructurally, the number of membrane-bound vesicles, which were approximately 70 nm in size and hard to distinguish from pinocytic vesicles, apparently increased in type-I AEC and endothelial cells at 5 MAT in the small-sized group, in comparison with the control group receiving physiological saline. The number of vesicles in the large-sized group was almost same as that in the control group. On the other hand, in both nanoparticle groups, lysosomes filled with nanoparticles appeared in alveolar macrophages from 30 MAT to 24 HAT. These results indicate that PLGA nanoparticles might be quickly transferred from the alveolar space to the blood vessel via type-I alveolar epithelial cells and excreted into urine, and that there is a threshold for particle size, less than approximately 70 nm in diameter, with regard to absorption through the alveolar wall.
Resumen La XDR-TB (resistente a isoniazida, rifampicina, alguna fluoroquinolona y al menos una en... more Resumen La XDR-TB (resistente a isoniazida, rifampicina, alguna fluoroquinolona y al menos una entre kanamicina, amikacina o capreomicina), ha causado efectos devastadores en pacientes con SIDA y es prácticamente incurable. Se presentan 12 casos de localización pulmonar en pacientes no SIDA. Se trataron con esquemas que incluyeron en todos linezolid y en 9 moxifloxacino, todos negativizaron el examen directo y cultivo del esputo. Nueve pacientes cumplieron criterios de curación, 1 está aún en tratamiento y 2 abandonaron. Ocho pacientes presentaron efectos adversos, en solo 1 caso debió suspenderse la tioridazina. La utilización de linezolid, moxifloxacina y tioridazina han contribuido a la evolución satisfactoria de estos pacientes. Estos fármacos son considerados de utilidad en la serie reportada, debiendo ser utilizados en centros especializados con experiencia en el manejo de la TB MR y XDR-TB.
Initial multidrug-resistant (MDR) tuberculosis (TB) in HIV-negative patients treated at a Buenos ... more Initial multidrug-resistant (MDR) tuberculosis (TB) in HIV-negative patients treated at a Buenos Aires referral hospital from 1991 to 2000 was examined by using molecular clustering of available isolates. Of 291 HIV-negative MDRTB patients, 79 were initially MDR. We observed an ascending trend of initial MDRTB during this decade (p=0.0033). The M strain, which was responsible for an institutional AIDS-associated outbreak that peaked in 1995 to 1997, caused 24 of the 49 initial MDRTB cases available for restriction fragment length polymorphism. Of those, 21 were diagnosed in 1997 or later. Hospital exposure increased the risk of acquiring M strain-associated MDRTB by approximately two and a half times. The emergence of initial MDRTB among HIV-negative patients after 1997 was apparently a sequel of the AIDS-related outbreak. Because the prevalence of M strain-associated disease in the study population did not level out by the end of the decade, further expansion of this disease is possible.
Biomédica : revista del Instituto Nacional de Salud, 2004
Mycobacterium avium complex (MAC) infections are the most frequent systemic infections associated... more Mycobacterium avium complex (MAC) infections are the most frequent systemic infections associated with advanced AIDS. DNA probes for accurate identification of mycobacteria are available but are very expensive in many Latin American settings. Consequently, most Latin American diagnostic laboratories employ inaccurate and outdated tests for mycobacteria identification. Therefore, PCR restriction analysis (PRA) of the hsp65 gene was evaluated for the identification of 163 MAC human isolates originated from Spain and South America. The predominant PRA type in each country was: M. avium type I in Argentina (23/42, 55%) and Brazil (48/72, 67%), M. avium type II in Spain (18/26, 69%) and M. avium type III in Colombia (10/23, 43%). The Colombia frequency is noteworthy, since the PRA type III was quite infrequent in the other three countries. Furthermore, its presence has not been reported outside the Americas. The advantages and disadvantages of PRA in diagnostic mycobacteriology are discu...
