Proteus mirabilis UreR coordinates cellular functions required for urease activity.

A hallmark of Proteus mirabilis infection of the urinary tract is the formation of stones. The ability to induce urinary stone formation requires urease, a nickel metalloenzyme that hydrolyzes urea. This reaction produces ammonia as a byproduct, which can serve as a nitrogen source and weak base that raises the local pH. The resulting alkalinity induces the precipitation of ions to form stones. Transcriptional regulator UreR activates expression of urease genes in a urea-dependent manner. Thus, urease genes are highly expressed in the urinary tract where urea is abundant. Production of mature urease also requires the import of nickel into the cytoplasm and its incorporation into the urease apoenzyme. Urease accessory proteins primarily acquire nickel from one of two nickel transporters and facilitate incorporation of nickel to form mature urease. In this study, we performed a comprehensive RNA-seq to define the P. mirabilis urea-induced transcriptome as well as the UreR regulon. We identified UreR as the first defined regulator of nickel transport in P. mirabilis. We also offer evidence for the direct regulation of the Ynt nickel transporter by UreR. Using bioinformatics, we identified UreR-regulated urease loci in 15 Morganellaceae family species across three genera. Additionally, we located two mobilized UreR-regulated urease loci that also encode the ynt transporter, implying that UreR regulation of nickel transport is a conserved regulatory relationship. Our study demonstrates that UreR specifically regulates genes required to produce mature urease, an essential virulence factor for P. mirabilis uropathogenesis. IMPORTANCE: Catheter-associated urinary tract infections (CAUTIs) account for over 40% of acute nosocomial infections in the USA and generate $340 million in healthcare costs annually. A major causative agent of CAUTIs is Proteus mirabilis, an understudied Gram-negative pathogen noted for its ability to form urinary stones via the activity of urease. Urease mutants cannot induce stones and are attenuated in a murine UTI model, indicating this enzyme is essential to P. mirabilis pathogenesis. Transcriptional regulation of urease genes by UreR is well established; here, we expand the UreR regulon to include regulation of nickel import, a function required to produce mature urease. Furthermore, we reflect on the role of urea catalysis in P. mirabilis metabolism and provide evidence for its importance.

Genomic profiling of pan-drug resistant proteus mirabilis Isolates reveals antimicrobial resistance and virulence gene landscape.

Proteus mirabilis is a gram-negative pathogen that caused significant opportunistic infections. In this study we aimed to identify antimicrobial resistance (AMR) genes and virulence determinants in two pan-drug resistant isolate "Bacteria_11" and "Bacteria_27" using whole genome sequencing. Proteus mirabilis "Bacteria_11" and "Bacteria_27" were isolated from two different hospitalized patients in Egypt. Antimicrobial susceptibility determined using Vitek 2 system, then whole genome sequencing (WGS) using MinION nanopore sequencing was done. Antimicrobial resistant genes and virulence determinants were identified using ResFinder, CADR AMR database, Abricate tool and VF analyzer were used respectively. Multiple sequence alignment was performed using MAFFT and FastTree, respectively. All genes were present within bacterial chromosome and no plasmid was detected. "Bacteria_11" and "Bacteria_27" had sizes of approximately 4,128,657 bp and 4,120,646 bp respectively, with GC content of 39.15% and 39.09%. "Bacteria_11" and "Bacteria_27" harbored 43 and 42 antimicrobial resistance genes respectively with different resistance mechanisms, and up to 55 and 59 virulence genes respectively. Different resistance mechanisms were identified: antibiotic inactivation, antibiotic efflux, antibiotic target replacement, and antibiotic target change. We identified several genes associated with aminoglycoside resistance, sulfonamide resistance. trimethoprim resistance tetracycline resistance proteins. Also, those responsible for chloramphenicol resistance. For beta-lactam resistance, only blaVEB and blaCMY-2 genes were detected. Genome analysis revealed several virulence factors contribution in isolates pathogenicity and bacterial adaptation. As well as numerous typical secretion systems (TSSs) were present in the two isolates, including T6SS and T3SS. Whole genome sequencing of both isolates identify their genetic context of antimicrobial resistant genes and virulence determinants. This genomic analysis offers detailed representation of resistant mechanisms. Also, it clarifies P. mirabilis ability to acquire resistance and highlights the emergence of extensive drug resistant (XDR) and pan-drug resistant (PDR) strains. This may help in choosing the most appropriate antibiotic treatment and limiting broad spectrum antibiotic use.

