Toward First-line Molecular Diagnosis of Ocular Infectious Disease

Technology has driven the development of microbiology since its earliest days. Antonie van Leeuwenhoek first observed bacteria through the first microscope in the 1670s. However, it was more than 2 centuries before Robert Koch grew the first pure culture of a bacterium—Bacillus anthracis—in 1881 using sterilized cut potato slices as the medium. Koch was frustrated that many other bacteria visible under the microscope could not be grown on this medium. His assistant Walther Hesse began to experiment with using gelatin to grow bacteria, but he was confounded by the liquefaction of gelatin by the growing microbes (which we now know was due to secreted proteases). Hesse's wife, Lina, provided the solution, introducing her husband to the use of agar, an algal polysaccharide used to help solidify jellies. Through this serendipity, the agar plate was born. Since 1882, culture on the agar plate has been the gold standard for the detection and identification of pathogenic bacteria and fungi. The invention of the ultracentrifuge in the 1920s allowed the isolation of pure viruses, including herpes simplex (HSV), varicella zoster, cytomegalovirus (CMV), and Epstein–Barr virus.