Proteus mirabilis uroepithelial cell adhesin (UCA) fimbria plays a role in the colonization of the urinary tract

Hand contamination and hand hygiene knowledge and practices among commercial transport users after the SARS-CoV-2 virus (COVID-19) scare, Enugu State, Nigeria

Contaminated hands are one of the most common modes of microorganism transmission that are responsible for many associated infections in healthcare, food industries, and public places such as transportation parks. Public health approaches during COVID-19 pandemic have shown that hand hygiene practices and associated knowledge are critical measure to control the spread of infectious agent. Hence, assessment of commercial transport users' knowledge, belief and practices on hand hygiene, and potential contamination with infectious agents which is the aim of the study, aligns with general health concern of quantifying contamination risk levels to predict disease outbreaks. This study utilized a randomized sampling approach to select 10 frequently used commercial parks within two districts in the State: Enugu and Nsukka. The parameters analysed include a cross-sectional questionnaire survey, hand swab and hand washed samples collected from dominant hand of participants. A total of 600 participants responded to the questionnaire survey, while 100 participants' hand swabs were examined for microbial contamination. This study recorded a high prevalence of fungal (90.0%) and bacterial (87.0%) species; 20 species of fungus were identified with prevalence range of 1% to 14%; 21 bacterial species were isolated with prevalence range of 1% to 16%. These species were identified as either opportunistic, non-invasive, or pathogenic, which may constitute a health concern amongst immunocompromised individuals within the population. Aspergillus spp. (14%), was the most common fungal species that was exclusively found amongst Nsukka commercial users, while E. coli was the most prevalent isolated bacterial species amongst Nsukka (12%) and Enugu (20%) commercial park users. Prevalence of fungal contamination in Nsukka (94.0%; 47/50) and Enugu (86.0%; 43/50) were both high. Prevalence of bacterial contamination was higher in Enugu than Nsukka but not significantly (47[94.0%] vs. 40[80.0%], p = 0.583). A greater number of participants (99.3%) were aware of the importance of hand hygiene, however with low compliance rate aside "after using the toilet" (80%) and "before eating" (90%), other relevant hand washing and sanitizing practices were considered less important. With these observations, we can emphatically say that despite the COVID-19 scare, commercial park users within the sampled population do not efficiently practice quality hand wash and hygiene measures, hence, risking the widespread of infectious agents in situation of disease outbreak or among immunocompromised individuals.

Role of Bacterial Surface Components in the Pathogenicity of Proteus mirabilis in a Murine Model of Catheter-Associated Urinary Tract Infection

Proteus mirabilis (PM) is a Gram-negative, rod-shaped bacterium that causes catheter-associated urinary tract infections (CAUTIs). The specific roles of bacterial surface components (BSCs) in PM pathogenicity and CAUTIs remain unknown. To address this knowledge gap, we utilized relevant in vitro adhesion/invasion models and a well-established murine model of CAUTI to assess the ability of wildtype (WT) and seven mutant strains (MSs) of PM with deficiencies in various genes encoding BSCs to undergo the infectious process (including adhesion to catheters) in both model systems. Overall, MSs adhesion to catheters and the different cell types tested was significantly reduced compared to WT, while no invasion of cells was evident at 24 h. In vivo, WT showed a greater number of planktonic (urine) bacteria, bacteria adherent to catheters, and bacteria adherent to/invading bladder tissue when compared to the MSs. Bacterial counts in urine for PMI3191 and waaE mutants were lower than that for WT and other MSs. The complementation of mutated BSC genes resulting in the biggest defects restored the invasion phenotype both in vitro and in vivo. BSCs play a critical role at various steps in the pathogenicity of PM including adhesion to indwelling medical devices and adhesion/invasion of urinary tissue in vivo.

