How do you treat a male patient with a positive Lactobacillus (lactic acid bacteria) urine culture?

Treatment of Lactobacillus in Male Urine Culture

In a male patient with Lactobacillus isolated from urine culture, treatment should NOT be initiated unless there are clear symptoms of urinary tract infection, as Lactobacillus is typically a contaminant or commensal organism and asymptomatic bacteriuria should not be treated. 1

Initial Assessment

Determine if the patient is truly symptomatic:

• Look specifically for acute dysuria, fever, gross hematuria, suprapubic pain, or signs of systemic infection (rigors, hypotension) 1
• In elderly males, assess for acute confusion, new urinary incontinence, or functional decline that cannot be explained by other causes 1
• Document whether symptoms preceded the urine culture or appeared after it was obtained

Clinical Context of Lactobacillus in Male Urine

Lactobacillus is an extremely unusual pathogen in males and should raise immediate suspicion for:

• Specimen contamination - This is the most likely explanation, as lactobacilli are not part of normal male urogenital flora 2
• Mixed flora/polymicrobial contamination - If other organisms are present, this strongly suggests contamination 3
• Laboratory error or mislabeling - Consider whether the specimen was truly from this male patient

Lactobacilli are vaginal commensals and are almost never true urinary pathogens, even in females where they are part of normal flora 2, 4. In males, their presence is even more suspect.

Management Algorithm

If the patient is asymptomatic:

• Do not treat - Asymptomatic bacteriuria should not be treated in males 1
• Do not repeat the urine culture unless symptoms develop 1
• Avoid screening urine cultures in asymptomatic patients 1

If the patient has genuine UTI symptoms:

• Obtain a fresh, properly collected urine specimen (clean-catch midstream or condom catheter with careful technique) 1
• Send for repeat culture and susceptibility testing before starting antibiotics 5
• If repeat culture grows Lactobacillus as a pure isolate with pyuria (≥10 WBCs/high-power field), consider it a potential pathogen only in this rare circumstance 1, 2
• Treat as a complicated UTI in males with a 14-day course of empiric therapy: amoxicillin plus aminoglycoside, second-generation cephalosporin plus aminoglycoside, or third-generation cephalosporin 5
• Adjust therapy based on susceptibility results when available 5

If repeat culture shows different organisms:

• This confirms the original Lactobacillus was a contaminant 3
• Treat based on the new culture results following standard male UTI guidelines 5

Critical Pitfalls to Avoid

• Never treat based on a single positive culture without symptoms - This drives unnecessary antimicrobial resistance 1
• Do not obtain urine cultures in asymptomatic males - This leads to inappropriate treatment of colonization 1
• Recognize that Lactobacillus in male urine is almost always contamination - True infection is extraordinarily rare 2
• Avoid short-course therapy (7 days) in symptomatic males - Men require 14 days when prostatitis cannot be excluded 5