Chapter 12-13 Strept Entero Pneumo Flashcards
describe the microbe streptococcus agalctiae
group B, beta hemolytic, chain like growth, aerobic, polysaccharide capsule
where is streptococcus agalactiae found
lower GI tract
what diseases does streptococcus agalactiae cause
-pneumonia in neonates
-bacteremia and meningitis
- urinary infections in pregnant women
what protects against streptococcus agalactiae
antibodies against group B polysaccharide Ag
what causes streptococcal toxic shock syndrome
strains of different S pyogenes or S agalactiae
what type of microbe is enterococcus faecalis and where is it found
-gram positive cocci
- alpha and non hemolytic
- facultative anaerobes
- GI flora
describe the virulence of enterococcus faecalis
high mutliple antibiotic resistance - plasmid and chromosomal
what is the epidemiology for enterococcus faecalis
elderly
- long hospitalization
- high nosocomial risk
what is VRSA caused by
vancomycin resistance enterococci
what streptococci strain is seen as diplo-cocci
streptococcus pneumoniae
what does Beta hemolysis on blood agar plates cause
clearing at and around colonies in streptococcus pyogenes
what is alpha hemolysis due to
partial lysis of eythrocytes in S mitis and S pneumoniae
what does green color on agar plates mean
pneumolysin degrading hemoglobin
what are lancefield groups
a way to classify streptococci. A-W
what is group A in lancefield groups
N-Ac glucosamine and rhamnose
what is group B in lancefield groups
rhamnose and N-Ac-glucosamine + galactose
what is rapid strep throat test based on
group A serological responses
what are streptococcal classification methods
-lancefield groups
-biochemical, metabolic classification
- DNA sequencing - phylogenetic analysis
describe DNA sequencing - phylogenetic analysis
- sequencing the emm gene for the required virulence factor protein M
what is M protein
- cell wall component that is an important virulence factor
- membrane- anchored
what do anti- M antibodies do
prevent infection of S.pyogenes but many serotypes
what does M protein do
- binds keratinocytes, the main cell type in outer skin layer
- binds fibrinogen, blocking surface from complement system components
- binds complement control proteins and inhibits formation of opsonins by complement cascade
what are capsules
virulence factors that prevent phagocytosis
what are the capsules of group A strains made of
hyaluronic acid
what does F protein do
provides adherence to the fibronectin of throat epithelial cells
what does lipoteichoic acid do
adheres to the fibronectin epithelial cell coat
what is likely the basis for repeated nature of strep throat and deep tissue infections
adhesion based uptake of cocci into epithelial cells
what is the M protein anti complement action through
factor H
what does capsulae C3 peptidase do
destroys opsonizing C3b complement opsonization
what does G protein do
binds Fc of IgG preventing phagocytosis based on Fc receptors
what disease does streptococcus pyogenes cause
pharyngitis
what do streptolysins S, O do
lysis of erythrocytes (beta hemolysis) and phagocyte lysosomal membranes
what causes scarlet fever and what is the virulence factor
streptococcus pyogenes
- a superantigen SPE
what do pryogenic SPEs cause
-pyoderma (impetigo)
- erysipelas
what does flesh eating streptococcus pyogenes cause
-streptococcal gangrene
- progression to deep, systemic infection leads to multi organ failure and death
- necrotizing fasciitis
what is the term for strep throat
acute pharyngitis
what type of reaction is glomerulonephritis
type III hypersensitivity
what type of reaction if rheumatic fever
type II hypersensitivity
what is chorea
brain function impairment
what type of reaction is the sequelae of a S. pyogenes infection
immune complex III hypersensitivity
what can acute rheumatic fever cause
myocarditis and arthritis
describe acute rheumatic fever
-non supprative sequela with some strains
- less than 10% of population is susceptible
- fever is non responsive to penicillin because disease is autoimmune
- high frequency of reoccurence
what are the complications of streptococcus pyogenes
glomerulonephritis, rheumatic fever, and chorea
what are the complications of staphylococcus aureus
-SSS
- impetigo
- food poisoning
- toxic shock syndrome
- boild
- abscesses
describe streptococcus pneumoniae
-alpha hemolytic
- gram positive diplococci
how many cases of streptococcus pneumoniae are there per year in the US
500,000
what type of streptococcus pneumoniae strains are virulent
only encapsulated strains
what is the epidemiology and prevention of pneumococcal pneumonia
- high carrier rates for S pneumoniae
- capsular vaccine available
what is the causative agent, epidemiology, and prevention for kiebsiella penumonia
- kiebsiella pneumoniae, an enterobacterium
- often resistant to antibiotics, fatal nosocomial pneumonias
- no vaccine available
what is the treatment for mycoplasmal pneumonia
no vaccine available
what are the 3 major pneumonia causing agents
- streptococcus pneumoniae
- kiebsiella pneumoniae
- mycoplasma penumoniae
what is the treatment of choice for streptococcal pneumonia
penicillin
what are the virulence factors for S pneumoniae
-alpha hemolysis
- capsule
- secretory IgA protease
what causes meningitis
S pneumoniae
describe streptococcus pneumoniae
-alpha hemolytic
- gram positive diplococci
