Methenamine hippurate compared with trimethoprim for the prevention of recurrent urinary tract infections: a randomized clinical trial

Urinary tract infections: pathogenesis, host susceptibility and emerging therapeutics

Urinary tract infections (UTIs), which include any infection of the urethra, bladder or kidneys, account for an estimated 400 million infections and billions of dollars in health-care spending per year. The most common bacterium implicated in UTI is uropathogenic Escherichia coli, but diverse pathogens including Klebsiella, Enterococcus, Pseudomonas, Staphylococcus and even yeast such as Candida species can also cause UTIs. UTIs occur in both women and men and in both healthy and immunocompromised patients. However, certain patient factors predispose to disease: for example, female sex, history of prior UTI, or the presence of a urinary catheter or other urinary tract abnormality. The current clinical paradigm for the treatment of UTIs involves the use of antibiotics. Unfortunately, the efficacy of this approach is dwindling as the prevalence of antimicrobial resistance rises among UTI isolates, and the immense quantity of antibiotics prescribed annually for these infections contributes to the emergence of resistant pathogens. Therefore, there is an urgent need for new antibiotics and non-antibiotic treatment and prevention strategies. In this Review, we discuss how recent studies of bacterial pathogenesis, recurrence, persistence, host-pathogen interactions and host susceptibility factors have elucidated new and promising targets for the treatment and prevention of UTIs.

Guidelines for the Prevention, Diagnosis, and Management of Urinary Tract Infections in Pediatrics and Adults: A WikiGuidelines Group Consensus Statement

Importance

Traditional approaches to practice guidelines frequently result in dissociation between strength of recommendation and quality of evidence.

Objective

To create a clinical guideline for the diagnosis and management of urinary tract infections that addresses the gap between the evidence and recommendation strength.

Evidence Review

This consensus statement and systematic review applied an approach previously established by the WikiGuidelines Group to construct collaborative clinical guidelines. In May 2023, new and existing members were solicited for questions on urinary tract infection prevention, diagnosis, and management. For each topic, literature searches were conducted up until early 2024 in any language. Evidence was reported according to the WikiGuidelines charter: clear recommendations were established only when reproducible, prospective, controlled studies provided hypothesis-confirming evidence. In the absence of such data, clinical reviews were developed discussing the available literature and associated risks and benefits of various approaches.

Findings

A total of 54 members representing 12 countries reviewed 914 articles and submitted information relevant to 5 sections: prophylaxis and prevention (7 questions), diagnosis and diagnostic stewardship (7 questions), empirical treatment (3 questions), definitive treatment and antimicrobial stewardship (10 questions), and special populations and genitourinary syndromes (10 questions). Of 37 unique questions, a clear recommendation could be provided for 6 questions. In 3 of the remaining questions, a clear recommendation could only be provided for certain aspects of the question. Clinical reviews were generated for the remaining questions and aspects of questions not meeting criteria for a clear recommendation.

Conclusions and Relevance

In this consensus statement that applied the WikiGuidelines method for clinical guideline development, the majority of topics relating to prevention, diagnosis, and treatment of urinary tract infections lack high-quality prospective data and clear recommendations could not be made. Randomized clinical trials are underway to address some of these gaps; however further research is of utmost importance to inform true evidence-based, rather than eminence-based practice.

Management of Bacteriuria and Urinary Tract Infections in the Older Adult

Urinary tract infection (UTI) is one of the most frequent bacterial infections diagnosed in older adults and the most common reason for antibiotic prescriptions in nursing homes. Distinguishing between asymptomatic bacteriuria and UTI in older adults can be challenging and implementing a systematic approach to diagnosis using standard toolkits or algorithms is recommended for patients residing in post-acute and long-term care settings. This article reviews the pathophysiology, microbiology, diagnostic approach, treatment, and approaches to prophylaxis in the older adult.

