Unique ability of the Proteus mirabilis capsule to enhance mineral growth in infectious urinary calculi

Understanding the role of zinc ions on struvite nucleation and growth in the context of infection urinary stones

Taking into account that in recent decades there has been an increase in the incidence of urinary stones, especially in highly developed countries, from a wide range of potentially harmful substances commonly available in such countries, we chose zinc for the research presented in this article, which is classified by some sources as a heavy metal. In this article, we present the results of research on the influence of Zn2+ ion on the nucleation and growth of struvite crystals-the main component of infection urinary stones. The tests were carried out in an artificial urine environment with and without the presence of Proteus mirabilis bacteria. In the latter case, the activity of bacterial urease was simulated chemically, by systematic addition of an aqueous ammonia solution. The obtained results indicate that Zn2+ ions compete with Mg2+ ions, which leads to the gradual replacement of Mg2+ ions in the struvite crystal lattice with Zn2+ ions to some extent. This means co-precipitation of Mg-struvite (MgNH4PO4·6H2O) and Znx-struvite (Mg1-xZnxNH4PO4·6H2O). Speciation analysis of chemical complexes showed that Znx-struvite precipitates at slightly lower pH values than Mg-struvite. This means that Zn2+ ions shift the nucleation point of crystalline solids towards a lower pH. Additionally, the conducted research shows that Zn2+ ions, in the range of tested concentrations, do not have a toxic effect on bacteria; on the contrary, it has a positive effect on cellular metabolism, enabling bacteria to develop better. It means that Zn2+ ions in artificial urine, in vitro, slightly increase the risk of developing infection urinary stones.

Investigating the impact of the genetic variant CXCR1 (rs2234671) in individuals with urinary tract infections

BACKGROUND

Urinary tract infections (UTIs) are currently posing a worldwide health concern by affecting millions of people. The genetic variant rs2234671 in the CXCR1-interleukin-8 receptor is closely related to a raised UTI risk.

OBJECTIVES

In this work, the impact of CXCR1 (rs2234671) on UTI individuals was examined.

METHODS

The demographic features of 30 recurrent UTI patients and 20 controls were thoroughly investigated. Bacterial isolation and identification were performed by the implementation of cultural and biochemical methods. DNA extraction, purification of all samples from both patients and healthy people, and IL-8 rs2234671 (C/G) SNP genotyping using T-ARMS-PCR were performed. The significance of the results was evaluated by carrying out a statistical analysis.

FINDINGS

The patient's average age was 34.63 ± 11.44 years, and controls averaged 30.30 ± 8.59 years (P= 0.156). No significant gender difference existed (P= 0.804). Escherichia coli (63.3%) was predominant, followed by Proteus mirabilis (26.7%), Enterococcus faecalis (23.3%), Klebsiella pneumoniae (10.0%), and Pseudomonas aeruginosa (20.0%). No significant association was found between bacterial species frequency, age, or sex. From the CXCR1 (rs2234671) frequency comparison, a higher GG genotype incidence in UTI patients than controls was extracted (26.7% vs. 15.0%), though not statistically significant. Risk analysis revealed that GG homozygous and C/G heterozygous genotypes were not UTI risk factors (OR = 2.47 and OR = 1.85, respectively). Moreover, the allele frequencies displayed no significant difference between the patients and controls (G allele: 66.7% vs. 66.7%; C allele: 33.3% vs. 33.3%).

MAIN CONCLUSIONS

Although no significant association between CXCR1 (rs2234671) and UTI was found, the GG genotype may point to the increasing probability of UTI risk. Additional research is required to confirm and expand these conclusions.

Spectrum of Bacterial Pathogens from Urinary Infections Associated with Struvite and Metabolic Stones

OBJECTIVE

The purposes of this multi-center study were to evaluate the rate of infection stones and to evaluate the urine cultures of patients with infection stones.

MATERIALS

Charts of adulpatients with urinary stones were reviewed and data on stone analyses and urine cultures were collected.

RESULTS

In total, 1204 renal stone formers (RSFs) from 10 countries were included (776 males, 428 females). Fifty-six patients (4.6%) had struvite stones. The highest frequency of struvite stones was observed in India (23%) and Pakistan (18%). Lower rates were reported in Canada (2%), China (3%), Argentina (3%), Iraq (3%), Italy (3.5%) and Poland (3%), and intermediate rates in Egypt (5.5%) and Bulgaria (5.4%). Urine cultures were retrieved from 508 patients. Patients with struvite stones had a positive culture in 64.3% of the samples and patients with other stones, in 26.7%. In struvite stones, the most common isolates were Escherichia coli (27.7%) and Proteus spp. (27.7%), followed by Klebsiella spp. (16.7%); in other types of stone, it was Escherichia coli (47.6%), followed by Gram-positive bacteria (14.0%) Conclusions: The struvite stone composition was associated with a urinary infection, although an infection was not demonstrable with a conventional midstream urine culture in about 30%.

The immune responses to different Uropathogens call individual interventions for bladder infection

Urinary tract infection (UTI) caused by uropathogens is the most common infectious disease and significantly affects all aspects of the quality of life of the patients. However, uropathogens are increasingly becoming antibiotic-resistant, which threatens the only effective treatment option available-antibiotic, resulting in higher medical costs, prolonged hospital stays, and increased mortality. Currently, people are turning their attention to the immune responses, hoping to find effective immunotherapeutic interventions which can be alternatives to the overuse of antibiotic drugs. Bladder infections are caused by the main nine uropathogens and the bladder executes different immune responses depending on the type of uropathogens. It is essential to understand the immune responses to diverse uropathogens in bladder infection for guiding the design and development of immunotherapeutic interventions. This review firstly sorts out and comparatively analyzes the immune responses to the main nine uropathogens in bladder infection, and summarizes their similarities and differences. Based on these immune responses, we innovatively propose that different microbial bladder infections should adopt corresponding immunomodulatory interventions, and the same immunomodulatory intervention can also be applied to diverse microbial infections if they share the same effective therapeutic targets.

