What is the best treatment approach for a pregnant patient with a bacterial infection?

Treatment of Bacteriuria in Pregnancy

Pregnant women with bacteriuria of any concentration should receive treatment at the time of diagnosis AND intrapartum antibiotic prophylaxis, as bacteriuria indicates heavy genital tract colonization with Group B Streptococcus (GBS). 1

Immediate Treatment Approach

First-Line Antibiotic Selection

Penicillins and cephalosporins are the safest antibiotic classes for treating bacterial infections during pregnancy and should be your first choice. 1, 2

• Beta-lactam antibiotics (penicillins and cephalosporins) have decades of clinical experience demonstrating safety for both mother and fetus 2, 3
• These agents achieve adequate placental transfer and bactericidal levels in fetal tissues while maintaining excellent safety profiles 1
• For urinary tract infections specifically, beta-lactams alone or in combination are preferred 3

Antibiotics to AVOID

You must avoid the following antibiotic classes during pregnancy due to fetal toxicity: 1, 2

• Tetracyclines - cause fetal bone and tooth abnormalities 1
• Fluoroquinolones - contraindicated due to cartilage toxicity concerns 1, 4
• Aminoglycosides - known fetal ototoxicity (use only if absolutely necessary with careful serum monitoring) 1, 2
• Trimethoprim-sulfamethoxazole - avoid especially in first trimester due to neural tube defect risk 1

Alternative Safe Options

If beta-lactam allergy exists or additional coverage is needed: 3

• Azithromycin - extensively studied and safe throughout pregnancy 3, 4
• Metronidazole - safe for anaerobic coverage; earlier teratogenicity concerns have been disproven 1, 4
• Nitrofurantoin - acceptable for urinary tract infections (avoid near term due to hemolysis risk) 3
• Fosfomycin - single-dose option for uncomplicated UTIs 3

Special Considerations for GBS Bacteriuria

Why GBS Bacteriuria Matters

Any quantity of GBS in urine during pregnancy indicates heavy genital colonization and requires both immediate treatment AND intrapartum prophylaxis. 1

• GBS bacteriuria is a marker for substantial genital tract colonization regardless of concentration 1
• These women do NOT need vaginal/rectal screening at 35-37 weeks since treatment is already indicated 1
• Both symptomatic and asymptomatic GBS urinary infections require treatment at diagnosis PLUS intrapartum prophylaxis 1

Intrapartum Prophylaxis Protocol

For women with documented GBS bacteriuria, administer intrapartum antibiotic prophylaxis during labor: 1

• Penicillin G is preferable to ampicillin for routine prophylaxis due to narrower spectrum and less selection pressure for resistant organisms 1
• Prophylaxis should begin at least 4 hours before delivery for optimal neonatal protection 1
• This prevents early-onset neonatal GBS disease, which can cause sepsis, meningitis, and death 1

Critical Pitfalls to Avoid

Common Errors in Management

• Do NOT use oral fluconazole for any reason during pregnancy, especially first trimester - this is for fungal infections and carries teratogenic risk 5, 6
• Do NOT skip intrapartum prophylaxis even if the initial bacteriuria was treated - the colonization persists 1
• Do NOT use fluoroquinolones despite their effectiveness in non-pregnant patients - fetal cartilage damage risk is unacceptable 1, 4
• Ensure laboratory reports any GBS bacteriuria to both prenatal and delivery providers - communication failures lead to missed prophylaxis 1

Documentation Requirements

Label all urine specimens to indicate pregnancy status so laboratories know to report ANY quantity of GBS, not just clinically significant counts 1

Treatment Duration and Follow-Up

• Treat symptomatic UTIs according to standard pregnancy protocols (typically 7 days for lower tract, longer for pyelonephritis) 1
• Consider test-of-cure cultures after treatment completion, as pregnancy physiology may affect treatment efficacy 4
• Re-testing after several weeks is advisable to detect recurrence or treatment failure 4

Risk-Benefit Analysis

The benefits of treating bacteriuria in pregnancy far outweigh antibiotic risks: 2, 4

• Untreated bacteriuria leads to pyelonephritis in 20-40% of pregnant women
• GBS can cause premature delivery, premature rupture of membranes, and life-threatening neonatal sepsis 1
• Penicillins and cephalosporins have established safety records spanning decades of use 2
• The risk of anaphylaxis to penicillin (0.001% fatal reactions) is vastly outweighed by prevention of neonatal disease 1