MMSC 428 EXAM 1 | QUESTIONS AND
ANSWERS | WITH COMPLETE SOLUTION
Streptococcus pyogenes treatment - - Correct answer-:-penicillins: not a lot of
resistance is seen, so partially synthetic ampicillin and amoxicillin are commonly
used for treatment (especially for children)
Streptococcus pyogenes culture - - Correct answer-:-sample obtained from throat
swab
-culture techniques (media, aerobic vs. anaerobic) are not well standardized
between clinics, leads to varied results of Streptolysin O vs. S
-SBA can be used as media, but throat biota may overpopulate
-selective strep agar (SSA) contains neomycin and polymyxin B to inhibit growth
of throat biota
-colonies will appear small, dry and surrounded by large zones of B-hemolysis
streptococcus pyogenes antigen detection - - Correct answer-:-point of care
assays ( done in Dr. office) that use commercial Abs to detect Strep pyogenes cell
wall antigens in patient sample
-most commonly used tests to identify Strep pyogenes related pharyngitis
,streptococcus pyogenes serology - - Correct answer-:-anti-streptolyin O (ASO):
titer will be low for noninvasive infections like strep throat
-anti-DNase B (ADN-B): positive early, is the preferred test
-streptozyme: looks for antibodies against many Strep pyogenes Ags, is very
sensitive test for invasive infections used, can be used to monitor progression of
disease
sequelae - - Correct answer-:conditions due to immunological reactions
(secondary to an infection)
-symptoms are not due to the infectious agent itself
acute glomerulonephritis (AGN) - - Correct answer-:-post streptococcal
sequealae, usually associated with Strep pyogenes skin infections
-type 3 hypersensitivity response
-strep pyogenes Ags in blood bind to Abs to form immune complexes
-large immune complexes will get stuck in the glomerulus, and when the body
attempts to clear the complexes with complication activation, WBC
degranulation, etc. it will cause extensive damage to kidney
-when infection clears the damage is typically reversed
-treated with penicillin
acute rheumatic fever (ARF) - - Correct answer-:-post streptococcal sequelae,
usually associated with Strep pyogenes bacterial pharyngitis (strep throat) that is
not treated quickly
-body produces Abs against strep pyogenes M proteins, Abs cross react with
antigens found on heart tissue
-antibodies attack heart tissue (type 1 hypersensitivity) and lead to progressive
valve damage
,-treated with penicillin
streptococcus algalactaiae (group B strep) - - Correct answer-:-gram positive strep
-aerotolerant anaerobe
-have group B Lancefield antigens
-produce CAMP factor which is toxic to humans (CAMP test)
-positive hippurate hydrolysis test
-produce carbohydrate super antigen that overstimulates immune system (similar
function to endotoxin/ LPS)
-produces 6 serotypes of capsules that contain sialic acid (weak immunogens)
-may be part of normal biota, typically on vaginal mucosa
-weakly virulent, cause less invasive diseases, mainly effects newborns (rarely
affects adults)
-fastidious, requires blood to be cultured
-colonies are small and have small zones of B-hemolysis
CAMP test - - Correct answer-:a test that is used to detect CAMP factor in group B
strep
-staph aureus is streaked onto an SBA plate
-bacteria that is suspected to be group B strep is streaked perpendicularly
-after incubation, if. there is enhanced hemolysis in the crossover zone of the 2
bacteria it is considered positive for CAMP factor
group B strep and perinatal infections - - Correct answer-:-Strep algalacticae is
found in the vaginal mucosa and neonates with weak immune systems are
inoculated during birth
, -early onset: within first 7 days of deliver bacteremia and pneumonia occur due to
aspirated Strep algalacticae
-late onset: ~ 3-8 weeks after birth the child will present with bacterial meningitis
that is caused by initial bacteremia that passes the blood brain barrier
-risk factors: premature brith, prolonged rupture of aminotic membrane (vaginal
biota will enter uterus)
group B strep (GBS) prevention in neonates - - Correct answer-:prenatal
screenings and care are important
-vaginal and urine cultures are screened during pregnancy
-lim broth: contains antibiotics to suppress growth of vaginal biota and only look
for GBS
-granada agar & carrot broth: B hemolytic group B strep will appear organge
-PCR can be used to amplify and identify DNA specific to GBS
Streptococcus groups C,G and F - - Correct answer-:-all are B-hemolytic
-small colonies contain group A, C, F or G lancefield Ag's
-Strep anginosus (small colony) is commensal bacteria in microbiota that is B-
hemolytic, and produces pinpoint size colonies (< 0.5 mm)
-large colonies contain group C or G lancefield Ags
-Strep dysgalactiae subsp. equismillis (large colony) is potentially pathogenic and
associated with pyogenic pharyngitis cases
streptococcus group D - - Correct answer-:-non-hemolytic
- "streptococcus bovis group"
-S. equinis, S. infantarius, S. gallolyticus and S. alactolyticus are all part of normal
biota in GI tract, mucous membranes and vaginal mucosa
