A decision tree and nomogram were developed to predict the Mixed-Infection phenotype.<h4>Results</h4>Three clinical phenotypes were identified through machine learning: Mycoplasma-Dominant (37.7%), characterized by Mycoplasma infection with moderate inflammatory response; Mixed-Infection (28.2%), characterized by multi-pathogen coinfection, the youngest age group, and the most extended hospital stays; and High-Inflammation (34.1%), characterized by elevated CRP and WBC levels. This evidence concerns the gene CRP and infection.