Table 1. Sites of Colonization and Infections in Humans, Non-Group A and Non-Group B Streptococcal Pathogens

Streptococcus	Normal residence	Infection
Group C and G (pyogenes-like or large colony forming organisms) GGS (S. equi, S. equisimillis, S. zooepidemicus)	oropharyngeal flora, vagina rectum skin S. canis is a zoonotic agent	pharyngitis skin infection bacteremia endocarditis meningitis osteomyelitis septic arthritis respiratory tract infection puerperal infection neonatal sepsis toxic shock-like syndrome rhabdomyolysis
Viridans groups of streptococci39	oropharynx, gastrointestinal tract, and genital tract	endocarditis infections in neutropenic patients
Mitis  group   S. mitis   S. gordonii   S. oralis   S. sanguis   S. parasanguis   (S. pneumoniae)*	dental plaques, oropharynx and gastrointestinal tract	Bacteremia, endocarditis, meningitis ARDS
Anginosus or "S. mlleri" group S. anginosus S. constellatus S. intermedius	oropharynx, gastrointestinal tract, and vaginal flora, skin	pyogenic infections, brain, liver, and appendiceal abscesses Associated with polymicrobial infection Endocarditis
Salivarius group   S. salivarius   S. thermophilus   S. vestibularis	tongue and gastrointestinal tract	A frequent contaminant and rarely cause infection, such as bacteremia, meningitis
Bovis group   S. bovis   S. equinus   S. alactolyticus	oropharynx, gastrointestinal, genital tract	bacteremia and endocarditis in patients with malignancies of gastrointestinal tract especially with biotype I meningitis
Mutans group   S. mutans   S. rattus   S. cricetus   S. downei   S. sobrinus   S. macacae	dental plaques and tooth surfaces	dental caries endocarditis
"Nutritionally variant streptococci" renamed Abiotrophia     A. adjacens     A. defectivus	oropharynx	endocarditis, sepsis pancreatic abscess otitis media eye infections (conjunctivitis, and crystalline keratopathy)

*Taxonomically, S. pneumoniae is a member of VGS but it is not considered a VGS organism.

Table 2.  Susceptibility of Group C Streptococci from Various Reports

Table 3.  Susceptibility of Group G Streptococci from Various reports. 

*Isolates from cancer patients

Table 4.  Susceptibility of Group C and Group G Streptococci (49,62,84)

Table 5. Recommended Therapy for VGS Infections [Download PDF]

Endocarditis due to penicillin susceptible viridans streptococci and Streptococcus bovis (Minimum Inhibitory Concentration <0.1 mg/mL).

Native valve infection:  Use any of the following:

1.       Penicillin G 12-18 million units per day in continuous drip or 6 divided dose plus gentamicin 3 mg/kg IV as single dose or 3 divided doses for 2 weeks.

2.       Penicillin G 12-18 million units per day in continuous drip or 6 divided dose for 4 weeks.

3.       Ceftriaxone 2 g IV or IM daily for 4 weeks.

4.       Vancomycin 30 mg/kg not to exceed 2 g IV in 2 divided doses for 4 weeks.

Prosthetic valve infection.

Penicillin or vancomycin as 2 and 3 for 6 weeks plus gentamicin at the same dose as above for at

least 2 weeks.

Endocarditis due to viridans streptococci and Streptococcus bovis relatively resistant to

penicillin G (Minimum Inhibitory Concentration >0.1 mg/ml and <0.5 mg/ml)*

1.       18 million U/24 h IV either continuously or in six equally divided doses for 4 weeks plus

      gentamicin 3 mg/kg IV as single dose or 3 divided doses for 2 weeks.

2.       Vancomycin 30 mg/kg not to exceed 2 g IV in 2 divided doses for 4 weeks.

Endocarditis due to viridans streptococci with (MIC >0.5 mg/ml) or nutritionally variant streptococci 

1.    Aqueous crystalline penicillin G sodium, 18-30 million U/24 h IV either continuously or in six equally divided doses or, ampicillin sodium 12 g/24 h IV either continuously or in six     divided doses plus gentamicin sulfate 1 mg/kg IM or IV every 8 h for 4-6 weeks*

2.    Vancomycin** hydrochloride 30 mg/kg per 24 h IV in two equally divided doses, to exceed 2g/24 h unless serum levels are monitored plus gentamicin sulfate (similar dose as above)    for 4-6 weeks*

For patients with prosthetic valve endocarditis due to streptococcus

            Treat as resistant streptococcus (MIC >0.5 mg/ml) for 6-8 weeks

For patients with bacteremia without endocarditis due to viridans group of streptococcus and NVS.

1.       Penicillin G 12-18 million units IV continuously or in 6 divided doses for 2 weeks.

2.       Ceftriaxone 2 g IV or IM daily for 2 weeks

3.       Clindamycin 300 mg IV or PO q8h for weeks***

4.       Vancomycin 30 mg/kg not to exceed 2 g IV in 2 divided doses for 2 weeks.

For patients with meningitis due to viridans group of streptococcus or NVS

1.       Ceftriaxone 2 g IV or IM daily or cefotaxime 2 g IV q6h for 2 weeks

2.       Penicillin 18-30 million units IV in 6 divided doses for 2 weeks

3.       Vancomycin 30 mg/kg not to exceed 2 g IV in 2 divided doses for 2 weeks

For patients with mixed infection where viridans group of streptococcus or NVS is found

1.       Beta-lactam/beta-lactamase inhibitor combinations at the recommended dose

2.       Imipenem 500-750 mg every 6-8 hours IV.

3.       Above agents or clindamycin plus gentamicin.

*4-week therapy recommended for patients with symptoms <3 months in duration; 6-week therapy           

  recommended fro patients with symptoms greater than 3 months in duration plus

**Vancomycin therapy is recommended for patients allergic to beta-lactams; cephalosporins is not   

  acceptable unless shown to be effective by susceptibility testing

***Clindamycin susceptibility should be checked.

Table 6.   Prophylactic Regimens for Dental, Oral, Respiratory Tract or Esophageal

 Procedures (From Recommendations Of The American Heart Association, 1997) ( 17 ) [Download PDF]

*Total children’s dose should not exceed adult dose

**Cephalosporins should not be used in individuals with immediate-type hypersensitivity reaction

    (urticaria, angioedema, or anaphylaxis) to penicillins

Figure 1.  In Vitro Activities of Selected Antimicrobial Agents Versus 4 Streptococcal Species Streptococcal Isolates From 43 U.S. Medical Centers From 1993-4.  (Modified from Doern et al (22))