Group D Strep.Cocci
● Enterococci
:
● Characteristics
:
Gram +ve \ Catalase –ve \ cocci in chain \ Beta hemolytic s.cocci
belong to group D Lancefield (e.g., Ent. faecalis and Ent. faecium )
✓ Location : Enterococci are members of the normal flora of the colon.
● Virulence
:
✓ They are very hardy organisms resisting :
▪ hypertonic (6.5%) saline
▪ bile.
▪ penicillin G.
✓ Enterococcus faecalis has been shown to form biofilms sticking to medical
devices.
● Diseases
:
1. UTI : especially in hospitalized patients.
2. subacute endocarditis : particularly in patients who have undergone
gastrointestinal or urinary tract surgery or instrumentation.
3. Intra‐abdominal and pelvic infections , typically in combination with anaerobes.
● Laboratory :
✓ Specimen collection : pus, urine
✓ Direct microscopy : gram +ve cocci in chain
✓ Culture :
▪ Blood agar : clear zone of hemolysis.
▪ Macconkey's agar "6.5 NaCl" : selective.
▪ Bile esculin agar : selective for all group D streptococci, black
discoloration of the agar occur.
✓ Biochemical test :
▪ esculin hydrolyzation test : +ve
● ‐ve for agalactiae
● Treatment :
a. They are resistant to penicillin G
b. Combination of penicillin and aminoglycoside is advised
c. Vancomycin also work
d. Some enterococci developed resistance to vancomycin which is treated with
linezolid.
●Non enterococci
:
● Classification
:
Gram +ve \ Catalase –ve \ cocci in chain \ Beta hemolytic s.cocci belong
Str.
to group D Lancefield . Bovis.
● Enterococci
:
● Characteristics
:
Gram +ve \ Catalase –ve \ cocci in chain \ Beta hemolytic s.cocci
belong to group D Lancefield (e.g., Ent. faecalis and Ent. faecium )
✓ Location : Enterococci are members of the normal flora of the colon.
● Virulence
:
✓ They are very hardy organisms resisting :
▪ hypertonic (6.5%) saline
▪ bile.
▪ penicillin G.
✓ Enterococcus faecalis has been shown to form biofilms sticking to medical
devices.
● Diseases
:
1. UTI : especially in hospitalized patients.
2. subacute endocarditis : particularly in patients who have undergone
gastrointestinal or urinary tract surgery or instrumentation.
3. Intra‐abdominal and pelvic infections , typically in combination with anaerobes.
● Laboratory :
✓ Specimen collection : pus, urine
✓ Direct microscopy : gram +ve cocci in chain
✓ Culture :
▪ Blood agar : clear zone of hemolysis.
▪ Macconkey's agar "6.5 NaCl" : selective.
▪ Bile esculin agar : selective for all group D streptococci, black
discoloration of the agar occur.
✓ Biochemical test :
▪ esculin hydrolyzation test : +ve
● ‐ve for agalactiae
● Treatment :
a. They are resistant to penicillin G
b. Combination of penicillin and aminoglycoside is advised
c. Vancomycin also work
d. Some enterococci developed resistance to vancomycin which is treated with
linezolid.
●Non enterococci
:
● Classification
:
Gram +ve \ Catalase –ve \ cocci in chain \ Beta hemolytic s.cocci belong
Str.
to group D Lancefield . Bovis.
