SHMT2 and susceptibility to pneumonia measurement: We confirmed that five (4 of which are metabolic) mutants (purB::Tn, pdhA::Tn, SAUSA300_1231::Tn, glyA::Tn, and pyc::Tn) were significantly attenuated in the acute pneumonia model by infecting mice with individual transposon mutants (Fig. 4B).