Tuberculosis (TB) remains a leading cause of death globally among infectious diseases that has killed more numbers of people than any other infectious diseases. Animal models have become the lynchpin for mimicking human infectious diseases. Research on TB could be facilitated by animal challenge models such as the guinea pig, mice, rabbit and non-human primates. No single model presents all aspects of disease pathogenesis due to considerable differences in disease resistance/susceptibility between these models. Availability of a wide range of animal strains, Mycobacterium tuberculosis strains, route of infection and doses affect the disease progression and intervention outcome. Different animal models have contributed significantly to the drug and vaccine development, identification of biomarkers, understanding of TB immunopathogenesis and host genetic influence on infection. In this review, the commonly used animal models in TB research are discussed along with their advantages and limitations.

e Inhalable clofazimine-containing dry powder microparticles (CFM-DPI) and native clofazimine (CFM) were evaluated for activity against Mycobacterium tuberculosis in human monocyte-derived macrophage cultures and in mice infected with a low-dose aerosol. Both formulations resulted in 99% killing at 2.5 g/ml in vitro. In mice, 480 g and 720 g CFM-DPI inhaled twice per week over 4 weeks reduced numbers of CFU in the lung by as much as log 10 2.6; 500 g oral CFM achieved a log 10 0.7 reduction. C lofazimine (CFM) is a riminophenazine possessing activity against various species of both drug-sensitive and -resistant mycobacteria, including Mycobacterium leprae, M. tuberculosis, and M. avium-M. intracellulare (1). Its MIC against M. tuberculosis H37Rv is 0.15 to 2.5 g/ml (2). CFM is very hydrophobic, and its gastrointestinal absorption is low. At therapeutic oral doses, it may cause discoloration of the skin. High lipophilicity, long half-life (ϳ70 days), and high retention in tissues may cause toxicity (3, 4). These properties of CFM contribute to its low ranking (category 5) on the WHO list of second-line therapy choices for multidrug-and extensively drug-resistant tuberculosis (TB) (5).We hypothesize that CFM as a dry powder microparticle formulation for inhalation (CFM-DPI) might hold advantages for generating drug levels at the primary site of infection that would not otherwise be achievable (6). We present preliminary findings showing that (i) CFM-DPI retains the antimicrobial properties of native CFM in vitro and (ii) CFM-DPI is more efficacious in treating experimental tuberculosis than if given orally.CFM-DPI was prepared by spray drying, which was carried out independently at two locations: in South Africa using a Buchi mini-spray dryer (model B-290) and in India using a Labultima LU 20 spray dryer. Commercially purchased CFM (Sigma) was dissolved in dimethyl sulfoxide (DMSO) or ethanol and L-leucine in distilled water. Spray drying conditions (7) were similar at both locations. The resulting particle size (1 to 5 m) of CFM-DPI was suitable for deep lung delivery (Fig. 1A and B).In order to confirm the intracellular killing kinetics of CFM-DPI, M. tuberculosis bacilli residing in human monocyte-derived macrophages were comparatively exposed to CFM in both native and dry-powder form. Monocytes were isolated from heparinized human blood collected with informed consent (Pretoria University Ethics Committee approved). Standard procedures of density gradient/plastic adherence were employed and monocytes cultured in RPMI 1640, supplemented with 5% autologous serum, interleukin-3, and granulocyte-macrophage colony-stimulating factor for 7 days at 37°C in 5% CO 2 . Approximately 10 5 macrophages were infected with H37Rv at a multiplicity of infection of 10 over 18 h, and unbound bacilli were removed with phosphate-buffered saline (pH 7.4). CFM and CFM-DPI (concentrations ranging from 0.15 to 2.5 g/ml) were added to the infected macrophages and incubated for 2 days. Intracellular killing of bacilli was determined by ...

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BackgroundThe aim of this multicentric prospective study in India was to assess the value of several microbiological tools that contribute to the diagnosis of tuberculosis (TB) according to HIV status.MethodsStandard microbiological tools on individual specimens were analyzed.ResultsAmong the 807 patients with active TB, 131 were HIV-infected, 316 HIV-uninfected and 360 had HIV-unknown status. Among the 980 non-active TB subjects, 559 were at low risk and 421 were at high risk of M. tuberculosis (Mtb) exposure. Sensitivity of smear microscopy (SM) was significantly lower in HIV-infected (42.2%) than HIV-uninfected (75.9%) (p = 0.0001) and HIV-unknown pulmonary TB patients (61.4%) (p = 0.004). Specificity was 94.5% in non-TB patients and 100% in health care workers (HCW) and healthy family contacts. Automated liquid culture has significantly higher diagnostic performances than solid culture, measured by sensitivity (74.7% vs. 55.9%) (p = 0.0001) and shorter median time to detection (TTD) (12.0 vs. 34.0 days) (p = 0.0001). Specificity was 100% in HCW and cured-TB patients, but was lower in non-TB patients (89%) due to isolation of Mycobacteria other than tuberculosis (MOTT). TTD by both methods was related to AFB score. Contamination rate was low (1.4%). AccuProbe hybridization technique detected Mtb in almost all culture-positive specimens, but MOTT were found in 4.7% with a significantly higher frequency in HIV-infected (15%) than HIV-uninfected TB patients (0.5%) (p = 0.0007). Pre-test classification significantly increased the diagnostic value of all microbiological tests in pulmonary TB patients (p<0.0001) but to a lesser degree in extrapulmonary TB patients.ConclusionsConventional microbiological tools led to results similar to those already described in India special features for HIV-infected TB patients included lower detection by SM and culture. New microbiological assays, such as the automated liquid culture system, showed increased accuracy and speed of detection.

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