Gaps in knowledge and recurrent urinary tract infections in women

PURPOSE OF REVIEW

The focus of this review is to present recent literature and gaps in knowledge (GIKs) surrounding the current and future treatment and prevention of uncomplicated recurrent urinary tract infections (rUTIs) in women.

RECENT FINDINGS

Recurrent urinary tract infections are common, significantly reduce quality of life, and create a substantial economic burden to the healthcare system. They are disproportionately affecting the postmenopausal women. Antibiotics, which are used for the treatment and prophylaxis of uncomplicated rUTI, have become problematic, as there is a global rise in allergy and resistance to these agents and their use is associated with further antimicrobial resistance. Thus, in recent decades, several alternative, nonantibiotic approaches have been evaluated.

SUMMARY

There is a critical need for a concerted and standardized methodology for diagnosing, treating, and monitoring women with rUTIs. Additionally, novel nonantibiotic alternative treatment and preventive measures for UTIs are desperately required to address the global issue of antibiotic recalcitrance in all age groups, and specifically older women. Research efforts have sought to develop alternative and more effective techniques; many of which appear to be promising, but require additional evaluation and validation through clinical trials.

Recurrent UTI in Women-Risk Factors and Management

Urinary tract infections (UTIs) are common in women; more than 50% of women will be diagnosed with a UTI in her lifetime. Many of these women will go on to develop recurrent UTI. Nevertheless, evidence-based prevention of recurrent UTI is under-utilized. Here, the authors provide detailed practical advice on UTI prevention with a thorough review of the evidence. Non-antibiotic prevention measures discussed include increased fluid intake, vaginal estrogen therapy, methenamine, and cranberry. Antibiotic prophyalxis for carefully selected patients is also discussed.

Use of Methenamine for Urinary Tract Infection Prophylaxis: Systematic Review of Recent Evidence

INTRODUCTION AND HYPOTHESIS

Antibiotic resistance is an unavoidable consequence of antibiotic use and growing rates of resistance are an urgent issue. Methenamine is a non-antibiotic alternative used for urinary tract infection (UTI) prophylaxis. The objective of this review is to evaluate recently published literature regarding the efficacy and safety of methenamine for UTI prophylaxis.

METHODS

PubMed, Embase, and CENTRAL databases were queried in March 2023 using the following search terms: urinary tract infection, cystitis, bacteriuria, or dysuria, and methenamine. Studies prior to 2012 were excluded from this review to focus on appraisal of the most recent evidence. Prospective and controlled retrospective trials were included for review.

RESULTS

A total of seven studies (three prospective and four retrospective) met the inclusion criteria for review. Two of the 3 prospective studies demonstrated no or non-inferior differences in clinical efficacy to prevent recurrent UTIs between methenamine and antibiotic prophylaxis and the third showed decreased rates of UTI with methenamine use in patients with short-term indwelling catheters compared with cranberry alone. The retrospective studies consistently supported the efficacy and safety of methenamine for UTI prophylaxis in a variety of populations and clinical settings. Adverse effects reported with methenamine were similar to comparators and included nausea, abdominal pain, and headache.

CONCLUSIONS

The use of methenamine for UTI prophylaxis was shown to be effective in a variety of settings without an increased risk of adverse effects compared with prophylactic antibiotics. Larger blinded clinical trials are needed to further define the role of methenamine in UTI prophylaxis.