Isolation and Characterization of Lytic Proteus Virus 309

Proteus mirabilis is frequently associated with complicated urinary tract infections (UTIs) and is the main cause of catheter-associated urinary tract infections (CAUTIs). Treatment of such infections is complicated and challenging due to the biofilm forming abilities of P. mirabilis. If neglected or mistreated, infections may lead to life-threating conditions such as cystitis, pyelonephritis, kidney failure, and bacteremia that may progress to urosepsis. Treatment with antibiotics, especially in cases of recurring and persistent infections, leads to the development of resistant strains. Recent insights into phage therapy and using phages to coat catheters have been evaluated with many studies showing promising results. Here, we describe a highly lytic bacteriophage, Proteus_virus_309 (41,740 bp), isolated from a wastewater treatment facility in Cape Town, South Africa. According to guidelines of the International Committee on Taxonomy of Viruses (ICTV), bacteriophage 309 is a species within the genus Novosibovirus. Similar to most members of the genus, bacteriophage 309 is strain-specific and lyse P. mirabilis in less than 20 min.

Novel Phage-Derived Depolymerase with Activity against Proteus mirabilis Biofilms

The adherence of Proteus mirabilis to the surface of urinary catheters leads to colonization and eventual blockage of the catheter lumen by unique crystalline biofilms produced by these opportunistic pathogens, making P. mirabilis one of the leading causes of catheter-associated urinary tract infections. The Proteus biofilms reduce efficiency of antibiotic-based treatment, which in turn increases the risk of antibiotic resistance development. Bacteriophages and their enzymes have recently become investigated as alternative treatment options. In this study, a novel Proteus bacteriophage (vB_PmiS_PM-CJR) was isolated from an environmental sample and fully characterized. The phage displayed depolymerase activity and the subsequent genome analysis revealed the presence of a pectate lyase domain in its tail spike protein. The protein was heterologously expressed and purified; the ability of the purified tail spike to degrade Proteus biofilms was tested. We showed that the application of the tail spike protein was able to reduce the adherence of bacterial biofilm to plastic pegs in a MBEC (minimum biofilm eradication concentration) assay and improve the survival of Galleria mellonella larvae infected with Proteus mirabilis. Our study is the first to successfully isolate and characterize a biofilm depolymerase from a Proteus phage, demonstrating the potential of this group of enzymes in treatment of Proteus infections.

Proteus mirabilis Biofilm: Development and Therapeutic Strategies

Proteus mirabilis is a Gram negative bacterium that is a frequent cause of catheter-associated urinary tract infections (CAUTIs). Its ability to cause such infections is mostly related to the formation of biofilms on catheter surfaces. In order to form biofilms, P. mirabilis expresses a number of virulence factors. Such factors may include adhesion proteins, quorum sensing molecules, lipopolysaccharides, efflux pumps, and urease enzyme. A unique feature of P. mirabilis biofilms that build up on catheter surfaces is their crystalline nature owing to their ureolytic biomineralization. This leads to catheter encrustation and blockage and, in most cases, is accompanied by urine retention and ascending UTIs. Bacteria embedded in crystalline biofilms become highly resistant to conventional antimicrobials as well as the immune system. Being refractory to antimicrobial treatment, alternative approaches for eradicating P. mirabilis biofilms have been sought by many studies. The current review focuses on the mechanism by which P. mirabilis biofilms are formed, and a state of the art update on preventing biofilm formation and reduction of mature biofilms. These treatment approaches include natural, and synthetic compounds targeting virulence factors and quorum sensing, beside other strategies that include carrier-mediated diffusion of antimicrobials into biofilm matrix. Bacteriophage therapy has also shown successful results in vitro for combating P. mirabilis biofilms either merely through their lytic effect or by acting as facilitators for antimicrobials diffusion.

Potentially Probiotic Lactobacillus Strains Derived from Food Intensify Crystallization Caused by Proteus mirabilis in Urine

Proteus mirabilis is a common cause of infectious urolithiasis. The first stage in the formation of urinary stones is the crystallization of mineral salts in the urine induced by urease activity of this microorganism. Lactobacillus spp. are an important component of the human microbiota and in large quantities occur in foods. Regardless of their origin, those with probiotic properties are proposed as an alternative to antibiotic therapy in the treatment of urinary tract infections. The aim of the study was to check the effect of selected Lactobacillus plantarum and Lactobacillus brevis strains on crystallization caused by P. mirabilis in an in vitro experiment. It has been confirmed that selected Lactobacillus strains have antibacterial properties and colonize the urinary tract epithelium. During 24-h incubation of bacterial cultures, containing P. mirabilis and individual Lactobacillus strains, in synthetic urine, bacterial viability (CFU/mL), pH, and crystallization were determined. Crystallization was assessed quantitatively and qualitatively using AAS and XRD techniques as well as phase-contrast microscopy. It has been shown that in the presence of selected Lactobacillus strains, the culture pH increases faster, especially after 8 h of incubation, compared with the pure P. mirabilis culture. An increase in pH reduces the viability of P. mirabilis; however, in the presence of some lactobacilli, the uropathogen grows more intensively. The presence of Lactobacillus also affected crystallization by increasing its intensity, and the resulting crystals were larger in size. Tested L. plantarum and L. brevis strains could therefore accelerate the formation of urinary stones and development of infection.