Genetic characteristics of chromosomally integrated carbapenemase gene (blaNDM-1) in isolates of Proteus mirabilis.

OBJECTIVE: This study aims to conduct an in-depth genomic analysis of a carbapenem-resistant Proteus mirabilis strain to uncover the distribution and mechanisms of its resistance genes. METHODS: The research primarily utilized whole-genome sequencing to analyze the genome of the Proteus mirabilis strain. Additionally, antibiotic susceptibility tests were conducted to evaluate the strain's sensitivity to various antibiotics, and related case information was collected to analyze the clinical distribution characteristics of the resistant strain. RESULTS: Study on bacterial strain WF3430 from a tetanus and pneumonia patient reveals resistance to multiple antibiotics due to extensive use. Whole-genome sequencing exposes a 4,045,480 bp chromosome carrying 29 antibiotic resistance genes. Two multidrug-resistant (MDR) gene regions, resembling Tn6577 and Tn6589, were identified (MDR Region 1: 64.83 Kb, MDR Region 2: 85.64 Kbp). These regions, consist of integrative and conjugative elements (ICE) structures, highlight the intricate multidrug resistance in clinical settings. CONCLUSION: This study found that a CR-PMI strain exhibits a unique mechanism for acquiring antimicrobial resistance genes, such as blaNDM-1, located on the chromosome instead of plasmids. According to the results, there is increasing complexity in the mechanisms of horizontal transmission of resistance, necessitating a comprehensive understanding and implementation of targeted control measures in both hospital and community settings.

Distinct Commensals Induce Interleukin-1ß via NLRP3 Inflammasome in Inflammatory Monocytes to Promote Intestinal Inflammation in Response to Injury.

The microbiota stimulates inflammation, but the signaling pathways and the members of the microbiota involved remain poorly understood. We found that the microbiota induces interleukin-1ß (IL-1ß) release upon intestinal injury and that this is mediated via the NLRP3 inflammasome. Enterobacteriaceae and in particular the pathobiont Proteus mirabilis, induced robust IL-1ß release that was comparable to that induced by the pathogen Salmonella. Upon epithelial injury, production of IL-1ß in the intestine was largely mediated by intestinal Ly6C(high) monocytes, required chemokine receptor CCR2 and was abolished by deletion of IL-1ß in CCR2(+) blood monocytes. Furthermore, colonization with P. mirabilis promoted intestinal inflammation upon intestinal injury via the production of hemolysin, which required NLRP3 and IL-1 receptor signaling in vivo. Thus, upon intestinal injury, selective members of the microbiota stimulate newly recruited monocytes to induce NLRP3-dependent IL-1ß release, which promotes inflammation in the intestine.

In vitro and in vivo study of antibacterial and anti-encrustation coating on ureteric stents.

OBJECTIVES: To investigate the ability of propolis-coated ureteric stents to solve complications, especially urinary tract infections (UTIs) and crusting, in patients with long-term indwelling ureteric stents through antimicrobial and anti-calculus activities. MATERIALS AND METHODS: Polyurethane (PU) ureteric stents were immersed in the ethanol extract of propolis (EEP), a well-known antimicrobial honeybee product, and subjected to chemical, hydrophilic, and seismic tests. The antimicrobial activity of the EEP coating was then examined by in vitro investigation. Proteus mirabilis infection was induced in rats within uncoated and EEP-coated groups, and the infection, stone formation, and inflammation were monitored at various time points. RESULTS: The characterisation results showed that the hydrophilicity and stability of the EEP surface improved. In vitro tests revealed that the EEP coating was biocompatible, could eliminate >90% of bacteria biofilms attached to the stent and could maintain bacteriostatic properties for up to 3 months. The in vivo experiment revealed that the EEP-coating significantly reduced the amount of bacteria, stones, and salt deposits on the surface of the ureteric stents and decreased inflammation in the host tissue. CONCLUSIONS: Compared with clinically used PU stents, EEP-coated ureteric stents could better mitigate infections and prevent encrustation. Thus, this study demonstrated that propolis is a promising natural dressing material for ureteric stents.