Ucl fimbriae regulation and glycan receptor specificity contribute to gut colonisation by extra-intestinal pathogenic Escherichia coli

Extra-intestinal pathogenic Escherichia coli (ExPEC) belong to a critical priority group of antibiotic resistant pathogens. ExPEC establish gut reservoirs that seed infection of the urinary tract and bloodstream, but the mechanisms of gut colonisation remain to be properly understood. Ucl fimbriae are attachment organelles that facilitate ExPEC adherence. Here, we investigated cellular receptors for Ucl fimbriae and Ucl expression to define molecular mechanisms of Ucl-mediated ExPEC colonisation of the gut. We demonstrate differential expression of Ucl fimbriae in ExPEC sequence types associated with disseminated infection. Genome editing of strains from two common sequence types, F11 (ST127) and UTI89 (ST95), identified a single nucleotide polymorphism in the ucl promoter that changes fimbriae expression via activation by the global stress-response regulator OxyR, leading to altered gut colonisation. Structure-function analysis of the Ucl fimbriae tip-adhesin (UclD) identified high-affinity glycan receptor targets, with highest affinity for sialyllacto-N-fucopentose VI, a structure likely to be expressed on the gut epithelium. Comparison of the UclD adhesin to the homologous UcaD tip-adhesin from Proteus mirabilis revealed that although they possess a similar tertiary structure, apart from lacto-N-fucopentose VI that bound to both adhesins at low-micromolar affinity, they recognize different fucose- and glucose-containing oligosaccharides. Competitive surface plasmon resonance analysis together with co-structural investigation of UcaD in complex with monosaccharides revealed a broad-specificity glycan binding pocket shared between UcaD and UclD that could accommodate these interactions. Overall, our study describes a mechanism of adaptation that augments establishment of an ExPEC gut reservoir to seed disseminated infections, providing a pathway for the development of targeted anti-adhesion therapeutics.

ExPEC infection of the urinary tract and bloodstream is frequently seeded from an intestinal reservoir, necessitating an understanding of the mechanisms that promote gut colonisation. Here we employed molecular and structural approaches to define the regulation and function of ExPEC Ucl fimbriae as a gut colonisation factor. We describe how mutations in the non-coding regulatory region of the ucl promoter cause increased Ucl fimbriae expression and promote enhanced gut colonisation via tuned induction by a global regulator that senses oxygen stress. We further define the glycan receptor targets of Ucl fimbriae and characterise the structural features of the Ucl adhesin that facilitate these interactions. These findings explain how ExPEC can adapt to survival in the gut to seed extra-intestinal infection.

Detection of Carbapenem Resistance of Proteus mirabilis Strains Isolated from Foxes, Raccoons and Minks in China

Proteus mirabilis, an opportunistic pathogen, is found to be an emerging threat to both animals and humans for a variety of infections. However, the characteristics of P. mirabilis infections from foxes, raccoons and minks remain unclear. In this context, we identified the antibiotic resistance genes and virulence genes of P. mirabilis isolates from foxes, raccoons and minks in China. Most isolates showed resistance to florfenicol (90.57%), trimethoprim-sulfamethoxazole (73.58%), and imipenem (71.70%). A total of 73.58% of isolates were resistant to antibiotics from at least three or more classes, and were categorized as multi-drug resistant. A total of 33.33% of the isolates were resistant to antibiotics from seven classes. The most prevalent resistant were sul1 (94.34%), followed by floR, blaTEM, aac(6’)Ib-cr and blaOXA-1 with the detection rate of 88.68%, 83.02%, 71.70% and 60.38%, respectively. Among the 51 P. mirabilis isolates that were resistant to beta-lactam antibiotics, all isolates carried at least one beta-lactam gene. In addition, blaNDM and blaOXA-24 genes were firstly reported in carbapenem-resistant P. mirabilis isolates from foxes, raccoons and minks. All isolates exhibited the virulence genes ureC, zapA, pmfA, atfA and mrpA. P. mirabilis isolates carrying all detected 10 virulence genes from different animal species showed different lethal abilities in a G. mellonella larvae model. More importantly, the profiles of antibiotic resistance genes of isolates from fur animals and the environment were generally similar, and phylogenetic analysis showed that the P. mirabilis isolates from farm environment samples may have close relatedness with that from animals.

Virulence factors of Proteus mirabilis clinical isolates carrying blaKPC-2 and blaNDM-1 and first report blaOXA-10 in Brazil

INTRODUCTION

Proteus mirabilis is one of the main pathogens that cause urinary tract infections. Therefore, the aim of this study was to analyze and compare the genetic profile of 36 clinical isolates of P. mirabilis that carry and do not carry the bla_KPC and bla_NDM gene with respect to virulence factors (mrpG, pmfA, ucaA, nrpG and pbtA) and antimicrobial resistance (bla_VIM,bla_IMP, bla_SPM, bla_GES,bla_OXA-23-like, bla_OXA-48-like, bla_OXA-58-like and bla_OXA-10-like).

METHODS

The virulence and resistance genes were investigated by using PCR and sequencing.

RESULTS

ERIC-PCR typing showed that the isolates showed multiclonal dissemination and high genetic variability. The gene that was most found bla_OXA-10-like (n = 18), followed by bla_KPC (n = 10) and bla_NDM (n = 8). To our knowledge, this is the first report of bla_OXA-10 in P. mirabilis in Brazil, as well as the first report of the occurrence of P. mirabilis co-carrying bla_OXA-10/bla_KPC and bla_OXA-10/bla_NDM. The bla_NDM or bla_KPC carrier isolates showed important virulence genes, such as ucaA (n = 8/44.4%), pbtA (n = 10/55.5%) and nrpG (n = 2/11.1%). However, in general, the non-carrier isolates of bla_KPC and bla_NDM showed a greater number of virulence genes when compared to the carrier group.

CONCLUSION

Clinical isolates of P. mirabilis, in addition to being multi-drug resistant, presented efficient virulence factors that can establish infection outside the gastrointestinal tract.

Proteus mirabilis from community-acquired urinary tract infections (UTI-CA) shares genetic similarity and virulence factors with isolates from chicken, beef and pork meat

Proteus mirabilis is an opportunistic pathogen associated with a variety of infections in humans, especially those in the urinary tract. The isolation of this pathogen in foods of animal origin such as meat is poorly documented and should not be neglected, in view of the zoonotic risk that this can pose to human health. Thus, the objective of this study was to evaluate the prevalence, virulence profile, and similarity between P. mirabilis strains isolated from chicken, beef, and pork meat and those causing community-acquired urinary tract infections (UTI-CA), in order to better understand the role of this bacterium as a zoonotic pathogen. P. mirabilis was isolated from the three types of meat and was found to be more prevalent in chicken. All isolates exhibited several genotypic and phenotypic virulence characteristics, such as adhesion capacity in HEp-2 cell culture, biofilm formation, cytotoxicity in Vero cells and genes that express fimbriae (mrpA, pmfA, ucaA, atfA), hemolysin (hpmA), proteases (zapA and ptA) and siderophore receptor (ireA). UTI-CA strains showed a higher prevalence of ucaA and ireA genes, whereas those from the chicken meat had a higher prevalence of the atfA gene compared with the isolates from the beef and pork meat. It was observed that chicken meat and UTI-CA strains mainly formed very strong biofilms, whereas strains isolated from beef and pork formed more weak and moderate biofilms. Several strains from meat showed close genetic similarity to those from UTI-CA and had the same virulence profiles. Thus, meats may be an important source of the dissemination of P. mirabilis responsible for causing UTIs in the community.

Proteus mirabilis causing cellulitis in broiler chickens

Given the need to understand the virulence profile of Proteus mirabilis isolates from cellulitis in broiler chickens and their ability to cause lesions, the present study aimed to characterize genotypically and phenotypically the virulence profiles of two strains of P. mirabilis isolated from cellulitis in broilers, as well as to evaluate their ability to experimentally reproduce the lesions in vivo. The strain with the highest virulence potential (LBUEL-A33) possessed mrpA, pmfA, ucaA, atfA (fimbriae), zapA, ptA (proteases), hpmA (hemolysin), and ireA (siderophore) genes, formed a very strong biofilm, and expressed the pattern of aggregative adhesion and cytotoxicity in Vero cells. The strain with the lowest virulence potential (LBUEL-A34) did not present the pmfA and ucaA genes, but expressed the pattern of aggregative adhesion, formed a strong biofilm, and did not show cytotoxicity. Both strains developed cellulitis in an animal model within 24 h post-inoculation (PI), and the degree of lesions was not significantly altered up to 120 h PI. The LBUEL-A33 strain was also inoculated in combination with an avian pathogenic Escherichia coli (APEC 046), and the lesions showed no significant changes from the individual inoculation of these two strains. Histological analysis showed that the LBUEL-A33 strain developed characteristic cellulitis lesions. Thus, both strains of P. mirabilis isolated in our study have several virulence factors and the ability to develop cellulitis in broilers.

