Host defense mechanisms in urinary tract infections

Urinary Tract Infection Diagnostic and Management Considerations in People with Spinal Cord Injury and Neurogenic Bladder

Urinary tract infections (UTIs) are common complications in people with neurogenic bladder. Prevention, diagnosis, and treatment are challenging for several reasons, including a high prevalence of asymptomatic bacteriuria and catheter use, frequent ambiguous nonlocalizing signs and symptoms, increased risk for complications and difficult-to-treat pathogens, and a lack of effective preventative methods. Current research aims to improve elicitation and evaluation of signs and symptoms, implement algorithms to avoid urine cultures in asymptomatic patients and use appropriate antibiotics for UTI, and identify novel effective prevention methods.

Etiology, presentation and management of urinary tract infections in multiple sclerosis patients: A review of the current literature

Urinary tract infections (UTIs) present a formidable challenge in the care of individuals affected by multiple sclerosis (MS). Lower urinary tract dysfunction is a prevalent issue among MS patients, predisposing them to an elevated risk of UTIs. When left untreated, UTIs can further exacerbate the already compromised quality of life in individuals with MS. The diagnosis and management of UTIs in MS patients necessitate a careful clinical evaluation. The objective of this review is to delineate preventive strategies and current and developing therapeutic approaches for preventing and treating UTIs associated with urinary dysfunction, catheterization, and upper urinary tract infections in patients with MS. Effectively addressing UTIs and urinary tract dysfunction in individuals with multiple sclerosis calls for a comprehensive, interdisciplinary approach.

Epidemiology, definition and treatment of complicated urinary tract infections

UTIs are amongst the most frequent bacterial infections. However, the clinical phenotypes of UTI are heterogeneous and range from rather benign, uncomplicated infections to complicated UTIs (cUTIs), pyelonephritis and severe urosepsis. Stratification of patients with UTIs is, therefore, important. Several classification systems exist for the description and classification of UTIs, with the common rationale that cUTIs have a higher risk of recurrence or chronification, progression or severe outcome than uncomplicated UTIs. The pathophysiology and treatment of cUTIs and pyelonephritis are driven more by host factors than by pathogen attributes. cUTIs and pyelonephritis are associated with high antimicrobial resistance rates among causative pathogens. However, antimicrobial resistance rates can differ substantially, depending on the population being studied and whether the data being analysed are from surveillance studies, registry data or interventional studies, in which specific inclusion and exclusion criteria are used for patient selection. For example, antibiotic resistance rates are higher in patients with urosepsis than in those with less severe infections. Thus, treatment outcomes differ substantially among studies, ranging from 50% to almost 100% clearance of infection, depending on the patient population analysed, the UTI entities included and the primary outcome of the study. Pyelonephritis and cUTIs have emerged as infection models for the study of novel antibiotics, including extensive investigation of novel substances active against Gram-negative bacteria.

Characterizing Patients with Recurrent Urinary Tract Infections in Vesicoureteral Reflux: A Pilot Study of the Urinary Proteome

Recurrent urinary tract infections (UTIs) pose a significant burden on the health care system. Underlying mechanisms predisposing children to UTIs and associated changes in the urinary proteome are not well understood. We aimed to investigate the urinary proteome of a subset of children who have vesicoureteral reflux (VUR) and recurrent UTIs because of their risk of developing infection-related renal damage. Improving diagnostic modalities to identify UTI risk factors would significantly alter the clinical management of children with VUR. We profiled the urinary proteomes of 22 VUR patients with low grade VUR (1-3 out of 5), a history of recurrent UTIs, and renal scarring, comparing them to those obtained from 22 age-matched controls. Urinary proteins were analyzed by mass spectrometry followed by protein quantitation based on spectral counting. Of the 2,551 proteins identified across both cohorts, 964 were robustly quantified, as defined by meeting criteria with spectral count (SC) ≥2 in at least 7 patients in either VUR or control cohort. Eighty proteins had differential expression between the two cohorts, with 44 proteins significantly up-regulated and 36 downregulated (q <0.075, FC ≥1.2). Urinary proteins involved in inflammation, acute phase response (APR), modulation of extracellular matrix (ECM), and carbohydrate metabolism were altered among the study cohort.

