"Figure 2.38: Clostridium difficile, a gram-positive, rod-shaped bacterium, causes severe colitis and diarrhea, often after the normal gut microbiota is eradicated by antibiotics. modification of work by Centers for Disease Control and Prevention. Public Domain. Figure 2.39: A gram-stained specimen of Streptococcus pyogenes shows the chains of cocci characteristic of this organism’s morphology. (c) American Society of Microbiology. Redistribution authorized with attribution. Figure 2.40: In this gram-stained specimen, the violet rod-shaped cells forming chains are the gram-positive bacteria Bacillus cereus. Credit a: modification of work by (c) Bibliomaniac 15. CC BY 3.0 Unported. https://commons.wikimedia.org/wiki/File:Bacillus_cereus_and_Escherichia_coli.jpg; credit b: modification of work by Centers for Disease Control and Prevention. Public Domain. https://commons.wikimedia.org/wiki/File:Bacillus_cereus_01.png Figure 2.41: This SEM of Staphylococcus aureus illustrates the typical grape-like clustering of cells. modification of work by Centers for Disease Control and Prevention. Public Domain. Figure 2.42: M. tuberculosis grows on Löwenstein-Jensen (LJ) agar in distinct colonies. Centers for Disease Control and Prevention. Public Domain."