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Lactic acid bacteria
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Emily cheung
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Cards (48)
What type of bacteria are lactic acid bacteria, including Streptococcus?
They are
non-spore
forming and
non-motile
.
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How do lactic acid bacteria obtain energy?
They obtain energy by
substrate level phosphorylation
, not by
electron transport
or
oxidative phosphorylation
.
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What do lactic acid bacteria primarily use for energy?
They normally obtain energy only from
sugars
.
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What is the biosynthetic capability of lactic acid bacteria?
They have limited biosynthetic capability and require many
vitamins
, amino acids,
purines
, and
pyrimidines
.
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What type of anaerobes are lactic acid bacteria?
They are
aerotolerant anaerobes
.
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What type of media do lactic acid bacteria usually grow on?
They are usually grown on media containing
yeast
,
peptone
, and a fermentable
carbohydrate
.
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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.
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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
.
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What are the main genera of lactic acid bacteria?
Streptococcus
: chains of cells
Lactobacillus
: rods
Pediococcus
: pairs or tetrads
Leuconostoc
: spheres in chains
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How can lactic acid bacteria be grouped?
They can be grouped by their
fermentation patterns
.
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What are some common products that contain lactic acid bacteria?
Many are probiotics found in yogurts and
Yakult
.
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What is the shape and division pattern of Streptococcus bacteria?
Streptococcus bacteria are
spherical
cells that divide only in one plane, forming
chains
.
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What type of media do Streptococcus require for growth?
They require
complex media
for growth.
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What is the hemolytic activity of beta-hemolytic Streptococcus?
Beta-hemolytic Streptococcus
causes
complete hemolysis
, resulting in a clear zone.
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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.
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Who is the Lancefield classification named after?
It is named after
Rebecca
Lancefield.
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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.
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What is the habitat of Group A beta-hemolytic Streptococcus?
30%
of healthy people may be carriers in their throat and nasopharynx.
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What test is used to determine the sensitivity of Group A Streptococcus?
They are very sensitive to
bacitracin
, which is used to test sensitivity.
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What are the symptoms of strep throat?
Symptoms include red spotting near the
uvula
, swollen uvula, and white follicles on
tonsils
.
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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
.
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What causes scarlet fever?
Scarlet fever
usually results from a sore throat caused by a
pyrogenic
toxin-producing
organism.
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What are the symptoms of scarlet fever?
Symptoms include fever,
toxic shock
, and an
erythematous
rash.
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How many antigenically distinct toxins are associated with scarlet fever?
There are three antigenically distinct toxins:
A
,
B
, and
C
.
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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
.
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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
.
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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
.
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What are the potential consequences of rheumatic fever?
It can cause serious damage to heart valves, leading to
rheumatic heart disease
.
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How many cases of rheumatic fever occur worldwide each year?
Approximately
470,000
cases occur per year worldwide.
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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.
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What are the symptoms of glomerulonephritis?
Symptoms include lack of
kidney function
,
blood
in urine, and
edema
in swollen extremities.
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What is the predominant species in Group B streptococci?
agalactiae
is the predominant species in this Lancefield group.
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What is the significance of Group B streptococci in newborns?
They may cause serious infections in newborns, such as
septicemia
,
pneumonia
, and
meningitis
.
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What is the hippurate test used for?
The hippurate test is used to determine if some
streptococci
can hydrolyze sodium hippurate.
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What are Group D streptococci associated with?
They are associated with
fecal flora
and can cause urinary and wound infections.
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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
.
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What is the viridans group of streptococci?
The viridans group includes many species that are normal inhabitants of the throat and
nasopharynx
of humans.
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What is the role of Streptococcus mutans in dental health?
mutans causes dental caries by producing
lactic acid
that removes
calcium
from teeth.
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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.
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What is the shape of Streptococcus pneumoniae?
It is a
lancet-shaped
organism, usually arranged in pairs.
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