Methenamine for urinary tract infection prophylaxis: A systematic review

Urinary tract infections (UTIs) commonly affect many patient populations. Recurrent UTIs (rUTIs) can be particularly problematic and lead to potential hospitalizations, multiple antibiotic courses, and have a potential negative impact on quality of life. To prevent UTIs, antibiotics are frequently used for prophylaxis; however, antibiotic prophylaxis has notable untoward consequences including but not limited to potential adverse effects and development of antibiotic resistance. Methenamine, an antiseptic agent initially available in 1967, has re-emerged as a potential option for UTI prophylaxis in various populations, including older adults and renal transplant recipients. The objective of this systematic review was to evaluate the clinical effectiveness and safety of methenamine for UTI prophylaxis. A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance was performed. A PubMed, Embase, and Cochrane library search was conducted to identify relevant English-language studies evaluating methenamine for UTI prophylaxis including randomized controlled trials, case-control studies, and meta-analyses through June 2023. Articles were excluded if the studies did not primarily describe or evaluate methenamine for UTI prophylaxis, were commentaries/viewpoints articles, point prevalence studies, review articles, studies that evaluated methenamine used with another agent, and any duplicate publications from searched databases. A total of 11 articles were identified for inclusion. This systematic review suggests methenamine generally appears to be an effective and well-tolerated antibiotic-sparing option for UTI prophylaxis. Furthermore, the pharmacology, dosage and formulation, warnings, precautions, and safety considerations of methenamine that provide potential clinical considerations regarding its use for UTI prophylaxis are described. Further studies are needed to evaluate the clinical utility of methenamine for UTI prophylaxis.

Efficacy of methenamine with methylthioninium in the treatment of dysuria: a randomized clinical study

INTRODUCTION AND HYPOTHESIS

Dysuria is a common symptom present in several urological and gynecological conditions. Management relies on the underlying disease but may require additional symptomatic treatment. This study evaluated the combination of methenamine 250 mg and methylthioninium chloride 20 mg in the treatment of dysuria versus phenazopyridine.

METHODS

This was a multicenter, single-blind, randomized, superiority clinical trial, including individuals over 18 with dysuria and a score ≥ 5 points on the pre-treatment categorical scale for pain. The primary outcome was the proportion of participants presenting excellent clinical response within 24 h after treatment. Improvement up to 72 h, time to reach improvement, sustained healing, investigators' opinion, and safety were also evaluated.

RESULTS

Three hundred and fifteen participants were evaluated. Demographic characteristics and symptoms of dysuria were comparable between groups at baseline. The difference in the excellent response rate between treatments within 24 h was 12.7% (95% CI 6.16, 19.21) for pain, 9.4% (95% CI 3.32, 15.39) for burning, and 12.7% (95% CI 6.37, 18.99) for burning on urination, all in favor of the test drug, which was also superior from 36 to 48 h. Treatments were similar concerning time to reach the absence of symptoms and in the percentage of participants with sustained healing after 72 h.

CONCLUSIONS

The association of methenamine with methylthioninium is superior to phenazopyridine in the treatment of dysuria.

A practical guide on the non-antibiotic options available in the prevention of recurrent urinary tract infections in women

Urinary Tract infection (UTI) is one of the most common infections worldwide, patients present to multiple different specialities in the community, primary and secondary care. Antibiotics are considered standard first line therapy in the treatment of urinary tract infections, however there is an alarming rise in global antibiotic resistance rates, so much so that the World Health Organisation has labelled antibiotic resistance as one of the biggest challenges to public health in our lifetime, publishing a global action plan to tackle this challenge. As a result, there is an increasing need to discover non-antibiotic alternatives, recently a number of novel therapies have been introduced into clinical practice. These are divided into oral, topical, intravesical and immunomodulation therapies. The aim of this paper is to summarise the current non-antibiotic treatments as a practical guide to utilise in patient care.

Definitions of Urinary Tract Infection in Current Research: A Systematic Review

Defining urinary tract infection (UTI) is complex, as numerous clinical and diagnostic parameters are involved. In this systematic review, we aimed to gain insight into how UTI is defined across current studies. We included 47 studies, published between January 2019 and May 2022, investigating therapeutic or prophylactic interventions in adult patients with UTI. Signs and symptoms, pyuria, and a positive urine culture were required in 85%, 28%, and 55% of study definitions, respectively. Five studies (11%) required all 3 categories for the diagnosis of UTI. Thresholds for significant bacteriuria varied from 103 to 105 colony-forming units/mL. None of the 12 studies including acute cystitis and 2 of 12 (17%) defining acute pyelonephritis used identical definitions. Complicated UTI was defined by both host factors and systemic involvement in 9 of 14 (64%) studies. In conclusion, UTI definitions are heterogeneous across recent studies, highlighting the need for a consensus-based, research reference standard for UTI.

