Molecular investigation of recurrent tuberculosis in patients from Rwanda.

SETTING: Pulmonary tuberculosis (TB) patients enrolled in four provinces of Rwanda. OBJECTIVE: To determine the cause of recurrent TB. DESIGN: Serial Mycobacterium tuberculosis isolates obtained from patients with recurrent TB from January 2002 to September 2005 were genotyped by spoligotyping and mycobacterial interspersed repetitive unit-variable number of tandem repeat (MIRU-VNTR) typing. Drug resistance was determined by phenotypic susceptibility testing and sequencing of rpoB, katG, inhA and embB genes. RESULTS: Among 710 culture-positive TB patients enrolled in the study, initial drug susceptibility testing results were available for 638. Sixty-nine of these had multidrug-resistant (MDR) TB and 569 were non-MDR-TB. Among the MDR-TB patients, 22 had follow-up isolates after cure (n = 12) or chronic infection (n = 10). The DNA patterns of sequential isolates from 4 of the 12 previously cured MDR-TB patients were different, indicating re-infection. DNA patterns of isolates from the remaining 8 previously cured and 10 chronic MDR-TB patients were identical, suggesting reactivation and treatment failure, respectively. Among the non-MDR-TB patients, disease recurrence was observed in one case; this was determined to be due to reactivation after initial mixed infection. CONCLUSION: These results document a high treatment failure/reactivation rate for MDR-TB and suggest that re-infection within 2 years may not be a common cause of recurrent TB in this setting.

Results of a national survey on drug resistance among pulmonary tuberculosis patients in Rwanda.

BACKGROUND: One of the principal objectives of tuberculosis (TB) control is to minimise the emergence of drug resistance. The first national survey was conducted in Rwanda to determine the prevalence of M. tuberculosis drug resistance. METHODS: Sputum samples were collected from all new and retreatment cases in the health districts from November 2004 to February 2005. Drug susceptibility testing of isolates against first-line drugs was performed by the proportion method. RESULTS: Of 616 strains from new cases, 6.2% were resistant to isoniazid, 3.9% to rifampicin and 3.9% were multidrug-resistant TB. Among 85 strains from previously treated cases, the prevalence of resistance was respectively 10.6%, 10.6% and 9.4% (MDR-TB strains). Eight MDR cases showed additional resistance to ethambutol and streptomycin. CONCLUSION: The level of MDR-TB among TB patients in Rwanda is high. The main reasons of this emergence of MDR-TB can be attributed to the disorganisation of the health system, migration of the population during the 1994 civil war and poor success rates, with a high number of patients transferred out and lost to follow-up. On the other hand, the use of treatment regimens administered twice weekly during the continuation phase could be another important factor and merit further investigations.

[Primary and acquired resistance to antituberculous drugs in strains of Mycobacterium tuberculosis isolated in Rwanda]. / Résistance primaire et acquise aux antituberculeux des souches de Mycobacterium tuberculosis isolées au Rwanda.

This study was undertaken within the framework of a surveillance project on the resistance of Mycobacterium tuberculosis to first-line antituberculosis drugs in four provinces of Rwanda with a high prevalence of tuberculosis (TB). The purpose was to determine the prevalence of primary and acquired resistance of M. tuberculosis to major antituberculosis drugs. A cohort of patients (n=710) with pulmonary TB documented by positive microscopic examinations of exhaustive samples was recruited at 7 treatment centers. Sputum samples were cultured on Löwenstein-Jensen and Coletsos media. Sensitivity to antituberculosis drugs was tested using a BACTEC 460 radiometric system. M. tuberculosis was isolated in 644 of the 710 patients (90.7%). A total of 296 out of 573 tested for HIV infection (51.7%) were positive. Primary resistance to one, two, three or four antituberculosis drugs was observed in 3.5%, 2.9%, 1.4% and 5.7% respectively. The prevalence of acquired resistance to antituberculosis drugs was 11.2%. Primary monoresistance to streptomycin was the most prevalent (2.3%) followed by resistance to ethambutol (1%). The combined rate of multiresistance was 11.6% with 7% involving new cases and 25.5% involving retreatment. This study showed that the rates of primary and acquired resistance to first-line antituberculosis drugs were high and that TB was associated with HIV infection. The National TB Control Program must implement measures to coordinate diagnosis and management of TB and HIV infection.

