I know there has been a lot of discussion about using probiotics to treat bowel issues, but they may also be useful for treating UTIs.
keep in mind that probiotic research is in its infancy.

From: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2684288/

Trials with probiotics

Trials on the use of probiotics in urology patients to date had small numbers of participants only. There are small studies on the use of probiotics in renal calculi due to enteric hyperoxaluria, recurrent candida vulvovaginitis, as well as UTIs.[50?52] In patients with neurogenic bladder trials with encouraging results have been performed with instillation of non-pathogenic E. coli into the bladder.[53,54] To date two clinical trials are on the way to explore the effects of oral and topical probiotics in RUTI.[55,56] No trials in this area have been started or performed in the UK.

The RUTI is a significant healthcare problem worldwide for many women and even more so in specific patient populations. Patients with spinal cord injury and neurogenic bladder as well as patients with long-term urinary catheter all share the problem of RUTI. These patients do have more complicated UTI and develop resistance to standard antibiotics. The recent reports on MRSA, C. difficile and other problem pathogens in the UK leave no doubt that alternative, preventive and economic therapeutic options to antibiotics are urgently needed.

The use of oral probiotics has not been sufficiently tested in RUTI and they have not been tested at all in patients with neurogenic bladder or long-term urinary catheter. Recently, Darouiche et al. tested the topical use of probiotics in patients with neurogenic bladder. After instillation of a benign E. coli strain into the bladder of these patients, they found decreased rates of RUTI especially in those, where the bladder was successfully colonised.[57] The same group started to look at urinary catheters coated with probiotic microorganisms in contrast to catheters coated with antimicrobials. Twelve adult inpatients with neurogenic bladders requiring indwelling urinary catheters had E. coli HU2117-coated catheters inserted for 28 days. With this method, the rate of symptomatic UTI was reduced to 0.15 cases per 100 patient-days compared to published average rates of 2.72 cases per 100 patient-days in such patients.[30] In women, the topical use of Lactobacilli released from a vaginal suppository has been investigated in a pilot trial in nine women. It was shown that E. coli positive cultures reduced from 5.0 ? 1.6 episodes to 1.3 ? 1.2, P < 0.0007 over 12-month period.[58] The cited studies did not report any serious side effects or intolerance, but suggested that severely immunocompromised hosts may only be trialled with caution.

A trial with oral probiotics is currently under way in the Netherlands (NAPRUTI trial) using different strains of oral probiotics, containing L. rhamnosus and Lactobacillus reuteri.[55] In this multicentre double blind trial, 280 postmenopausal women are randomised to receive either oral Lactobacilli or standard antibiotic treatment for RUTI. Patients are treated for 12 months with a follow-up of 3 months. Another trial in the United States investigates the use of a topical single strain probiotic with Lactobacillus crispatus.[56] This single centre trial investigates uncomplicated RUTI in premenopausal women only. A total of 100 female patients are randomised to receive either placebo or topical Lactobacilli as a vaginal capsule for 3 months with a follow-up of 6 months. Neither trial compares premenopausal to postmenopausal treatment with probiotics. Moreover, probiotics are not expected to completely eradicate infections but to lower the rate of recurrence and prevent development of bacterial resistance. In this regard, the trial designs do not describe precautions or scenarios on the use of probiotics in episodes of UTI severe enough to require additional treatment.

Probiotics can be regarded as the single most powerful alternative option under clinical development for the prevention and treatment of chronic infection.[59] Given the enormous burden on patients, as well as the scientific and economic problem caused by RUTI, the investigation of probiotics is of potentially crucial importance for patient benefit and clinical science. Laboratory and clinical research on live microorganisms have opened a major research field with increasing numbers of investigations and trials. Little is known about the complex interaction of the human bacterial flora with the human body. From an evolutionary point of view, live microorganisms have provided the human body with crucial functions in digestion and immunemodulation. The human body did not have to develop these functions and is employing the hosted flora of microorganisms ?as a metabolic ?organ? exquisitely tuned to our physiology? on its outer surfaces.[60] The bacterial flora of the gut has a weight of approximately 1-2 kg and is thought to be metabolically as important as the liver.[61] As the live microorganisms used in probiotics are often isolated from the human flora, trials with specific probiotics will help to elucidate the role of these bacteria in the human body's eco-system. Data and experience gained from clinical trials with probiotics will direct laboratory research and help to train clinicians in their future clinical use.

The harmful effects of antibiotics have always been somewhat overlooked. The scientific importance of trials with probiotics is not only to investigate their potential use in recurrent infection, but also the containment and therapy of the side effects of antimicrobial chemotherapy itself.

A major concept in urological therapy is to prevent the recurrence of UTI. Investigations on live microorganisms derived from the human gut flora will drive forward the field of preventive medicine in the therapy of RUTI. Similar to nutritional aspects in medicine probiotics acknowledge the complex nature of infection. Despite longstanding knowledge of immunosuppressive effects of poor nutrition, the introduction of perioperative enteral nutrition has only recently been developed.[62] Perioperative enteral nutrition has a major impact on the body's ability to resist infection. This view and treatment strategy has now been added to antibiotic therapy for infection in most surgical specialties, giving evidence of the need for complementary anti-infective prevention and treatment.[63,64] As described above, despite definitive clinical evidence on the positive effects of probiotics, so far sufficiently powered studies using probiotics in RUTI have only recently been commenced.[65,66]