STREP Flashcards
What kind of pathogen is Strep?
bacteria
Is Strep Gram positive or negative?
Gram positive
Is Strep oxalase positive or negative (lab test)?
Negative
Is strep catalase positive or negative (lab test)?
Negative
fun fact: catalase is an enzyme that bacteria use to avoid hydrogen peroxide by turning it into oxygen and water
What would Strep look like on a microscope slide?
Purple spheres (cocci) in chains or pairs
What is a Group A Strep strain?
S. pyogenes
What is the epidemiology/distribution of group A (S. pyogenes) Strep?
-10% in mucosa
-Commonly found on the skin
-Beta hemolytic (destroys red blood cells)
How can Strep pyogenes (Group A) infect the host (pathogenesis)?
Can adhere to mucosal surfaces and invade
What is the presentation of a Strep pyogenes (Group A) infection?
-Pharyngitis (strep throat)
-Skin/soft tissue infections: non-purulent cellulitis, impetigo
-May lead to necrotizing fascitis (flesh eating disease): extreme pain, rapid, deadly, surgical intervention may be necessary
-Toxins released may cause Scarlet fever, Toxic shock
-Post infection syndromes: rheumatic fever, glomerulonephritis
What are symptoms of Scarlet fever caused by group A strep pyogenes?
-Strawberry (red) tongue
-Scarlatina rash: macular and stretchy (sandpaper rash)
What are the symptoms of Toxic shock caused by group A strep pyogenes?
-Nilosky sign from toxin release
-decrease in BP
-Extreme sickness
What are the symptoms of a post-infection Rheumatic fever caused by group A strep pyogenes?
Autoimmune response causing the body to attack its own cells (common in 5-15 year olds), onset in about 3 weeks
-Myocarditis (inflammation of the heart/valves)
-Arthritis, Syndenham’s chorea (involuntary movements), subcutaneous nodules, erythema marginatum (pink circular rash on limbs/trunk)
JONES CRITERIA used to diagnose
Joints (arthritis)
Ocarditis (heart)
Nodules (subcutaneous)
Erythema marginatum (rash)
Syndenham’s chorea (involuntary movement)
What are the symptoms of a post-infection glomerulonephritis caused by group A strep pyogenes?
Type III hypersensitivity reaction when body is trying to eliminate the bacteria
-hematuria (blood in urine)
-oliguria (less urine output)
-Hypertension
-fever
How can we diagnose a group A strep pyogenes infection?
-Strep test for throat
-can do culture if needed
-lab tests (oxalase, catalase)
-symptom evaluation (JONES, etc.)
What treatments are available for Group A strep pyogenes infections?
-Penicillin or Amoxicillin (amox more in peds)
-Cephalexin
-Clindamycin
-Azithromycin can be used, but not recommended due to increased resistance of macrolide
What is a group B Strep strain?
Strep agalactiae
Is group B strep beta-hemolytic?
Yes
What is Strep agalactiae?
Group B strep which can cause neonatal sepsis (soft tissue infections, bacteremia)
-pregnant women are swabbed for this before birth so they cannot transmit it to the newborn
What is the treatment for Group B Strep agalactiae infections?
-Penicillin/Amoxicillin
-Cephalexin
-Clindamycin
-Azithromycin not recommended due to increasing resistance of macrolide
Why might Beta lactam antibiotics like penicillins sometimes not work as well on strep pneumoniae?
Group B strep is becoming more resistant to these antibiotics (30% resistant)
What could be seen on a culture of strep pneumoniae?
purple diplococcus (pairs of spheres)
What kind of infections can Strep pneumoniae cause?
-Otitis media (middle ear infection)
-Pneumonia
-Sinusitis
-Conjunctivitis (pink eye)
-Can cause meningitis (we have vaccines for this: Prevnar and Pneumovax)
Who is more susceptible to Staph pneumoniae infections?
Elderly, immunocompromised, those with other critical infections
What is the treatment for S. pneumoniae infection?
-Ceftriaxone (IV)
-Cefdinir (IV)
-Cefuroxime (IV)
*if beta-lactam antibiotic resistant/allergy:
-Levofloxacin
-Vancomycin
-Linezolid
***Only different treatment line than other types of strep in this lecture
What is Viridans strep?
-Oral/GI flora which can contaminate cultures
-MAY cause wound infection, skin/soft tissue infections, and bacteremia with endocarditis
Is Viridans strep beta hemolytic?
NO! alpha hemolytic
How can Viridans Strep infections be treated?
-Penicillin/Amoxicillins
-Cephalexin
-Clindamycin
-Azithromycin not recommended due to increased resistance of macrolide
What is group D strep (GDS)?
A strep infection associated with GI malignancy
What is the FIRST LINE treatment for Strep groups A-G?
Penicillin and Amoxicillin
