Pneumonia is infection of the lung parenchyma, most commonly caused by streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilus influenzae, and viruses (influenza, SARS-CoV-2). In the WikiBiome framework, pneumonia exemplifies the metal battleground at the host-pathogen interface — the outcome of infection depends on the competition for zinc, manganese, and iron between host nutritional immunity and pathogen metal acquisition systems.
Metal Ecology
- Zinc vs. manganese: Host calprotectin sequesters both Zn and Mn at infection sites. S. pneumoniae responds by upregulating high-affinity Mn transporters (PsaA) to maintain Mn-SOD defense against oxidative killing. Zinc can directly inhibit pneumococcal manganese uptake, providing a mechanistic basis for zinc supplementation in pneumonia [1].
- Iron: Pneumonia pathogens deploy siderophores and heme acquisition systems; host hepcidin elevation during infection restricts systemic iron [2].
- Infection metallomics: Siderophore and metallophore detection in patient specimens enables pathogen identification and outcome prediction in critical care [2].
Gut-Lung Axis
- Gut dysbiosis increases pneumonia susceptibility via impaired systemic immune priming.
- COVID-19 pneumonia is compounded by gut barrier failure and endotoxemia [3].
- Antibiotic treatment of pneumonia disrupts gut colonization resistance, enabling secondary infections.
Cross-References
- streptococcus pneumoniae — primary bacterial pathogen
- klebsiella — Gram-negative pneumonia pathogen
- calprotectin — host Zn/Mn sequestration at infection site
- zinc — inhibits pneumococcal Mn uptake
- nutritional immunity — metal restriction as antimicrobial defense
- sepsis — pneumonia as leading cause of sepsis