Nanotheranostic applications in pulmonary infections

Pulmonary infections are caused when microbial pathogens like bacteria, viruses, or fungi invade and damage both airways and lung tissues, triggering inflammation and the accumulation of immune cells in the bronchi, bronchial tree, and lungs. This process leads to the appearance of symptoms such as fever, cough, and respiratory difficulty, or dyspnea, as the alveoli can be filled with liquid or pus. The most common types of pulmonary infections are pneumonia, bronchitis, bronchiolitis, tuberculosis, empyema, and lung abscess, which can be acute or chronic, with an estimated global incidence of 344 million episodes in 2021. For this reason, lung infection requires an early laboratory diagnosis, which specifically identifies the causal agent, which is then targeted with direct antimicrobial treatment, helping to fight the specific pathogen and combat antimicrobial resistance, and allows the implementation of targeted infection control measures, such as isolation, to prevent spread, as well as antimicrobial susceptibility testing. This also allows to monitor patient outcomes in healthcare settings, as well as adjusting treatment as needed, leading to better patient prognosis and public health approaches. In addition, antimicrobial drug resistance (AMDR, or AMR) appears when infections become resistant to antimicrobial drugs, making treatments ineffective and thus leading to increased mortality and morbidity of the affected patients. As a result, in 2021, the global burden on antimicrobial resistance in lower respiratory infections (LRIs) was 20.89 deaths per 100.000 individuals. Thus, the search and development of new early diagnostic alternatives and effective treatments for lung infections related to antimicrobial resistance is necessary. This urgent need is driven by the limited effectiveness of current antibiotics, rising healthcare costs, increased patient mortality, and the potential for AMR to become a leading cause of death globally. In this respect, nanotheranostics is an emerging multi- and interdisciplinary field that merges nanotechnology with diagnostics and therapeutics, creating single nanosystems to simultaneously detect disease, deliver drugs, and monitor treatment effectiveness for personalized medicine. This approach involves the use of nanomaterials to diagnose diseases, deliver therapeutics, and monitor treatment response, which makes it an effective approach to the development of modern diagnostic techniques as well as formulations that enhance antibiotic activity in the treatment of respiratory infections. Thus, the objective of this review is to explore the applications and uses of nanotheranostics for the diagnosis, treatment, and prevention of lung infections in order to obtain a rapid diagnosis with an effective treatment that prevents the appearance of resistance.