Lactobacillus spp. isolated from urine generally does not require treatment because these organisms are often part of the normal bacterial flora of the genitourinary (GU) and gastrointestinal tracts, are generally of low virulence, are rarely associated with urinary tract infections (UTIs) and may in fact have potential benefits in preventing UTIs. ^1-4

In a study involving female urinary microbiome, subjects with urgency urinary incontinence were less likely to have Lactobacillus spp. based on 16S rRNA gene sequencing of transurethral catheter urine than those without symptoms, suggestive of possible protective role of this organism in female GU tract.¹

Although Lactobacillus UTI is rare, one particular species, Lactobacillus delbrueckii, has been implicated in several case reports involving primarily elderly women.^3,4

Vaginal colonization with lactobacilli provides a natural, nonspecific defense mechanism against infection in part by production of lactic acid and lowering of the regional pH which, when combined with hydrogen peroxide production by commensal anaerobes, interferes with colonization of the vaginal mucosal surfaces by potential pathogens. Lactobacilli also interfere with the adherence of pathogens by production of biosurfactants.³ It’s no surprise that lactobacilli are often considered “friendly bugs” and used in many probiotic preparations.

Bonus Pearl: Did you know that contrary to the current dogma, urine is not necessarily sterile.  Even in asymptomatic people, it may contain several organisms, including Lactobacillus, Gardnerella, Streptococcus, Staphylococcus (not aureus) and Corynebacterium? ⁵

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References

1. Pearce MM, Hilt EE, Rosenfeld AM, et al. The female urinary microbiome: a comparison of women with and without urgency urinary incontinence. mBio 2014;5:e01283-14. https://pubmed.ncbi.nlm.nih.gov/25006228/
2. Thomas-White K, Forster SC, Kumar N, et al. Culturing of female bladder bacteria reveals an interconnected urogenital microbiota. Nature Communications 2018;9:1557. https://www.nature.com/articles/s41467-018-03968-5.pdf (urine not sterile, bladder with lactobacillus prevention, normal asymptomatic
3. Darbro BW, Petroelje BK, Doern GV. Lactobacillus delbureckii as the cause of urinary tract infection. J Clin Microbiol 2009;47:275-277. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2620876/#:~:text=Urinary%20tract%20infections%20caused%20by,a%20setting%20of%20ureteral%20obstruction.
4. Maillet F, Passeron A, Podglajen I, et al. Lactobacillus delbrueckii urinary tract infection in a male patient. Med Mal Infect 2019;49:225-230. https://www.sciencedirect.com/science/article/pii/S0399077X1830787X?via%3Dihub
5. Reid G. The scientific basis for probiotic strains of Lactobacillus. App Env Microbiol 1999;65:3763-3766. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC99697/

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