Is treatment of asymptomatic bacteruria (presence of bacteria in urine) indicated in a pregnant patient with a urine culture positive for Staphylococcus saprophyticus (Staph saprophyticus) who does not have urinary complaints?

Treatment of Asymptomatic Bacteriuria in Pregnant Patients

Treatment of asymptomatic bacteriuria in pregnant patients is strongly recommended, including for those with Staphylococcus saprophyticus, even without urinary symptoms. 1, 2

Rationale for Treatment

• Untreated asymptomatic bacteriuria in pregnancy significantly increases the risk of pyelonephritis from 20-35% to 1-4% with treatment 2
• Antimicrobial treatment reduces the risk of preterm birth from approximately 53 per 1000 to 14 per 1000 (low-quality evidence) 1
• Treatment lowers the chance of very low birth weight from approximately 137 per 1000 to 88 per 1000 (moderate-quality evidence) 1
• The American College of Obstetricians and Gynecologists and the US Preventive Services Task Force support screening and treatment of asymptomatic bacteriuria in pregnancy 1

Screening Recommendations

• A urine culture should be collected at one of the initial prenatal visits early in pregnancy 1, 2
• Asymptomatic bacteriuria occurs in 2-7% of pregnant women 1, 2
• Urine culture is the gold standard for diagnosis; other screening methods are not sufficiently effective 3

Treatment Approach

• For pregnant women with asymptomatic bacteriuria, including those with Staphylococcus saprophyticus:

  • A 4-7 day course of antimicrobial treatment is recommended rather than a shorter duration (weak recommendation, low-quality evidence) 1, 2
  • Single-dose regimens have shown lower rates of bacteriuria clearance compared to short-course regimens and are not recommended 2, 4

• Preferred antibiotics (based on susceptibility testing):

  • Nitrofurantoin is often preferred due to its safety profile in pregnancy and effectiveness 2, 5
  • Beta-lactam antibiotics such as ampicillin or cephalexin are safe alternatives during pregnancy 2, 5
  • The shortest effective course should be used 1

Follow-up Recommendations

• After completing antibiotic treatment, a follow-up urine culture is recommended to confirm clearance of the infection 2, 6
• Recurrence is common (up to one-third of patients) and may require re-treatment 2, 6

Common Pitfalls to Avoid

• Don't use single-dose therapy, as it has lower efficacy in pregnant women 1, 2
• Don't delay treatment of confirmed bacteriuria in pregnant women, as untreated cases can progress to pyelonephritis 2
• Don't overlook follow-up cultures after treatment, as recurrence is common 2, 6
• Avoid tetracyclines and fluoroquinolones during pregnancy due to potential adverse effects on fetal development 5

Special Considerations

• While a recent study in the Netherlands suggested that nontreatment of asymptomatic bacteriuria may be acceptable for selected low-risk women, further evaluation in other populations is necessary before changing the recommendation to screen and treat all pregnant women 1
• The optimal duration of therapy will vary depending on the antimicrobial given 1