Ventilator-associated pneumonia is caused by a web of interactions between host, agent, and environmental factors. The major causative agents include Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Acinetobacter baumannii. Surveillance programs help verify diagnoses, detect epidemics, collect and analyze data, test hypotheses, and manage outbreaks. Preventive measures focus on aseptic technique and limiting the spread of infections.