Streptococcus agalactiae (Group B Strep)

Gram Stain

• Gram positive cocci in chains (aerobic)

Clinical Significance

This organism is part of the commensal flora of gastrointestinal and female genital tracts.

It is associated with neonatal infections (sepsis, meningitis, and pneumonia), maternal fever, and postpartum infections.

It can also cause skin and soft tissue infections (especially cellulitis related to lymphedema, vascular insufficiency, chronic dermatitis, radiation induced damage post mastectomy, or toe web intertrigo), bone and joint infections, endocarditis, bacteremia, meningitis, medical device related infections (especially prosthetic joints), and urinary tract infections.

Adult patients with diabetes, cirrhosis, neurogenic bladder, immunosuppression, or malignancy are most at risk.

Usual Susceptibility Pattern

This organism is resistant to TMP/SMX and tetracyclines. There is significant resistance to macrolides and clindamycin.

It is susceptible to penicillin/ampicillin, cephalosporins, vancomycin, and linezolid.

Some strains exhibit penicillin tolerance.