SEM-EDX linear scanning: a new tool for morpho-compositional analysis of growth bands in urinary stones

The genesis and growth of calculi are imprinted in their structure, so the pathogenesis of lithiasis could potentially be read via proper analytical techniques. In this study, electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) is used to obtain a description of the morphology and compositional structure of a single bladder stone. This technique establishes the chemical and crystalline architecture of the urolith to assess the effect of the chemical environment on its growth. Scanning electron microscopy-backscattered electrons (SEM-BSE) images clearly show that the stone has a multilayered structure. These layers and Liesegang ring-like structures are characterized by one predominant chemical component but also by slighter compositional changes. The mean crystalline components are determined by X-ray diffraction (DRX), infrared spectroscopy (FT-IR), and Raman analysis (RMN). Elemental analysis along a radial trajectory of the calculus by EDX linear scanning (EDX-LS) also reveals the compositional structure of the layers and the spatial distribution of the main chemical components. EDX-LS data processing reveals concentration profiles that clearly show morpho-compositional growth bands, which correspond to precipitation waves and urinary concentration peaks. The width of the growth bands is independent of the radial position, layer, and element analyzed. We conclude that the bands observed are a consequence of slight changes in the biochemical composition of the urine and consequently reflect a short-term biological cycle of the renal system. This non-specific growth rate suggests that stone formation is a kinetically controlled phenomenon in which promoters of crystal cluster aggregation may have played a key role.

Aggregation of poorly crystalline and amorphous components of infectious urinary stones is mediated by bacterial lipopolysaccharide

Poorly crystalline and amorphous precipitate (PCaAP) is one of the components of the so-called infectious urinary stones, which are the result of the activity of urease-producing microorganisms, mainly from the Proteus species, in particular Proteus mirabilis. The main component of this kind of stones is crystalline struvite (MgNH4PO4∙6H2O). Bacteria can build into the structure of the urinary stone and, in this way, they are one of the components of the urinary stone. From these three components - PCaAP, struvite and Proteus mirabilis - PCaAP exhibits the greatest ability to aggregate. The present study focuses on the aggregation of PCaAP. In particular, an influence of lipopolysaccharide (LPS) isolated from Proteus mirabilis on aggregation of PCaAP is presented. An aggregation of PCaAP is characterized by cross-sectional area of aggregates and zeta potential. The results demonstrate that, in artificial urine, the influence of freely suspended LPS on aggregation of PCaAP depends on the concentrations of LPS. Small concentrations of freely suspended LPS enhance the aggregation of PCaAP compared to the control test. For high concentrations of freely suspended LPS the formation of aggregates of PCaAP is inhibited. LPS, which is not freely suspended, but covers polystyrene latex beads, has no such properties. The investigations provide evidence for the importance of biological regulation in the PCaAP aggregation process.

An In Vitro Bladder Model for Studying Catheter-Associated Urinary Tract Infection and Associated Analysis of Biofilms

Urethral catheters are among the most widely used medical devices, applied to manage a wide range of conditions in hospital, community, and care home settings. In long-term catheterized individuals, infection with Proteus mirabilis frequently complicates the care of patients owing to formation of extensive crystalline biofilms. Here we describe the use of an in vitro bladder model of the catheterized urinary tract and associated analyses to study P. mirabilis crystalline biofilm formation. The model originally described by Stickler et al. (1999, 310:494-501, Methods Enzymol) replicates a complete sterile closed drainage system as used in clinical practice, and permits formation of biofilms directly on catheters under conditions representative of those encountered in vivo. Models may be used to replicate either established infection or early stage colonization, and we describe a range of associated methods for quantification and visualization of biofilms formed on catheters. These methods are also easily adapted to study catheter-associated biofilm formation by other urinary tract pathogens.

An antimicrobial impregnated urinary catheter that reduces mineral encrustation and prevents colonisation by multi-drug resistant organisms for up to 12 weeks

Two major complications of indwelling urinary catheterisation include infection and mineral encrustation of the catheter. Our antimicrobial urinary catheter (AUC) impregnated with rifampicin, triclosan, and sparfloxacin has demonstrated long-term protective activity against major uropathogens. This study aimed to firstly assess the ability of the AUC to resist mineral encrustation in the presence and absence of bacteria. Secondly, it aimed to investigate the AUC's anti-biofilm activity against multi-drug resistant organisms. There was no difference in surface roughness between AUC and control segments. In a static and a perfusion model, phosphate deposition was significantly reduced on AUCs challenged with P. mirabilis. Furthermore, none of the AUCs blocked during the 28 day test period, unlike controls. The AUC prevented colonisation by methicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, extended-spectrum beta-lactamase producing E. coli, and carbapenemase-producing E. coli for 12 consecutive weekly challenges. All three drugs impregnated into the catheter continued to exert protective activity throughout 12 weeks of constant perfusion. The drugs appear to migrate into the crystalline biofilm to continually protect against bacteria not it direct contact with the catheter surface. In conclusion, the AUC reduces mineral encrustation and may increase time to blockage in the presence of P. mirabilis, and does not predispose to mineral deposition under other conditions. It also offers 12 weeks of protection against multi-drug resistant bacteria. STATEMENT OF SIGNIFICANCE: Infection and associated mineral encrustation of urinary catheters are two serious complications of indwelling urinary catheters. Others have attempted to address this through various technologies such as coatings, dips, and surface modifications to prevent infection and/or encrustation. However, all current 'anti-infective' urinary catheter technologies are limited to short-term use. Some patients with spinal injuries, multiple sclerosis, stroke survivors and others use long-term catheters for 4-12 weeks at a time with multiple catheterisation possibly throughout the rest of their life. We present a urinary catheter for long-term use that is impregnated with three antimicrobials by a patient-protected process to prevent infection and encrustation for up to 12 weeks, the maximum lifetime of a long-term catheter before it is changed.