Emergence and genomic chion of Proteus mirabilis harboring blaNDM-1 in Korean companion dogs.

Proteus mirabilis is a commensal bacterium dwelling in the gastrointestinal (GI) tract of humans and animals. Although New Delhi metallo-ß-lactamase 1 (NDM-1) producing P. mirabilis is emerging as a threat, its epidemiology in our society remains largely unknown. LHPm1, the first P. mirabilis isolate harboring NDM-1, was detected from a companion dog that resides with a human owner. The whole-genome study revealed 20 different antimicrobial resistance (AMR) genes against various classes of antimicrobial agents, which corresponded to the MIC results. Genomic regions, including MDR genes, were identified with multiple variations and visualized in a comparative manner. In the whole-genome epidemiological analysis, multiple phylogroups were identified, revealing the genetic relationship of LHPm1 with other P. mirabilis strains carrying various AMR genes. These genetic findings offer comprehensive insights into NDM-1-producing P. mirabilis, underscoring the need for urgent control measures and surveillance programs using a "one health approach".

Identification of mechanisms modulating chlorhexidine and octenidine susceptibility in Proteus mirabilis.

AIMS: We aimed to identify mechanisms underlying the tolerance of Proteus mirabilis-a common cause of catheter associated urinary tract infection-to the clinically used biocides chlorhexidine (CHD) and octenidine (OCT). METHODS AND RESULTS: We adapted three clinical isolates to grow at concentrations of 512 µg ml-1 CHD and 128 µg ml-1 OCT. Genetic characterization and complementation studies revealed mutations inactivating the smvR repressor and increasing smvA efflux expression were associated with adaptation to both biocides. Mutations in mipA (encoding the MltA interacting protein) were less prevalent than smvR mutations and only identified in CHD adapted populations. Mutations in the rppA response regulator were exclusive to one adapted isolate and were linked with reduced polymyxin B susceptibility and a predicted gain of function after biocide adaptation. Biocide adaptation had no impact on crystalline biofilm formation. CONCLUSIONS: SmvR inactivation is a key mechanism in both CHD and OCT tolerance. MipA inactivation alone confers moderate protection against CHD, and rppA showed no direct role in either CHD or OCT susceptibility.

Emergence of extensive drug resistance and high prevalence of multidrug resistance among clinical Proteus mirabilis isolates in Egypt.

BACKGROUND: Proteus mirabilis is an opportunistic pathogen that has been held responsible for numerous nosocomial and community-acquired infections which are difficult to be controlled because of its diverse antimicrobial resistance mechanisms. METHODS: Antimicrobial susceptibility patterns of P. mirabilis isolates collected from different clinical sources in Mansoura University Hospitals, Egypt was determined. Moreover, the underlying resistance mechanisms and genetic relatedness between isolates were investigated. RESULTS: Antimicrobial susceptibility testing indicated elevated levels of resistance to different classes of antimicrobials among the tested P. mirabilis clinical isolates (n = 66). ERIC-PCR showed great diversity among the tested isolates. Six isolates (9.1%) were XDR while all the remaining isolates were MDR. ESBLs and AmpCs were detected in 57.6% and 21.2% of the isolates, respectively, where blaTEM, blaSHV, blaCTX-M, blaCIT-M and blaAmpC were detected. Carbapenemases and MBLs were detected in 10.6 and 9.1% of the isolates, respectively, where blaOXA-48 and blaNDM-1 genes were detected. Quinolone resistant isolates (75.8%) harbored acc(6')-Ib-cr, qnrD, qnrA, and qnrS genes. Resistance to aminoglycosides, trimethoprim-sulfamethoxazole and chloramphenicol exceeded 80%. Fosfomycin was the most active drug against the tested isolates as only 22.7% were resistant. Class I or II integrons were detected in 86.4% of the isolates. Among class I integron positive isolates, four different gene cassette arrays (dfrA17- aadA5, aadB-aadA2, aadA2-lnuF, and dfrA14-arr-3-blaOXA-10-aadA15) and two gene cassettes (dfrA7 and aadA1) were detected. While class II integron positive isolates carried four different gene cassette arrays (dfrA1-sat1-aadA1, estXVr-sat2-aadA1, lnuF- dfrA1-aadA1, and dfrA1-sat2). CONCLUSION: P. Mirabilis ability to acquire resistance determinants via integrons may be held responsible for the elevated rates of antimicrobial resistance and emergence of XDR or even PDR strains limiting the available therapeutic options for management of infections caused by those strains.

