Lactobacillus Species in Urine: No Treatment Required
Lactobacillus species isolated from urine cultures should not be treated with antibiotics, as these organisms are normal vaginal and periurethral commensals that indicate specimen contamination rather than true urinary tract infection. 1, 2
Why Lactobacillus is Not a Uropathogen
Lactobacillus species, along with coagulase-negative staphylococci and Corynebacterium species, are explicitly excluded as clinically relevant urine isolates in otherwise healthy individuals. 1, 2
The American Academy of Pediatrics specifically states that organisms such as Lactobacillus spp are not considered clinically relevant urine isolates for otherwise healthy children aged 2-24 months, and this principle extends to adults. 1
These organisms represent normal flora from the vaginal and periurethral area that contaminate urine specimens during collection, particularly with voided or inadequately collected samples. 1, 2
Clinical Approach When Lactobacillus is Isolated
If the Patient Has UTI Symptoms:
Repeat the urine culture using meticulous collection technique, preferably via catheterization, to rule out contamination before considering any treatment. 2
If repeat culture remains negative or shows only Lactobacillus while symptoms persist, investigate alternative diagnoses for urinary symptoms rather than treating the Lactobacillus. 2
If the Patient is Asymptomatic:
Do not treat asymptomatic bacteriuria with Lactobacillus, as treatment fosters antimicrobial resistance and paradoxically increases recurrent UTI episodes. 1, 2
Treatment of asymptomatic bacteriuria increases the risk of symptomatic infection, bacterial resistance, and healthcare costs. 1
Critical Pitfall to Avoid
Never classify patients with Lactobacillus-positive cultures as having "complicated UTI." This misclassification leads to inappropriate use of broad-spectrum antibiotics with unnecessarily prolonged treatment durations. 1, 2
The European Association of Urology and American Urological Association guidelines emphasize that complicated UTI designation should be reserved for patients with true anatomic/functional abnormalities or multidrug-resistant uropathogens, not contaminant organisms. 1, 2
Beneficial Role of Lactobacillus in UTI Prevention
While Lactobacillus in urine cultures represents contamination, Lactobacillus-containing probiotics can be considered as a non-antibiotic alternative for prevention of recurrent UTIs, particularly in postmenopausal women (combined with vaginal estrogen) or as an alternative to antibiotic prophylaxis. 2
Vaginal administration of Lactobacillus suppositories following antimicrobial therapy reduced UTI recurrence rates from 47% to 21% in one study. 3
However, evidence quality for oral Lactobacillus probiotics remains limited with inconsistent results across studies. 2
The most commonly studied strains with potential benefit are Lactobacillus rhamnosus GR1 and Lactobacillus reuteri RC14. 4