Medical Care
Group B streptococci are likely to be sensitive to penicillin and ampicillin. However, resistance to penicillin has been increasing, as documented in studies done in Hong Kong and Japan. [20, 21] Group B streptococci have never been as exquisitely sensitive to penicillin as group A β-hemolytic streptococci; therefore, the initial therapy for GBS infection has always been high-dose parenteral penicillin or ampicillin. Cephalosporins, such as cefazolin and ceftriaxone, can often be used for the treatment of penicillin-sensitive infections.
Although clindamycin and erythromycin were at one time uniformly active against group B streptococci, resistance has been increasing. One large study that examined the susceptibility patterns of more than 4800 GBS isolates showed that 32% were resistant to erythromycin and 15% were resistant to clindamycin and that 99% of clindamycin-resistant strains were also resistant to erythromycin. [10] According to Centers for Disease Control and Prevention reports published between 2006 and 2009, GBS resistance to clindamycin ranged from 13% to 20%, and resistance to erythromycin ranged from 25% to 32%. [4]
In another study conducted in an upstate New York community hospital, investigators reported 38.4% resistance to clindamycin and 50.7% resistance to erythromycin in 688 GBS-positive cultures. [5] Therefore, sensitivity testing should be done before these agents are used. Oral clindamycin remains an excellent agent for use after a course of parenteral therapy for bone, soft-tissue, and lung infections, if the isolate is susceptible.
Because of possible resistance to clindamycin, vancomycin remains the initial treatment of choice for GBS infection in patients who are allergic to penicillin. Penicillin, ampicillin, and vancomycin remain the treatments of choice for endocarditis. Although vancomycin may be adequate for treatment of GBS meningitis in patients who are allergic to penicillin, skin testing and desensitization for penicillin therapy might be considered. Penicillin has not been demonstrated to be superior to vancomycin for treatment of GBS endocarditis. There have been rare case reports of vancomycin-resistant strains of GBS. [22]
Although fluoroquinolones appear to have efficacy against isolates of group B streptococci, resistance to fluoroquinolones has recently been reported. [23]
In general, if ampicillin, penicillin, vancomycin, or ceftriaxone cannot be used, consultation with an infectious diseases specialist is strongly recommended. In situations in which an empiric antibiotic must be chosen, referring to the local antibiogram can be extremely helpful.
Surgical Care
Consultation with a surgeon and surgical intervention are important.
Patients with pneumonia may require empyema drainage.
Patients with endocarditis, bacteremia, and sepsis may require heart valve replacement.
Patients with soft-tissue infection, septic arthritis, osteomyelitis, diskitis, and epidural abscess caused by GBS infection often require surgery combined with parenteral antibiotic therapy for resolution.
Necrotizing fasciitis and septic arthritis are surgical emergencies.
A patient with an epidural abscess may require emergency surgery.
Urinary tract infections and pelvic abscesses may require relief of genitourinary obstruction and abscess drainage for resolution.
Consultations
Various consultations may be required for optimal outcomes in patients with GBS infection. An infectious diseases specialist can often be helpful in choosing the antibiotic and duration of therapy, especially if the susceptibility report shows resistance to penicillins, vancomycin, and cephalosporins.
Appropriate surgical support is critical for a good outcome.
Patients with pneumonia may require a pulmonologist or surgeon for empyema drainage.
Patients with bacteremia, endocarditis, or line-related sepsis may require a cardiovascular surgeon for valve replacement.
Patients with soft-tissue infections, osteomyelitis, epidural abscess, diskitis, or arthritis require a rheumatologist for arthrocentesis and an orthopedic surgeon or neurosurgeon for possible surgical opinion and intervention.
Patients with a urinary tract infection or pelvic abscess may require a urologist or gynecologist for surgical opinion and possible relief of obstruction and abscess drainage.
