Final answer:
In cases of GBS treatment where the patient is allergic to penicillin but at low risk for anaphylaxis, cefazolin would generally be prescribed.
Step-by-step explanation:
The GBS treatment regimen for a patient who is allergic to penicillin but at low risk for anaphylaxis is cefazolin. Cefazolin is a first-generation cephalosporin that can be used in patients with penicillin allergies so long as they are not at high risk for a severe allergic reaction. Other options, such as clindamycin and vancomycin, may be considered if the patient has a history of a more significant hypersensitivity or if the bacteria are resistant to cephalosporins. While gentamicin is an aminoglycoside antibiotic used in some cases, it is not typically the first choice for GBS prophylaxis in penicillin-allergic patients without severe allergies.