Background Whole-genome sequencing has shown that the Mycobacterium tuberculosis infection proces... more Background Whole-genome sequencing has shown that the Mycobacterium tuberculosis infection process can be more heterogeneous than previously thought. Compartmentalized infections, exogenous reinfections, and microevolution are manifestations of this clonal complexity. The analysis of the mechanisms causing the microevolution —the genetic variability of M. tuberculosis at short time scales— of a parental strain into clonal variants with a patient is a relevant issue that has not been yet completely addressed. To our knowledge, a whole genome sequence microevolution analysis in a single patient with inadequate adherence to treatment has not been previously reported. Case presentation In this work, we applied whole genome sequencing analysis for a more in-depth analysis of the microevolution of a parental Mycobacterium tuberculosis strain into clonal variants within a patient with poor treatment compliance in Argentina. We analyzed the whole-genome sequence of 8 consecutive Mycobacteri...
The International Journal of Tuberculosis and Lung Disease
A multicentre evaluation was performed to assess two rapid low-cost methods, MTT (3-[4.5dimethylt... more A multicentre evaluation was performed to assess two rapid low-cost methods, MTT (3-[4.5dimethylthiazol-2-yl]-2.5-diphenyltetrazolium bromide) and resazurin assays, for testing the susceptibility of Mycobacterium tuberculosis to the first-line anti-tuberculosis drugs rifampicin (RMP), isoniazid (INH), ethambutol (EMB) and streptomycin (SM). M E T H O D S : Thirty coded M. tuberculosis strains were sent to seven laboratories located in Latin America, representing six countries. Each site performed the colorimetric assays, MTT and resazurin, blind for the first-line drugs RMP, INH, EMB and SM. The minimum inhibitory concentration results obtained were compared to the conventional proportion method on Löwenstein-Jensen medium. R E S U L T S : After establishing the breakpoint concentrations, excellent results were obtained for RMP, INH and EMB, with levels of specificity and sensitivity of between 96% and 99%. C O N C L U S I O N : MTT and resazurin assays are promising, accessible new alternative methods for middle-and low-resource countries that need low-cost methods to perform rapid susceptibility testing of M. tuberculosis to key anti-tuberculosis drugs.
The Journal of antimicrobial chemotherapy, Jan 25, 2018
To describe the distributions of bedaquiline and linezolid MIC values for the Mycobacterium tuber... more To describe the distributions of bedaquiline and linezolid MIC values for the Mycobacterium tuberculosis WT population and to define the corresponding epidemiological cut-offs (ECOFFs) in three Latin American countries. MICs of bedaquiline and linezolid were determined by the resazurin microtitre assay (REMA). In phase 1, interlaboratory reproducibility was assessed using a panel of 10 fully susceptible M. tuberculosis strains. Phase 2 involved MIC determination for 248 clinical isolates from Argentina (n = 58), Brazil (n = 100) and Peru (n = 90) from patients who were treatment-naive for bedaquiline and linezolid. We then determined the ECOFFs for bedaquiline and linezolid by the eyeball method and the ECOFFinder statistical calculator. Phase 1: REMA MIC values in the three sites were either identical to each other or differed by one 2-fold dilution from the consensus value with the exception of a single value. Phase 2: the bedaquiline MIC range was 0.0039-0.25 mg/L for pan-suscept...
The "Spanish" flu pandemic, which occurred a century ago, is considered the most devast... more The "Spanish" flu pandemic, which occurred a century ago, is considered the most devastating in human history. An estimated one third of world population fell ill with flu and more than 2.5% of them died. The course of the epidemic had two main waves (1918 and 1919) and showed an unusual W-shaped morbidity/mortality distribution. Death was not a direct outcome of flu itself but rather a consequence of secondary bacterial bronchopneumonia, for which antibiotics had not yet been discovered. Pre-existing pulmonary tuberculosis was also accountable for increased flu death rates during the pandemic. As it happened in Europe, in Argentina the epidemic had two main waves, with ample variation in mortality by region. Available treatment at the time included diet, throat antiseptic rinses, low doses of quinine valerianate, salicylates, codeine as a cough suppressant, and camphor oil. Primitive anti-pneumococcal vaccines and immune sera were also applied. Upon the disclosure of the ...
