Term
| Where are Streptococci considered normal flora? |
|
Definition
| Oral cavity, GI tract, and genital tract |
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|
Term
| Are Streptococci Gram-positive or Gram-negative? |
|
Definition
| Gram-positive, arranged in chains |
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Term
| How are Streptococci taxonomically classified? |
|
Definition
Based on the type of hemolysis on blood agar plates:
- no hemolysis: gamma
- partial hemolysis: alpha/Viridans streptococci
- complete hemolysis: beta
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Term
| What do pneumococci refer to? |
|
Definition
a synonym for Streptococcus pneumoniae
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Term
| What hemolytic group are Streptococcus pneumoniae considered a part of? |
|
Definition
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|
Term
| What does the term "viridans" refer to? |
|
Definition
| All other alpha-hemolytic Streptococcus once S. pneumoniae has been ruled out |
|
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Term
| What are two hemolysins/toxins produced by Group A Streptococcus? |
|
Definition
| Streptolysin O and pyrogenic exotoxin |
|
|
Term
| What is Streptolysin O similar to? |
|
Definition
| Staphylococcal alpha toxin |
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Term
| What does a high antibody to streptolysin O (ASO) signify and how sensitive is it? |
|
Definition
| a recent infection with Group A streptococcus, positive 85% of the time (whereas ASO + antihyaluronidae is positive 95% of the time) |
|
|
Term
| What does pyrogenic exotoxin/erythrogenic toxin do? |
|
Definition
| stimulates cytokine release, causes a red rash (scarlet fever) |
|
|
Term
| How are the genes for pyrogenic exotoxin carried? |
|
Definition
| By a bacteriophage. But a minority of strains carry this toxin. |
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Term
| What are 7 clinical conditions caused by group A Streptococcus? |
|
Definition
- pharyngitis
- Scarlet fever
- impetigo
- erysipelas
- puerperal infections
- wound and burn infections
- toxic shock syndrome
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|
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Term
| What percent of the population is a carrier for pharyngitis-causing Streptococcus and how long does it last? |
|
Definition
| 2-10% of the population, for 1-4 wks after the infection |
|
|
Term
| How is pharyngitis-causing Streptococcus spread? |
|
Definition
| by direct contact or aerosols |
|
|
Term
| Where is pharyngitis-causing Streptococcus found? |
|
Definition
| in the throat, sometimes the anus |
|
|
Term
| What are the common signs of scarlet fever? |
|
Definition
- strep throat with a characteristic deep red rash on cheeks, temples, and buccal mucosa
- "strawberry tongue"
- punctate hemorrhages on palates
- "sandpaper" rash on trunk, arms, and legs
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|
|
Term
What are some post-streptococcal sequelae?
|
|
Definition
| acute rheumatic fever and acute glomerulonephritis |
|
|
Term
| What are the consequences of acute rheumatic fever? |
|
Definition
fever, carditis, subcutaneous nodules, migratory polyarthritis, and MOST importantly, heart valve damage, including murmurs and cardiac enlargement
|
|
|
Term
| What is the mechanism of action for developing acute rheumatic fever? |
|
Definition
| M protein fragments from certain serotypes of Strep cross-react immunologically with cardiac tissue |
|
|
Term
| What is acute glomerulonephritis and what can it result in? |
|
Definition
A post-infectious complication of Group A Strep infection during childhood, can occur 10 days after respiratory infection
- causes lesions of the glomeruli that take weeks-months to recover and may lead to renal failure and death |
|
|
Term
| What is the pathogenesis behind acute glomerulonephritis? |
|
Definition
| immunologic mechanism involving antigen-antibody complexes in the kidney |
|
|
Term
| What is impetigo and how does it start? |
|
Definition
A group A strep infection of the skin that starts with an insect bite or minor abrasion, beginning as small vesicles with erythema that become pustular and later crusted
* may co-infect with S. aureus |
|
|
Term
| What is a possible complication of impetigo caused by group A strep infection? |
|
Definition
|
|
Term
| What is ersipelas and how does it present? |
|
Definition
| A Group A strep infection of skin and subcutaneous tissues (commonly the face)- presents as a spreading area of erythema and edema with rapidly advancing edges, as well as pain, fever, and lymphadenopathy |
|
|
Term
| What are puerperal infections and how can they be prevented? |
|
Definition
infection of the endometrium with Group A Strep at delivery that spread to other organs via the lymphatics ("childbed fever")
- preventable by hand washing |
|
|
Term
| What do Streptococci produce that causes a toxic shock-like syndrome? |
|
Definition
|
|
Term
| What are the clinical symptoms of Toxic shock-like syndrome? |
|
Definition
| shock, diarrhea, rash, renal impairment, respiratory failure |
|
|
Term
| What is the mortality rate of Toxic-shock-like syndrome caused by Streptococci? |
|
Definition
|
|
Term
| How do rapid Group A strep tests work and do you always follow up with a culture? |
|
Definition
| immunological assays for group A antigen that are 80-90% sensitive (follow up in children with culture only if results are negative) and 99% specific |
|
|
Term
| When are strep throat cultures recommended for adults? |
|
Definition
| If Neisseria gonorrhoeae is suspected (not for routine primary evaluation of pharyngitis or confirmation of negative rapid antigen tests) |
|
|
Term
| When are antibody tests used for Group A Streptococci and what is the main antibody tested for? |
|
Definition
To confirm cases of acute rheumatic fever or glomerulonephritis (because cultures will be negative)
- antistreptolysin O |
|
|
Term
| What percent of women carry Group B Streptococci as part of their normal vaginal flora? |
|
Definition
|
|
Term
| What is the clinical manifestation of Group B Streptococci infection in newborns and what was the mortality rate in the 1980s? |
|
Definition
| neonatal sepsis and meningitis, 10-60% |
|
|
Term
| What was the leading bacterial cause of disease and death among newborns in USA in 1998? |
|
Definition
| Group B Streptococci infection |
|
|
Term
| What are the clinical manifestations of Group B Streptococci in older children and adults? |
|
Definition
| puerperal fever at delivery, gynecologic surgery infections, skin and soft tissue infections |
|
|
Term
How can Group B Streptococci infection in neonatals be prevented?
