Comparison of the QuantiFERON®-TB Gold assay and tuberculin skin test to detect latent tuberculosis infection among target groups in Trinidad & Tobago Comparación entre la prueba QuantiFERON®-TB Gold y la prueba cutánea de la tuberculina para detectar la infección tuberculosa latente en grupos destinatarios en Trinidad y Tabago

OBJECTIVE: To compare the QuantiFERON®-TB Gold (QFT-G) assay and tuberculin skin test (TST) in screening/diagnosis of latent tuberculosis infection (LTBI) among individuals in Trinidad & Tobago at high risk for TB. METHODS: A total of 560 individuals (TB patient contacts, HIV patients, health care workers, prison inmates, and TB patients [controls]) were recruited for the study. Blood was drawn and processed using the QFT-G assay, followed by immediate administration of TST solution on subjects' forearm. Data were analyzed with Epi InfoTM 3.5.1 software. Results were compared across the target groups using the chi-square test (P OBJETIVO: Comparar la prueba QuantiFERON®-TB Gold (QFT-G) con la prueba cutánea de la tuberculina (PPD) para el tamizaje y diagnóstico de la infección tuberculosa latente (ITBL) en personas con alto riesgo de tuberculosis en Trinidad y Tabago. MÉTODOS: Para el estudio, se reclutó un total de 560 individuos (personas en contacto con pacientes de tuberculosis, pacientes con VIH, trabajadores de la salud, presidiarios y pacientes de tuberculosis [grupo testigo]). Las muestras de sangre se extrajeron y procesaron utilizando la prueba QFT-G, seguida de la aplicación inmediata de la solución de PPD en el antebrazo de las personas. Los datos se analizaron con el software Epi InfoTM 3.5.1. Los resultados obtenidos en los grupos destinatarios se compararon utilizando la prueba de la ji al cuadrado (P < 0,05). RESULTADOS: La prueba QFT-G detectó la infección tuberculosa latente en 51% de los individuos (la mayoría de los resultados positivos se presentaron en el grupo testigo) mientras que la prueba PPD la detectó en 39,4% (P = 0,001). En términos generales, la prueba QFT-G detectó la infección tuberculosa latente con mayor frecuencia que la PPD en todos los individuos, excepto en aquellos del grupo testigo, donde el índice de detección favoreció a la PPD. La prueba QFT-G produjo resultados indeterminados y no reactivos en algunos pacientes con VIH, pero requirió menos tiempo de respuesta que la PPD (23,3 h contra 70,2 h; P < 0.0001). La prueba PPD tuvo un costo menor por individuo que la QFT-G (US$3,70 en comparación con US$18,60; P = 0.0008). CONCLUSIONES: La prueba QFT-G tuvo un costo más elevado, pero la tasa de detección fue más alta en la mayoría de los grupos destinatarios y el tiempo de respuesta fue más rápido en comparación con la PPD. Sin embargo, la sensibilidad de la prueba QFT-G fue inferior entre los individuos inmunodeficientes. Por consiguiente, se deben tomar las precauciones necesarias para utilizar la prueba QFT-G en el tamizaje y diagnóstico de ITBL en entornos de escasos recursos y alta prevalencia de VIH como Trinidad y Tabago

Finer characterization of Mycobacterium tuberculosis using spoligotyping and 15-loci MIRU-VNTRs reveals phylogeographical specificities of isolates circulating in Guyana and Suriname

International audienceIn this study we used spoligotyping and 15-loci MIRU-VNTRs for a finer characterization of Mycobacterium tuberculosis strains isolated from patients residing in Guyana (n=74) and Suriname (n=80). The mean age of the patients was 38.5years (36.5 and 40.2years for Guyana vs. Suriname), with a male-to-female sex-ratio of 2.25 for Guyana vs. 4.27 in Suriname. Spoligotyping and 15-loci MIRU-VNTRs led to a total of 41 and 65 different patterns respectively, with an overall clustering rate of 83.8% vs. 68.8%. Combined spoligotyping and VNTR analysis led to the detection of 18 clusters of 2-41 isolates, with an overall clustering of 67.5% and a recent "n-1" transmission rate of 55.8%. Importantly, Guyana was characterized by a significantly higher percentage of clustered isolates than Suriname (79.7% vs. 56.3%; p=0.0019). Three big spoligo/MIRU (SIT/MIT) clusters containing >10 isolates each were shared between the 2 countries, and concerned: T1 sublineage cluster 53/861 (n=41, 37 in Guyana vs. 4 in Suriname); EAI6-BGD1 sublineage cluster 1340/860 (n=16, 3 in Guyana vs. 13 in Suriname); and T1 sublineage cluster 131/146 (n=11, 6 in Guyana vs. 5 in Suriname); as well as 2 smaller clusters of 2 and 3 isolates respectively. However, the relative phylogeographical specificities of strains in circulation as well as a lack of drug-resistance observed among strains from Suriname suggested that trans-border transmission of drug-resistant isolates occurred less frequently than thought. Tracing and interrupting transmission channels of a specific clone (SIT53/15-MIT861) should become a priority in Guyana, not only because it is by far most abundant but also because it accounts for almost half of the drug resistant isolates (n=8/17, 47.1%) in our study, and clustered 5/12 (41.7%) MDR isolates

