Lactic acid bacteria

• What type of bacteria are lactic acid bacteria, including Streptococcus?

  They are non-spore forming and non-motile.
• How do lactic acid bacteria obtain energy?

  They obtain energy by substrate level phosphorylation, not by electron transport or oxidative phosphorylation.
• What do lactic acid bacteria primarily use for energy?

  They normally obtain energy only from sugars.
• What is the biosynthetic capability of lactic acid bacteria?

  They have limited biosynthetic capability and require many vitamins, amino acids, purines, and pyrimidines.
• What type of anaerobes are lactic acid bacteria?

  They are aerotolerant anaerobes.
• What type of media do lactic acid bacteria usually grow on?

  They are usually grown on media containing yeast, peptone, and a fermentable carbohydrate.
• How do lactic acid bacteria respond to acidic conditions?

  They are tolerant of acid and can grow at pH 6, which many other bacteria cannot.
• Why is the ability to produce and tolerate high concentrations of lactic acid beneficial for lactic acid bacteria?

  It eliminates competition and is used in selective media.
• What are the main genera of lactic acid bacteria?

  • Streptococcus: chains of cells
  • Lactobacillus: rods
  • Pediococcus: pairs or tetrads
  • Leuconostoc: spheres in chains
• How can lactic acid bacteria be grouped?

  They can be grouped by their fermentation patterns.
• What are some common products that contain lactic acid bacteria?

  Many are probiotics found in yogurts and Yakult.
• What is the shape and division pattern of Streptococcus bacteria?

  Streptococcus bacteria are spherical cells that divide only in one plane, forming chains.
• What type of media do Streptococcus require for growth?

  They require complex media for growth.
• What is the hemolytic activity of beta-hemolytic Streptococcus?

  Beta-hemolytic Streptococcus causes complete hemolysis, resulting in a clear zone.
• What is the difference between alpha and gamma hemolysis in Streptococcus?

  Alpha hemolysis is incomplete hemolysis producing a greenish-brown zone, while gamma hemolysis shows no hemolysis.
• Who is the Lancefield classification named after?

  It is named after Rebecca Lancefield.
• What is Group A Streptococcus and its significance?

  Group A Streptococcus is S. pyogenes, which is beta-hemolytic and causes many streptococcal diseases in humans.
• What is the habitat of Group A beta-hemolytic Streptococcus?

  1. 30% of healthy people may be carriers in their throat and nasopharynx.
• What test is used to determine the sensitivity of Group A Streptococcus?

  They are very sensitive to bacitracin, which is used to test sensitivity.
• What are the symptoms of strep throat?

  Symptoms include red spotting near the uvula, swollen uvula, and white follicles on tonsils.
• What is streptococcal impetigo and who is most affected?

  Streptococcal impetigo is characterized by small vesicles on the skin forming a thin amber crust, mostly affecting young children.

  
• What causes scarlet fever?

  Scarlet fever usually results from a sore throat caused by a pyrogenic toxin-producing organism.
• What are the symptoms of scarlet fever?

  Symptoms include fever, toxic shock, and an erythematous rash.
• How many antigenically distinct toxins are associated with scarlet fever?

  There are three antigenically distinct toxins: A, B, and C.
• What is the significance of the resurgence of scarlet fever in the UK in 2014/15?

  There were 5,746 cases recorded, the highest rates in 50 years, with a mortality rate of 25 per 100,000.
• What is cellulitis and its potential complications?

  Cellulitis is an infection of the deep layers of the skin that can spread and cause necrotizing fasciitis.
• What is rheumatic fever and when does it occur?

  Rheumatic fever occurs in a small percentage of individuals 2-3 weeks after an untreated pharyngeal infection caused by beta-hemolytic group A strep.
• What are the potential consequences of rheumatic fever?

  It can cause serious damage to heart valves, leading to rheumatic heart disease.
• How many cases of rheumatic fever occur worldwide each year?

  Approximately 470,000 cases occur per year worldwide.
• What is glomerulonephritis and when does it typically occur?

  Most cases occur about a week after a group A strep infection, either skin or throat.
• What are the symptoms of glomerulonephritis?

  Symptoms include lack of kidney function, blood in urine, and edema in swollen extremities.
• What is the predominant species in Group B streptococci?

  1. agalactiae is the predominant species in this Lancefield group.
• What is the significance of Group B streptococci in newborns?

  They may cause serious infections in newborns, such as septicemia, pneumonia, and meningitis.
• What is the hippurate test used for?

  The hippurate test is used to determine if some streptococci can hydrolyze sodium hippurate.
• What are Group D streptococci associated with?

  They are associated with fecal flora and can cause urinary and wound infections.
• What is the significance of vancomycin resistance in Group D streptococci?

  Vancomycin resistance has increased from virtually 0 to nearly 50% in some communities over 10 years.
• What is the viridans group of streptococci?

  The viridans group includes many species that are normal inhabitants of the throat and nasopharynx of humans.
• What is the role of Streptococcus mutans in dental health?

  1. mutans causes dental caries by producing lactic acid that removes calcium from teeth.
• What is the significance of viridans streptococci in bacterial endocarditis?

  Viridans streptococci are a significant cause of bacterial endocarditis, which can be fatal if not treated.
• What is the shape of Streptococcus pneumoniae?

  It is a lancet-shaped organism, usually arranged in pairs.