Genotypic and phenotypic profiles of virulence factors and antimicrobial resistance of Proteus mirabilis isolated from chicken carcasses: potential zoonotic risk

Proteus mirabilis is an opportunistic pathogen often associated with a variety of human infections acquired both in the community and in hospitals. In this context, the present work aimed to evaluate the genotypic and phenotypic characteristics of the virulence factors and antimicrobial resistance determinants of 32 P. mirabilis strains isolated from chicken carcasses in a poultry slaughterhouse in the north of the state of Paraná, Brazil, in order to assess a potential zoonotic risk. The isolates presented a variety of virulence genes that contribute to the development of infection in humans. The mrpA, pmfA, atfA (fimbriae), ireA (siderophores receptor), zapA, ptA (Proteases), and hpmA (hemolysin) genes were found in 32 (100%) isolates and ucaA (fimbriae) in 16 (50%). All isolates showed aggregative adherence in HEp-2 cells and formed biofilms. Of all strains, 27 (84.38%) showed cytotoxic effects in Vero cells. Antimicrobial susceptibility was tested using 20 antimicrobials, in which 25 (78.13%) strains were considered multidrug-resistant. The presence of blaESBL and blaampC genes conferring resistance to β-lactams and qnr to quinolones were also detected in the isolates after presumption in the phenotypic test, in which 7 (21.88%) isolates contained the CTX-M-2 group, 11 (34.38%) contained CIT group and 19 (59.38%) contained qnrD. Therefore, chicken carcasses contaminated with P. mirabilis may pose a health risk to the consumer, as these isolates have a variety of virulence and antimicrobial resistance characteristics that can be found in P. mirabilis strains isolated from human infections.

Analysis of inflammatory cytokine expression in the urinary tract of BALB/c mice infected with Proteus (P.) mirabilis and enteroaggregative Escherichia (E.) coli (EAEC) strains

This study aimed to analyze the proinflammatory cytokine mRNA expression in the urinary tract of BALB/c mice infected with bacterial strains with uropathogenic potential. Groups of four 6-week-old female BALB/c mice were intraurethrally inoculated with 5 × 10⁷ colony-forming units (CFU) of P. mirabilis ATCC29906, EAEC O42, P. mirabilis RTX339, or sterile saline (control group) and then sacrificed at 0, 2, 4, 7, or 10 days post-infection (p.i.). Samples were cultured to determine the CFU/mL in urine or CFU/g in the bladders and kidneys. Cytokine expression (tumor necrosis factor (TNF)-α and interleukin (IL)-1β, -6, and -8) was evaluated in the target organs using real-time PCR and immunohistochemistry; histology was examined with hematoxylin and eosin staining. The results are presented as the means and standard deviations and were compared using one-way ANOVA, with p < 0.05 indicating significant differences. Bacteriuria was not detected in the infected groups; bacterial colonization occurred in the target organs at all time points, but was higher in mice infected with EAEC O42 or P. mirabilis RTX339 at 7 days p.i. The expression of all cytokine mRNAs was seen, but only the levels of the IL-8 protein increased in situ at 7 days p.i. in the P. mirabilis RTX339 and EAEC O42 groups in both organs. Morphological alterations, observed in all of the infected groups, were more prominent in the EAEC O42 and P. mirabilis RTX339 groups. The findings provide insights into the uropathogenicity and inflammatory cytokine expression in the urinary tract of mice infected with three previously untested bacterial strains.

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.

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.

Structures of two fimbrial adhesins, AtfE and UcaD, from the uropathogenProteus mirabilis

The important uropathogenProteus mirabilisencodes a record number of chaperone/usher-pathway adhesive fimbriae. Such fimbriae, which are used for adhesion to cell surfaces/tissues and for biofilm formation, are typically important virulence factors in bacterial pathogenesis. Here, the structures of the receptor-binding domains of the tip-located two-domain adhesins UcaD (1.5 Å resolution) and AtfE (1.58 Å resolution) from twoP. mirabilisfimbriae (UCA/NAF and ATF) are presented. The structures of UcaD and AtfE are both similar to the F17G type of tip-located fimbrial receptor-binding domains, and the structures are very similar despite having only limited sequence similarity. These structures represent an important step towards a molecular-level understanding ofP. mirabilisfimbrial adhesins and their roles in the complex pathogenesis of urinary-tract infections.

