Pneumonia exposure to cigarettes or air pollution, malnutrition, and poverty. The use of acid-suppressing medications — such as proton-pump inhibitors or H2 blockers — is associated with an increased risk of pneumonia. Approximately 10% of people who require mechanical ventilation develop ventilator associated pneumonia, and people with gastric feeding tube have an increased risk of developing of aspiration pneumonia. For people with specific variants of FER gene, the risk of death is reduced in sepsis caused by pneumonia. However, for those with TLR6 variants, the risk of getting Legionnaires' disease is increased. Bacteria are the most-common cause of community-acquired pneumonia (CAP),
Community-acquired pneumonia monocytogenes" and a variety of mycobacteria. CAP-causing viruses may also be transferred from mother to child; herpes simplex virus (the most common) is life-threatening, and adenoviridae, mumps and enterovirus can also cause pneumonia. Another cause of CAP in this group is "Chlamydia trachomatis", acquired at birth but not causing pneumonia until two to four weeks later; it usually presents with no fever and a characteristic, staccato cough. CAP in older infants reflects increased exposure to microorganisms, with common bacterial causes including "Streptococcus pneumoniae", "Escherichia coli", "Klebsiella pneumoniae", "Moraxella catarrhalis" and "Staphylococcus aureus". Maternally-derived syphilis is also a cause of CAP