Emerging Non-Antibiotic Options Targeting Uropathogenic Mechanisms for Recurrent Uncomplicated Urinary Tract Infection

Urinary tract infections (UTIs) are the most frequent bacterial infections in the clinical setting. Even without underlying anatomic or functional abnormalities, more than 40% of women experience at least one UTI in their lifetime, of which 30% develop recurrent UTIs (rUTIs) within 6 months. Conventional management with antibiotics for rUTIs may eventually lead to the development of multidrug-resistant uropathogens. Targeting of the pathogenicity of rUTIs, the evolution of uropathogenic Escherichia coli (UPEC), and inadequate host defenses by immune responses should be explored to provide non-antibiotic solutions for the management of rUTIs. The adaptive evolution of UPEC has been observed in several aspects, including colonization, attachment, invasion, and intracellular replication to invade the urothelium and survive intracellularly. Focusing on the antivirulence of UPEC and modulating the immunity of susceptible persons, researchers have provided potential alternative solutions in four categories: antiadhesive treatments (i.e., cranberries and D-mannose), immunomodulation therapies, vaccines, and prophylaxis with topical estrogen therapy and probiotics (e.g., Lactobacillus species). Combination therapies targeting multiple pathogenic mechanisms are expected to be a future trend in UTI management, although some of these treatment options have not been well established in terms of their long-term efficacy. Additional clinical trials are warranted to validate the therapeutic efficacy and durability of these techniques.

Urinary Tract Infection Frequency and Prescription Prophylaxis in Females and Males with Recurrent Urinary Tract Infection

Females and males with recurrent urinary tract infections may receive prescription prophylaxis to reduce the infection frequency. Little is known about how prescription prophylaxis differs between patients meeting and exceeding the minimum threshold for recurrent urinary tract infections. The objectives of this study were to estimate the association between infection frequency and receipt of prescription prophylaxis and describe the type of prescription prophylaxis initiated. This observational study used de-identified fully-insured commercial insurance data from the Midwest from 2003-2016 to identify females and males under age 64 with recurrent urinary tract infections. The patients were categorized as having three or more urinary tract infections in twelve months or only two infections in six months. Multiple logistic regression models were used to determine the association between the infection frequency and receipt of prophylaxis. The frequency of the type of prophylaxis initiated was measured. The odds of receiving prophylaxis were greater in the females and males with three or more infections compared to the patients with only two infections. Estrogen prophylaxis was initiated at a higher rate in females aged 45-63 with two infections than the females with three or more infections. Prescription prophylaxis in females and males with recurrent urinary tract infections differs between those meeting and exceeding the minimum frequency threshold.

Methenamine is as effective as antibiotics at preventing urinary tract infections

The studyHarding C, Mossop H, Homer T, et al. Alternative to prophylactic antibiotics for the treatment of recurrent urinary tract infections in women: multicentre, open label, randomised, non-inferiority trial. BMJ 2022;376:e068229.To read the full NIHR Alert, go to: https://evidence.nihr.ac.uk/alert/methenamine-as-good-as-antibiotics-preventing-urinary-tract-infections/.

Management of urinary tract infections in the era of antimicrobial resistance

Urinary tract infections (UTIs) are among the most common infections globally, imposing a substantial personal and economic burden on individuals and health resources. Despite international health concerns and sustained public awareness campaigns about the emergence of resistant microorganisms through the inappropriate therapeutic use of antimicrobial agents, the problem of antimicrobial resistance (AMR) is worsening, and AMR in UTIs represents a critical global healthcare issue. This narrative review summarizes evidence-based scientific material, recommendations from the current medical literature, and the latest clinical guidelines on antibiotic and antibiotic-sparing strategies for managing urological infections, including practical approaches to improve the management of patients with acute and recurrent UTIs (rUTIs) in routine clinical practice. Novel emerging therapies and prophylaxis options are described as potential alternatives to overcome the abuse and overuse of antibiotics and the practical application of the guideline recommendations and issues relating to best practice in managing UTIs.

