What medication is used as a second line for GBS prophylaxis if penicillin is not suitable?

The second-line medication for Group B Streptococcus (GBS) prophylaxis when penicillin is not suitable is cefazolin. This antibiotic belongs to the cephalosporin class and has a broad spectrum of activity, including effectiveness against GBS. It is recommended for use in individuals who have a low-risk allergy to penicillin, as it provides adequate coverage while minimizing the risk of allergic reactions.

Cefazolin is preferred because it has better pharmacokinetic properties than some alternatives, allowing for effective concentrations to be achieved in the maternal bloodstream and the fetal circulation. This is crucial for preventing vertical transmission of GBS to the newborn during labor.

In the context of the other medications, erythromycin is generally used for patients with a high-risk allergy to penicillin, but it does not cover GBS effectively, especially in cases of resistant strains. Vancomycin may also be used in cases of severe penicillin allergy or for patients who have a significant risk of allergic reactions, however, it is typically reserved for those with a higher level of resistance concerns. Amoxicillin, while similar to penicillin, is not a preferred second-line agent due to its efficacy profile and potential for allergic reactions in individuals with a history of penicillin