From the Guidelines
No, bacitracin with polymyxin B ointment is not a sulfa antibiotic. This topical antibiotic combination contains two different antibiotics: bacitracin, which is a polypeptide antibiotic that works by inhibiting bacterial cell wall synthesis, and polymyxin B, which is a cyclic peptide that disrupts bacterial cell membranes. Neither of these components belongs to the sulfonamide (sulfa) class of antibiotics. According to a 2022 practice parameter update on drug allergy 1, sulfonamide antimicrobials are structurally different from nonantimicrobial sulfonamides due to the presence of an aromatic amine group at the N4 position. The study also notes that there is minimal concern for cross-reactivity between sulfonamide–nonantimicrobials in patients with histories of reactions to sulfonamide antibiotics. Some key points to consider when evaluating the safety of bacitracin with polymyxin B ointment in patients with sulfa allergies include:
- The mechanism of action of bacitracin and polymyxin B is distinct from that of sulfa antibiotics, which work by inhibiting bacterial folic acid synthesis 1.
- The combination ointment is commonly used to prevent infection in minor cuts, burns, or scrapes by providing broad-spectrum antibacterial coverage against many gram-positive and gram-negative bacteria.
- Patients with sulfa allergies can generally use bacitracin with polymyxin B ointment safely without risk of triggering a sulfa-related allergic reaction, as supported by the lack of cross-reactivity between sulfonamide–nonantimicrobials in patients with histories of reactions to sulfonamide antibiotics 1.
From the Research
Bacitracin with Polymyxin B Ointment
- The provided studies do not directly address whether bacitracin with polymyxin B ointment is a sulfa antibiotic 2, 3, 4, 5, 6.
- Bacitracin and polymyxin B are mentioned as components of various topical antibiotic ointments, but their classification as sulfa antibiotics is not discussed 2, 3, 4, 5, 6.
- Sulfa antibiotics, such as silver sulfadiazine, are mentioned in some studies, but there is no indication that bacitracin or polymyxin B are sulfa antibiotics 4.
- The studies focus on the efficacy and interactions of bacitracin and polymyxin B with other antibiotics, such as neomycin and mupirocin, in preventing wound infections and eradicating bacteria 2, 3, 5, 6.