Bacterial biofilm formation on indwelling urethral catheters

Urethral catheters are the most commonly deployed medical devices and used to manage a wide range of conditions in both hospital and community care settings. The use of long-term catheterization, where the catheter remains in place for a period >28 days remains common, and the care of these patients is often undermined by the acquisition of infections and formation of biofilms on catheter surfaces. Particular problems arise from colonization with urease-producing species such as Proteus mirabilis, which form unusual crystalline biofilms that encrust catheter surfaces and block urine flow. Encrustation and blockage often lead to a range of serious clinical complications and emergency hospital referrals in long-term catheterized patients. Here we review current understanding of bacterial biofilm formation on urethral catheters, with a focus on crystalline biofilm formation by P. mirabilis, as well as approaches that may be used to control biofilm formation on these devices. SIGNIFICANCE AND IMPACT OF THE STUDY: Urinary catheters are the most commonly used medical devices in many healthcare systems, but their use predisposes to infection and provide ideal conditions for bacterial biofilm formation. Patients managed by long-term urethral catheterization are particularly vulnerable to biofilm-related infections, with crystalline biofilm formation by urease producing species frequently leading to catheter blockage and other serious clinical complications. This review considers current knowledge regarding biofilm formation on urethral catheters, and possible strategies for their control.

Influence of various uropathogens on crystallization of urine mineral components caused by Proteus mirabilis

Infectious urolithiasis is a consequence of long-standing urinary tract infections with urease-positive bacteria, especially Proteus spp. However, because of the often mixed nature of urinary tract infections, in the case of urinary stones formation, several species of bacteria may be involved in the process. The purpose of the study was to determine the impact of the bacterial species: Escherichia coli, Klebsiella pneumoniae, Providencia stuartii, Pseudomonas aeruginosa and Staphylococcus aureus on the crystallization caused by Proteus mirabilis. The studies were conducted in synthetic urine with the addition of P. mirabilis and a representative of another species. During the experiments the viability of bacteria, pH, presence and morphology of crystals, and the intensity of crystallization were assessed. Crystallization of calcium and magnesium phosphates occurred in all investigated configurations. However, there were differences observed in the course and intensity of crystallization between the mixed culture and the P. mirabilis culture. Although most intense crystallization took place in the pure culture of P. mirabilis it was also demonstrated that the presence of other uropathogens increased the survival of P. mirabilis. This synergistic effect could be responsible for the persistence and recurrence of urolithiasis in the urinary tract.

Pathogenesis of Proteus mirabilis Infection

Proteus mirabilis, a Gram-negative rod-shaped bacterium most noted for its swarming motility and urease activity, frequently causes catheter-associated urinary tract infections (CAUTIs) that are often polymicrobial. These infections may be accompanied by urolithiasis, the development of bladder or kidney stones due to alkalinization of urine from urease-catalyzed urea hydrolysis. Adherence of the bacterium to epithelial and catheter surfaces is mediated by 17 different fimbriae, most notably MR/P fimbriae. Repressors of motility are often encoded by these fimbrial operons. Motility is mediated by flagella encoded on a single contiguous 54-kb chromosomal sequence. On agar plates, P. mirabilis undergoes a morphological conversion to a filamentous swarmer cell expressing hundreds of flagella. When swarms from different strains meet, a line of demarcation, a "Dienes line," develops due to the killing action of each strain's type VI secretion system. During infection, histological damage is caused by cytotoxins including hemolysin and a variety of proteases, some autotransported. The pathogenesis of infection, including assessment of individual genes or global screens for virulence or fitness factors has been assessed in murine models of ascending urinary tract infections or CAUTIs using both single-species and polymicrobial models. Global gene expression studies performed in culture and in the murine model have revealed the unique metabolism of this bacterium. Vaccines, using MR/P fimbria and its adhesin, MrpH, have been shown to be efficacious in the murine model. A comprehensive review of factors associated with urinary tract infection is presented, encompassing both historical perspectives and current advances.

Fluoxetine and thioridazine inhibit efflux and attenuate crystalline biofilm formation by Proteus mirabilis

Proteus mirabilis forms extensive crystalline biofilms on indwelling urethral catheters that block urine flow and lead to serious clinical complications. The Bcr/CflA efflux system has previously been identified as important for development of P. mirabilis crystalline biofilms, highlighting the potential for efflux pump inhibitors (EPIs) to control catheter blockage. Here we evaluate the potential for drugs already used in human medicine (fluoxetine and thioridazine) to act as EPIs in P. mirabilis, and control crystalline biofilm formation. Both fluoxetine and thioridazine inhibited efflux in P. mirabilis, and molecular modelling predicted both drugs interact strongly with the biofilm-associated Bcr/CflA efflux system. Both EPIs were also found to significantly reduce the rate of P. mirabilis crystalline biofilm formation on catheters, and increase the time taken for catheters to block. Swimming and swarming motilies in P. mirabilis were also significantly reduced by both EPIs. The impact of these drugs on catheter biofilm formation by other uropathogens (Escherichia coli, Pseudomonas aeruginosa) was also explored, and thioridazine was shown to also inhibit biofilm formation in these species. Therefore, repurposing of existing drugs with EPI activity could be a promising approach to control catheter blockage, or biofilm formation on other medical devices.

Stones in special situations

There are several special situations in which urinary lithiasis presents management challenges to the urologist. An in-depth knowledge of the pathophysiology, unique anatomy, and treatment options is crucial in order to maintain good health in these patients. In this review, we summarize the current literature on the management of the following scenarios: bladder stones, stones in bowel disease, during pregnancy, in association with renal anomalies, with skeletal deformities, in urinary diversions, and in children.

Proteus mirabilis and Urinary Tract Infections

Proteus mirabilis is a Gram-negative bacterium and is well known for its ability to robustly swarm across surfaces in a striking bulls'-eye pattern. Clinically, this organism is most frequently a pathogen of the urinary tract, particularly in patients undergoing long-term catheterization. This review covers P. mirabilis with a focus on urinary tract infections (UTI), including disease models, vaccine development efforts, and clinical perspectives. Flagella-mediated motility, both swimming and swarming, is a central facet of this organism. The regulation of this complex process and its contribution to virulence is discussed, along with the type VI-secretion system-dependent intra-strain competition, which occurs during swarming. P. mirabilis uses a diverse set of virulence factors to access and colonize the host urinary tract, including urease and stone formation, fimbriae and other adhesins, iron and zinc acquisition, proteases and toxins, biofilm formation, and regulation of pathogenesis. While significant advances in this field have been made, challenges remain to combatting complicated UTI and deciphering P. mirabilis pathogenesis.

Bacteriophage Can Prevent Encrustation and Blockage of Urinary Catheters by Proteus mirabilis

Proteus mirabilis forms dense crystalline biofilms on catheter surfaces that occlude urine flow, leading to serious clinical complications in long-term catheterized patients, but there are presently no truly effective approaches to control catheter blockage by this organism. This study evaluated the potential for bacteriophage therapy to control P. mirabilis infection and prevent catheter blockage. Representative in vitro models of the catheterized urinary tract, simulating a complete closed drainage system as used in clinical practice, were employed to evaluate the performance of phage therapy in preventing blockage. Models mimicking either an established infection or early colonization of the catheterized urinary tract were treated with a single dose of a 3-phage cocktail, and the impact on time taken for catheters to block, as well as levels of crystalline biofilm formation, was measured. In models of established infection, phage treatment significantly increased time taken for catheters to block (∼ 3-fold) compared to untreated controls. However, in models simulating early-stage infection, phage treatment eradicated P. mirabilis and prevented blockage entirely. Analysis of catheters from models of established infection 10 h after phage application demonstrated that phage significantly reduced crystalline biofilm formation but did not significantly reduce the level of planktonic cells in the residual bladder urine. Taken together, these results show that bacteriophage constitute a promising strategy for the prevention of catheter blockage but that methods to deliver phage in sufficient numbers and within a key therapeutic window (early infection) will also be important to the successful application of phage to this problem.

Urinary tract infections: epidemiology, mechanisms of infection and treatment options

Urinary tract infections (UTIs) are a severe public health problem and are caused by a range of pathogens, but most commonly by Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis and Staphylococcus saprophyticus. High recurrence rates and increasing antimicrobial resistance among uropathogens threaten to greatly increase the economic burden of these infections. In this Review, we discuss how basic science studies are elucidating the molecular details of the crosstalk that occurs at the host-pathogen interface, as well as the consequences of these interactions for the pathophysiology of UTIs. We also describe current efforts to translate this knowledge into new clinical treatments for UTIs.

Infectious and immunologic phenotype of MECP2 duplication syndrome

MECP2 (methyl CpG binding protein 2) duplication causes syndromic intellectual disability. Patients often suffer from life-threatening infections, suggesting an additional immunodeficiency. We describe for the first time the detailed infectious and immunological phenotype of MECP2 duplication syndrome. 17/27 analyzed patients suffered from pneumonia, 5/27 from at least one episode of sepsis. Encapsulated bacteria (S.pneumoniae, H.influenzae) were frequently isolated. T-cell immunity showed no gross abnormalities in 14/14 patients and IFNy-secretion upon ConA-stimulation was not decreased in 6/7 patients. In 6/21 patients IgG₂-deficiency was detected – in 4/21 patients accompanied by IgA-deficiency, 10/21 patients showed low antibody titers against pneumococci. Supra-normal IgG₁-levels were detected in 11/21 patients and supra-normal IgG₃-levels were seen in 8/21 patients – in 6 of the patients as combined elevation of IgG₁ and IgG₃. Three of the four patients with IgA/IgG₂-deficiency developed multiple severe infections. Upon infections pronounced acute-phase responses were common: 7/10 patients showed CRP values above 200 mg/l. Our data for the first time show systematically that increased susceptibility to infections in MECP2 duplication syndrome is associated with IgA/IgG₂-deficiency, low antibody titers against pneumococci and elevated acute-phase responses. So patients with MECP2 duplication syndrome and low IgA/IgG₂ may benefit from prophylactic substitution of sIgA and IgG.

Evaluation of environmental scanning electron microscopy for analysis of Proteus mirabilis crystalline biofilms in situ on urinary catheters

Proteus mirabilis is a common cause of catheter-associated urinary tract infections and frequently leads to blockage of catheters due to crystalline biofilm formation. Scanning electron microscopy (SEM) has proven to be a valuable tool in the study of these unusual biofilms, but entails laborious sample preparation that can introduce artefacts, undermining the investigation of biofilm development. In contrast, environmental scanning electron microscopy (ESEM) permits imaging of unprocessed, fully hydrated samples, which may provide much insight into the development of P. mirabilis biofilms. Here, we evaluate the utility of ESEM for the study of P. mirabilis crystalline biofilms in situ, on urinary catheters. In doing so, we compare this to commonly used conventional SEM approaches for sample preparation and imaging. Overall, ESEM provided excellent resolution of biofilms formed on urinary catheters and revealed structures not observed in standard SEM imaging or previously described in other studies of these biofilms. In addition, we show that energy-dispersive X-ray spectroscopy (EDS) may be employed in conjunction with ESEM to provide information regarding the elemental composition of crystalline structures and demonstrate the potential for ESEM in combination with EDS to constitute a useful tool in exploring the mechanisms underpinning crystalline biofilm formation.

