Streptococcus and Enterococcus Flashcards
What are the culture characteristics of Streptococcus pneumoniae?
GPC, dipplicocci, lancet-shaped
Catalase negative
alpha hemolytic
Optochin sensitive
bile soluble
No Lancefield antigen
What diseases are associated with Streptococcus pneumoniae?
- Community acquired pneumonia
- Meningitis
- Sinus infection
- Otitis media
- Blood stream infection
- Endocarditis
- May be associated with joint infections if disseminated
Can Streptococcus pneumoniae be identified by MALDI?
- Not reliable identified by MALDI-TOF ( Cannot be distinguished from other members of the Streptococcus mitis/oralis group)
*Optochin test (24h) or Bile solubility (<1hr) can be performed
** Rapid test- Lateral flow assay with CSF or urine. moderate sensitivity, high specificity
What is Group A Strep (GAS)?
Streptococcus pyogenes
Characteristics of GAS?
beta hemolytic
catalase negative
GPC
What diseases are associated with GAS?
- Pharyngitis (rapid test) and followed by culture (MOST COMMMON)
- Necrotizing fasciitis (life-threatning and skin must be surgically removed)
- Recovered from brain biopsies
- Toxic Shock Syndrome
What are complications of GAS pharyngitis?
- Rheumatic fever- inflammation in heart, blood vessels, and joints
- glomerulonephritis-inflammation to the filtering part of the kidneys (glomerulus)
- abscesses
- bloodstream infection
- otitis media -> meningitis
- Streptococcal toxic shock syndrome
What is Group B Strep?
Streptococcus agalactiae
Characteristics of GBS?
Lancefield Antigen B
Beta hemolysis
GPC
Diseases associated with GBS?
- Meningitis (neonates)
- Bacteremia
- Endocarditis
- Pneumonia
- Skin and soft tissue infections
How are pregnant women screened for GBS?
- Vaginal/rectal swab recommended at 36-37 weeks of pregnancy
- Carrot broth (orange if positive). If negative broth, then must streak of GBS specific agar
- Positive women are administered IV abx when labor starts
What other diseases are associated with Streptococcus angionosus?
- Pharyngitis
- BSI and endocarditis
- Pneumonia
- Intra abdominal infections
- Abscesses!!
- Abscesses in liver -hallmark presentation
Which Streptococcus sp is most associated with head, neck and oral abscesses?
Streptococcus angionosus
Where is Streptococcus angionosus found? (3 tracts)
respiratory, GI, and reproductive tract!
normally does not cause disease.
Who smells like butterscotch?
Streptococcus angionosus
Which Streptoccocus sp is associated with colon cancer and endocarditis?
Streptococcus bovis group
S. bovis
S. infantarious
S. gallolyticus
Also associated with infective endocarditis!
Who is part of Group D Streptococcus?
Non-enterococci: S. bovis
Enterococci: E. faecium and E. faecalis
Diseases associated with E. faecalis?
- BSI and endocarditis (prosthetic heart valves and males)
- UTIs (catheters)
- Peritoneal infections
nosocomial
What is E. faecium/faecalis intrinsically resistant to?
- Cephalosporins (may appear susceptible in vitro but is not in vivo!)
- Clindamycin (used for gram positives only)
- Aminoglycosides
- Bactrim
Which Serine-type d-Ala-d-Ala transpeptidase mediates Amp resistance in E. faecium?
1) Overproduction of PBP5
2) Mutations in PBP5
Beta lactamases can be inhibited by sulbactam
How is vancomycin resistance mediated in VRE?
vanA and vanB = plasmid based!
VanC - chromosomal E. gallinarium and E. casseliflavus
an alanine in the cell wall is changed into a lactate residue so Vancomycin cannot bind.
Vancomycin usually bind D-ala-D-ala on peptidoglycan
Which Enterococci are intrinsically resistant to Vancomycin and why?
They have vanC on chromosome
Enterococcus gallinerum and
Enterococcus casseliflavus/flavencens
Diseases associated with Streptococcus mutans?
causes dental cavities
may also cause infective endocarditis
Who causes subacute infective endocarditis in patient with prosthetic devices? (occurs over months)
Strep group Equivalent of S. epi
Viridians group Strep
(All except the beta hemolytic strep)
