As in numerous other areas, the comparatively simple technique of polymerase chain reaction (PCR) has revolutionized the field of infectious diseases. Whether this is through sequencing the genomes of key pathogens or developing vaccines by genetic manipulation, PCR-driven molecular biology has stamped its mark on infectious diseases. It is particularly fascinating to consider how PCR has influenced, and continues to influence, disease management and to realize how influential this research technology has become as a practical diagnostic tool.
Its role in this context can be broadly split into diagnosis, epidemiology, and prognostic monitoring. However, before considering the utility of the PCR, it is useful to discuss infectious diseases and the additional considerations required for using PCR for their management.
Infectious diseases can be broadly split into groups corresponding to the causative pathogen: bacterial (tuberculosis [TB], pseudomembranous colitis [PMC], sepsis) and viral (acquired immunodeficiency syndrome [AIDS], hepatitis C, influenza) are two simple groupings. Viral pathogens are the most common causes of infectious diseases worldwide (e.g., common cold with numerous viral causes), with bacterial pathogens often being more serious when they strike. The remaining categories are more complex and include the eukaryotes. A major group are the Protozoa, including the causes of many classical tropical diseases (e.g., malaria and sleeping sickness). The fungal pathogens (Pneumocystis pneumonia [PCP]) are frequently opportunistic, causing infections worldwide in individuals with reduced or impaired immunity.