Zosyn (Piperacillin/Tazobactam) Use in Pregnancy
Piperacillin/tazobactam is safe to use during pregnancy and is classified as FDA Pregnancy Category B, with no evidence of fetal harm in humans and explicit guideline endorsement as "compatible" throughout all trimesters. 1, 2
Safety Profile and Classification
Piperacillin/tazobactam carries FDA Pregnancy Category B designation, indicating animal reproduction studies have revealed no evidence of harm to the fetus, though adequate well-controlled studies in pregnant women are lacking. 2
The European Respiratory Society explicitly lists piperacillin/tazobactam as "compatible" for use during pre-conception and first trimester, placing it among accepted penicillin-based therapies for pregnant patients. 1
No cases of congenital defects have been reported in humans with piperacillin/tazobactam use during pregnancy. 1
Teratology studies in mice and rats at doses up to half the maximum recommended human daily dose showed no evidence of harm to the fetus. 2
Clinical Indications in Pregnancy
For upper urinary tract infections (pyelonephritis) in pregnancy, piperacillin/tazobactam is recommended as a third-line option, particularly in pregnant women with a history of infection caused by microorganisms resistant to third or fourth-generation cephalosporins. 3
Piperacillin/tazobactam is effective for polymicrobial infections, nosocomial infections, and serious infections requiring broad-spectrum coverage when first-line agents (penicillins and cephalosporins) are inadequate. 4, 5
The combination is particularly useful for infections likely due to beta-lactamase producing organisms, where standard penicillins would be ineffective. 5, 6
Pharmacokinetic Considerations
Piperacillin/tazobactam crosses the placenta and is present in breast milk, though it has low oral bioavailability which limits infant exposure during breastfeeding. 1
The drug should be used with caution during nursing, as piperacillin is excreted in low concentrations in human milk. 2
Critical Safety Warnings
Rare but serious bone marrow suppression (leucopenia, neutropenia, thrombocytopenia) has been reported with piperacillin/tazobactam use during pregnancy, though this is reversible upon discontinuation. 7
Monitor complete blood counts if prolonged therapy (>10-14 days) is required, as hematological reactions occur in <1% of patients but can be significant. 7
The sodium content (42.5 mg per gram of piperacillin) may be clinically important in pregnant patients with conditions like preeclampsia or heart disease, as patients receiving usual doses would receive 255-765 mg/day of sodium. 2
Preferred Alternatives When Appropriate
First-line antibiotics for most bacterial infections in pregnancy remain amoxicillin and cephalexin, which have decades of safety data and should be used when adequate for the infection. 8, 9
For severe infections requiring broad-spectrum coverage, ceftriaxone plus metronidazole is a safe alternative that may be preferred over piperacillin/tazobactam depending on the clinical scenario. 1
Second-generation cephalosporins are the suggested first option for empirical treatment of upper UTIs in pregnancy, with piperacillin/tazobactam reserved for resistant organisms. 3
Practical Clinical Algorithm
Use piperacillin/tazobactam in pregnancy when:
- Severe polymicrobial or nosocomial infection requires broad-spectrum coverage 4, 5
- Culture results demonstrate resistance to first-line agents (penicillins, cephalosporins) 3
- History of infection with beta-lactamase producing organisms 5
- Patient has failed or cannot tolerate first-line agents 3
Avoid or use alternative agents when: