Streptococcus is a genus of bacteria identified and named by Viennese surgeon Albert Theodor Billroth (1829-94) in 1877. A combination of the Ancient Greek streptosmeaning twisted and Modern Latinization of coccusmeaning spherical bacterium from Ancient Greek kokkos meaning berry. Dr. Billroth thought the streptococcus bacterium resembled a chain of berries, as you can see in the image on the left.
A decade later, Scottish surgeon and bacteriologist Alexander Ogston (1844-1929) named the staphylococcus bacterium based on the same formation as streptococcus. In this case, Dr. Ogston chose the Ancient Greek word staphyle meaning a bunch of grapes, and the stunning resemblance can easily be seen in the image on the right.
The -coccus suffix can be combined with other prefixes to indicate spherical bacteria: diplococcus, pneumococcus, etc.
Image of streptococcus bacterium courtesy Sanofi Pasteur used with permission under a creative commons 3.0 license.
Imageof staphylococcus bacterium courtesy Carl Zeiss Microscopy used with permission under a creative commons 3.0 license.