Elucidating the genetic basis of crystalline biofilm formation in Proteus mirabilis

Proteus mirabilis forms extensive crystalline biofilms on urethral catheters that occlude urine flow and frequently complicate the management of long-term-catheterized patients. Here, using random transposon mutagenesis in conjunction with in vitro models of the catheterized urinary tract, we elucidate the mechanisms underpinning the formation of crystalline biofilms by P. mirabilis. Mutants identified as defective in blockage of urethral catheters had disruptions in genes involved in nitrogen metabolism and efflux systems but were unaffected in general growth, survival in bladder model systems, or the ability to elevate urinary pH. Imaging of biofilms directly on catheter surfaces, along with quantification of levels of encrustation and biomass, confirmed that the mutants were attenuated specifically in the ability to form crystalline biofilms compared with that of the wild type. However, the biofilm-deficient phenotype of these mutants was not due to deficiencies in attachment to catheter biomaterials, and defects in later stages of biofilm development were indicated. For one blocking-deficient mutant, the disrupted gene (encoding a putative multidrug efflux pump) was also found to be associated with susceptibility to fosfomycin, and loss of this system or general inhibition of efflux pumps increased sensitivity to this antibiotic. Furthermore, homologues of this system were found to be widely distributed among other common pathogens of the catheterized urinary tract. Overall, our findings provide fundamental new insight into crystalline biofilm formation by P. mirabilis, including the link between biofilm formation and antibiotic resistance in this organism, and indicate a potential role for efflux pump inhibitors in the treatment or prevention of P. mirabilis crystalline biofilms.

Proteus sp. – an opportunistic bacterial pathogen – classification, swarming growth, clinical significance and virulence factors

The genus Proteus belongs to the Enterobacteriaceae family, where it is placed in the tribe Proteeae, together with the genera Morganella and Providencia. Currently, the genus Proteus consists of five species: P. mirabilis, P. vulgaris, P. penneri, P. hauseri and P. myxofaciens, as well as three unnamed Proteus genomospecies. The most defining characteristic of Proteus bacteria is a swarming phenomenon, a multicellular differentiation process of short rods to elongated swarmer cells. It allows population of bacteria to migrate on solid surface. Proteus bacteria inhabit the environment and are also present in the intestines of humans and animals. These microorganisms under favorable conditions cause a number of infections including urinary tract infections (UTIs), wound infections, meningitis in neonates or infants and rheumatoid arthritis. Therefore, Proteus is known as a bacterial opportunistic pathogen. It causes complicated UTIs with a higher frequency, compared to other uropathogens. Proteus infections are accompanied by a formation of urinary stones, containing struvite and carbonate apatite. The virulence of Proteus rods has been related to several factors including fimbriae, flagella, enzymes (urease - hydrolyzing urea to CO2 and NH3, proteases degrading antibodies, tissue matrix proteins and proteins of the complement system), iron acqusition systems and toxins: hemolysins, Proteus toxin agglutinin (Pta), as well as an endotoxin - lipopolysaccharide (LPS). Proteus rods form biofilm, particularly on the surface of urinary catheters, which can lead to serious consequences for patients. In this review we present factors involved in the regulation of swarming phenomenon, discuss the role of particular pathogenic features of Proteus spp., and characterize biofilm formation by these bacteria.

Unique surface and internal structure of struvite crystals formed by Proteus mirabilis

Crystallization of struvite from artificial urine in the presence of Proteus mirabilis microorganisms depends strongly on pH value. At small value of pH, struvite yields crystals of coffin-like habit with very specific structure. The analysis using scanning electron microscopy shows that the crystals possess well-defined faces, but higher magnifications show very specific structuration as if the crystals were built from small three-dimensional subunits. The possible role of microorganisms in the formation of such a structuration is analyzed. At higher pH value, the crystals exhibit dendritic growth with main trunk and branches. Although the formation mechanism of the specific structuration as well as dendritic structures is unknown, the nature of forces for such an alignment is analyzed. The revealed porous internal structure of struvite is also analyzed. The investigations provide evidence for the importance of biological regulation in crystallization process.

Structure of the core part of the lipopolysaccharide from Proteus mirabilis genomic strain HI4320

The structure of the core part of the lipopolysaccharide from Proteus mirabilis genomic strain HI4320 was studied. Core oligosaccharide was isolated by mild acid hydrolysis of the lipopolysaccharide and analyzed by NMR spectroscopy and mass spectrometry as well as chemical methods. The structure of the oligosaccharide was established.

Transcriptome of Proteus mirabilis in the murine urinary tract: virulence and nitrogen assimilation gene expression

The enteric bacterium Proteus mirabilis is a common cause of complicated urinary tract infections. In this study, microarrays were used to analyze P. mirabilis gene expression in vivo from experimentally infected mice. Urine was collected at 1, 3, and 7 days postinfection, and RNA was isolated from bacteria in the urine for transcriptional analysis. Across nine microarrays, 471 genes were upregulated and 82 were downregulated in vivo compared to in vitro broth culture. Genes upregulated in vivo encoded mannose-resistant Proteus-like (MR/P) fimbriae, urease, iron uptake systems, amino acid and peptide transporters, pyruvate metabolism enzymes, and a portion of the tricarboxylic acid (TCA) cycle enzymes. Flagella were downregulated. Ammonia assimilation gene glnA (glutamine synthetase) was repressed in vivo, while gdhA (glutamate dehydrogenase) was upregulated in vivo. Contrary to our expectations, ammonia availability due to urease activity in P. mirabilis did not drive this gene expression. A gdhA mutant was growth deficient in minimal medium with citrate as the sole carbon source, and loss of gdhA resulted in a significant fitness defect in the mouse model of urinary tract infection. Unlike Escherichia coli, which represses gdhA and upregulates glnA in vivo and cannot utilize citrate, the data suggest that P. mirabilis uses glutamate dehydrogenase to monitor carbon-nitrogen balance, and this ability contributes to the pathogenic potential of P. mirabilis in the urinary tract.

