Do you treat Lactobacillus bacteriuria in pregnancy?

Do Not Treat Lactobacillus Bacteriuria in Pregnancy

Lactobacillus species isolated in urine culture during pregnancy should not be treated with antibiotics, as Lactobacillus is part of the normal vaginal and urogenital flora and does not represent pathogenic bacteriuria requiring intervention.

Rationale for Non-Treatment

Lactobacillus is Not a Uropathogen

• Lactobacillus species are commensal organisms that colonize the vaginal and periurethral area and frequently contaminate urine specimens, particularly in pregnant women 1, 2
• The guidelines for asymptomatic bacteriuria specifically target uropathogens such as Escherichia coli, which accounts for the majority of true bacteriuria cases 3
• When guidelines recommend screening for and treating asymptomatic bacteriuria in pregnancy, they refer to pathogenic organisms that cause the 20-35% risk of pyelonephritis if untreated 1, 2

Evidence-Based Screening Targets True Pathogens

• Asymptomatic bacteriuria requiring treatment is defined as ≥10^5 colony-forming units per mL of a single uropathogen on clean-catch midstream urine culture 4
• The organisms that warrant treatment are those associated with progression to pyelonephritis and adverse pregnancy outcomes—primarily gram-negative enteric bacteria like E. coli, Klebsiella, and Proteus species 3, 5
• Lactobacillus does not fit the microbiological criteria for pathogenic bacteriuria that the screening and treatment recommendations were designed to address 1, 2

Clinical Approach

When Lactobacillus is Isolated

• If a urine culture grows Lactobacillus species, consider this a contaminated specimen or normal flora rather than true bacteriuria 1
• No antibiotic treatment is indicated for Lactobacillus bacteriuria 1, 2
• If the patient is symptomatic with dysuria or frequency, repeat the urine culture with careful midstream clean-catch technique to identify a true uropathogen 4, 6

Organisms That Do Require Treatment

• Treat these organisms when found in asymptomatic bacteriuria: E. coli, Klebsiella, Proteus, Enterococcus, and Group B Streptococcus 2, 6, 3
• Group B Streptococcus bacteriuria at any concentration requires both immediate treatment and intrapartum prophylaxis during labor 6
• Use nitrofurantoin 100 mg twice daily for 4-7 days as first-line therapy (avoid at term), or cephalexin 500 mg four times daily for 4-7 days as an alternative 2, 4, 6

Common Pitfall to Avoid

The most common error is treating Lactobacillus as if it were a uropathogen simply because it grew on culture. This leads to unnecessary antibiotic exposure during pregnancy, disrupts normal protective vaginal flora, and does not address the actual indication for treating asymptomatic bacteriuria—which is preventing pyelonephritis from true uropathogens 1, 2, 3.