Evaluation of the resazurin microtiter assay for rapid detection of ofloxacin resistance in M. tuberculosis.

OBJECTIVE: To evaluate the performance of the colorimetric resazurin microtiter assay (REMA) method for the detection of ofloxacin resistance. METHODS: A panel of 120 multidrug-resistant Mycobacterium tuberculosis strains was tested blindly by the REMA method and compared with the results obtained using the BACTEC 460 method. RESULT: A very good correlation was observed between the two methods. CONCLUSION: The REMA method is simple, rapid and can be an inexpensive alternative procedure for the rapid detection of anti-tuberculosis drug resistance in laboratories with limited resources.

The role of technical assistance in expanding access to Xpert(®) MTB/RIF: experience in sub-Saharan Africa.

To improve tuberculosis (TB) diagnosis, many national TB programmes have committed to deploying Xpert(®) MTB/RIF. Implementation of this relatively new technology has suffered from a lack of comprehensive technical assistance, however, including the formulation of policies and plans to address operational issues. While providing technical assistance, we observed numerous operational challenges in the implementation and scale-up of Xpert in five sub-Saharan African countries: low coverage, poor laboratory infrastructure, limited access, poor linkages to treatment, inadequate data on outcomes, problems with specimen transport, diagnostic algorithms that are not aligned with updated World Health Organization recommendations on target patient groups and financing challenges. We recommend better country preparedness and training, laboratory information and quality systems, supply management and referral mechanisms.

De nombreux programmes nationaux tuberculose (TB) se sont engagés à déployer le Xpert® MTB/RIF afin d'améliorer le diagnostic de la TB. La mise en oeuvre de cette technique relativement nouvelle a cependant souffert d'un manque d'assistance technique d'ensemble, notamment la formulation de politiques et de plans destinés à prendre en compte les problèmes opérationnels. Lorsque nous avons fourni cette assistance technique, nous avons observé de nombreux défis opérationnels dans la mise en oeuvre et l'expansion du Xpert dans cinq pays d'Afrique sub-saharienne : une faible couverture, une infrastructure de laboratoire limitée, un accès limité, des liens médiocres avec la prise en charge thérapeutique, des données insuffisantes sur les résultats, des problèmes de transport des échantillons, des algorithmes de diagnostic qui ne sont pas en accord avec les dernières recommandations de l'Organisation Mondiale de la Santé relatives aux groupes cibles de patients et des défis financiers. Nous recommandons une meilleure préparation et formation des pays, une information des laboratoires et des systèmes de contrôle de qualité, une gestion des stocks et des mécanismes de référence.

Con el propósito de mejorar el diagnóstico de la tuberculosis, muchos programas nacionales han decidido generalizar la práctica de la prueba Xpert® MTB/RIF. Sin embargo, la introducción de esta técnica relativamente nueva se ha dificultado debido a una falta de asistencia técnica integral, que comprenda la formulación de normas y de planes que aborden los aspectos operativos. Durante la experiencia de prestación de asistencia técnica, se observaron múltiples dificultades operativas en la ejecución y en la ampliación de escala de la técnica Xpert en cinco países de África subsahariana, a saber: la baja cobertura, la insuficiencia de las infraestructuras de laboratorio, el acceso limitado, la escasa vinculación con el tratamiento, la deficiencia de los datos sobre los desenlaces, los problemas relacionados con el transporte de las muestras, los algoritmos diagnósticos que no corresponden a las recomendaciones actualizadas de la Organización Mundial de la Salud en materia de grupos destinatarios de pacientes y las dificultades de financiamiento. Se recomienda procurar una mejor preparación y una mayor capacitación en el país, perfeccionar los sistemas de información y control de calidad de los laboratorios y poner en práctica procedimientos de gestión de los suministros y mecanismos de remisión.

Limited fluoroquinolone resistance among Mycobacterium tuberculosis isolates from Rwanda: results of a national survey.

