We always enjoy Craven's editorials1,2 on pneumonia prevention as they are accurate and constructive. In his previous editorial in CHEST (July 2006),1 Craven acknowledged that antibiotic prophylaxis with selective digestive decontamination (SDD) is a valid strategy that reduces mortality. The SDD philosophy is based on the carrier state concept, which distinguishes among three different types of pneumonia (primary endogenous, secondary endogenous, and exogenous pneumonia), due to a limited range of potentially pathogenic microorganisms (six “normal” organisms and nine “abnormal” organisms). Each of the three types of pneumonia requires different prophylactic interventions. Parenteral antimicrobial agents control primary endogenous pneumonia, enteral antimicrobial agents prevent secondary endogenous pneumonia, and only a high level of hygiene can control exogenous pneumonia. SDD using hygiene, and parenteral and enteral antimicrobial agents is a prophylactic protocol that aims at the control of exogenous, primary endogenous, and secondary endogenous pneumonias, and at a reduction in mortality.