Lactic acid bacteria

Cards (48)

  • 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.