Proteome-wide identification of epitope-based vaccine candidates against multi-drug resistant Proteus mirabilis

Proteus mirabilis is one of the important pathogens of urinary tract and exhibits resistance to multiple drugs. Development of vaccine tends to be the most promising and cost-effective remedy against the said pathogen. Herein, we implement a combinatorial approach for screening proteins harboring potential broad-spectrum antigenic epitopes in the proteome of P. mirabilis. The targets are host non-homologous, essential and virulent, and have localization in the extracellular and outer membrane. Immuno-informatics revealed antigenic, surface exposed and broad-spectrum B-cell derived T-cell epitopes for three membrane usher family candidates: AtfC, PMI2533 and PMI1466, which could evoke a substantial immune response. Protein-protein interactions of targeted three proteins have shown their involvement in biologically significant pathways indispensable for the growth and survival of the pathogen. The antigenic epitopes are conserved among all completely annotated strains and docked deeply in the binding cavity of the most prevalent allele-DRB1*0101 in human population. Future work is necessary to characterize the shortlisted proteins and epitopes for immune protection in animal models.

Investigation of the activity of new derivatives of 1,3-diazinone-4 and their acyclic precursors with respect to bacteria of the genus Proteus

Introduction: The present paper provides a study of the activity of the new 1,3-diazinon-4 derivatives and their acyclic precursors under the laboratory cipher PYaTd1, PYaTs2, PYaTs3 and PYaTs4 against microorganisms of the genus Proteus, which is of high importance at the moment as the growing resistance of the Proteus to previously highly active antibiotics dictates the need to search for effective antimicrobial agents that meet modern safety requirements.

Materials and Methods: The study of the activity of the compounds was carried out on collection and freshly isolated strains from patients with different pathologies. The strains were identified using the BIOMIC V3 apparatus (Giles Scientific, USA) to verify genus and species identity. The strains used in the study were previously examined for susceptibility to antibacterial drugs by the Disc Method to assess the presence or absence of resistance. The activity of the new compounds was studied by the serial dilution method.

Results: The results of the study showed that the compounds PYaTd1, PYaTs2, PYaTs3 and PYaTs4 show a different activity against bacteria of the genus Proteus. The substance PYaTs2 is ineffective. With respect to strains P.mirabilis and P.rettgeri, the minimum inhibitory concentration of the compounds PYaTs3, PYaTs4 and PYaTd1 ranges from 4 μg/ml to 16 μg/ml.

Conclusion: Thus, by the average aggregate indices, regardless of the species and strain of bacteria, the most effective compound is PYaTd1, the MIC50 of which is within 10 μg/ml, which proves it to be promising and makes further development worthwhile.

Genome-wide transposon mutagenesis of Proteus mirabilis: Essential genes, fitness factors for catheter-associated urinary tract infection, and the impact of polymicrobial infection on fitness requirements

The Gram-negative bacterium Proteus mirabilis is a leading cause of catheter-associated urinary tract infections (CAUTIs), which are often polymicrobial. Numerous prior studies have uncovered virulence factors for P. mirabilis pathogenicity in a murine model of ascending UTI, but little is known concerning pathogenesis during CAUTI or polymicrobial infection. In this study, we utilized five pools of 10,000 transposon mutants each and transposon insertion-site sequencing (Tn-Seq) to identify the full arsenal of P. mirabilis HI4320 fitness factors for single-species versus polymicrobial CAUTI with Providencia stuartii BE2467. 436 genes in the input pools lacked transposon insertions and were therefore concluded to be essential for P. mirabilis growth in rich medium. 629 genes were identified as P. mirabilis fitness factors during single-species CAUTI. Tn-Seq from coinfection with P. stuartii revealed 217/629 (35%) of the same genes as identified by single-species Tn-Seq, and 1353 additional factors that specifically contribute to colonization during coinfection. Mutants were constructed in eight genes of interest to validate the initial screen: 7/8 (88%) mutants exhibited the expected phenotypes for single-species CAUTI, and 3/3 (100%) validated the expected phenotypes for polymicrobial CAUTI. This approach provided validation of numerous previously described P. mirabilis fitness determinants from an ascending model of UTI, the discovery of novel fitness determinants specifically for CAUTI, and a stringent assessment of how polymicrobial infection influences fitness requirements. For instance, we describe a requirement for branched-chain amino acid biosynthesis by P. mirabilis during coinfection due to high-affinity import of leucine by P. stuartii. Further investigation of genes and pathways that provide a competitive advantage during both single-species and polymicrobial CAUTI will likely provide robust targets for therapeutic intervention to reduce P. mirabilis CAUTI incidence and severity.