A First Assessment of Mycobacterium tuberculosis Genetic Diversity and Drug-Resistance Patterns in Twelve Caribbean Territories

With the exception of some French-speaking islands, data on tuberculosis (TB) in the Caribbean are scarce. In this study, we report a first assessment of genetic diversity of a convenience sample of Mycobacterium tuberculosis strains received from twelve Caribbean territories by spoligotyping and describe their drug-resistance patterns. Of the 480 isolates, 40 (8.3%) isolates showed resistance to at least one anti-TB drug. The proportion of drug-resistant strains was significantly higher in The Bahamas (21.4%; P=0.02), and Guyana (27.5%; P<0.0001), while it was significantly lower in Jamaica (2.4%; P=0.03) than in other countries of the present study. Regarding genetic diversity, 104 distinct spoligotype patterns were observed: 49 corresponded to clustered strains (2 to 93 strains per cluster), while 55 remained unclustered among which 16 patterns were not reported previously. Combining the study results with regional data retrieved from the international SITVIT2 database underlined a connection between frequency of certain M. tuberculosis phylogenetic lineages and the language spoken, suggesting historical (colonial) and ongoing links (trade, tourism, and migratory flows) with European countries with which they shared a common past

Evaluation of Methods for Rapid Detection of Resistance to Isoniazid and Rifampin in Mycobacterium tuberculosis Isolates Collected in the Caribbean ▿

The rapid identification of drug-resistant strains of Mycobacterium tuberculosis is crucial for the timely initiation of appropriate antituberculosis therapy. The performance of the Genotype MTBDRplus assay was compared with that of the Bactec 460 TB system, a “gold standard” culture-based method. The Genotype MTBDRplus assay was quicker and more cost-effective for the detection of rifampin resistance, but it was not as good for the detection of isoniazid-resistant strains in our setting

First Insight into Mycobacterium tuberculosis Epidemiology and Genetic Diversity in Trinidad and Tobago▿

This report is based on a 1-year recruitment of all of the culture-positive Mycobacterium tuberculosis cases in Trinidad and Tobago (n = 132). The study population was characterized by a high male-to-female sex ratio of 4 and a human immunodeficiency virus-tuberculosis (TB) coinfection rate of 30%. It mainly occurred among African descendants, who represent 37.5% of the total population but 69.7% of all TB cases (P < 0.001). Spoligotyping resulted in 25 different patterns and 12 clusters (2 to 74 strains per cluster), with the predominance of a highly conserved spoligotype international type clone, SIT566

Improving quality in national reference laboratories: The role of SLMTA and mentorship

Background: The Nigerian Institute of Medical Research houses two reference laboratories: the virology and tuberculosis laboratories. Both were enrolled in the Strengthening Laboratory Management Toward Accreditation (SLMTA) programme. Objective: To describe the impact of SLMTA and discuss factors affecting the results, with an emphasis on mentorship. Methods: The SLMTA programme was implemented from April 2010 through November 2012. Participants attended three workshops and executed quality improvement projects; laboratory auditors evaluated performance using a standard checklist. The virology laboratory did not receive mentorship; however, the tuberculosis laboratory had an international mentor who visited the laboratory four times during the programme, spending two to four weeks embedded within the laboratory during each visit. Results: There was an overall improvement in the performance of both laboratories, with the virology laboratory increasing 13% (from 80% at baseline to 93% at exit audit) and the tuberculosis laboratory increasing 29% (from 66% to 95%). These scores were maintained nine months later at the surveillance audit. Conclusion: The SLMTA programme resulted in improved and sustained quality management performance for both laboratories. Mentoring was a possible factor in the substantial improvement made by the tuberculosis laboratory and should be considered in order to augment the training received from the SLMTA workshops