Targeting Pseudomonas aeruginosa ventilator-associated pneumonia with a non-antibiotic and biofilm-disrupting live biotherapeutic: preclinical safety and efficacy study

Abstract Background. Ventilator-associated pneumonia (VAP) is the second most common hospital-acquired infection and is associated with high morbidity and mortality. The insertion of the endotracheal tube (ETT) compromises the host’s bronchial defenses and facilitates the formation of microbial biofilms and VAP. Although antibiotics remain the cornerstone treatment, their efficacy is often compromised by poor biofilm penetration and the prevalence of multidrug-resistant bacteria. This reveals the need to develop novel non-antibiotic therapeutic strategies. We engineered a non-pathogenic strain of the pulmonary bacteria Mycoplasma pneumoniae CV2 to express anti-biofilm and bactericidal enzymes (VAP platform). The therapeutic effect was validated in a murine model of Pseudomonas aeruginosa infection and ex vivo in ETTs of patients with P. aeruginosa -induced VAP. Methods. We evaluated the safety of an improved version of CV2 (CV8, Mycochassis) in a miniature pig model, and its efficacy with the VAP therapeutic platform (CV8_VAP) in a piglet model of P. aeruginosa -induced VAP. CV8_VAP was administered via intralobe instillation or nebulization. We assessed the platform’s ability to degrade biofilms formed on ETTs in vivo and its impact on the airway microbiota. We evaluated bacterial load in the lungs, inflammatory responses, histopathological and the clinical outcomes to provide a comprehensive characterization of therapeutic efficacy and safety. Findings. VAP platform reduced biofilm thickness and P. aeruginosa load in ETTs and lungs, with the nebulized route showing enhanced efficacy. CV8_VAP contributed on microbiome diversity restoration. Inflammatory markers in the lung were markedly decreased, suggesting a local immunomodulatory effect. Interpretation. These findings support that CV8_VAP as a promising, non-antibiotic therapeutic strategy for treating VAP caused by P. aeruginosa . Funding. The project that gave rise to these results has received funding from “La Caixa” Foundation (HR18-00058), and the European Research Council under the European Union’s Horizon 2020 research and innovation program (670216).