PTX3 and infection: Clear correlations have emerged in numerous studies between systemic (i.e., in the plasma) and local (i.e., in the bronchoalveolar lavage (BAL)) levels of PTX3 and both the presence and severity of infections caused by diverse pathogens (e.g., Aspergillus fumigatus-A. fumigatus, Pseudomonas species, and, more recently, SARS-CoV-2) [12,13,14], and an established body of evidence points to this PRM as a diagnostic/prognostic marker of opportunistic infections, including those sustained by S. aureus [11].