Gram Positive Rods
Gram Positive Rods are a group of bacteria which can be identified by their shape and Gram Stain colour.
Bacteria are broadly divided into two groups, Rods and Cocci depending on the shape of their cells. Cocci refer to bacteria which are spherical, whereas Rods are rod shaped.
During an identification process known as Gram Staining, bacteria can appear purple or pink which shows if they are Gram Positive or Gram Negative. Gram Positive bacteria have a thick layer of peptidoglycan which holds the Crystal Violet stain used in Gram Staining and so appear purple under the microscope. Gram Negative bacteria have a thin layer of peptidoglycan held between two membranes. This is not able to hold the stain and therefore the bacteria appear pink.
A clinically significant genus within Gram Positive Rods is the Mycobacterium genus. There are around 57 different strains of Mycobacteria within the genus, including serious pathogens in both humans and animals. They are often found growing in water and food sources but can also colonise human hosts asymptomatically. The issue with Mycobacterium is their resistance to antibiotics. Mycobacterium tuberculosis has been identified as totally drug resistant (i.e. resistant to all currently available drugs) in India and Iran since 2012.