The possibility of using BCG-a Mycobacterium bovis strain of attenuated virulence-for PPD product... more The possibility of using BCG-a Mycobacterium bovis strain of attenuated virulence-for PPD production instead of a virulent strain of M. bovis has been considered to avoid the biological risks involved in the procedure. The potency and specificity of a PPD tuberculin prepared from BCG was compared in guinea pigs with that of PPD produced from strain AN5 (two batches), a virulent strain of M. bovis: the European Communities Standard (ECS), and a reference batch prepared at the Pan American Zoonoses Center (CPZ). The potency of the BCG-PPD was also assessed in cows naturally infected with M. bovis in comparison with the other two PPD and a third (WS) produced at the Central Veterinary Laboratory, Weybridge, United Kingdom. Finally, the antigenic value of BCG-PPD was compared with that of CPZ and ECS in an ELISA against sera from tuberculous and healthy cattle. In the above assays, BCG-PPD showed a lower sensitivity and specificity than PPD produced from virulent M. bovis. Therefore its use either for tuberculin testing of cattle or as antigen in the ELISA test for detecting bovine IgG anti-M. bovis antibodies would not seem advisable.
C5a anaphylatoxin is a component of the complement system involved in the modulation of T-cell po... more C5a anaphylatoxin is a component of the complement system involved in the modulation of T-cell polarization. Herein we investigated whether C5a receptors, C5aR and C5L2, modulate the cytokine profiles induced by Mycobacterium tuberculosis (Mtb). We analyzed the impact of both receptors on T helper cell polarization induced by the multidrug resistant outbreak strain named M, which is a poor IFN-γ inducer compared with the laboratory strain H37Rv. To this aim, we first blocked C5aR or C5L2 of peripheral blood monocytes (Mo) from patients with tuberculosis and healthy donors, then we stimulated the Mo either with H37Rv or the M strain, and finally we analyzed cytokine profiles of Mo/macrophages (MΦ) and CD4(+) T-cells. We found that: (i) Mtb modulated the expression of both C5a receptors, (ii) C5aR inhibited the expansion of CD4(+)IFN-γ(+) lymphocytes stimulated by the M strain but not by H37Rv, (iii) both receptors modulated the Mo/MΦ cytokine expression induced by Mtb. We conclude that C5aR, but not C5L2, plays a role in T helper cell polarization induced by Mtb and that this effect is strain- and donor-dependent. We speculate that the epidemiologically successful M strain takes advantage of this C5aR-mediated inhibition of Th1 polarization to survive within the host.
The tuberculosis (TB) epidemic is fueled by a parallel Human Immunodeficiency Virus (HIV) epidemi... more The tuberculosis (TB) epidemic is fueled by a parallel Human Immunodeficiency Virus (HIV) epidemic, but it remains unclear to what extent the HIV epidemic has been a driver for drug resistance inMycobacterium tuberculosis (Mtb). Here we assess the impact of HIV co-infection on the emergence of resistance and transmission ofMtbin the largest outbreak of multidrug-resistant TB in South America to date. By combining Bayesian evolutionary analyses and the reconstruction of transmission networks utilizing a new model optimized for TB, we find that HIV co-infection does not significantly affect the transmissibility or the mutation rate ofMtbwithin patients and was not associated with increased emergence of resistance within patients. Our results indicate that the HIV epidemic serves as an amplifier of TB outbreaks by providing a reservoir of susceptible hosts, but that HIV co-infection is not a direct driver for the emergence and transmission of resistant strains.
Background The Mtb strain (LAM3/SIT33 genotype) named Ra was first detected in 1994 as causing an... more Background The Mtb strain (LAM3/SIT33 genotype) named Ra was first detected in 1994 as causing an HIVrelated MDR-TB outbreak in a referral hospital, Rosario, Argentina, 1994-96 [1]. Although hospital transmission has long been contained, the Ra strain is still circulating in the community and occasionally appears in sites distant from the outbreak hotspot [2]. Purpose This study aims to gain insight into strain evolution and transmission dynamics of the Ra strain.
Background. The growing international mobility of persons may hinder efforts made in low-resource... more Background. The growing international mobility of persons may hinder efforts made in low-resource countries to control tuberculosis (TB). During a study originally aimed to explore tuberculosis transmission among Paraguayan patients, evidence was found of across-border migration of a multidrug-resistant (MDR) Mycobacterium tuberculosis strain. Methods. The study population consisted of 166 patients with AFB smear positive pulmonary tuberculosis enrolled in the national survey of tuberculosis drug resistance in 2002-2003. M. tuberculosis drug susceptibility was determined by the proportion method on solid medium. IS6110 DNA fingerprinting and spoligotyping were performed according to internationally standardized methods. The software BioNumerics (Applied Maths, Belgium) was used for computer-assisted analysis and comparison with genotypes held in the Argentinean database. Results and Discussion. One of the isolates showed both IS6110 fingerprint and spoligopattern of a notorious mult...
A remarkable input to the epidemiology of tuberculosis was not the only benefit of the molecular ... more A remarkable input to the epidemiology of tuberculosis was not the only benefit of the molecular tools developed in the early nineties for Mycobacterium tuberculosis intra-species differentiation. These genotyping methods served also to unveil specimen cross-contamination, which was until then overlooked in laboratories culturing mycobacteria. This error consists in the accidental carry-over of bacilli from a specimen with high bacterial load to that, or those, processed subsequently. The ensuing detection of falsely positive cultures can result in a wrong diagnosis of tuberculosis and the initiation of a long-lasting treatment with potentially toxic drugs. This series of errors implies the mismanagement of patients, the distraction of public health system resources, and the distortion of epidemiological data. M. tuberculosis laboratory cross-contamination was detected wherever investigated systematically, with a median rate of 3% of all positive cultures. The confirmation of this e...
The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease, 2005
A multicentre evaluation was performed to assess two rapid low-cost methods, MTT (3-[4.5-dimethyl... more A multicentre evaluation was performed to assess two rapid low-cost methods, MTT (3-[4.5-dimethylthiazol-2-yl]-2.5-diphenyltetrazolium bromide) and resazurin assays, for testing the susceptibility of Mycobacterium tuberculosis to the first-line anti-tuberculosis drugs rifampicin (RMP), isoniazid (INH), ethambutol (EMB) and streptomycin (SM). Thirty coded M. tuberculosis strains were sent to seven laboratories located in Latin America, representing six countries. Each site performed the colorimetric assays, MTT and resazurin, blind for the first-line drugs RMP, INH, EMB and SM. The minimum inhibitory concentration results obtained were compared to the conventional proportion method on Lowenstein-Jensen medium. After establishing the breakpoint concentrations, excellent results were obtained for RMP, INH and EMB, with levels of specificity and sensitivity of between 96% and 99%. MTT and resazurin assays are promising, accessible new alternative methods for middle- and low-resource cou...
