Micro| Gram Positive Bacteria

3.03 Gram Positive Bacteria   Microbiology review for the USMLE Step 1 Exam.   Gram positive bacteria are characterized by their ability to retain the violet stain during the gram stain procedure, due to their thick peptidoglycan cell walls Gram positive bacteria can be cocci (spherical) or bacilli (rod-shaped) Cocci can be grouped in clusters, pairs, or chains Gram positive cocci in pairs or chains include streptococcus (pairs or chains), enterococcus (pairs), and staphylococcus (clusters) Hemolysis describes the ability of a bacteria species to break down red blood cells and is categorized as alpha (partial), beta (complete), or gamma (none) Coagulase activity refers to the presence of an enzyme that causes blood to coagulate and is present in some staphylococcus species Gram positive bacilli can be aerobic (listeria, bacillus, corynebacterium) or anaerobic (clostridium)