Do you treat Lactobacillus species in urine?

Management of Lactobacillus Species in Urine

Lactobacillus species isolated in urine should not be treated as they are not considered clinically relevant urinary pathogens in otherwise healthy individuals. 1

Understanding Lactobacillus in Urine

Lactobacillus species are normal flora of the vagina and are typically considered contaminants when cultured from urine specimens, particularly in female patients. According to the American Academy of Pediatrics guidelines, organisms such as Lactobacillus spp, coagulase-negative staphylococci, and Corynebacterium spp are not considered clinically relevant urine isolates for otherwise healthy individuals 1.

Key considerations:

• Lactobacilli are part of the normal bacterial flora of the vagina
• They are generally considered contaminants in urine cultures
• Treatment of non-pathogenic bacteria can lead to:
  • Disruption of normal flora
  • Increased risk of antibiotic resistance
  • Potential for more symptomatic infections

Clinical Decision Algorithm

1. Assess for symptoms

   • If asymptomatic → Do not treat Lactobacillus in urine
   • If symptomatic → Consider other causes; Lactobacillus is rarely pathogenic

2. Evaluate colony count

   • Even at counts ≥50,000 CFUs/mL, Lactobacillus is not considered a urinary pathogen in immunocompetent individuals 1

3. Consider patient factors

   • Immunocompromised status
   • Urological abnormalities
   • Recent urological procedures

Evidence Supporting Non-Treatment

The European Association of Urology (2024) and Infectious Diseases Society of America (2019) guidelines strongly recommend against treating asymptomatic bacteriuria in most populations 1. This principle extends to non-pathogenic organisms like Lactobacillus.

Research suggests that treating asymptomatic bacteriuria may actually be harmful:

• May increase the risk of symptomatic infection 1
• Can foster antimicrobial resistance 1
• May eliminate protective bacterial strains 1

In fact, some studies suggest that Lactobacillus species may have a protective effect against urinary tract infections caused by uropathogenic bacteria 2, 3, 4. Lactobacilli can inhibit the growth of coliforms that commonly cause UTIs 3.

Rare Exceptions

While extremely rare, there have been isolated case reports of Lactobacillus delbrueckii causing urinary tract infection in specific circumstances 5. These cases are exceptional and do not change the general recommendation against treatment.

Potential Benefits of Lactobacillus

Rather than being treated as pathogens, Lactobacillus species are sometimes used therapeutically:

• Probiotic Lactobacillus strains have been studied for prevention of recurrent UTIs 3, 4
• Lactobacilli may help restore normal vaginal flora and reduce UTI risk 6
• They can interfere with adherence and colonization of uropathogenic bacteria 6

Common Pitfalls to Avoid

1. Overtreatment: Treating non-pathogenic organisms leads to unnecessary antibiotic use
2. Misinterpretation: Confusing colonization/contamination with infection
3. Ignoring context: Failing to consider the patient's clinical presentation
4. Disrupting protective flora: Eliminating beneficial bacteria that may prevent pathogenic colonization

By following these evidence-based guidelines, clinicians can avoid unnecessary antibiotic use, prevent antimicrobial resistance, and potentially preserve protective bacterial flora that may help prevent future urinary tract infections.