Potential antivirulence activity of sub-inhibitory concentrations of ciprofloxacin against Proteus mirabilis isolates: an in-vitro and in-vivo study.

BACKGROUND: Proteus mirabilis is a significant nosocomial pathogen that is frequently associated with a wide range of infections, necessitating heightened attention to mitigate potential health risks. Hence, this study was performed to investigate the impact of sub-minimum inhibitory concentrations (MICs) of ciprofloxacin (CIP) on Proteus mirabilis clinical isolates. METHODS: The sub-MICs of CIP were selected using the growth curve approach. The untreated and treated isolates with sub-MICs of CIP were assessed for their biofilm development, motilities on agar, and other virulence factors. The cell morphology of untreated and treated isolates with sub-MIC of CIP was explored using electron microscope. Moreover, the expression levels of the virulence genes in isolates were measured using quantitative real-time PCR. RESULTS: Data revealed that sub-MICs of CIP significantly (p < 0.05), in a concentration-dependent manner, inhibited biofilm formation and other virulence factors in the selected isolates. Electron microscope analysis showed cell enlargement and various abnormalities in the cell wall and membrane integrity. CONCLUSION: Sub-MICs of CIP exhibited inhibition of virulence and alterations in morphological integrity against P. mirabilis isolates.

Molecular characterization of a carbon dioxide-dependent Proteus mirabilis small-colony variant isolated from a clinical specimen.

INTRODUCTION: Carbon dioxide-dependent Proteus mirabilis has been isolated from clinical specimens. It is not clear whether mutations in carbonic anhydrase are responsible for the carbon dioxide dependence of P. mirabilis. The pathogenicity of carbon dioxide-dependent P. mirabilis also remains unclear. The purpose of this study was to determine the cause carbon dioxide dependence of P. mirabilis and its pathogenicity. METHODS: The DNA sequence of can encoding carbonic anhydrase of a carbon dioxide-dependent P. mirabilis small colony variant (SCV) isolate was analyzed. To confirm that impaired carbonic anhydrase activity is responsible for the formation of the carbon dioxide-dependent SCV phenotype of P. mirabilis, we performed complementation experiments using plasmids with intact can. Additionally, mouse infection experiments were performed to confirm the change in virulence due to the mutation of carbonic anhydrase. RESULTS: We found that the can gene of the carbon dioxide-dependent P. mirabilis SCV isolate showed had a frameshift mutation with a deletion of 1 bp (c. 173delC). The can of P. mirabilis encodes carbonic anhydrase was also found to function in Escherichia coli. The cause of the carbon dioxide-dependent SCV phenotype of P. mirabilis was an abnormality in carbonic anhydrase. Nevertheless, no changes were observed in virulence due to the mutation of carbonic anhydrase in mouse infection experiments. CONCLUSIONS: The can gene is essential for the growth of P. mirabilis in ambient air. The mechanisms underlying this fitness advantage in terms of infection warrant further investigation.

Preferential catabolism of l- vs d-serine by Proteus mirabilis contributes to pathogenesis and catheter-associated urinary tract infection.

Proteus mirabilis is a common cause of urinary tract infection, especially in catheterized individuals. Amino acids are the predominant nutrient for bacteria during growth in urine, and our prior studies identified several amino acid import and catabolism genes as fitness factors for P. mirabilis catheter-associated urinary tract infection (CAUTI), particularly those for d- and l-serine. In this study, we sought to determine the hierarchy of amino acid utilization by P. mirabilis and to examine the relative importance of d- vs l-serine catabolism for critical steps in CAUTI development and progression. Herein, we show that P. mirabilis preferentially catabolizes l-serine during growth in human urine, followed by d-serine, threonine, tyrosine, glutamine, tryptophan, and phenylalanine. Independently disrupting catabolism of either d- or l-serine has minimal impact on in vitro phenotypes while completely disrupting both pathways decreases motility, biofilm formation, and fitness due to perturbation of membrane potential and cell wall biosynthesis. In a mouse model of CAUTI, loss of either serine catabolism system decreased fitness, but disrupting l-serine catabolism caused a greater fitness defect than disrupting d-serine catabolism. We, therefore, conclude that the hierarchical utilization of amino acids may be a critical component of P. mirabilis colonization and pathogenesis within the urinary tract.

