RESUMEN
Tuberculosis (TB) is a global public health problem, with the highest burden occurring in low-income countries. In these countries, the use of more sensitive diagnostics, such as Xpert MTB/RIF (Xpert), is still limited by costs. A cost-saving strategy to diagnose other diseases is to pool samples from various individuals and test them with single tests. The samples in positive pool samples are then retested individually to identify the patients with the disease. We assessed a pooled testing strategy to optimize the affordability of Xpert for the diagnosis of TB. Adults with presumptive TB attending hospitals or identified by canvassing of households in Abuja, Nigeria, were asked to provide sputum for individual and pooled (4 per pool) testing. The agreement of the results of testing of individual and pooled samples and costs were assessed. A total of 738 individuals submitted samples, with 115 (16%) being Mycobacterium tuberculosis positive. Valid Xpert results for individual and pooled samples were available for 718 specimens. Of these, testing of pooled samples detected 109 (96%) of 114 individual M. tuberculosis-positive samples, with the overall agreement being 99%. Xpert semiquantitative M. tuberculosis levels had a positive correlation with the smear grades, and the individual sample-positive/pooled sample-negative results were likely due to the M. tuberculosis concentration being below the detection limit. The strategy reduced cartridge costs by 31%. Savings were higher with samples from individuals recruited in the community, where the proportion of positive specimens was low. The results of testing of pooled samples had a high level of agreement with the results of testing of individual samples, and use of the pooled testing strategy reduced costs and has the potential to increase the affordability of Xpert in countries with limited resources.
Asunto(s)
Técnicas Bacteriológicas/economía , Técnicas Bacteriológicas/métodos , Técnicas de Diagnóstico Molecular/economía , Técnicas de Diagnóstico Molecular/métodos , Mycobacterium tuberculosis/aislamiento & purificación , Esputo/microbiología , Tuberculosis Pulmonar/diagnóstico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Costos y Análisis de Costo , Países en Desarrollo , Femenino , Costos de la Atención en Salud , Humanos , Masculino , Persona de Mediana Edad , Nigeria , Sensibilidad y Especificidad , Adulto JovenRESUMEN
Background: Inadequate diagnostic processes and human resources in laboratories contribute to a high burden of tuberculosis (TB) in low- and middle-income countries. Direct smear microscopy is relied on for TB diagnosis; however; sensitivity rates vary. To improve sensitivity of direct microscopy; the researchers employed several approaches; including sputum digestion and concentration of acid-fast bacilli (AFB); a technique which uses commercial bleach. Objectives: This study compared methods used to diagnose active Mycobacterium tuberculosis infections. Methods: Three sputum specimens were collected from each of 340 participants in Abuja; Nigeria; over two consecutive days. Direct microscopy was performed on all specimens; following microscopy; one specimen from each patient was selected randomly for bleach sedimentation and one for Lowenstein-Jensen culture.Results: Direct microscopy produced 28.8% AFB-positive results; whilst bleach sedimentation resulted in 30.3%. When compared with the cultures; 26.5% were AFB true positive using direct microscopy and 27.1% using bleach sedimentation. Whilst the specificity rate between these two methods was not statistically significant (P = 0.548); the sensitivity rate was significant (P = 0.004).Conclusion: Based on these results; bleach increases the sensitivity of microscopy compared with direct smear and has similar specificity. When diagnosing new cases of pulmonary TB; one bleach-digested smear is as sensitive as three direct smears; reducing waiting times for patients and ensuring the safety of laboratory technicians
Asunto(s)
Infecciones por Mycobacterium , Sensibilidad y Especificidad , Hipoclorito de Sodio , Tuberculosis Pulmonar/diagnósticoRESUMEN
INTRODUCTION: Since the endorsement of GeneXpert MTB/RIF by the WHO, many countries have embarked on implementing this technology. OBJECTIVE: We outline the cost of installing GeneXpert in district hospitals in Abuja, Nigeria. METHODS: We prospectively documented costs related to the installation of GeneXpert at five sites. Costs were collected from receipts received from suppliers and normalized to USD 2012 values. RESULTS: Costs were often identified after initiating installation for many reasons. Installation varied widely between sites with sufficient space and power supply; sites with insufficient space or power supply and costs not directly associated with site installation. The basic cost for installation was USD 2,621.98 per machine. Sites that required additional space cost close to USD 7,000.00. CONCLUSION: Space and power requirements have a significant effect on installation costs. Countries need to carefully consider the placement of Xpert machines based on the quality and size of the available infrastructure.
Asunto(s)
Equipo para Diagnóstico/economía , Tuberculosis Pulmonar/diagnóstico , Tuberculosis Pulmonar/economía , Análisis Costo-Beneficio , Países en Desarrollo/economía , Salud Global/economía , Recursos en Salud/economía , Humanos , Nigeria/epidemiologíaRESUMEN
BACKGROUND: Nigeria has the tenth highest burden of tuberculosis (TB) among the 22 TB high-burden countries in the world. This study describes the biodiversity and epidemiology of drug-susceptible and drug-resistant TB in Ibadan, Nnewi and Abuja, using 409 DNAs extracted from culture positive TB isolates. METHODOLOGY/PRINCIPAL FINDINGS: DNAs extracted from clinical isolates of Mycobacterium tuberculosis complex were studied by spoligotyping and 24 VNTR typing. The Cameroon clade (CAM) was predominant followed by the M. africanum (West African 1) and T (mainly T2) clades. By using a smooth definition of clusters, 32 likely epi-linked clusters related to the Cameroon genotype family and 15 likely epi-linked clusters related to other "modern" genotypes were detected. Eight clusters concerned M. africanum West African 1. The recent transmission rate of TB was 38%. This large study shows that the recent transmission of TB in Nigeria is high, without major regional differences, with MDR-TB clusters. Improvement in the TB control programme is imperative to address the TB control problem in Nigeria.
