general characteristics of streptococci Flashcards
Streptococcal pyrogenic exotoxin A (or SpeA), SpeB,are _________. They massively activate the immune system like the staph superantigens that can create cytokine storms, leading to sepsis and death.
are superantigens.
Streptococcal pyrogenic exotoxin A (or SpeA), SpeB,are _________. They massively activate the immune system like the staph superantigens that can create cytokine storms, leading to sepsis and death.
are superantigens.
which condition is described by the following? Usually occurs age 5-15, with peak in early school years.
Spread by droplets. Crowding enhances spread.
Asymptomatic carriage rates can be 15-30%.
pharyngitis
which condition described: 2-4 day incubation period.
Enlarged tonsils with patchy exudates, pain, swollen lymph nodes, fever 101° or higher.
Type specific anti-M antibody protects against recurrence of infection with the infecting serotype.
Usually self-limited, but early treatment with penicillin reduces risk of ARF…but this is not true for AGN.
phayrngitis
__________was a streptococcal infection that frequently developed after giving birth.
Puerperal fever
what is a superficial purulent skin infection (aka a pyoderma) described by:
Most common in children
May follow insect bites
Weeping vesicles that form honey-colored crusts
Can be focus for more invasive disease
GAS impetigo
__________ follows pharyngeal infections, not skin infections.
Acute rheumatic fever
_________is a form of impetigo that has invaded more deeply described by annular lesions showing pustular centers and ulceration
Ecthyma
A form of streptococcal cellulitis, chararcterized by fiery-red erythema and edema with rapidly advancing, well-demarcated edges
symptoms include: Pain
Fever
Lymphadenopathy
erypsipelas
which age group does erypsipelas affect?
children and elderly
what is described by the following: An acute inflammatory condition of the skin.
Deeper infection than impetigo or erysipelas (see histological image).
Localized pain, erythema, swelling and heat.
cellulitis
_________is commonly associated with a localized infection, such as folliculitis or a carbuncle, a foreign body (splinter, catheter) or surgical wound.
Strep cellulitis is more rapidly spreading and associated with lymphangitis and fever.
Staph cellulitis
\_\_\_\_\_\_\_\_\_\_\_\_is a life-threatening deep tissue infection that spreads along fascial planes. 40-70% mortality Infection often begins innocuously Skin trauma, bruise Rapid progression of necrosis Up to an inch per hour
Streptococcal Toxic Shock & Necrotizing fasciitis
these early symptoms describe which condition?Flu-like symptoms
Brawny edema
Extreme pain in infected area way out of proportion to the appearance of the lesion
Spreading erythema (redness of skin), eccymosis (hematoma) with vesicles enlarging to purple bullae
streptococcal Toxic Shock & Necrotizing fasciitis
how do you treat streptococaal toxic shock and necrotizing fasciitis?
Debridement
Aggressive use of broad spectrum antibiotics immediately
High levels of penicillin and clindamycin if S. pyogenes is detected
Massive amounts of IV fluids may be needed
Monitor cardiac out put closely
__________superantigens cause stretpoccooal toxic shock and necrotizing fasciitis.
streptococcal pyrogenic exotoxins
Streptococcal toxic shock also causes a widespread rash that ______ when pressure is applied, but this is not quite as common as with S. aureus TSS.
blanches
how do you diagnose STSS?
A. Isolation of GAS from a clinically significant specimen in a patient who is hypotensive (systolic BP less than 90 mm HG).
AND
B. Patient has two or more of the following:
i. renal impairment
ii. coagulopathy
iii. liver dysfunction
iv. acute respiratory distress syndrome (ARDS)
v. a generalized erythematous macular rash
vi. soft-tissue necrosis (including necrotizing fasciitis or myositis or gangrene)
What is the Jones criteria for acute rheumatic fever? major and minor manifestations.
ARF Guidelines for Diagnosis of Initial Attack of ARF: The Jones Criteria Major manifestations *Carditis *Polyarthritis Chorea Erythema marginatum Subcutaneous nodules
Minor manifestations Clinical findings Arthralgia Fever Lab findings Elevated acute phase reactants Erythrocyte sed rate C-reactive protein Prolonged PR interval
what are the non-supparative sequelae of S. pyogenes infections?
Acute rheumatic fever and Acute glomerulonephritis
ARF usually develops in young children after_________ .
pharyngitis
what are the major manifestations of AGN?
Major manifestations
Clinical findings
Edema
Hypertension
Hematuria (rust-colored urine)
Proteinuria
Malaise, headache, back pain
Lab findings
Increased glomerular intracapillary cellularity
Ig, complement C3, and strep antigens present
Almost all glomeruli involved, some tubules
what is the treatment and prognosis for AGN?
Treatment: Benzathine penicillin ( a slow-release form). However, no treatment alters long-term prognosis, treat to manage acute kidney problems.
Prognosis: usually excellent, especially in children. A small fraction of patients may develop a chronic renal insufficiency.
what is the treatment for most S. pyogenes infections?
Most S. pyogenes infections: Penicillin
No resistance to penicillins so far.
Pen is the drug of choice: safe, narrow spectrum, low cost.
For patients with penicillin allergies: clindamycin, azithromycin
how are more serious invasive infections of S. pyogenes treated?
Serious invasive infections:
Initiate broad spectrum antibiotics if Group A strep is identified; high levels of penicillin and clindamycin (which is more effective in deep infections)
Surgical debridement required; locate source of infection
Monitor cardiac output carefully
Dialysis and hemoperfusion
IVIG (intravenous immunoglobulin)
this describes which bacteria: Diplococci Reaction positive for Group B antigen Bacitracin resistant Hydrolysis of bile esculin Narrow ring of b-hemolysis CAMP factor: a GBS factor that synergizes with S. aureus hemolysin to cause increased lysis of red cells.
S. agalactiae
what is the major virulence factor for group B strep?why?
capsule; Capsule serves as an antiphagocytic factor.
the following describes which disease: Neonatal
Early onset (7 days or younger)
Septicemia, respiratory distress, meningitis
More common in pre-term infants
Mothers had intraamniotic infection
Late Onset (2 wks to 2 mos)
Half of these also are pre-term infants
Bacteremia
Meningitis
Most survivors have permanent neurologic sequelae
GBS disease
be aware: Now 2/3 of invasive GBS disease are not associated with pregnancy
Increases with age: incidence for >65 group is 2X that of 50-64.
Fatality rate in GBS pneumonia, for instance, can be up to 85%.
High morbidity and mortality; associated with diabetes, heart disease, malignancy.
High incidence in nursing homes.
fyi card
what has reduced the incidence of GBS in neonates?
Prenatal screening and intrapartum IV administration of antibiotic (penicillin) to infected mothers and mothers with risk factors has greatly reduced incidence.
when ins intrapartum prophylaxis indicated in a pregrant woman for GBS infection ?
previous infant with invasive GBS disease, GBS bacteruria during current pregnancy, and GBS status uknown
the following describes which bacteria:Part of the normal oral microbiota
Usually a-hemolytic
Don’t react antibodies against Lancefield antigens
Distinguished from enterococci by inability to grow in 6.5% NaCl
Distinguished from pneumococci by resistance to optochin (a chemical; ethylhydrocupreine).
viridans stretpococci
The viridans or green strep (because of alpha hemolysis) are inhabitants of the________
oral cavity
what is a classic biofilm?
dental plaque
name four groups of viridans streptococi.
S. anginosus, S. mitis, S. mutans, S. salivarius and S. sanguinis groups.