OBJECTIVES: There is an increasing interest in the possible role of fluoroquinolone antibiotics for the treatment of tuberculosis (TB), but widespread use of these antibiotics for the treatment of other bacterial infections may select for fluoroquinolone-resistant Mycobacterium tuberculosis strains. METHODS: We evaluated fluoroquinolone susceptibility using the proportion method (ofloxacin, critical concentration 2.0 mg/L) in isolates from patients enrolled in a national drug resistance survey in Rwanda from November 2004 to February 2005. RESULTS: Of the 701 M. tuberculosis isolates studied, 617 (88%) were susceptible to all first-line drugs, 32 (4.6%) were multidrug-resistant (MDR) and 52 (7.4%) were resistant to one or more first-line drugs but not MDR. Ofloxacin resistance was found in four (0.6%) of the isolates; three of them being MDR and one susceptible to all first-line drugs. Mutations in the gyrA gene were found in all ofloxacin-resistant strains at codons 80 and 94. CONCLUSIONS: Our finding is not alarming for Rwanda, but highlights the general risk of producing resistance to fluoroquinolones, jeopardizing the potential for these drugs to be used as second-line anti-TB agents in the programmatic management of drug-resistant TB and creating incurable TB strains.

Resistance primaire et acquise aux antituberculeux des souches de Mycobacterium tuberculosis isolees au Rwanda

Le cadre de l'etude de la resistance de Mycobacterium tuberculosis aux antituberculeux de premiere ligne se situe dans quatre provinces du Rwanda a forte prevalence de tuberculose (TB). L'objectif etait de determiner les prevalences de resistance primaire et acquise de M. tuberculosis aux antituberculeux majeurs. Une cohorte de patients avec TB pulmonaire a microscopie positive (n=710) echantillonnes de maniere exhaustive a ete incluse entre septembre 2002 et mars 2004 dans 7 centres de traitement. Leurs expectorations ont ete ensemencees sur milieux de Lowenstein-Jensen et Coletsos. La sensibilite aux antituberculeux a ete testee par la methode radiometrique BACTEC 460. Sur 710 malades;M. tuberculosis a ete isole chez 644 (90;7). Parmi eux; 296/573 (51;7) etaient positifs pour le VIH. La resistance primaire a un; deux; trois ou quatre antituberculeux etait de 3;5; 2;9; 1;4et 5;7respectivement. La resistance acquise a un antituberculeux etait de 11;2. La monoresistance primaire a la streptomycine etait la plus frequente (2;3); suivie de la resistance a l'ethambutol (1). Le taux combine de multiresistance representait 11;6; avec 7chez les nouveaux cas et 25;5chez les re-traites. Les taux de resistance primaire et acquise aux antituberculeux de premiere ligne sont eleves et la TB est associee au VIH. Le Programme National de lutte contre la TB devrait mettre en place une bonne coordination dans le diagnostic et la prise en charge de la TB et de l'infection par le VIH

Resistance primaire et acquise aux antituberculeux des souches de Mycobacterium tuberculosis isolees au Rwanda

Le cadre de l'etude de la resistance de Mycobacterium tuberculosis aux antituberculeux de premiere ligne se situe dans quatre provinces du Rwanda a forte prevalence de tuberculose (TB). L'objectif etait de determiner les prevalences de resistance primaire et acquise de M. tuberculosis aux antituberculeux majeurs. Une cohorte de patients avec TB pulmonaire a microscopie positive (n=710) echantillonnes de maniere exhaustive a ete incluse entre septembre 2002 et mars 2004 dans 7 centres de traitement. Leurs expectorations ont ete ensemencees sur milieux de Lowenstein-Jensen et Coletsos. La sensibilite aux antituberculeux a ete testee par lamethode radiometrique BACTEC 460. Sur 710malades;M. tuberculosis a ete isole chez 644 (90;7). Parmi eux; 296/573 (51;7) etaient positifs pour leVIH. La resistance primaire a un; deux; trois ou quatre antituberculeux etait de 3;5; 2;9; 1;4et 5;7respectivement. La resistance acquise a un antituberculeux etait de 11;2. La monoresistance primaire a la streptomycine etait la plus frequente (2;3); suivie de la resistance a l'ethambutol (1). Le taux combine de multiresistance representait 11;6; avec 7chez les nouveaux cas et 25;5chez les re-traites. Les taux de resistance primaire et acquise aux antituberculeux de premiere ligne sont eleves et la TB est associee au VIH. Le Programme National de lutte contre la TB devrait mettre en place une bonne coordination dans le diagnostic et la prise en charge de la TB et de l'infection par le VIH