Validation of the CDC biofilm reactor as a dynamic model for assessment of encrustation formation on urological device materials

Contemporary medical science is reliant upon the rational selection and utilization of devices, and therefore, an increasing need has developed for in vitro systems aimed at replicating the conditions to which urological devices will be subjected to during their use in vivo. We report the development and validation of a novel continuous flow encrustation model based on the commercially available CDC biofilm reactor. Proteus mirabilis-induced encrustation formation on test biomaterial sections under varying experimental parameters was analyzed by X-ray diffraction, infrared- and Raman spectroscopy and by scanning electron microscopy. The model system produced encrusted deposits similar to those observed in archived clinical samples. Results obtained for the system are highly reproducible with encrustation being rapidly deposited on test biomaterial sections. This model will have utility in the rapid screening of encrustation behavior of biomaterials for use in urological applications.

Structure and serology of O-antigens as the basis for classification of Proteus strains

This review is devoted to structural and serological characteristics of the O-antigens (O-polysaccharides) of the lipopolysaccharides of various Proteus species, which provide the basis for classifying Proteus strains to Oserogroups. The antigenic relationships of Proteus strains within and beyond the genus as well as their O-antigenrelated bioactivities are also discussed.

Role of bacterial biofilms in urinary tract infections

Bacterial urinary tract infections represent the most common type of nosocomial infection. In many cases, the ability of bacteria to both establish and maintain these infections is directly related to biofilm formation on indwelling devices or within the urinary tract itself. This chapter will focus on the role of biofilm formation in urinary tract infections with an emphasis on Gram-negative bacteria. The clinical implications of biofilm formation will be presented along with potential strategies for prevention. In addition, the role of specific pathogen-encoded functions in biofilm development will be discussed.

Complicated catheter-associated urinary tract infections due to Escherichia coli and Proteus mirabilis

Catheter-associated urinary tract infections (CAUTIs) represent the most common type of nosocomial infection and are a major health concern due to the complications and frequent recurrence. These infections are often caused by Escherichia coli and Proteus mirabilis. Gram-negative bacterial species that cause CAUTIs express a number of virulence factors associated with adhesion, motility, biofilm formation, immunoavoidance, and nutrient acquisition as well as factors that cause damage to the host. These infections can be reduced by limiting catheter usage and ensuring that health care professionals correctly use closed-system Foley catheters. A number of novel approaches such as condom and suprapubic catheters, intermittent catheterization, new surfaces, catheters with antimicrobial agents, and probiotics have thus far met with limited success. While the diagnosis of symptomatic versus asymptomatic CAUTIs may be a contentious issue, it is generally agreed that once a catheterized patient is believed to have a symptomatic urinary tract infection, the catheter is removed if possible due to the high rate of relapse. Research focusing on the pathogenesis of CAUTIs will lead to a better understanding of the disease process and will subsequently lead to the development of new diagnosis, prevention, and treatment options.

The type III secretion system of Proteus mirabilis HI4320 does not contribute to virulence in the mouse model of ascending urinary tract infection

The Gram-negative enteric bacterium Proteus mirabilis is a frequent cause of urinary tract infections (UTIs) in individuals with long-term indwelling catheters or with complicated urinary tracts. The recent release of the P. mirabilis strain HI4320 genome sequence has facilitated identification of potential virulence factors in this organism. Genes appearing to encode a type III secretion system (TTSS) were found in a low GC-content pathogenicity island in the P. mirabilis chromosome. This island contains 24 intact genes that appear to encode all components necessary to assemble a TTSS needle complex, plus at least two putative secreted effector proteins and their chaperones. The genetic organization of the TTSS genes is very similar to that of the TTSS of Shigella flexneri. RT-PCR analysis indicated that these genes are expressed at low levels in vitro. However, insertional mutation of two putative TTSS genes, encoding the requisite ATPase and a possible negative regulator, resulted in no change in either the growth rate of the mutant or the secreted protein profile compared to wild-type. Furthermore, there was no difference in quantitative cultures of urine, bladder and kidney between the ATPase mutant and the wild-type strain in the mouse model of ascending UTI in either independent challenge or co-challenge experiments. The role of the P. mirabilis TTSS, if any, is yet to be determined.

[Metabolic aspects of bowel use in urologic surgery]

Urinary diversion, pouches and orthotopic bladder replacement have been made possible by the use of bowel segments in urologic surgery. The most important complications at short and long-term are metabolic disorders due to the permanent contact of urine with the bowel segment or the exclusion of this segment from bowel continuity. Metabolic acid-base problems occur immediately after the derivation beginning and depend on the renal capacity to compensating. The metabolic disorder due to the exclusion of a bowel segment appears generally years later, after complete depletion of physiologic reserves (vitamin B12). Perfect knowledge of early and late metabolic complications of urinary diversion allows a more accurate indication, a more adequate selection of the derivation type, an improved patient followup, and better long-term results. Metabolic complications constitute the best selection criteria for urinary diversion; subsequently, only a few techniques are likely to persist in the future.

Strategies for the development of the urinary catheter

Indwelling urinary catheters are utilized in the management of a wide range of conditions both in an acute and a chronic setting. However, utilization of this type of device is associated with a number of issues, including an increased propensity to develop bacteriuria, symptomatic infection and also encrusted deposits on the device. The development of novel biomaterials, incorporation of therapeutic agents and other strategies to minimize the issues associated with these devices are discussed in this review.

Binding of harvested bacterial exopolymers to the surface of calcite

Biologically produced exopolysaccharides (EPS) affect calcite dissolution and precipitation. In this study, natural alkaliphilic microbial isolates were collected from biofilms on historic limestone. The isolates were screened for their ability to produce significant quantities of EPS in cultures. The most productive isolates were identified by 16S rRNA sequence analysis as a close relative of Bacillus cereus. EPS with different chemical structures were harvested from the isolates. Isothermal titration calorimetry (ITC) was used to quantify the thermodynamics of binding by the harvested EPS to calcite. The binding was described by a Langmuir adsorption isotherm. Characterization of the EPS showed that binding strength to calcite depended on the chemical nature of the polymer.

