gram positive pyogenic cocci Flashcards
Staphylococcus
aureus Morphology/Structure
Gram positive
pyogenic cocci
Staphylococcus
aureus Modes of Transmission
Normal flora of
human mucosa:
nasal passages,
vagina, skin.
Usually enters
through a
wound.
Staphylococcus
aureus Virulence Factors
Coagulase (prevents
phagocytosis and
concentrates toxins),
Capsule,
hyaluronidase, β
lactamase,
exfoliative toxins
(with SSS),
superantigens with
toxic shock
syndrome. Some
strains can kill
WBCs.
Staphylococcus
aureus Disease/Symptoms
Cutaneous infections
(impetigo, boils,
folliculitis), more serious
is scalded skin
syndrome (SSS), Can
also cause septicemia,
meningitis, toxic shock
syndrome
Staphylococcus
aureus Diagnostics
MSA plate - yellow,
ferments mannitol
Coagulase +
Catalase +
Staphylococcus
aureus Immune Response
Superantigens
cause non-specific
activation of T
cells and
massive cytokine release, leading to
symptoms of toxic
shock syndrome.
Streptococcus
pyogenes (also called
group A strep) Morphology/Structure
Gram positive
pyogenic cocci
Streptococcus
pyogenes (also called
group A strep) Mode of Transmission
Some people
have as normal
flora.
Transmitted
though hand
contact with
nasal discharge
and skin contact
with impetigo
lesions
Streptococcus
pyogenes (also called
group A strep) Virulence Factors
Streptolysins
(streptokinase), M
proteins, capsule,
hyaluronidase,
erythrogenic toxin
(Scarlet fever).
Streptococcus
pyogenes (also called
group A strep) Diseases/Symptoms
Strep throat symptoms
red throat, tonsils,
swollen lymph,
Rheumatic fever, nausea
glomerulonephritis,
impetigo, scarlet fever,
necrotizing fasciitis
Streptococcus
pyogenes (also called
group A strep) Diagnostics
Fever, patches of pus
in throat, swollen
lymph nodes, absence
of cough.
Rapid Antigen
Detection Tests
β hemolysis
Catalase -
bacitracin sensitive
Streptococcus
pyogenes (also called
group A strep) Treatment/Prevention
Penicillin usually.
For necrotizing
fasciitis - drain and
remove dead skin
Streptococcus
pyogenes (also called
group A strep) Immune Response
Erythrogenic toxin
acts as a
superantigens
cause scarlet
fever.
Streptococcus
agalactiae (also called
group B strep) Morphology/structure
Gram positive
pyogenic cocci
Streptococcus
agalactiae (also called
group B strep) Modes of Transmission
Normal flora of
up to 40% of
population
vagina, pharynx,
large intestine
Streptococcus
agalactiae (also called
group B strep) Virulence Factors
Capsule, pore
forming toxin allows
entry into host
Streptococcus
agalactiae (also called
group B strep) Diseases/Symptoms
Pneumonia
Majority of neonatal
meningitis
Streptococcus
agalactiae (also called
group B strep) Diagnostics
Catalase –
β hemolysis
Strep B
bacitracin resistant
Streptococcus
agalactiae (also called
group B strep) Prevention/Treatment
Strept B is tested for
in pregnant women
since it can cause
neonatal menengitits
treat with ampicillin or
amoxicilin
Streptococcus
agalactiae (also called
group B strep) Immune Response
Natural microbe of
intestines and
vagina, but can
cause excessive
inflammation,
sepsis, and death
in infants and
elderly
Streptococcus
pneumoniae
(Pneumococcus) Morphology/Structure
Gram positive
pyogenic cocci
Streptococcus
pneumoniae
(Pneumococcus) Modes of Transmission
Normal flora of
human pharynx
Streptococcus
pneumoniae
(Pneumococcus) Virulence Factors
Capsule, Produces
hemolysin and H2O2
which damages CNS
and immune system.
Major cause of
community acquired
pneumonia
Streptococcus
pneumoniae
(Pneumococcus) Diseases/Symptoms
Pneumonia, can lead to
meningitis, sinusitis and
otitis media (ear
infection)
Streptococcus
pneumoniae
(Pneumococcus) Diagnostics
Catalase -
α hemolysis
optochin sensitive
Streptococcus
pneumoniae
(Pneumococcus) Prevention/Treatment
Routine vaccine for
children,
Prevnar vaccine
recommeded to
adults 65 and older.
Can be treated with
amoxicillin
Streptococcus
pneumoniae
(Pneumococcus) Immune Response
Hemolysin and
H2O2 cause
damage CNS and
immune system.
Enterococcus faecalis
(Streptococcus
faecalis) Morphology/structure
Gram positive
pyogenic cocci
Enterococcus faecalis
(Streptococcus
faecalis) Modes of Transmission
Normal flora of
GI tract.
Commonly
transmitted in
hospitals through
direct or passive
contact.
Enterococcus faecalis
(Streptococcus
faecalis) Virulence Factors
Plasmid encoded
hemolysin and
aggregation
substance promotes
host cell lysis,
Suppresses action of
lymphocytes,
Produces biofilms
Enterococcus faecalis
(Streptococcus
faecalis) Diseases/Symptoms
Urinary tract infections
(UTI), endocarditis,
bacteremia, necrotizing
fasciitis (flesh eating
bacteria)
Enterococcus faecalis
(Streptococcus
faecalis) Diagnostics
Catalase -
γ hemolysis (plasmid -
α hemolysis) ,
differntiated from
Streptococcus by
resistance to
dissolving in bile and
high salts.
Enterococcus faecalis
(Streptococcus
faecalis) Prevention/Treatment
Often resistant to
penicillins and
cephalosporin, often
use vancomycin,
however, now seeing
VRE, use daptomycin
Enterococcus faecalis
(Streptococcus
faecalis) Immune Response
Not common in
healthy individuals.
Usually a
nosocomial
infection where
antibiotic use is
high (leads to
VRE).
Staphylococcus
aureus Prevention/Treatment
Incision and drainage
of localized lesions.
Treated with
methicillin, unless
MRSA, then treat
with vancomycin.
