Streptococci Vs

1

• Streptococci Vs
• Ery 5/Da 2
• Multiple mechanisms of resistance
• Macrolides (eryth., clarith., roxith.)
• Lincosamides (clindamycin, lincomycin)
• Ribosomal modification (erm gene) conferring
  resistance to all macrolides and lincosamides
  constitutive (R/Ery,Da) or inducible (R/Ery,
  S/Da, ICR )
• An efflux pump (mef gene, R/Ery, S/Da, ICR-)
• Unknown mechanism (S/Ery, R/Da)

2

• Streptococci Vs
• Ery 5/Da 2
• Phenotypes
• S/Ery, S/Da
• R/Ery, R/Da (constitutive)
• R/Ery, S/Da, ICR (report as R/Da)
• R/Ery, S/Da, ICR- (efflux, report as S/Da)
• S/Ery, R/Da (unknown mechanism,
• report S/Ery, R/Da )
• Ery 5 and Da 2 in adjacent positions (13 mm)
• Note Corynebacterium sp. isolates are tested the
  same way - Ery 5 and Da 2 (13mm)

3

• Staphylococci Vs
• Ery 5/Da 2
• Multiples mechanism of resistance
• Macrolides (eryth., clarith., roxith.)
• Lincosamides (clindamycin, lincomycin)
• Ribosomal modification (erm gene) conferring
  resistance to all macrolides and lincosamides
  constitutive or inducible (R/Ery, S/Da, ICR )
• An efflux pump (mef gene, R/Ery, S/Da, ICR-)

4

• Staphylococci Vs
• Ery 5/Da 2
• Phenotypes
• S/Ery, S/Da
• R/Ery, R/Da (constitutive)
• R/Ery, S/Da, ICR (report as R/Da)
• R/Ery, S/Da, ICR- (efflux, report as S/Da)
• Ery 5 and Da 2 in adjacent positions (15 mm)

5
Staphylococcus aureus isolate resistant to
erythromycin with a large flattened clindamycin
zone (R/Ery, S/Da, ICR) Report R/Da Da 2/Ery5
15 cm edge to edge
6
The same S. aureus isolate (R/Ery, S/Da,
ICR) Da 2/Ery5 18 cm edge to edge
7
S. aureus isolate resistant to erythromycin with
a large flattened clindamycin zone (R/Ery, S/Da,
ICR) Report R/Da Da 2/Ery5 15 cm edge to edge
8
An MRSA isolate resistant to erythromycin and
susceptible to clindamycin (R/Ery, S/Da, ICR-)
Report S/Da