Methenamine hippurate to prevent recurrent urinary tract infections in older women: protocol for a randomised, placebo-controlled trial (ImpresU)

INTRODUCTION

Methenamine hippurate is a urinary antiseptic used as preventive treatment for recurrent urinary tract infections (UTIs) in some Scandinavian countries. However, the scientific evidence for the preventive effect and safety for longer-term use is limited. The aim of this study is to assess whether methenamine hippurate can reduce the incidence of UTIs in older women with recurrent UTIs.

METHODS AND ANALYSIS

The ImpresU consortium is a collaboration between Norway, Sweden, Poland and the Netherlands. The study is a randomised, controlled, triple-blind phase IV clinical trial. Women ≥70 years with recurrent UTIs are screened for eligibility in a general practice setting. We aim to include 400 women in total, with 100 recruited from each collaborating country. The participants are randomised to treatment with methenamine hippurate 1 g or placebo tablets two times per day for a treatment period of 6 months, followed by a drug-free follow-up period of 6 months. The primary outcome is number of antibiotic treatments for UTIs during the treatment period. The secondary outcomes include number of antibiotic treatments for UTIs during the follow-up period and self-reported symptom of severity and duration of UTI episodes. Differences in complications between the treatment groups are measured as safety outcomes. We also aim to investigate whether strain characteristics or phylogenetic subgroups of Escherichia coli present in the urine culture at inclusion have a modifying effect on the outcomes.

ETHICS AND DISSEMINATION

Ethical approvals are obtained in all participating countries. The results will be communicated in peer-reviewed journals and at scientific conferences.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT04077580); EudraCT: 2018-002235-15.

Management of uncomplicated recurrent urinary tract infections

OBJECTIVES

To discuss optimal management of recurrent urinary tract infections (UTIs) in women. About every second woman experiences at least one UTI in her lifetime, of those 30% experience another UTI, and 3% further recurrences. Especially young healthy women without underlying anatomical deficiencies suffer from recurrent UTIs (rUTI), which are associated with significant morbidity and reduction in quality of life.

METHODS

This is a narrative review, investigating publications dealing with recurrent UTI in women. Risk factors and options for management are discussed.

RESULTS

The increased susceptibility of women to rUTI is based on the female anatomy in addition to behavioural, genetic, and urological factors. However, why some women are more likely than others to develop and maintain rUTI remains to be clarified. Invasive characteristics of certain uropathogenic Escherichia coli that are able to form extra- and intracellular biofilms and may therefore cause delayed release of bacteria into the bladder, may play a role in this setting. Treatment recommendations for an acute episode of rUTI do not differ from those for isolated episodes. Given the nature of rUTI, different prophylactic approaches also play an important role. Women with rUTI should first be counselled to use non-antibiotic strategies including behavioural changes, anti-adhesive treatments, antiseptics, and immunomodulation, before antibiotic prophylaxis is considered. In addition to the traditional treatment and prophylactic therapies, new experimental strategies are emerging and show promising effects, such as faecal microbiota transfer (FMT), a treatment option that transfers microorganisms and metabolites of a healthy donor's faecal matter to patients using oral capsules, enemas, or endoscopy. Initial findings suggest that FMT might be a promising treatment approach to interrupt the cycle of rUTI. Furthermore, bacteriophages, infecting and replicating in bacteria, have been clinically trialled for UTIs.

CONCLUSION

Due to the limitation of available data, novel treatment options require further clinical research to objectify the potential in treating bacterial infections, particularly UTIs.