Micro| Streptococcus Species

3.05 Streptococcus Species   Microbiology review for the USMLE Step 1 Exam.   Streptococcus bacteria are gram positive cocci that form linear chains Hemolysis refers to the ability of bacteria to break down red blood cells and is classified as alpha (partial), beta (complete), or gamma (none) Alpha hemolytic streptococci include viridans streptococci and Streptococcus pneumoniae Viridans streptococci, particularly Streptococcus mutans, are common causes of dental cavities and endocarditis, while Streptococcus pneumoniae is a common cause of pneumonia Beta hemolytic streptococci include Group A streptococci (Streptococcus pyogenes) and Group B streptococci (Streptococcus agalactiae) Group A streptococci can cause strep throat, impetigo, and cellulitis, as well as more serious infections like scarlet fever and rheumatic fever Group B streptococci are commonly found in the vagina and rectum, and can cause infections in newborns and pregnant women, as well as urinary tract infections and pneumonia Gamma hemolytic streptococci include the Enterococcus species, which can cause urinary tract infections, endocarditis, and other infections, and can be resistant to some antibiotics Lancefield grouping refers to the presence of different types of carbohydrate antigens on the surface of streptococcus bacteria and is used in classification and identification of streptococcus species