Building a Better Mouse Model for Mycobacterium abscessus: Julianna Proietto’s Innovations in Chronic Infection Research
- Ray Sullivan
- 2 days ago
- 2 min read
At the 2025 Theobald Smith Society Spring Symposium, Julianna Proietto, Senior Animal Specialist at the Center for Discovery and Innovation, Hackensack Meridian Health, presented a detailed overview of her work developing a robust mouse model for Mycobacterium abscessus (Mab) pulmonary infection. Her talk addressed a critical gap in preclinical research: how to establish a chronic, reproducible infection in immunocompetent mice to evaluate new treatments for this drug-resistant pathogen.
M. abscessus is an environmental bacterium capable of causing severe lung infections, particularly in people with cystic fibrosis or compromised immune systems. It is notoriously resistant to antibiotics, and reliable preclinical models are essential for developing new therapies. However, Mab is often cleared too quickly in standard mouse models, limiting their usefulness.
To overcome this, Proietto’s team adopted an innovative approach: embedding Mab in agar beads before intratracheal inoculation. This technique shields the bacteria from the mouse’s innate immune system, allowing a sustained infection. Through rigorous protocol development—including roller bottle cultures, precise bead emulsification in mineral oil, and size filtration—her team produced consistently sized beads (150–250 µm), ensuring reproducible bacterial loads across trials.
Early inoculation attempts using plastic gavage tools led to erratic CFU counts. Switching to a metal gavage and optimizing bead delivery (using 3D-printed stoppers and glass syringes) dramatically improved consistency. The team also refined mouse positioning and sedation techniques, adopting a recumbent position and avoiding ketamine/xylazine due to respiratory suppression.
Their optimized model demonstrated stable infections with consistent CFU counts and granulomatous lung pathology persisting through at least 21 days. Ziehl-Neelsen staining confirmed dense intracellular bacteria in granuloma centers—key hallmarks of chronic infection.
This model provides an ethically sound, reproducible, and cost-effective alternative to immunosuppressed mouse models. With it, the Dick and Dartois Lab are now positioned to test new antibiotic regimens against Mab. Proietto’s meticulous work underscores the importance of technical refinement in animal models and offers a valuable resource for labs developing therapies against this challenging pathogen.
See Julianna’s talk at https://youtu.be/9XvUJPzraTA
Proietto J, Tatek B, Folvar C, Jimenez DC, Alshiraihi IM, Gonzalez-Juarrero M, Saliu F, Vacca F, Cirillo DM, Lore N, Dick T, Dartois V, Aragaw WW. Preparation of Agar Bead Embedded Mycobacterium abscessus to Inoculate Immunocompetent Mice Intratracheally. J Vis Exp. 2025 Apr 25;(218). doi: 10.3791/67602. PMID: 40354234.