Polylactide-glycolide (PLGA) nanoparticles have been developed as pulmonary drug delivery carrier... more Polylactide-glycolide (PLGA) nanoparticles have been developed as pulmonary drug delivery carriers. To investigate their behavior, small-(d50 = 74 nm) and large-sized (d50 = 250 nm) FITC-conjugated PLGA nanoparticles were intratracheally administered to rats and were traced for 5, 30 and 60 minutes and 24 hours after administration (HAT). Immunohistochemically, a, FITCpositive reaction was observed in type-I alveolar epithelial cells (type-I AEC), endothelial cells and alveolar macrophages in the lungs from 5 minutes after treatment (MAT) to 24 HAT in both nanoparticle groups. In the kidneys, a positive reaction was observed in proximal tubular epithelial cells at 30 MAT; the reaction peaked at 60 MAT and was reduced at 24 HAT, while no positive reaction was seen in other sites. Ultrascructurally, the number of membrane-bound vesicles, which were approximately 70 nm in size and hard to distinguish from pinocytic vesicles, apparently increased in type-I AEC and endothelial cells at 5 MAT in the small-sized group, in comparison with the control group receiving physiological saline. The number of vesicles in the large-sized group was almost same as that in the control group. On the other hand, in both nanoparticle groups, lysosomes filled with nanoparticles appeared in alveolar macrophages from 30 MAT to 24 HAT. These results indicate that PLGA nanoparticles might be quickly transferred from the alveolar space to the blood vessel via type-I alveolar epithelial cells and excreted into urine, and that there is a threshold for particle size, less than approximately 70 nm in diameter, with regard to absorption through the alveolar wall.
Resumen La XDR-TB (resistente a isoniazida, rifampicina, alguna fluoroquinolona y al menos una en... more Resumen La XDR-TB (resistente a isoniazida, rifampicina, alguna fluoroquinolona y al menos una entre kanamicina, amikacina o capreomicina), ha causado efectos devastadores en pacientes con SIDA y es prácticamente incurable. Se presentan 12 casos de localización pulmonar en pacientes no SIDA. Se trataron con esquemas que incluyeron en todos linezolid y en 9 moxifloxacino, todos negativizaron el examen directo y cultivo del esputo. Nueve pacientes cumplieron criterios de curación, 1 está aún en tratamiento y 2 abandonaron. Ocho pacientes presentaron efectos adversos, en solo 1 caso debió suspenderse la tioridazina. La utilización de linezolid, moxifloxacina y tioridazina han contribuido a la evolución satisfactoria de estos pacientes. Estos fármacos son considerados de utilidad en la serie reportada, debiendo ser utilizados en centros especializados con experiencia en el manejo de la TB MR y XDR-TB.
Initial multidrug-resistant (MDR) tuberculosis (TB) in HIV-negative patients treated at a Buenos ... more Initial multidrug-resistant (MDR) tuberculosis (TB) in HIV-negative patients treated at a Buenos Aires referral hospital from 1991 to 2000 was examined by using molecular clustering of available isolates. Of 291 HIV-negative MDRTB patients, 79 were initially MDR. We observed an ascending trend of initial MDRTB during this decade (p=0.0033). The M strain, which was responsible for an institutional AIDS-associated outbreak that peaked in 1995 to 1997, caused 24 of the 49 initial MDRTB cases available for restriction fragment length polymorphism. Of those, 21 were diagnosed in 1997 or later. Hospital exposure increased the risk of acquiring M strain-associated MDRTB by approximately two and a half times. The emergence of initial MDRTB among HIV-negative patients after 1997 was apparently a sequel of the AIDS-related outbreak. Because the prevalence of M strain-associated disease in the study population did not level out by the end of the decade, further expansion of this disease is possible.
Biomédica : revista del Instituto Nacional de Salud, 2004
Mycobacterium avium complex (MAC) infections are the most frequent systemic infections associated... more Mycobacterium avium complex (MAC) infections are the most frequent systemic infections associated with advanced AIDS. DNA probes for accurate identification of mycobacteria are available but are very expensive in many Latin American settings. Consequently, most Latin American diagnostic laboratories employ inaccurate and outdated tests for mycobacteria identification. Therefore, PCR restriction analysis (PRA) of the hsp65 gene was evaluated for the identification of 163 MAC human isolates originated from Spain and South America. The predominant PRA type in each country was: M. avium type I in Argentina (23/42, 55%) and Brazil (48/72, 67%), M. avium type II in Spain (18/26, 69%) and M. avium type III in Colombia (10/23, 43%). The Colombia frequency is noteworthy, since the PRA type III was quite infrequent in the other three countries. Furthermore, its presence has not been reported outside the Americas. The advantages and disadvantages of PRA in diagnostic mycobacteriology are discu...
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