|
|
Definition
- routinely culture vagina and rectal area of pregnant women during the last month of pregnancy
- if +, give penicillin to mother during delivery
- if there is premature rupture of membranes or signs of lethargy/abnormality, treat the baby
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|
|
Term
| What are the morphological characteristics of Streptococcus pneumoniae? |
|
Definition
| Gram positive, diplococci with short chains, round/oval/lancet shape, encapsulated |
|
|
Term
| What type of hemolysis do Streptococcus pneumoniae colonies produce? |
|
Definition
| alpha hemolytic (may look donut or mucoid) |
|
|
Term
| What is the most common cause of bacterial pneumonia in adults? What else does it cause? |
|
Definition
Streptococcus pneumoniae:
- severe meningitis
- middle ear infection
- sinusitis
- abdominal or wound infection
|
|
|
Term
| What the two types of Streptococcus pneumoniae vaccines? |
|
Definition
For adults >65yrs: against 23 strains (which cause 88% of pneumococcal disease)
for children btwn 6 wks-5yrs: 13-valent, esp. important for those with chronic heart/lung disorders or immunosuppressive conditions |
|
|
Term
| What serotype of Streptococcus pneumoniae is most often associated with antibiotic resistance and prevalent in many regions of the world? |
|
Definition
|
|
Term
| What protects Streptococcus pneumoniae from phagocytosis? |
|
Definition
| the capsule (unencapsulated mutatnts are avirulent) |
|
|
Term
| What is a distinguishing characteristic of Streptococcus pneumoniae on gram stain? |
|
Definition
|
|
Term
| What should you treat moderately resistant Streptococcus pneumoniae with if the infection is not in the CNS, and what are the alternatives for high level resistance or meningitis? |
|
Definition
| Penicillin G, or 3rd generation cephalosporins or vancomycin |
|
|
Term
| Where are Viridans Streptococci considered normal flora and what are four specific species? |
|
Definition
mouth, gut, genitalia:
- Streptococcus mutans
- Streptococcus milleri
- Streptococcus mitis
- Streptococcus salivarius
|
|
|
Term
| What are Streptococcus milleri associated with? |
|
Definition
| brain and liver abscesses |
|
|
Term
| What are Streptococcus mutans group associated with? |
|
Definition
|
|
Term
| Which two species of Viridans Streptococcus cause subacute bacterial endocarditis and how should they be detected/treated? |
|
Definition
S. mitis and S. salivarius
- blood cultures
- treat with penicillin for weeks |
|
|
Term
| How is endocarditis treated? |
|
Definition
| very sensitive to penicillin G (also given prophylactically prior to dental procedures) |
|
|
Term
| What are abiotrophia defectiva and granulicatella adiacens? |
|
Definition
| nutritionally deficient Streptococci that will not grow on ordinary blood agar |
|
|
Term
| What is a possible cause of endocarditis to consider if the culture comes back negative? |
|
Definition
| nutritionally deficient Streptococci |
|
|
Term
| What is the morphological appearance of Enterococci? |
|
Definition
| Gram positive cocci in chains |
|
|
Term
| Which group of bacteria is located in the gut and thus very resistant to bile salts, acid, and NaCl? |
|
Definition
|
|
Term
| What diseases do enterococci cause? |
|
Definition
| opportunistic infections, urinary tract infections, and endocarditis |
|
|
Term
| Which species of Enterococci is most common? |
|
Definition
|
|
Term
| Which species of Enterococci is more resistant to antibiotics? |
|
Definition
| Enterococcus faecium (almost always resistant to ampicillin and becoming resistant to vancomycin) |
|
|
Term
| How are Enterococci classified and grown? |
|
Definition
non-hemolytic on sheep blood agar (classified as Group D)
grows on bile esculin agar, or in 6.5% NaCl broth (which separates it from non-hemolytic strep) |
|
|
Term
| What percent of urinary tract infections are associated with enterococcus? |
|
Definition
| 5% of outpatient UTIs and 10-30% of inpatient UTIs |
|
|
Term
| What is the best way to treat endocarditis caused by Enterococcus faecalis? |
|
Definition
| ampicillin + gentamicin (synergistic bacteriocidal action) |
|
|
Term
| What percent of Enterococci are resistant to vancomycin? |
|
Definition
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