Viridans-Group Streptococci

Background
  • A Gram Positive Bacteria in the Streptococcus Genus
  • In general, low virulence pathogens and likely Blood Culture Contaminant unless risk factor (21-50% of positive blood cultures are clinically significant)[1]

Types
  • Streptococcus milleri
  • Streptococcus sanguis
  • Streptococcus mitis
  • Streptococcus bovis

Risk Factors for Viridans Bacteremia[2]
  • neutropenia
  • oral mucositis
  • irradiation to the oral cavity
  • antibiotic prophylaxis with trimethoprim-sulfamethoxazole or fluoroquinolones
  • intravenous hyperalimentation
  • high dose chemotherapy

Antibiotic Sensitivities[3]
Category Antibiotic Viridans strep
PenicillinsPenicillin GI
Penicillin VI
MethicillinI
Nafcillin/OxacillinI
Cloxacillin/Diclox.I
Amino-PenicillinsAMP/AmoxI
Amox-ClavI
AMP-SulbI
Anti-Pseudomonal PenicillinsTicarcillinI
Ticar-ClavI
Pip-TazoI
PiperacillinI
CarbapenemsDoripenemS
ErtapenemS
ImipenemS
MeropenemS
AztreonamR
FluroquinolonesCiprofloxacinR
OfloxacinR
PefloxacinX1
LevofloxacinS
MoxifloxacinS
GemifloxacinS
GatifloxacinS
1st G CephaloCefazolinS
2nd G. CephaloCefotetanS
CefoxitinS
CefuroximeS
3rd/4th G. CephaloCefotaximeS
CefizoximeS
CefTRIAXoneS
CeftarolineS
CefTAZidimeI
CefepimeS
Oral 1st G. CephaloCefadroxilS
CephalexinS
Oral 2nd G. CephaloCefaclor/LoracarbefS
CefproxilR
Cefuroxime axetilS
Oral 3rd G. CephaloCefiximeS
CeftibutenR
Cefpodox/Cefdinir/CefditorenS
AminoglycosidesGentamicinX1
TobramycinX1
AmikacinX1
ChloramphenicolX1
ClindamycinX1
MacrolidesErythromycinX1
AzithromycinX1
ClarithromycinX1
KetolideTelithromycinX1
TetracyclinesDoxycyclineX1
MinocyclineX1
GlycylcyclineTigecyclineX1
DaptomycinX1
Glyco/LipoclycopeptidesVancomycinX1
TeicoplaninX1
TelavancinX1
Fusidic AcidX1
TrimethoprimX1
TMP-SMXX1
Urinary AgentsNitrofurantoinX1
FosfomycinX1
OtherRifampinX1
MetronidazoleX1
Quinupristin dalfoppristinX1
LinezolidX1
ColistimethateX1

Key
  • S susceptible/sensitive (usually)
  • I intermediate (variably susceptible/resistant)
  • R resistant (or not effective clinically)
  • S+ synergistic with cell wall antibiotics
  • U sensitive for UTI only (non systemic infection)
  • X1 no data
  • X2 active in vitro, but not used clinically
  • X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
  • X4 active in vitro, but not clinically effective for strep pneumonia

Table Overview

See Also

References
  1. Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
  2. Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
  3. Sanford Guide to Antimicrobial Therapy 2014
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