If left untreated, this growth can spread beyond the lung by process of metastasis into nearby tissue or other parts of the body.
Drugi pogosti bakterijski povzročitelji so še "Haemophilus influenzae" (v 20 % primerov), "Chlamydophila pneumoniae" (13 %), "Mycoplasma pneumoniae" (3 %) ter "Staphylococcus aureus", "Moraxella catarrhalis", "Legionella pneumophila" in gramnegativni bacili.