Gram Pos Cocci- Staphylococcus/Strep Flashcards
What is the cell wall of gram pos
thick wall of Petidoglycan in their wall
What type of aerobes are gram pos cocci and are they intra/extracellular pathogens
Faculative anaerobes
Primally extracellular
What are the types of blood agar lyses
B hemolysis- complete
A hemolysis- partial (causing green)
Y hemolysis- no lysis
What are the 2 tests to categorize g+ cocci
- Lancefield cell wall antigens
2. coagulase test (will be +)
Group A streptococcus- type of lysis, Antigen type, motility, Capsule +/-
B hemolytic
Group a lancefield antigen on cell wall
Non motile
Produce a capsule
What is the repersentative human pathogen + mc associated disease
Steptococcus pyogen
=Stretococcal pharyngitis
Assiciated diseases of streptococcus pyogens (5)
- step pharygitis
- Steptococcal skin inf
- Scarlet fever
- Step toxic shock syndrome
- post steptococcal complication
Streptococcal pharygitis- target, transmission, pathology, antibiotic
target- primarly children
transmission- large respiratory droplets
Pathology- abrubt sore throat, swollen lymph nodes, exudate, fever
Antibiotic- b lactams
what are the 3 types of streptococcal skin infections
- Impetigo
- cellulitis
- Necrotizing fascitits
Impetigo- age, symptoms, area of effect
Infection of superficial layers of skin epidermis
(highly contagoius)
-causes red sores that rupture, honey coloured crust around nose/mouth
Cellulities- symtoms/areas affected
rapid spreading infection of dermis + subcutenous fat in skin (skin may be swollen/warm)
-associated with burns, wounds, ulcers +surgical insision
Necrotizing fasciitis (flesh-eating disease)- symptoms, area affected, why
Inf that spreads into deeper subcutaneous tissue of skin/muscles/fascia casuing skin changes
- @ site of trauma or insision
- Severe pain, fever, weakness etc
What is scarlet fever due to
s pyogens strains that produce steptococcal pyrogenic exotoxins (spe)
what is the clinical picture of scarelet fever
Super antigens prodice inflammatory response that causes bumpy, bright red rash under skin
+fever
What triggers streptococcal toxic shock syndrome and what are the clinical effects
super antigens (spe) enter blood and activate up to 20% of t cells resulting in cytokine storm
- sustematic vessel leakiness, fever, multisytem organ involvement
What are examples of post streptococcal complications (3)
- Acute rheumatic fever (fever, inflamed jts, heart issues)
- Post infectious glomerulonephritis (pharyngitis/skin inf)
- PANDAS- ocd, anxiety etc
what type of blood agar does group b step: strep agalactica have
B hemolytic
How is steptococcus agalactiae transfered and who does it affect + cause
neonates from mothers thru infection of genital tracts
- Can cause neonatal pneumonia + meningitis
- also effects at risk elderly
Streptococcus mutans blood agar type and what is it the primary cause of
a hemolytic
Primary causes of dental cavities, plaques, abscesses
how does streptococcus mutans cause dental plaque (and what is a risk of infection)
S mutans metabolize sucrose producing sticky strands that allow them to adhere to teeth
- risk of endocarditis
Streptococcus pneumoniae blood agar type, and where is it usually colonized
a hemolytic
nasopharyngeal colonization (usually asymptomatic)
what is a serotype of a bacteria
Serotype: if strains of a bacterial species are so different that they induce different antibody responses, those strains are said to be serotypes (same species but immune system responds differently)
how is streptococcus pneumoniae transmitted and how does it evade host response
transmitted via respiratory droplet or direct contact
all serotypes produce a slightly dif polysaccharide capsul that impairs host phagocytosis
What is the most common cause of pneumia in adults + community aquired pneumia
Streptococus pneumoniae
How does streptococus pneumoniae affect the host + how to diagnpse
Bacteria progress down respiratory tract and trigger unflammating in alveolar space (airways fill with fluids)
- wil see lung consolidation in chest x ray
- pt will have feverm cough etc
What causes otis media, age range, symptoms
Streptococcus pneumia mc
Nasopharyngeal congestion may prevent normal clearing mechanism resulting in backup into the typically sterile middle ear
-6-24months of age
what is bacterial sinitus caused by and how can it be differentiated from viral infection
streptococcus pneumia
differentiated from viral sinitus due to persistence (>10 days) or severity of symptoms
what is the mc cause of menigitis and what is the clinical triad
Streptoccucus pneumia
High fever, stiff neck, severe headache
Enterococcus- blood agar type, who is it associated with, superbug associated with it
(TYPE OF STREPTOCOCCUS)
Y hemolytic
Associated with nosocomial infections in pts. who are immunocompromised in hospitals
Superbug- vancomyosin resisten enterococcus
Which will produce a + catalase test: streptococcus or staphylococcus
Staphylococcus
What staphlococcus produces + and - coagulase test
+ Staphylococcus aureus
- Coagulase neg staphylococcus
Staphlococcus- results on coagulase + catalase test and what does it excrete
positive on both
- secretes exoenzymes (proteases + lipases that damage host tissue)
What are the skin infections associated with staphylococcus aureus (3)
Paronychia- infect along border of nail
Folliculitis- Inflamation of hair follicle
Inflamed follicles/boils
What causes staphlococcal scaled skin syndrome/ritters disease, age, symptoms
age- <1
Exfoliatin toxins from stapholccoal aures
Blistering skin condition due to detachment of epidemis (impairs desmoglein 1)
What is staphlococcal toxic shock syndrome due to (and historical cause)
Superatigen Toxic shock syndrome toxin 1
- produces cytokine storm (+ eventually toxic shock)
- due to high absorbancy tapons
How is staphlococcas aureus food poisoining trigered, when do the symptoms start
Superantigens that trigger gut inflammation due to food contaminated by enterotoxins
-rapid onset on symptoms in 2-6 hours (mild)
What is septic arthritis due to and what are the symptoms
S. Aureus is most common cause
symptoms- acute pain, jt swelling, erythema, warmth, fever, inability to bear weight, decreased ROM
Osteomyelitis- cause and what does it cause
Staphlococcus aureus mc
Inflamation of bone/ bone marrow causing chills, fever, malaise, local pain/swelling
What % of people have MRSA on skin, and what does it have resistence to
1% of people have commensal MRSA on their skin
Resistant to methicillian + other B-lactams
What is the most common coagulase-negative staphlyococci (CoNS)
Staphylococcus epidermis (not normally infectious uness immunocompromised)
What is the second most common cause of urinary tract infections behind e coli
Coagulase-neg staphlycoci (CoNS)
What bacteria is most commonly associated with hospital aquired pneumonia
Staphlyococcus aureus
