Chapter 19 b- Strep

Microbiology 221 with Robison at Brigham Young University

About this deck

By: Rachel Farnsworth
Created: 2011-10-18
Size: 61 flashcards
Views: 2

About StudyBlue

STUDYBLUE makes things that make you better at school. Things like online flashcards with photos and audio. Things like personalized quizzes and friendly reminders about when (and what) to study next. Think of it as a digital backpack™: access to all of your study materials online and on your phone. STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj

Sign up (free) to study this.

streptococcus

gram positive cocci

arranged in pairs or chains

aerotolerant anaerobes

how are streptococcus categorized?

based on the lancefield classification

what is the lancefield classification

divides the streptococci into serotype groups based on the bacteria's C antigens

lancefield groups A and B include the significant streptococcal pathogens of humans

s. pyogenes

forms white colonies surrounded by zone of beta-hemolysis on blood agar plates

pathogenic strains often form a capsule

group A streptococci generally only cause disease in the following situations

normal microbiota are depleted

large inoculum enable the streptococci to establish themselves before antibodies are formed against them

specific immunity is impaired

structural components of strep

protein M

interferes with opsonization and lysis of the bacteria and hyaluronic acid capsule

hyaluronic acid capsule

acts to camouflage the bacteria

enzymes in strep

streptokinases, deoxynucleases, C5a peptidase all facilitate the spread of streptococci through tissues

pyrogenic toxins

stimulate macrophages and helpter T cells to release cytokines

streptolysins

lyse red blood cells, white blood cells, and platelets

when a Group a strep is cutaway

M protein fimbriae

C carb antigens

protein antigens

peptidoglycan

hyaluronic acid capsule

cytoplasm

group A strep diseases

pharyngitis

scarlet fever

pyoderma

streptococcal TSS

necrotixizing fascitis

rheumatic fever

glomerulonephritis

pharyngitis

strep throat

inflammation of the pharynx

scarlet fever

rash that begins on the chest and spreads across the body

pyoderma

confined, pus producing lesion that usually occurs on the face, arms, or legs

streptococcal TSS

bacteremia and severe multisystem infections

scarlet fever rash is caused by

erythrogenic toxin produced by s. pyogenes

erythrogenic toxin is involved in pathogensis of peurpera sepsis an infection of the uterus

necrotizing fascitis

toxin production destroys tissues and eventually muscle and fat tissue

rhematic fever

inflammation that leads to damage of heart valves muscle

glomerulonephritis

inflammation of the glomeruli and nephrons which bbstruct blood flow through the kidneys

post strepotococcal diseases

acute glomerulonephritis

rheumatic fever

AGN

acute glomerulonephritis

kidney damage may be caused by cross reacting antibodies (type 2) or deposition of immune complexes (type III) or toxins like SLO and SLS, can be self limiting or fatal

rheumatic fever

symptoms include carditis, abnormal EKG, painful arthritis, fever, etc

severe carditis can result in permanent damage to heart valves

responsible for 15000 deaths per year in US

diagnosis of strep disease A

agglutination and ELISA test utilizing antibodies directed against the bacteria's distinctive cell wall polysaccharide

incubation of the bacteria with bacitracin which inhibits its growth

treatment of strep disease A

penicillin G

sometimes in combination with an aminoglycoside

transmission and epidemiology of strep disease group A

children 1-15 yrs have higher carrier and disease rates

those with active disease are a large source of infection

transmitted by respiratory droplets and both direct and indrect contact

diagnosis by culture and rapid tests

hemolysis, bacitracin sensitivity, gram morphology, and catalase tests are useful

treatment is penicillin G

prevention and control of strep disease A

isolation, early and complete treatment

what group is streptococcus agalactiae in?

group B streptococcus

streptococcus agalactiae

gram positive cocci, divide to form chains

why are group B different from group A?

b have buttery colonies and smaller zone of beta hemolysis on blood agar plates and its resistance to bacitracin

colonizes the lower gastrointestinal, genital, or urinary tracts

pathogenicity of group B strep

often infects newborns who have not yet formed type-specific antibodies and whose mothers are uninfected (and so do not provide passive immunity)

produces various enzymes whose roles in causing disease is not yet understood

diseases group B

neonatal bacteremia

meningitis

penumonia

immunocompromised older patients are at risk from Group b strep infections

prevention of group B strep

prophylactic administration of penicillin at birth to children whose mothers urinary tracts are colonized with group B strep

immunization of women against group B strep to prevent infection of future children

alpha hemolytic streptococci is in what group

viridans group

alpha hemolytic streptococci

lack group-specific carbs and cant be grouped by lancefield system

many produce a green discoloration when grown on blood media

inhabit mouth, pharynx, GI, genital, and urinary tract

what causes dental caries/plaque production?

alpha hemolytic strep

if alpha hemolytic strep enters blood,

it can cause meningitis and endocarditis

streptococcus pneumoniae

gram positive cocci that most commonly forms pairs but may also form chains

unpigmented, alpha hemolytic colonies when grown on blood agar

anaerobic incubation produces beta hemolytic colonies

colonize mouth and pharynx but can cause disease in lungs

highest in children ad elderly

strep pneumoniae info

leading cause of human death before antibiotics

causes bacteria penumonias

causes otitis media cases in young children ,progressing to meningitis

tied to large polysaccharide capsule, identified with quellung test

pathogenicity of s. pneumoniae

phosphorylcholine

polysaccharide capsule

protein adhesin

secretory IgA protease

penumolysin

phosphorylcholine

stimulates cells to phagocytize the bacteriap

polysaccharide capsule

protects the bacteria from phagocytosis

protein adhesin

mediates binding of the cells to epithetial cells of the pharynx

secretory IgA protease

destroys IgA

pneumolysin

lyses epithelial cells and suppresses the digestion of the phagocytized bacteria

strep penumoniae diseases

penumococcal penumonia

sinusitis and otitis media

bacteremia and endocarditis

pneumococcal meningitis

pneumococal penumonia

bacteria multiply in the alveoli causing damage to the alveolar lining and an inflammatory response

sinusitis and otitis media

bacteria invade the sinuses or middle ear, often following a viral infection

bacteremia and endocarditis

bacteria in the bloodstream or in the lining of the heart

penumococcal menigitis

bacteria that have spread to the meninges

process of pneumococal pneumonia

as penumococci lyse, a cytoplasmic protein called pneumolsyin is released

this binds cholesterol in host cell membranes and causes their lysis

as pneumococci grow, they induce an acute inflammatory response

diagnosis of pneumoniae

gram stain of sputum smears

quellung reaction

anti capsular antibodies cause the capsule to swell, confirming the presence of bacteria, CAMP test

treatment of penumoniae

penicillin

prevention of pneumoniae

vaccine made from purified capsular material

provides long lasting immunity in normal adults but is not as effective in children, the elderly, or AIDS patients

enterrococcus

previously classified as group D streptococci but differed enough to be reclassified as a separate genus

form short chains and pairs and lack a capsule

found in the human colon but are rarely pathogenic at this site

can cause disease if they are introduced into other parts of the body, such as the urinary tract or bloodstream

what does enterrococus cause

nosocomial infections

treatment of enterrococcus

difficult because enterococci are often resistant to antimicrobials

prevention of enterococcus

difficult

especially in a health care setting, where patients often have weakened immune systems

About this deck

By: Rachel Farnsworth
Created: 2011-10-18
Size: 61 flashcards
Views: 2

About StudyBlue

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj