Asymptomatic Bacteriuria in Pregnancy
1. Initial Screening & Urinalysis Filter
Perform UFEME if urine albumin is positive.
Nitrite Positive
- Action: Send urine C&S.
- May consider treatment if near term or high risk group*.
Nitrite Negative
AND Leukocyte Positive
- Action: Send urine C&S.
- Review C&S result before starting antibiotic treatment.
Nitrite Negative
AND Leukocyte Negative
- Action: Send urine C&S for high risk group* if proteinuria ≥ x2.
*High-Risk Group Definition:
Diabetes mellitus, renal tract abnormalities, past/recent renal calculi, recurrent infection.
2. Urine C&S Interpretation
Review quantitative colony counts to determine clinical action.
🟢 CFU ≥ 10⁵
OR ≥ 10⁴ for (GBS)
Confirmed ASB:
- Action: Start antibiotic treatment.
- Repeat urine C&S is NOT routinely done.
🟡 CFU 10³ – 10⁴
CFU 10³ – 10⁴: Repeat urine C&S is recommended.
CFU < 10³: End
💊 Recommended Pregnancy Dose
All choices target a standard course duration of 5 days.
| Antibiotic Option | Dosing Regimen | Duration | Obstetric Remarks & Safety Cautions |
|---|---|---|---|
| Nitrofurantoin** | 50-100mg PO q6h (immediate release) OR 100mg PO q12h (modified release) |
5 Days |
Preferred • Reasonable to offer in first trimester if no appropriate alternatives available. • Contraindicated if eGFR <30 ml/min; avoid in third trimester. |
| Cephalexin | 1-2g/day in 2-4 divided doses PO | 5 Days | Preferred |
| Amoxicillin / Clavulanate*** | 625mg PO q8h | 5 Days |
Alternative • Generally safe (category B). • Warning: Linked to necrotizing enterocolitis (NEC) in preterm babies and after PROM. |
| Ampicillin / Sulbactam | 375-750mg PO q12h | 5 Days | Alternative |
| Cefuroxime | 500mg PO q12h | 5 Days | Alternative |