Urinary tract infections in patients with neurogenic bladder

Urinary tract infections (UTIs) in patients with neurogenic bladder are a major public health issue due to their high incidence and major consequences. Despite their frequency and potential severity, their physiopathology and management are poorly known. We provide a narrative literature review on the epidemiology, physiopathology, diagnostic criteria, microbiology, antimicrobial management, and prevention. UTIs among patients with neurogenic bladder are associated with high morbidity and healthcare utilization. Risk factors for UTI among this population are: indwelling catheter, urinary stasis, high bladder pressure, and bladder stones. Their diagnosis is a major challenge as clinical signs are often non-specific and rare. A urinary sample should be analyzed in appropriate conditions before any antibiotic prescription. According to most guidelines, a bacterial threshold≥103CFU/ml associated with symptoms is acceptable to define UTI in patients with neurogenic bladder. The management of acute symptomatic UTI is not evidence-based. A management with a single agent and a short antibiotic treatment of 10 days or less seems effective. Antibiotic selection should be based on the patient's resistance patterns. Asymptomatic bacteriuria should not be treated to avoid the emergence of bacterial resistance. Regarding preventive measures, use of clean intermittent catheterization, intravesical botulinum toxin injection, and prevention using antibiotic cycling are effective. Bacterial interference is promising but randomized controlled trials are needed. Large ongoing cohorts and randomized controlled trials should soon provide more evidence-based data.

Identification of inhibitor against H. pylori HtrA protease using structure-based virtual screening and molecular dynamics simulations approaches

The HtrA protease of Helicobacter pylori, which efficiently colonizes at the gastric epithelial of host cells, disrupts the mucosal integrity of E-cadherin and spreads inflammatory diseases including gastric cancer by cleaving the cell-cell adhesion of the host. The lack of knowledge on the molecular diversity, structural and functional behavior of HpHtrA necessitated the present study to explore its inhibition mechanism. At first, the similarity of HpHtrA with other gastro-intestinal pathogenic HtrA bacteria and its remote relationship with the Human HtrA homologs were ensured by the phylogenetic analysis and hence was identified as a novel therapeutic target for further design of inhibitors. The three dimensional structure of HpHtrA was modeled and simulated to achieve its stable conformation and was used as a receptor to screen for the possible lead compound through virtual screening (using ∼ 1.3 million compounds). Molecular dynamics simulations followed by the binding energy analysis revealed the affinity of the compound 300040 in forming a stable complex with HpHtrA and thereby revealed its potent role in inhibiting HpHtrA. It is also worthy to mention that, structurally, the ligand binding at the catalytic site of HpHtrA is mainly facilitated by the significant dynamics of L2 loop. Based on the present study, the hydroxyl-piperidine with 4-aminopiperidine scaffold is proposed to be one of the best possible lead compounds for the inhibition of H. pylori.

Urinary Tract Infections in Immunocompromised Patients with Diabetes, Chronic Kidney Disease, and Kidney Transplant

CONTEXT

This paper provides a brief overview of urinary tract infections (UTIs) in immunocompromised patients from the perspective of a practicing urologist.

OBJECTIVE

The primary objective was to provide an update on UTIs in immunocompromised patients. Diabetes mellitus (DM), chronic kidney disease, and kidney transplant (KT) are the most common clinical cases encountered by urologists. Diagnosis, management, and future research needs are summarised.

EVIDENCE ACQUISITION

We conducted a nonsystematic review of the literature. A comprehensive search of the PubMed database between 1996 and 2016 was performed.

EVIDENCE SYNTHESIS

Clinical diagnosis of UTIs in immunocompromised patients is challenging. Causative pathogens in DM are slightly different to those in the general population, but without any difference in resistance profiles. Keeping serum glucose under control is the most important preventive measure. The prevalence of UTIs in patients with autosomal dominant polycystic kidney disease (ADPKD) is 21-75%. Lipophilic antibiotics are effective in the treatment of infected cysts, albeit with a trend for lower effectiveness due to increasing resistance rates. UTIs are the most common infections in KT recipients, with a reported rate of 45-72%. Diagnostic challenges exist for both ADPKD and KT patients who develop UTIs. Treatment of UTIs should be tailored according to individual patient characteristics and the severity classification framework suggested by the European Society of Infections in Urology.

CONCLUSIONS

The underlying pathophysiology of UTIs in immunocompromised patients is not well known, which limits UTI management, including early diagnosis, treatment, and prevention. Future research to identify patients at higher risk of UTIs is necessary.

PATIENT SUMMARY

In this report we looked at patients with a weakened immune system who are more likely to develop a urine infection. We focused on the patient groups most commonly encountered in a urology setting. We found that these patients have a higher risk of urinary infection, but the signs of infection may be different to those in the general population. Early diagnosis is imperative in this group. Further research on early diagnosis and better individualised management strategies are necessary.

Urinary tract infections in multiple sclerosis

Background:

Urinary tract infections (UTIs) are commonly reported by people with multiple sclerosis (PwMS) and significantly impact quality of life.

Objective:

To provide an overview of the problem of UTIs in PwMS and offer a practical approach for the diagnosis and management.

Methods:

A review of the literature through a Pubmed search up to October 2015 was performed using the following keywords: multiple sclerosis, neurogenic bladder, urinary tract infections, relapse, dipsticks, culture, recurrent and prevention.

Results:

Noteworthy topics include the definition of a confirmed symptomatic UTI as a positive urine culture defined by >105 colony-forming units (CFU)/mL or >104 CFU/mL if a urethral catheter urine sample is taken, or any count of bacteria in a suprapubic bladder puncture specimen, both in addition to symptoms including fever, pain, changes in lower urinary tract symptoms or neurological status. Urinalysis is useful to exclude a UTI; however, on its own is insufficient to confirm a UTI, for which urine culture is required. Experts advise asymptomatic UTIs should not be treated except in the context of an acute relapse. From international guidelines, there is no validated strategy to prevent recurrent UTIs in PwMS.

Conclusion:

This review provides an overview of the diagnosis, treatment and prevention of UTIs in the setting of multiple sclerosis (MS).

Urinary tract infection in the neurogenic bladder

There is a high incidence of urinary tract infection (UTI) in patients with neurogenic lower urinary tract function. This results in significant morbidity and health care utilization. Multiple well-established risk factors unique to a neurogenic bladder (NB) exist while others require ongoing investigation. It is important for care providers to have a good understanding of the different structural, physiological, immunological and catheter-related risk factors so that they may be modified when possible. Diagnosis remains complicated. Appropriate specimen collection is of paramount importance and a UTI cannot be diagnosed based on urinalysis or clinical presentation alone. A culture result with a bacterial concentration of ≥10(3) CFU/mL in combination with symptoms represents an acceptable definition for UTI diagnosis in NB patients. Cystoscopy, ultrasound and urodynamics should be utilized for the evaluation of recurrent infections in NB patients. An acute, symptomatic UTI should be treated with antibiotics for 5-14 days depending on the severity of the presentation. Antibiotic selection should be based on local and patient-based resistance patterns and the spectrum should be as narrow as possible if there are no concerns regarding urosepsis. Asymptomatic bacteriuria (AB) should not be treated because of rising resistance patterns and lack of clinical efficacy. The most important preventative measures include closed catheter drainage in patients with an indwelling catheter and the use of clean intermittent catheterization (CIC) over other methods of bladder management if possible. The use of hydrophilic or impregnated catheters is not recommended. Intravesical Botox, bacterial interference and sacral neuromodulation show significant promise for the prevention of UTIs in higher risk NB patients and future, multi-center, randomized controlled trials are required.

Integrated Pathophysiology of Pyelonephritis

Pyelonephritis represents a subset of urinary tract infections that occur from bacteria ascending from the lower to the upper reaches of the genitourinary system, such as the kidney. The renal system contains a range of hydrodynamically and immunologically challenging, interconnected microenvironments where the invading pathogen may populate during the course of the infection. The situation at the infection foci changes dynamically, vacillating between bacterial colonization and clearance, to which the outcome is a summation of all host-pathogen elements in play. A selection of important determinants includes factors of microbial origin, effects of eukaryotic cell signaling, physiological facets of the infected organ, and signals from distal organs. Improved understanding of the multifactorial aspects of molecular pathogenesis of infection requires intravital, cross-disciplinary approaches with high spatio-temporal resolution. The advancement of such approaches promises to eventually provide a comprehensive understanding of the integrated pathophysiology of pyelonephritis.

