A Rabbit Model to Study Antibiotic Penetration at the Site of Infection for Nontuberculous Mycobacterial Lung Disease: Macrolide Case Study

Abstract

Nontuberculous mycobacterial pulmonary disease (NTM-PD) is a potentially fatal infectious disease requiring long treatment duration with multiple antibiotics and against which there is no reliable cure. Among the factors that have hampered the development of adequate drug regimens is the lack of an animal model that reproduces the NTM lung pathology required for studying antibiotic penetration and efficacy. Given the documented similarities between tuberculosis and NTM immunopathology in patients, we first determined that the rabbit model of active tuberculosis reproduces key features of human NTM-PD and provides an acceptable surrogate model to study lesion penetration. We focused on clarithromycin, a macrolide and pillar of NTM-PD treatment, and explored the underlying causes of the disconnect between its favorable potency and pharmacokinetics, and inconsistent clinical outcome. To quantify pharmacokinetic-pharmacodynamic target attainment at the site of disease, we developed a translational model describing clarithromycin distribution from plasma to lung lesions, including the spatial quantitation of clarithromycin and azithromycin in mycobacterial lesions of two patients on long-term macrolide therapy. Through clinical simulations, we visualized the coverage of clarithromycin in plasma and four disease compartments, revealing heterogeneous bacteriostatic and bactericidal target attainment depending on the compartment and the corresponding potency against nontuberculous mycobacteria in clinically relevant assays. Overall, clarithromycin’s favorable tissue penetration and lack of bactericidal activity indicated that its clinical activity is limited by pharmacodynamic rather than pharmacokinetic factors. Our results pave the way towards the simulation of lesion pharmacokinetic-pharmacodynamic coverage by multi-drug combinations, to enable the prioritization of promising regimens for clinical trials.

Activity of Tricyclic Pyrrolopyrimidine Gyrase B Inhibitor against Mycobacterium abscessus

“…To further characterize in vitro and ex vivo anti- M. abscessus activities of TPP8, kill experiments against M. abscessus ATCC 19977 growing in Middlebrook 7H9 broth were performed and the inhibitory potency of TPP8 against bacteria growing intracellularly in infected THP-1-derived macrophages (ATCC TIB-202) was determined ( 26 ). TPP8 was largely bacteriostatic in broth culture ( Fig.…”

“…They were as follows (with MIC values shown in Table 1 and determined by the broth microdilution method in parentheses): TPP8, 0.04 μM (0.02 μM); SPR719, 6 μM (1.5 μM); MXF, 6 μM (3 μM); CLR, 1.5 μM (3 μM). (B) To determine the activity against intracellular bacteria, THP-1 cells were prepared and differentiated into macrophages with phorbol-12-myristate-13-acetate for 24 h, and the resulting macrophages were infected with a multiplicity of infection of 10 for 3 h using M. abscessus ATCC 19977 as described previously ( 26 ) and treated with the same concentration range of TPP8, SPR719, MXF, or CLR as in panel A. Intracellular CFU were enumerated by plating samples on Middlebrook 7H10 agar after 3 days of treatment. Experiments in panels A and B were carried out three times independently, and the results are represented as mean values with standard deviations.…”

Activity of Tricyclic Pyrrolopyrimidine Gyrase B Inhibitor against Mycobacterium abscessus

“…To further characterize in vitro and ex vivo anti- M. abscessus activities of TPP8, kill experiments against M. abscessus ATCC19977 growing in Middlebrook 7H9 broth were performed and the inhibitory potency of TPP8 against bacteria growing intracellularly in infected THP-1 derived macrophages (ATCC TIB-202) was determined (26). TPP8 was largely bacteriostatic in broth culture (Fig.…”

“…They were as follows (with MIC values shown in Table 1 and determined by the microbroth dilution method in parentheses): TPP8, 0.04 μM (0.02 μM); SPR719, 6 μM (1.5 μM); MXF, 6 μM (3 μM), CLR, 1.5 μM (3 μM). (B) To determine the activity against intracellular bacteria, THP-1 cells were prepared and differentiated into macrophages with phorbol-12-myristate-13-acetate for 24h, the resulting macrophages were infected with an MOI of 10 for 3h using M. abscessus ATCC19977 as described previously (26) and treated with the same concentration range of TPP8, SPR719, MXF, or CLR as in (A) . Intracellular CFU were enumerated by plating samples on agar Middlebrook 7H10 agar after 3 days of treatment.…”

Drug development challenges in nontuberculous mycobacterial lung disease: TB to the rescue

“…In immunocompetent patients with bronchiectasis conditions—chronic obstructive pulmonary disease and cystic fibrosis being the most common—nodular or cavitary pathology is frequently seen. These presentations bear key similarities with TB in immunocompetent subjects ( Jain et al, 2017 ), where the most common microscopic finding is necrotizing granulomas and cavities with a central zone of necrosis surrounded by a rim of macrophages, neutrophils, lymphocytes, and fibroblasts ( Kaya et al, 2022 ). Although less frequent, NTM-PD may also occur in apparently healthy individuals with no common genetic or immunological defect, possibly associated with the presence of autoantibodies neutralizing specific cytokines ( Puel et al, 2022 ).…”