Is ampicillin safe for a breastfeeding woman to treat a Urinary Tract Infection (UTI)?

Ampicillin Safety for Breastfeeding Women with UTI

Ampicillin is compatible with breastfeeding for treating UTI, though it is not a first-line agent due to high bacterial resistance rates and inferior efficacy compared to other available antibiotics.

Breastfeeding Safety Profile

Ampicillin-class antibiotics are excreted in breast milk but are considered compatible with breastfeeding. 1 The FDA drug label notes that ampicillin used by nursing mothers may lead to sensitization of infants, but does not contraindicate its use during lactation. 1

• Penicillins, including ampicillin and aminopenicillins, are considered appropriate for use in lactating women at dosages at the low end of the recommended range. 2
• Most systemic antibiotics will be present in breast milk and could potentially cause falsely negative cultures in febrile infants or produce gastroenteritis due to alteration of intestinal flora. 3
• The decision should weigh the importance of the drug to the mother against potential infant sensitization. 1

Critical Limitation: Not Recommended for Empirical UTI Treatment

Ampicillin should not be used for empirical treatment of UTI due to very high prevalence of antimicrobial resistance worldwide. 3 This is a more important consideration than breastfeeding compatibility.

• Amoxicillin or ampicillin have relatively poor efficacy and very high resistance rates globally, making them inappropriate for empirical UTI therapy. 3
• In one cohort, persistent resistance to ampicillin was 84.9% among E. coli UTI isolates. 3

Preferred First-Line Alternatives Compatible with Breastfeeding

For lower UTI (cystitis) in breastfeeding women, the following are both effective and compatible with lactation:

• Amoxicillin-clavulanate (20-40 mg/kg per day in 3 doses): Listed as compatible with breastfeeding and recommended for oral UTI treatment. 3
• Nitrofurantoin (100 mg every 6 hours): First-choice agent with only 20.2% persistent resistance at 3 months and considered compatible with breastfeeding. 3
• Trimethoprim-sulfamethoxazole: First-choice agent if local resistance rates do not exceed 20%, compatible with breastfeeding in healthy term babies. 3
• Cephalosporins (e.g., cefuroxime): Compatible with breastfeeding and not teratogenic at usual therapeutic doses. 3

When Ampicillin Might Be Used

Ampicillin could only be considered if:

• Culture and susceptibility testing confirms the infecting organism is susceptible to ampicillin. 3
• Other recommended first-line agents cannot be used due to allergy or intolerance.
• The clinical situation allows waiting for culture results before initiating therapy (not typical for symptomatic UTI).

Common Pitfalls to Avoid

• Do not use ampicillin empirically without susceptibility data, as treatment failure is highly likely given resistance patterns. 3
• Avoid fluoroquinolones as first-line therapy during breastfeeding due to collateral damage concerns and FDA warnings about unfavorable risk-benefit ratios for uncomplicated UTI. 3
• Do not treat asymptomatic bacteriuria during breastfeeding, as this increases risk of symptomatic infection and bacterial resistance. 3
• Ensure the infant is healthy and term; avoid sulfonamides in infants who are glucose-6-phosphate dehydrogenase deficient, jaundiced, or premature. 3