Could Probiotics Be an Option for Treating and Preventing Urogenital Infections?

Gregor Reid, PhD, MBA, Andrew W. Bruce, MD, FRCS

In This Article


Worldwide, it is estimated that several hundred million women suffer from UTIs annually. This figure may even be an underestimate, given that there are 3 billion women in the world and that the incidence of uncomplicated UTI in women is 0.5 episodes per person per year with a recurrence rate of between 27% and 48%.[12] The annual cost to healthcare services is staggering, reaching $2 billion in the United States alone and over $6 billion worldwide.[13]

Risk factors for UTI include sexual intercourse with multiple partners and exposure to spermicidal agents.[14,15] Spermicides have a deleterious effect on the vaginal flora, causing loss of lactobacilli and an increase in pH, which stimulates the growth of gram-negative organisms and subsequent UTI. McGroarty and colleagues[16,17] clearly demonstrated the impact of nonoxynal-9 on the growth and adherence of urogenital bacteria and Candida. Additional risk factors for postmenopausal women include a history of previous genitourinary surgery and disturbed bladder function, as well as nonsecretor blood group status and loss of estrogen.[18,19]

Stamm and Hooton[20] reported in detail on the microbiologic patterns found in patients with UTIs. Escherichia coli is the responsible agent in most cases (up to 85%), followed by Staphylococcus saprophyticus[20] and enterococci.[21] Significant bacteriuria has been defined as 105 or more colony-forming organisms per milliliter (mL) of urine, but this has recently been changed to a cut-off of 103 per mL when associated with irritating bladder symptoms.[22]

The incidence of asymptomatic bacteriuria increases with age. Among school-aged girls, 1% to 2% are afflicted, compared with 2% to 5% of premenopausal women and 10% to 15% of postmenopausal women.[23] Coagulase-negative staphylococci and Enterococcus species are more frequently cultured from patients with asymptomatic bacteriuria. This syndrome is benign in nonpregnant women. However, 13% to 27% of pregnant women with asymptomatic bacteriuria will develop acute pyelonephritis,[24] and if this occurs late in the third trimester, it may result in premature labor.

Treatment of isolated lower UTI (acute cystitis) is simple and requires a short course (3 days) of the appropriate antibiotic. Trimethoprim-sulfamethoxazole (TMP-SMX) is most commonly prescribed in North America. Patients with recurrent episodes may self-administer repeated short courses of antibiotics, but long-term low-dose medication is usually preferred. This entails nightly intake of a small dose of an antibiotic (eg, TMP-SMX or nitrofurantoin for a period ranging from 6 months to 5 years). Although breakthroughs may occur with this regimen, in general it has proven to be effective in reducing recurrences.[25] Physicians' approaches to treatment of asymptomatic bacteriuria vary according to the clinical condition of the patient, but all are agreed that treatment is essential during pregnancy.

Unfortunately, antibiotic therapy is associated with both side effects and increasing bacterial resistance. TMP-SMX can cause skin reactions, diarrhea, yeast vaginitis, and the more serious Stevens-Johnson syndrome[26]; it can also promote gram-positive coccal infections in patients with spinal cord injury, who are highly susceptible to recurrent UTIs.[27] In the United Kingdom, TMP-SMX is not recommended for treatment of UTIs because of the sulfa component, and trimethoprim alone is used. A further concern with antibiotics is the increasing resistance of bacteria to many drug groups,[28] including fluoroquinolones.

The adverse impact of antibiotics on the vaginal flora is well known. Resistant strains appear in the gastrointestinal (GI) tract and then become dominant in the vaginal flora.[29] The use of prophylactic therapy does not change a patient's susceptibility to UTI, and re-infection tends to occur within weeks or months of discontinuing therapy.[30] Given the correlation between UTI and reduced quality of life,[31] and the enormous global population afflicted by this disease, it is surely appropriate to consider alternative remedies for prevention and treatment.


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