ANSWERS | WITH COMPLETE SOLUTION
Streptococcus pyogenes treatment - - Correct answer-:-penicillins: not a lot of
resistance is seen, so partially synthetic ampicillin and amoxicillin are commonly
used for treatment (especially for children)
Streptococcus pyogenes culture - - Correct answer-:-sample obtained from throat
swab
-culture techniques (media, aerobic vs. anaerobic) are not well standardized
between clinics, leads to varied results of Streptolysin O vs. S
-SBA can be used as media, but throat biota may overpopulate
-selective strep agar (SSA) contains neomycin and polymyxin B to inhibit growth
of throat biota
-colonies will appear small, dry and surrounded by large zones of B-hemolysis
streptococcus pyogenes antigen detection - - Correct answer-:-point of care
assays ( done in Dr. office) that use commercial Abs to detect Strep pyogenes cell
wall antigens in patient sample
-most commonly used tests to identify Strep pyogenes related pharyngitis
,streptococcus pyogenes serology - - Correct answer-:-anti-streptolyin O (ASO):
titer will be low for noninvasive infections like strep throat
-anti-DNase B (ADN-B): positive early, is the preferred test
-streptozyme: looks for antibodies against many Strep pyogenes Ags, is very
sensitive test for invasive infections used, can be used to monitor progression of
disease
sequelae - - Correct answer-:conditions due to immunological reactions
(secondary to an infection)
-symptoms are not due to the infectious agent itself
acute glomerulonephritis (AGN) - - Correct answer-:-post streptococcal
sequealae, usually associated with Strep pyogenes skin infections
-type 3 hypersensitivity response
-strep pyogenes Ags in blood bind to Abs to form immune complexes
-large immune complexes will get stuck in the glomerulus, and when the body
attempts to clear the complexes with complication activation, WBC
degranulation, etc. it will cause extensive damage to kidney
-when infection clears the damage is typically reversed
-treated with penicillin
acute rheumatic fever (ARF) - - Correct answer-:-post streptococcal sequelae,
usually associated with Strep pyogenes bacterial pharyngitis (strep throat) that is
not treated quickly
-body produces Abs against strep pyogenes M proteins, Abs cross react with
antigens found on heart tissue
-antibodies attack heart tissue (type 1 hypersensitivity) and lead to progressive
valve damage
,-treated with penicillin
streptococcus algalactaiae (group B strep) - - Correct answer-:-gram positive strep
-aerotolerant anaerobe
-have group B Lancefield antigens
-produce CAMP factor which is toxic to humans (CAMP test)
-positive hippurate hydrolysis test
-produce carbohydrate super antigen that overstimulates immune system (similar
function to endotoxin/ LPS)
-produces 6 serotypes of capsules that contain sialic acid (weak immunogens)
-may be part of normal biota, typically on vaginal mucosa
-weakly virulent, cause less invasive diseases, mainly effects newborns (rarely
affects adults)
-fastidious, requires blood to be cultured
-colonies are small and have small zones of B-hemolysis
CAMP test - - Correct answer-:a test that is used to detect CAMP factor in group B
strep
-staph aureus is streaked onto an SBA plate
-bacteria that is suspected to be group B strep is streaked perpendicularly
-after incubation, if. there is enhanced hemolysis in the crossover zone of the 2
bacteria it is considered positive for CAMP factor
group B strep and perinatal infections - - Correct answer-:-Strep algalacticae is
found in the vaginal mucosa and neonates with weak immune systems are
inoculated during birth
, -early onset: within first 7 days of deliver bacteremia and pneumonia occur due to
aspirated Strep algalacticae
-late onset: ~ 3-8 weeks after birth the child will present with bacterial meningitis
that is caused by initial bacteremia that passes the blood brain barrier
-risk factors: premature brith, prolonged rupture of aminotic membrane (vaginal
biota will enter uterus)
group B strep (GBS) prevention in neonates - - Correct answer-:prenatal
screenings and care are important
-vaginal and urine cultures are screened during pregnancy
-lim broth: contains antibiotics to suppress growth of vaginal biota and only look
for GBS
-granada agar & carrot broth: B hemolytic group B strep will appear organge
-PCR can be used to amplify and identify DNA specific to GBS
Streptococcus groups C,G and F - - Correct answer-:-all are B-hemolytic
-small colonies contain group A, C, F or G lancefield Ag's
-Strep anginosus (small colony) is commensal bacteria in microbiota that is B-
hemolytic, and produces pinpoint size colonies (< 0.5 mm)
-large colonies contain group C or G lancefield Ags
-Strep dysgalactiae subsp. equismillis (large colony) is potentially pathogenic and
associated with pyogenic pharyngitis cases
streptococcus group D - - Correct answer-:-non-hemolytic
- "streptococcus bovis group"
-S. equinis, S. infantarius, S. gallolyticus and S. alactolyticus are all part of normal
biota in GI tract, mucous membranes and vaginal mucosa