Complicated pyelonephritis caused by Proteus alimentorum in a woman with peritoneal cancer: a case report.

BACKGROUND: Proteus spp. are widespread in the environment and comprise a part of the normal flora of the human gastrointestinal tract. Only six species in this genus, including Proteus mirabilis, Proteus vulgaris, Proteus terrae, Proteus penneri, Proteus hauseri, and Proteus faecis, have been isolated from human clinical specimens. However, there are no reports of Proteus alimentorum isolated from humans, and the clinical characteristics of P. alimentorum infection are unknown. CASE PRESENTATION: An 85-year-old female patient with peritoneal cancer was hospitalized for complicated pyelonephritis and bacteremia caused by P. alimentorum. The patient received antimicrobial therapy and was discharged on day 7 of hospitalization. No recurrence was observed 14 days after the treatment. Various methods were used to identify the Proteus sp. Furthermore, the VITEK-2 GN ID card resulted in low discrimination between P. hauseri and P. penneri. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry showed P. hauseri with a spectral score of 2.22 as the best match. Nevertheless, the pathogen was identified as P. alimentorum based on genetic investigation using 16 S rRNA gene sequencing and biochemical tests. CONCLUSION: Proteus alimentorum is a human pathogen, and its infection has an excellent therapeutic response to antimicrobials based on antimicrobial susceptibility. Genomic methods may be helpful for the precise identification of P. alimentorum.

Genomes comparison of two Proteus mirabilis clones showing varied swarming ability.

BACKGROUND: Proteus mirabilis is a Gram-negative bacteria most noted for its involvement with catheter-associated urinary tract infections. It is also known for its multicellular migration over solid surfaces, referred to as 'swarming motility'. Here we analyzed the genomic sequences of two P. mirabilis isolates, designated K38 and K39, which exhibit varied swarming ability. METHODS AND RESULTS: The isolates genomes were sequenced using Illumina NextSeq sequencer, resulting in about 3.94 Mbp, with a GC content of 38.6%, genomes. Genomes were subjected for in silico comparative investigation. We revealed that, despite a difference in swarming motility, the isolates showed high genomic relatedness (up to 100% ANI similarity), suggesting that one of the isolates probably originated from the other. CONCLUSIONS: The genomic sequences will allow us to investigate the mechanism driving this intriguing phenotypic heterogeneity between closely related P. mirabilis isolates. Phenotypic heterogeneity is an adaptive strategy of bacterial cells to several environmental pressures. It is also an important factor related to their pathogenesis. Therefore, the availability of these genomic sequences will facilitate studies that focus on the host-pathogen interactions during catheter-associated urinary tract infections.

Infection responsive coatings to reduce biofilm formation and encrustation of urinary catheters.

AIMS: The care of patients undergoing long-term urethral catheterization is frequently complicated by Proteus mirabilis infection. This organism forms dense, crystalline biofilms, which block catheters leading to serious clinical conditions. However, there are currently no truly effective approaches to control this problem. Here, we describe the development of a novel theranostic catheter coating, to simultaneously provide early warning of blockage, and actively delay crystalline biofilm formation. METHODS AND RESULTS: The coating comprises of a pH sensitive upper polymer layer (poly(methyl methacrylate-co-methacrylic acid); Eudragit S 100®) and a hydrogel base layer of poly(vinyl alcohol), which is loaded with therapeutic agents (acetohydroxamic acid or ciprofloxacin hydrochloride) and a fluorescent dye, 5(6)-carboxyfluorescein (CF). The elevation of urinary pH due to P. mirabilis urease activity results in the dissolution of the upper layer and release of cargo agents contained in the base layer. Experiments using in vitro models, which were representative of P. mirabilis catheter-associated urinary tract infections, demonstrated that these coatings significantly delay time taken for catheters to block. Coatings containing both CF dye and ciprofloxacin HCl were able to provide an average of ca. 79 h advanced warning of blockage and extend catheter lifespan ca. 3.40-fold. CONCLUSIONS: This study has demonstrated the potential for theranostic, infection-responsive coatings to form a promising approach to combat catheter encrustation and actively delay blockage.