Proteus mirabilis is a common cause of single-species and polymicrobial catheter-associated urinary tract infections (CAUTIs). Prior studies have uncovered P. mirabilis virulence factors for single-species ascending UTI, but little is known concerning pathogenesis during CAUTI or polymicrobial infection. Using transposon insertion-site sequencing (Tn-Seq), we performed a global assessment of P. mirabilis fitness factors for CAUTI while simultaneously determining how coinfection with another CAUTI pathogen, Providencia stuartii, alters P. mirabilis fitness requirements. This approach provides six important contributions to the field: 1) the first global estimation of P. mirabilis genes essential for growth, 2) validation of a role for known P. mirabilis fitness factors during CAUTI, 3) identification of novel fitness factors, 4) identification of core fitness factors for both single-species and polymicrobial CAUTI, 5) identification of single-species fitness factors that are complemented during polymicrobial infection, and 6) identification of factors that only provide a competitive advantage during polymicrobial infection. We further demonstrate that the CAUTI model can be used to examine the interplay between fitness requirements of both species during coinfection. Investigation of fitness requirements for other pathogens during single-species and polymicrobial CAUTI will elucidate complex interactions that contribute to disease severity and uncover conserved targets for therapeutic intervention.

From Catheter to Kidney Stone: The Uropathogenic Lifestyle of Proteus mirabilis

Proteus mirabilis is a model organism for urease-producing uropathogens. These diverse bacteria cause infection stones in the urinary tract and form crystalline biofilms on indwelling urinary catheters, frequently leading to polymicrobial infection. Recent work has elucidated how P. mirabilis causes all of these disease states. Particularly exciting is the discovery that this bacterium forms large clusters in the bladder lumen that are sites for stone formation. These clusters, and other steps of infection, require two virulence factors in particular: urease and MR/P fimbriae. Highlighting the importance of MR/P fimbriae is the cotranscribed regulator, MrpJ, which globally controls virulence. Overall, P. mirabilis exhibits an extraordinary lifestyle, and further probing will answer exciting basic microbiological and clinically relevant questions.

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.

Distinct Residues Contribute to Motility Repression and Autoregulation in the Proteus mirabilis Fimbria-Associated Transcriptional Regulator AtfJ

Proteus mirabilis contributes to a significant number of catheter-associated urinary tract infections, where coordinated regulation of adherence and motility is critical for ascending disease progression. Previously, the mannose-resistant Proteus-like (MR/P) fimbria-associated transcriptional regulator MrpJ has been shown to both repress motility and directly induce the transcription of its own operon; in addition, it affects the expression of a wide range of cellular processes. Interestingly, 14 additional mrpJ paralogs are included in the P. mirabilis genome. Looking at a selection of MrpJ paralogs, we discovered that these proteins, which consistently repress motility, also have nonidentical functions that include cross-regulation of fimbrial operons. A subset of paralogs, including AtfJ (encoded by the ambient temperature fimbrial operon), Fim8J, and MrpJ, are capable of autoinduction. We identified an element of the atf promoter extending from 487 to 655 nucleotides upstream of the transcriptional start site that is responsive to AtfJ, and we found that AtfJ directly binds this fragment. Mutational analysis of AtfJ revealed that its two identified functions, autoregulation and motility repression, are not invariably linked. Residues within the DNA-binding helix-turn-helix domain are required for motility repression but not necessarily autoregulation. Likewise, the C-terminal domain is dispensable for motility repression but is essential for autoregulation. Supported by a three-dimensional (3D) structural model, we hypothesize that the C-terminal domain confers unique regulatory capacities on the AtfJ family of regulators.

IMPORTANCE

Balancing adherence with motility is essential for uropathogens to successfully establish a foothold in their host. Proteus mirabilis uses a fimbria-associated transcriptional regulator to switch between these antagonistic processes by increasing fimbrial adherence while simultaneously downregulating flagella. The discovery of multiple related proteins, many of which also function as motility repressors, encoded in the P. mirabilis genome has raised considerable interest as to their functionality and potential redundancy in this organism. This study provides an important advance in this field by elucidating the nonidentical effects of these paralogs on a molecular level. Our mechanistic studies of one member of this group, AtfJ, shed light on how these differing functions may be conferred despite the limited sequence variety exhibited by the paralogous proteins.