Asunto(s)
Variación Genética , Mycobacterium tuberculosis/genética , Tuberculosis/epidemiología , Adolescente , Adulto , Anciano , Análisis por Conglomerados , Evolución Molecular , Femenino , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Tipificación de Secuencias Multilocus , Mycobacterium tuberculosis/clasificación , Mycobacterium tuberculosis/aislamiento & purificación , Nigeria/epidemiología , Filogenia , Tuberculosis/transmisión , Tuberculosis Resistente a Múltiples Medicamentos/genética , Adulto JovenRESUMEN
This study provides with a first insight on Mycobacterium tuberculosis complex epidemiology and genetic diversity in the Cross River State, Nigeria. Starting with 137 smear positive patients recruited over a period of 12months (June 2008 to May 2009), we obtained 97 pure mycobacterial isolates out of which 81 (83.5%) were identified as M. tuberculosis complex. Genotyping revealed a total of 27 spoligotypes patterns with 10 clusters (n=64% or 79% of clustered isolates, 2-32 isolates/cluster), with patients in the age group range 25-34 years being significantly associated with shared-type pattern SIT61 (p=0.019). Comparison with SITVIT2 database showed that with the exception of a single cluster (SIT727/H1), all other clusters observed were representative of West Africa; the two main lineages involved were LAM10-CAM (n=42/81% or 51.8%) of M. tuberculosis and AFRI_2 sublineage of Mycobacterium africanum (n=27/81% or 33.3%). Subsequent 12-loci MIRU typing resulted in a total of 13 SIT/MIT clusters (n=52 isolates, 2-9 isolates per cluster), with a resulting recent n-1 transmission rate of 48.1%. Available drug-susceptibility testing (DST) results for 58/81 clinical isolates revealed 6/58% or 10.4% cases of multiple drug-resistance (MDR); 5/6 MDR cases were caused by strains belonging to LAM10-CAM lineage (a specific cluster SIT61/MIT266 in 4/6 cases, and an orphan spoligotype pattern in 1/6 case). Additionally, MIT266 was associated with streptomycin resistance (p=0.016). All the six MDRTB isolates were concomitantly resistance to streptomycin and ethambutol; however, 4/6 MDR strains with identical MIRU patterns were characterized by consecutive strain numbers hence the possibility of laboratory cross contamination could not be excluded in 3/4 serial cases. The present preliminary study underlines the usefulness of spoligotyping and 12-loci MIRU-VNTRs to establish a baseline of circulating genotypic lineages of M. tuberculosis complex in Nigeria.
Asunto(s)
Variación Genética , Mycobacterium tuberculosis/clasificación , Mycobacterium tuberculosis/genética , Tuberculosis/epidemiología , Adolescente , Adulto , Anciano , Análisis por Conglomerados , ADN Bacteriano , Farmacorresistencia Bacteriana Múltiple/genética , Evolución Molecular , Humanos , Persona de Mediana Edad , Repeticiones de Minisatélite , Tipificación Molecular , Mycobacterium tuberculosis/aislamiento & purificación , Nigeria/epidemiología , Filogenia , Adulto JovenRESUMEN
OBJECTIVE: To assess the efficacy of weekly zinc or zinc plus retinol as adjuncts for the treatment of pulmonary tuberculosis. METHODS: Double-blind, randomized, placebo-controlled trial in 350 patients >15 years old with smear-positive tuberculosis in Nigeria (ISRCTN36636609). In addition to antituberculous treatment, patients were randomly allocated to weekly supplements of zinc (90 mg), zinc plus retinol (5000 IU) or placebos for 6 months. Primary outcomes were time to sputum smear conversion and resolution of radiographic abnormalities. RESULTS: After 8 weeks of treatment, 68% had achieved sputum smear conversion, and the median conversion time was 6.5 weeks. Hazard ratios (HR, 95%CI) for sputum conversion relative to the placebo group were not significant for zinc (1.07, 0.92-1.29) or zinc plus retinol (0.89, 0.76-1.07). Significant predictors of time to sputum conversion were lung abnormality score, sputum smear grade, age and serum C-reactive protein. HIV co-infection and gender were not independent predictors of time to sputum conversion. There were no significant differences between supplement groups in clinical, radiological or laboratory outcomes at 2 months or 6 months. There were 9, 9 and 2 deaths in patients receiving zinc, zinc plus retinol or placebos, respectively. Mortality in those who received zinc (HR 1.71, 0.88-3.58) or zinc plus retinol (HR 1.54, 0.78-3.26) did not differ significantly from those who received placebos. Most deaths occurred in patients co-infected with HIV. CONCLUSIONS: Supplementation with zinc or zinc plus retinol did not lead to better outcomes than placebos, and caution is warranted regarding routine micronutrient supplementation, particularly in patients co-infected with HIV.