Infectious diseases are caused by microorganisms that release toxins or invade
body tissues. The most common pathogenic organisms are bacteria, viruses, fungi,
protozoa, and helminths. Systemic infections usually cause fevers, chills, sweats,
malaise, and occasionally headache, muscle and joint pain, or changes in mental
status, and even septic shock-MODS. Infectious diseases have always threatened
populations and caused great loss of life in history, but since the last century, with
the discovery of antibiotics, historical trends have been reversed. It is reported that
between 1990 and 2017, age-standardized disability-adjusted life year (DALY) rates
decreased by 41.3% (38.8-43.5) for infectious diseases. However, in 2017, lower
respiratory infections are still ranked as the third cause of DALYs.
Drug therapy is the one of most critical management strategies for infectious
diseases. Efficacy and safety of drug therapy should always be considered, especially
in elders, neonates and immunosuppressed patients. Off-label drug therapy has been
performed for complex infectious diseases, especially for new emerging infectious
diseases. However, off-label drug therapy can be extremely complex: some are
prone to rational use, while others are more susceptible to the issues of irrational
use. With the increasing rate of publication of data in this area, new evidence for
the efficacy and safety of different treatment approaches is constantly developing.
Thus, rigorous analysis of such data is imperative, which will guide future clinical
practice and guidelines.