Draft Genome Sequence and Gene Annotation of the Uropathogenic Bacterium Proteus mirabilis Pr2921

Here, we report the genome sequence of Proteus mirabilis Pr2921, a uropathogenic bacterium that can cause severe complicated urinary tract infections. After gene annotation, we identified two additional copies of ucaA, one of the most studied fimbrial protein genes, and other fimbriae related-proteins that are not present in P. mirabilis HI4320.

Fimbriae have distinguishable roles in Proteus mirabilis biofilm formation

Proteus mirabilis is one of the most common etiological agents of complicated urinary tract infections, especially those associated with catheterization. This is related to the ability of P. mirabilis to form biofilms on different surfaces. This pathogen encodes 17 putative fimbrial operons, the highest number found in any sequenced bacterial species so far. The present study analyzed the role of four P. mirabilis fimbriae (MR/P, UCA, ATF and PMF) in biofilm formation using isogenic mutants. Experimental approaches included migration over catheter, swimming and swarming motility, the semiquantitative assay based on adhesion and crystal violet staining, and biofilm development by immunofluorescence and confocal microscopy. Different assays were performed using LB or artificial urine. Results indicated that the different fimbriae contribute to the formation of a stable and functional biofilm. Fimbriae revealed particular associated roles. First, all the mutants showed a significantly reduced ability to migrate across urinary catheter sections but neither swimming nor swarming motility were affected. However, some mutants formed smaller biofilms compared with the wild type (MRP and ATF) while others formed significantly larger biofilms (UCA and PMF) showing different bioarchitecture features. It can be concluded that P. mirabilis fimbriae have distinguishable roles in the generation of biofilms, particularly in association with catheters.

Comparative proteomics of uropathogenic Escherichia coli during growth in human urine identify UCA-like (UCL) fimbriae as an adherence factor involved in biofilm formation and binding to uroepithelial cells

Uropathogenic Escherichia coli (UPEC) are the primary cause of urinary tract infection (UTI) in humans. For the successful colonisation of the human urinary tract, UPEC employ a diverse collection of secreted or surface-exposed virulence factors including toxins, iron acquisition systems and adhesins. In this study, a comparative proteomic approach was utilised to define the UPEC pan and core surface proteome following growth in pooled human urine. Identified proteins were investigated for subcellular origin, prevalence and homology to characterised virulence factors. Fourteen core surface proteins were identified, as well as eleven iron uptake receptor proteins and four distinct fimbrial types, including type 1, P, F1C/S and a previously uncharacterised fimbrial type, designated UCA-like (UCL) fimbriae in this study. These pathogenicity island (PAI)-associated fimbriae are related to UCA fimbriae of Proteus mirabilis, associated with UPEC and exclusively found in members of the E. coli B2 and D phylogroup. We further demonstrated that UCL fimbriae promote significant biofilm formation on abiotic surfaces and mediate specific attachment to exfoliated human uroepithelial cells. Combined, this study has defined the surface proteomic profiles and core surface proteome of UPEC during growth in human urine and identified a new type of fimbriae that may contribute to UTI.

Structure, Function, and Assembly of Adhesive Organelles by Uropathogenic Bacteria

Bacteria assemble a wide range of adhesive proteins, termed adhesins, to mediate binding to receptors and colonization of surfaces. For pathogenic bacteria, adhesins are critical for early stages of infection, allowing the bacteria to initiate contact with host cells, colonize different tissues, and establish a foothold within the host. The adhesins expressed by a pathogen are also critical for bacterial-bacterial interactions and the formation of bacterial communities, including biofilms. The ability to adhere to host tissues is particularly important for bacteria that colonize sites such as the urinary tract, where the flow of urine functions to maintain sterility by washing away non-adherent pathogens. Adhesins vary from monomeric proteins that are directly anchored to the bacterial surface to polymeric, hair-like fibers that extend out from the cell surface. These latter fibers are termed pili or fimbriae, and were among the first identified virulence factors of uropathogenic Escherichia coli. Studies since then have identified a range of both pilus and non-pilus adhesins that contribute to bacterial colonization of the urinary tract, and have revealed molecular details of the structures, assembly pathways, and functions of these adhesive organelles. In this review, we describe the different types of adhesins expressed by both Gram-negative and Gram-positive uropathogens, what is known about their structures, how they are assembled on the bacterial surface, and the functions of specific adhesins in the pathogenesis of urinary tract infections.