Why are Foley catheters so vulnerable to encrustation and blockage by crystalline bacterial biofilm?

Many patients undergoing long-term bladder catheterisation experience blockage and encrustation of their catheters. The problem stems from infection by urease producing bacteria, particularly Proteus mirabilis. Bacterial biofilms colonise the catheters, the activity of urease raises the pH and induces the deposition of calcium and magnesium phosphate crystals. In this study, a laboratory model of the catheterised bladder has been used to examine the early stages in the formation of the crystalline biofilms. The results show that initial cell adhesion is to the irregular surfaces surrounding the catheter eye-holes. Microcolonies form in depressions in these surfaces and spread to cover the entire surface of the rims around the eye-holes. Crystals then form around the bacterial populations and the biofilm starts to move down the lumenal surfaces of the catheters. The encrustation develops most extensively and generally blocks the catheter at or just below the eye-hole. There is a need to improve catheter design and manufacturing procedures for the eye-holes if the problems associated with the current devices are to be reduced.

Crystallization of urine mineral components may depend on the chemical nature of Proteus endotoxin polysaccharides

Formation of infectious urinary calculi is the most common complication accompanying urinary tract infections by members of the genus Proteus. The major factor involved in stone formation is the urease produced by these bacteria, which causes local supersaturation and crystallization of magnesium and calcium phosphates as carbonate apatite [Ca(10)(PO(4))(6).CO(3)] and struvite (MgNH(4)PO(4).6H(2)O), respectively. This effect may also be enhanced by bacterial polysaccharides. Macromolecules of such kind contain negatively charged residues that are able to bind Ca(2+) and Mg(2+), leading to the accumulation of these ions around bacterial cells and acceleration of the crystallization process. The levels of Ca(2+) and Mg(2+) ions bound by whole Proteus cells were measured, as well as the chemical nature of isolated LPS polysaccharides, and the intensity of the in vitro crystallization process was compared in a synthetic urine. The results suggest that the sugar composition of Proteus LPS may either enhance or inhibit the crystallization of struvite and apatite, depending on its chemical structure and ability to bind cations. This points to the increased importance of endotoxin in urinary tract infections.

Pathological and therapeutic significance of cellular invasion by Proteus mirabilis in an enterocystoplasty infection stone model

Proteus mirabilis infection often leads to stone formation. We evaluated how bacterium-mucin adhesion, invasion, and intracellular crystal formation are related to antibiotic sensitivity and may cause frequent stone formation in enterocystoplasties. Five intestinal (Caco-2, HT29, HT29-18N2, HT29-FU, and HT29-MTX) and one ureter cell line (SV-HUC-1) were incubated in artificial urine with five Proteus mirabilis strains. Fluorescence-activated cell sorting (FACS), laser scanning microscopy, and electron microscopy evaluated cellular adhesion and/or invasion, pathologic changes to mitochondria, and P. mirabilis-mucin colocalization (MUC2 and MUC5AC). An MTT (thiazolyl blue tetrazolium bromide) assay and FACS analysis of caspase-3 evaluated the cellular response. Infected cells were incubated with antibiotics at dosages representing the expected urinary concentrations in a 10-year-old, 30-kg child to evaluate bacterial invasion and survival. All cell lines showed colocalization of P. mirabilis with human colonic mucin (i.e., MUC2) and human gastric mucin (i.e., MUC5AC). The correlation between membrane mucin expression and invasion was significant and opposite for SV-HUC-1 and HT29-MTX. Microscopically, invasion by P. mirabilis with intracellular crystal formation and mitochondrial damage was found. Double membranes surrounded bacteria in intestinal cells. Relative resistance to cotrimoxazole and augmentin was found in the presence of epithelial cells. Ciprofloxacin and gentamicin remained effective. Membrane mucin expression was correlated with relative antibiotic resistance. Cell invasion by P. mirabilis and mucin- and cell type-related distribution and response differences indicate bacterial tropism that affects crystal formation and mucosal presence. Bacterial invasion seems to have cell type-dependent mechanisms and prolong bacterial survival in antibiotic therapy, giving a new target for therapeutic optimalization of antibiotic treatment.

Catheter-associated urinary tract infections

In the past few years it has been clearly demonstrated that the concept of bacterial biofilm production permits an understanding and provides some explanation of the pathogenesis, diagnosis and treatment of catheter-associated urinary tract infections. This concept describes the colonization of catheter surfaces and the movement of bacteria against the urinary flow. It explains the antibacterial resistance of these matrix-enclosed sessile populations of bacteria. The catheter encrustation can be observed as mineralizing bacterial biofilm. The differentiation in swarming cells exposing a much higher activity of the enzyme urease is responsible for the predominant role of Proteus mirabilis in obstructing encrustations. The guidelines for the prevention of catheter-associated urinary tract infections were developed over the past decades by clinicians and are still valid. They can now be better understood taking into consideration these new theories. As overuse of urethral catheters and non-compliance of their recommended use are still apparent, educational and surveillance programmes are needed to help maintain good standards of care.

Stereoselective synthesis of the alpha-glycoside of a KDO "C"-disaccharide

The reaction of tert-butyl (4,5,7, 8-tetra-O-acetyl-3-deoxy-alpha-D-manno-2-octulopyranosyl chloride)onate donor 7 with the 6-formylgalactopyranoside acceptor 4 in the presence of SmI(2) provided only the KDO alpha-C-disaccharide 8. The bulky tert-butyl ester in the donor was used to reverse the stereochemical outcome of C-glycosylation, stereoselectively forming the alpha-"C"-disaccharide of KDO.