Tuberculosis drug resistance in Bamako, Mali, from 2006 to 2014

Background

Although Drug resistance tuberculosis is not a new phenomenon, Mali remains one of the “blank” countries without systematic data.

Methods

Between 2006 and 2014, we enrolled pulmonary TB patients from local TB diagnostics centers and a university referral hospital in several observational cohort studies. These consecutive patients had first line drug susceptibility testing (DST) performed on their isolates. A subset of MDR was subsequently tested for second line drug resistance.

Results

A total of 1186 mycobacterial cultures were performed on samples from 522 patients, including 1105 sputa and 81 blood samples, yielding one or more Mycobacterium tuberculosis complex (Mtbc) positive cultures for 343 patients. Phenotypic DST was performed on 337 (98.3%) unique Mtbc isolates, of which 127 (37.7%) were resistant to at least one drug, including 75 (22.3%) with multidrug resistance (MDR). The overall prevalence of MDR-TB was 3.4% among new patients and 66.3% among retreatment patients. Second line DST was available for 38 (50.7%) of MDR patients and seven (18.4%) had resistance to either fluoroquinolones or second-line injectable drugs.

Conclusion

The drug resistance levels, including MDR, found in this study are relatively high, likely related to the selected referral population. While worrisome, the numbers remained stable over the study period. These findings prompt a nationwide drug resistance survey, as well as continuous surveillance of all retreatment patients, which will provide more accurate results on countrywide drug resistance rates and ensure that MDR patients access appropriate second line treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2060-7) contains supplementary material, which is available to authorized users.

Tuberculosis specific responses following therapy for TB: Impact of HIV co-infection

Characterizing perturbations in the immune response to tuberculosis in HIV can develop insights into the pathogenesis of coinfection. HIV+ TB+ and TB monoinfected (TB+) subjects recruited from clinics in Bamako prior to initiation of TB treatment were evaluated at time-points following initiation of therapy. Flow cytometry assessed CD4+/CD8+ T cell subsets and activation markers CD38/HLA-DR. Antigen specific responses to TB proteins were assessed by intracellular cytokine detection and proliferation. HIV+ TB+ subjects had significantly higher markers of immune activation in the CD4+ and CD8+ T cells compared to TB+ subjects. HIV+ TB+ had lower numbers of TB-specific CD4+ T cells at baseline. Plasma IFNγ levels were similar between HIV+ TB+ and TB+ subjects. No differences were observed in in-vitro proliferative capacity to TB antigens between HIV+ TB+ and TB+ subjects. Subjects with HIV+ TB+ coinfection demonstrate in vivo expansion of TB-specific CD4+ T cells. Immunodeficiency associated with CD4+ T cell depletion may be less significant compared to immunosuppression associated with HIV viremia or untreated TB infection.

[Epidemiologic aspects of pulmonary tuberculosis with positive bacilloscopy in the decade of 1995-2004]

The purpose of this study is to make an epidemiological description of pulmonary tuberculosis with sputum smear positive in Mali. This is a retrospective study conducted from January 1st, 1995 to December 31st, 2004 by the National Program for fighting against tuberculosis (located at the National Department of health), and where data were centralized. From this ten years period, 33,000 cases of tuberculosis (all forms of TB) have been notified in Mali, which represented an annual rate of 2750. Of those, 22,275 cases (67.5%) were sputum smear positive (with Ziehl Nielsen), this represented 1856 as annual rate. The prevalence of pulmonary TB with sputum smear positive is 185/100,000. During the study period a total of 13,638 (61.22%) cases of 22,275 cases of pulmonary TB with sputum smear positive have been given ant tuberculosis drugs; From these patients under therapy 2371 cases (17.38% ) disappear before the end of treatment.; 5851 cases (42.90%) have been considered as cured; 161 (1.18%) cases of treatment failure and 523 (3.93%) cases of death. The sex-ratio was 3.57 with young adults representing the majority of cases. Pulmonary TB with sputum smear positive treatment remains a challenge for National Programs for fighting against TB as well as its prevention.

Reconstitution of immune responses occurs very rapidly after initiation of therapy for tuberculosis (43.54)

Introduction: Immune reconstitution syndrome is a potentially fatal sequelae of HAART therapy in 20% of patients with HIV and 3–5% with tuberculosis who begin treatment. The role of CD4+T cells in its pathogenesis is poorly understood.

Methods: This study was done under an IRB approved protocol to study MTb specific immunity. Groups based on HIV status and local or disseminated MTb were evaluated for CD4+ T cell counts, Purified Protein Derivative (PPD) induced proliferation and cytokine induction using intracellular cytokine staining for IFN γ, IL2, TNFα and CFSE dilution at predefined times before and after starting therapy.

Results: In preliminary results, the first 3 HIV negative patients with MTb exhibited striking increase in MTb specific immunity in the first week of therapy. Percentage of IFN γ producing CD4+T cells increased from 1.96 and 0.48 to 4.46 and 1.34, and of TNF α producing cells increased from 0.85 and 0.45 to 3.96 and 1.06 in 2 patients. Proliferative responses also showed marked increases. Percent dividing cells increased from 4.3, 4.4 and 16.3 at baseline to 36.9, 11.9 and 39.6 at 1 week and 54.8 and 72.3 at 4 weeks of therapy. Total number of CD4+ T cells also increased.

Conclusions: Tuberculosis like HIV causes quantitative and qualitative changes in CD4+T cells . These are rapidly reversed when therapy is begun .This data provides insight into the pathogenesis of the immune reconstitution syndrome.