Factors implicated in pathogenesis of urinary tract infections in neurogenic bladders: some revered, few forgotten, others ignored

AIMS

To comprehensively review factors implicated in the pathogenesis of urinary tract infection in patients with neurogenic bladders, and to stimulate research, especially in the somewhat ignored and forgotten areas of this important clinical subject.

METHODS

In addition to reviewing relevant articles on pubmed, some important articles from previous times which were not available online were also procured and reviewed.

RESULTS

Intrinsic defence mechanisms including protective flora, anti-adherence mechanisms, urothelial, and immunological responses to bacterial binding and the blood supply to the urinary bladder may be impaired in patients with neurogenic bladders. Further, bacterial washout mechanisms may be compromised as a result of inefficient voiding, reflux, and altered hydrokinetics. Finally, catheterization itself contributes to urinary tract infection in patients with neurogenic bladders.

CONCLUSIONS

In order to address the issue of urinary tract infection in patients with neurogenic bladders, multiple factors need to be looked into and corrected. Further research is required, especially in the area of compromised host defence mechanisms. An individualized approach, which attempts to optimize each factor is recommended.

Tamm-Horsfall protein: a multilayered defence molecule against urinary tract infection

Urinary tract infection (UTI) is the most common nonepidemic bacterial infection in humans, representing a constant danger for the host. Both innate and adaptive components of the immune system as well as stromal cells including bladder epithelium are involved in the prevention and clearance of UTI. However, the particular properties of the urogenital tract, which does not comprise typical physical barriers like a mucus or ciliated epithelium, necessitate soluble mediators with potent immunomodulatory capabilities. One candidate molecule capable of both mediating direct antimicrobial activity and alerting immune cells is the evolutionary conserved Tamm-Horsfall protein (THP). Tamm-Horsfall protein is exclusively produced by the kidney in the distal loop of Henle; however, its definite physiological function remains elusive. Mounting evidence indicates that beyond a mere direct antimicrobial activity, THP exerts potent immunoregulatory activity. Furthermore, the genetic ablation of the THP gene leads to severe infection and lethal pyelonephritis in an experimental model of UTI. Recent data are provided demonstrating that THP links the innate immune response with specific THP-directed cell-mediated immunity. In light of these novel findings we discuss the particular role of THP as a specialized defence molecule. We propose an integrated model of protective mechanisms against UTI where THP acts by two principle nonmutually exclusive mechanisms involving the capture of potentially dangerous microbes and the ability of this peculiar glycoprotein to induce robust protective immune responses against uropathogenic bacteria.

Urinary tract infections and genitourinary abnormalities in Cameroonian men

OBJECTIVE

To compare the prevalence of genitourinary abnormalities in men diagnosed with urinary tract infection (UTI) in a Cameroonian hospital and those without.

PATIENTS AND METHODS

Consecutive adult men aged 18-75 years, whose midstream urine samples were received for microscopy, culture and sensitivity at the microbiology laboratory of the Yaounde University Teaching Hospital, Cameroon, constituted the study population. Genitourinary abnormalities were diagnosed from history, physical examination, abdominal and transrectal ultrasonography, plain abdominal X-ray, and if indicated urethrocystoscopy and biopsy.

RESULTS

Of the 206 patients who qualified, 179 completed the study and 63 (35.2%) were found to have UTI. A total of 41 (65.1%) patients with UTI (mean age 69.2 years) had at least one genitourinary abnormality, compared to 13 (11.2%) of those without UTI (mean age 61.9 years) (P < 0.001). The age-adjusted prevalence of genitourinary abnormalities was 59.4% in the UTI group and 12.1% in the non-UTI group (P < 0.001). The most frequent genitourinary abnormality in men with UTI was benign prostatic enlargement, followed by urethral stricture. The crude odds ratio (95% confidence intervals) for UTI associated with genitourinary abnormality was 14.77 (6.80-32.05), and the adjusted odds ratio 11.51 (7.08-29.46).

CONCLUSION

Urological evaluation of Cameroonian men with UTI, using simple history taking, physical examination, ultrasound examination and plain abdominal X-ray, could have significant clinical benefits in this tropical African region.