Frequency distribution of virulence factors and antibiotic resistance genes in uropathogenic Proteus species isolated from clinical samples.

One of the most common causes of urinary tract infections (UTIs) is Proteus species. Because there is little information on the pathogenicity of Proteus species isolated from Iran, we assessed their virulence characteristics and antibiotic resistance in this study. In Shahrekord, Iran, 260 isolates of Proteus causing UTIs were identified from patients. Polymerase chain reaction for gene amplification was used to determine virulence features and antibiotic resistance gene distribution in uropathogenic Proteus spp. After biochemical and molecular analysis, 72 (27.69%) of the 260 collected samples were recognized as Proteus mirabilis, and 127 (48.84%) specimens were Pr. vulgaris in both male and female forms. A significant interaction effect between Pr. mirabilis and Pr. vulgaris infections and the sex of patients was seen in both the male and female groups. No statistically significant difference was observed between Pr. mirabilis infection and season in different year seasons. However, in different seasons of the year, a statistically significant difference was observed between infection with Pr. vulgaris in autumn and other seasons. There was a considerable difference between Pr. mirabilis and Pr. vulgaris infections at different ages in various age groups. As people aged, infections occurred more frequently. Fim,pap,kspMT, and set1 genes had the highest expression in both Pr. vulgaris and Pr. mirabilis. Also, the highest rate of antibiotic resistance of Pr. vulgaris and Pr. mirabilis is attributed to the high expression of aac(3)-IV,tet(A), and blaSHV genes. In conclusion, identifying these genes as the key controllers of Proteus virulence factors might help with better infection management.

Adjustment in the Composition and Organization of Proteus mirabilis Lipids during the Swarming Process.

Proteus mirabilis, an opportunistic pathogen of the urinary tract, is known for its dimorphism and mobility. A connection of lipid alterations, induced by the rods elongation process, with enhanced pathogenicity of long-form morphotype for the development of urinary tract infections, seems highly probable. Therefore, research on the adjustment in the composition and organization of P. mirabilis lipids forming elongated rods was undertaken. The analyses performed using the ultra-high performance liquid chromatography with tandem mass spectrometry showed that drastic modifications in the morphology of P. mirabilis rods that occur during the swarming process are directly related to deprivation of the long-form cells of PE 33:1 and PG 31:2 and their enrichment with PE 32:1, PE 34:1, PE 34:2, PG 30:2, PG 32:1, and PG 34:1. The analyses conducted by the gas chromatography-mass spectrometry showed negligible effects of the swarming process on fatty acids synthesis. However, the constant proportions between unsaturated and saturated fatty acids confirmed that phenotypic modifications in the P. mirabilis rods induced by motility were independent of the saturation of the phospholipid tails. The method of the Förster resonance energy transfer revealed the influence of the swarming process on the melting of ordered lipid rafts present in the short-form rods, corresponding to the homogeneity of lipid bilayers in the long-form rods of P. mirabilis. Confocal microscope photographs visualized strong Rhod-PE fluorescence of the whole area of swarmer cells, in contrast to weak membrane fluorescence of non-swarmer cells. It suggested an increased permeability of the P. mirabilis bilayers in long-form rods morphologically adapted to the swarming process. These studies clearly demonstrate that swarming motility regulates the lipid composition and organization in P. mirabilis rods.

MrpH, a new class of metal-binding adhesin, requires zinc to mediate biofilm formation.

Proteus mirabilis, a Gram-negative uropathogen, is a major causative agent in catheter-associated urinary tract infections (CAUTI). Mannose-resistant Proteus-like fimbriae (MR/P) are crucially important for P. mirabilis infectivity and are required for biofilm formation and auto-aggregation, as well as for bladder and kidney colonization. Here, the X-ray crystal structure of the MR/P tip adhesin, MrpH, is reported. The structure has a fold not previously described and contains a transition metal center with Zn2+ coordinated by three conserved histidine residues and a ligand. Using biofilm assays, chelation, metal complementation, and site-directed mutagenesis of the three histidines, we show that an intact metal binding site occupied by zinc is essential for MR/P fimbria-mediated biofilm formation, and furthermore, that P. mirabilis biofilm formation is reversible in a zinc-dependent manner. Zinc is also required for MR/P-dependent agglutination of erythrocytes, and mutation of the metal binding site renders P. mirabilis unfit in a mouse model of UTI. The studies presented here provide important clues as to the mechanism of MR/P-mediated biofilm formation and serve as a starting point for identifying the physiological MR/P fimbrial receptor.