Multidrug-Resistant Proteus mirabilis Isolated From Newly Weaned Infant Rhesus Monkeys and Ferrets

Background:

Proteus mirabilis is an important uropathogen that causes complicated Urinary Tract Infection (UTI) and induces diarrhea in infants.

Objectives:

This study aimed to investigate P. mirabilis infection in newly weaned infant rhesus monkeys (Macaca mulatta) and ferrets (Mustela putorius furo) with diarrhea.

Materials and Methods:

Stool samples were collected from 74 rhesus monkeys and 12 ferrets with diarrhea. Proteus mirabilis was isolated from the samples through Polymerase Chain Reaction. The isolated P. mirabilis was subjected to antimicrobial susceptibility tests.

Results:

Seven (7/74, 9.5%) and four (4/12, 30%) P. mirabilis strains were detected in the stool samples collected from the monkeys and ferrets, respectively. Sequence analyses showed that the isolated P. mirabilis was closely related to P. mirabilis strain HI4320, which was isolated from the urine of a patient with a long-term indwelling urinary catheter. In addition, the isolates demonstrated multidrug resistance.

Conclusions:

Rhesus monkeys and ferrets are susceptible to P. mirabilis, making them useful as animal models for future studies on the mechanism of P. mirabilis-induced UTI and its corresponding treatment.

Transcriptional analysis of the MrpJ network: modulation of diverse virulence-associated genes and direct regulation of mrp fimbrial and flhDC flagellar operons in Proteus mirabilis

The enteric bacterium Proteus mirabilis is associated with a significant number of catheter-associated urinary tract infections (UTIs). Strict regulation of the antagonistic processes of adhesion and motility, mediated by fimbriae and flagella, respectively, is essential for disease progression. Previously, the transcriptional regulator MrpJ, which is encoded by the mrp fimbrial operon, has been shown to repress both swimming and swarming motility. Here we show that MrpJ affects an array of cellular processes beyond adherence and motility. Microarray analysis found that expression of mrpJ mimicking levels observed during UTIs leads to differential expression of 217 genes related to, among other functions, bacterial virulence, type VI secretion, and metabolism. We probed the molecular mechanism of transcriptional regulation by MrpJ using transcriptional reporters and chromatin immunoprecipitation (ChIP). Binding of MrpJ to two virulence-associated target gene promoters, the promoters of the flagellar master regulator flhDC and mrp itself, appears to be affected by the condensation state of the native chromosome, although both targets share a direct MrpJ binding site proximal to the transcriptional start. Furthermore, an mrpJ deletion mutant colonized the bladders of mice at significantly lower levels in a transurethral model of infection. Additionally, we observed that mrpJ is widely conserved in a collection of recent clinical isolates. Altogether, these findings support a role of MrpJ as a global regulator of P. mirabilis virulence.

Characterization of 17 chaperone-usher fimbriae encoded by Proteus mirabilis reveals strong conservation

Proteus mirabilis is a Gram-negative enteric bacterium that causes complicated urinary tract infections, particularly in patients with indwelling catheters. Sequencing of clinical isolate P. mirabilis HI4320 revealed the presence of 17 predicted chaperone-usher fimbrial operons. We classified these fimbriae into three groups by their genetic relationship to other chaperone-usher fimbriae. Sixteen of these fimbriae are encoded by all seven currently sequenced P. mirabilis genomes. The predicted protein sequence of the major structural subunit for 14 of these fimbriae was highly conserved (≥ 95% identity), whereas three other structural subunits (Fim3A, UcaA and Fim6A) were variable. Further examination of 58 clinical isolates showed that 14 of the 17 predicted major structural subunit genes of the fimbriae were present in most strains (>85%). Transcription of the predicted major structural subunit genes for all 17 fimbriae was measured under different culture conditions designed to mimic conditions in the urinary tract. The majority of the fimbrial genes were induced during stationary phase, static culture or colony growth when compared to exponential-phase aerated culture. Major structural subunit proteins for six of these fimbriae were detected using MS of proteins sheared from the surface of broth-cultured P. mirabilis, demonstrating that this organism may produce multiple fimbriae within a single culture. The high degree of conservation of P. mirabilis fimbriae stands in contrast to uropathogenic Escherichia coli and Salmonella enterica, which exhibit greater variability in their fimbrial repertoires. These findings suggest there may be evolutionary pressure for P. mirabilis to maintain a large fimbrial arsenal.