Septic shock caused by a carbon dioxide-dependent and extended spectrum ß-lactamase-producing Proteus mirabilis small colony variant in a long-term bedridden patient.

Here, we report a 60-year-old chronically bedridden man with cerebral palsy who had septic shock following a history of urinary tract infection with extended spectrum ß-lactamase-producing and auxotrophic Proteus mirabilis detected on blood and urine cultures. This auxotroph formed small colonies only on the blood agar at 24 h in 5% CO2, but not in the conditions without CO2, and lacked motility and some biochemical activities. The five-year history of stones in the right renal pelvis suggests chronic urinary tract infection with P. mirabilis requiring a 28-day antibiotic treatment. This paper highlights that the CO2-dependent P. mirabilis small colony variant may cause sepsis, probably due to chronic infection in uroliths, which should warrant immediate identification.

Antibiotic Sensitivity of Proteus mirabilis Urinary Tract Infection in Patients with Urinary Calculi.

Background: The study's objective was to determine Proteus mirabilis susceptibility in individuals with urinary tract infections and stones to antibiotics and prescribe optimal antimicrobial treatment. Methods: Nonrepetitive Proteus mirabilis strains were isolated from urine specimens obtained from 317 patients diagnosed with urinary stones from January, 2018, to December, 2021. A VITEK mass spectrometer was used for species identification, and a VITEK-compact 2 automatic microbial system was used for the antimicrobial susceptibility test (AST). Susceptibility to imipenem and cefoperazone/sodium sulbactam was tested by the disc diffusion method (K-B method). The antibiotic sensitivity of the strains was analyzed by sex and season. Results: A total of 317 patients were reviewed: 202 females (63.7%) and 115 males (36.3%). Proteus mirabilis infections were observed during spring (21.8%, n = 69), summer (26.2%, n = 83), autumn (33.8%, n = 107), and winter (18.2%, n = 57). Proteus mirabilis infections in females were diagnosed most often during the fall (24.3%, n = 77) and during the summer in males (11.0%, n = 35) (p = 0.010). Female patients responded best to levofloxacin (p = 0.014), and male patients responded best to sulfamethoxazole (p = 0.023). Seasonal variation in antibiotic sensitivity was confirmed, with significantly higher rates in the winter for cefuroxime (p = 0.002) and sulfamethoxazole (p = 0.002). Significant seasonal increases were also found in levofloxacin sensitivity during the summer (p = 0.005). Conclusions: Highly effective antibiotics such as cefoxitin and ceftazidime should be used empirically by considering antibiotic sensitivity changes by sex, season, and year. Regional studies should be conducted frequently.

Combined Application of Aminoglycosides and Ascorbic Acid in the Elimination of Proteus mirabilis Rods Responsible for Causing Catheter-Associated Urinary Tract Infections (CAUTIs)-A Molecular Approach.

Proteus mirabilis is a common cause of catheter-associated urinary tract infections (CAUTIs). In this study, we verified the effectiveness of amikacin or gentamicin and ascorbic acid (AA) co-therapy in eliminating uropathogenic cells, as well as searched for the molecular basis of AA activity by applying chromatographic and fluorescent techniques. Under simulated physiological conditions, a combined activity of the antibiotic and AA supported the growth (threefold) of the P. mirabilis C12 strain, but reduced catheter colonization (≤30%) in comparison to the drug monotherapy. Slight modifications in the phospholipid and fatty acid profiles, as well as limited (≤62%) 2',7'-dichlorofluorescein fluorescence, corresponding to the hydroxyl radical level, allowed for the exclusion of the hypothesis that the anti-biofilm effect of AA was related to membrane perturbations of the C12 strain. However, the reduced (≤20%) fluorescence intensity of propidium iodide, as a result of a decrease in membrane permeability, may be evidence of P. mirabilis cell defense against AA activity. Quantitative analyses of ascorbic acid over time with a simultaneous measurement of the pH values proved that AA can be an effective urine acidifier, provided that it is devoid of the presence of urease-positive cells. Therefore, it could be useful in a prevention of recurrent CAUTIs, rather than in their treatment.