Proteus species bloodstream infections: Comparative epidemiology of three species.

BACKGROUND: Although Proteus species are occasional causes of serious infections, their epidemiology has not been well defined. The objective was to describe the overall and species-specific occurrence and determinants of Proteus species bloodstream infection (BSI) in a large Australian population. METHODS: All Queensland residents with Proteus species BSI identified within the publicly funded healthcare system between 2000 and 2019 were included. RESULTS: A total of 2,143 incident episodes of Proteus species BSI were identified among 2,079 Queensland residents. The prevalence of comorbid illness differed with higher Charlson comorbidity scores observed with P. penneri and P. vulgaris, and higher prevalence of liver disease with P. penneri, higher comorbid cancer with P. vulgaris, and lower diabetes and renal disease prevalence with P. mirabilis BSIs. CONCLUSION: This study provides novel information on the epidemiology of Proteus species BSI.

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".

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.

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.

N-acetylcysteine prevents catheter occlusion and inflammation in catheter associated-urinary tract infections by suppressing urease activity.

Introduction: Proteus mirabilis is a key pathobiont in catheter-associated urinary tract infections (CA-UTIs), which is well known to form crystalline biofilms that occlude catheters. Urease activity alkylates urine through the release of ammonia, consequentially resulting in higher levels of Mg2+ and Ca2+ and formation of crystals. In this study, we showed that N-acetyl cysteine (NAC), a thiol antioxidant, is a potent urease inhibitor that prevents crystalline biofilm formation. Methods: To quantify urease activity, Berthelot's method was done on bacterial extracts treated with NAC. We also used an in vitro catheterised glass bladder model to study the effect of NAC treatment on catheter occlusion and biofilm encrustation in P. mirabilis infections. Inductively-coupled plasma mass spectrometry (ICP-MS) was performed on catheter samples to decipher elemental profiles. Results: NAC inhibits urease activity of clinical P. mirabilis isolates at concentrations as low as 1 mM, independent of bacterial killing. The study also showed that NAC is bacteriostatic on P. mirabilis, and inhibited biofilm formation and catheter occlusion in an in vitro. A significant 4-8log10 reduction in viable bacteria was observed in catheters infected in this model. Additionally, biofilms in NAC treated catheters displayed a depletion of calcium, magnesium, or phosphates (>10 fold reduction), thus confirming the absence of any urease activity in the presence of NAC. Interestingly, we also showed that not only is NAC anti-inflammatory in bladder epithelial cells (BECs), but that it mutes its inflammatory response to urease and P. mirabilis infection by reducing the production of IL-6, IL-8 and IL-1b. Discussion: Using biochemical, microbiological and immunological techniques, this study displays the functionality of NAC in preventing catheter occlusion by inhibiting urease activity. The study also highlights NAC as a strong anti-inflammatory antibiofilm agent that can target both bacterial and host factors in the treatment of CA-UTIs.

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.

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.

Whole genome sequencing of multidrug-resistant Proteus mirabilis strain PM1162 recovered from a urinary tract infection in China.

OBJECTIVES: Proteus mirabilis is an important opportunistic Gram-negative pathogen. This study reports the whole genome sequence of multidrug-resistant (MDR) P. mirabilis PM1162 and explores its antibiotic resistance genes (ARGs) and their genetic environments. METHODS: P. mirabilis PM1162 was isolated from a urinary tract infection in China. Antimicrobial susceptibility was determined, and whole genome sequencing (WGS) was performed. ARGs, insertion sequence (IS) elements, and prophages were identified using ResFinder, ISfinder, and PHASTER software, respectively. Sequence comparisons and map generation were performed using BLAST and Easyfig, respectively. RESULTS: On its chromosome, P. mirabilis PM1162 harboured 15 ARGs, including cat, tet(J), blaCTX-M-14 (three copies), aph(3')-Ia, qnrB4, blaDHA-1, qacE, sul1, armA, msr(E), mph(E), aadA1, and dfrA1. We focused our analysis on the four related MDR regions: (1) genetic contexts associated with blaCTX-M-14; (2) the prophage containing blaDHA-1, qnrB4, and aph(3')-Ia; (3) genetic environments associated with mph(E), msr(E), armA, sul, and qacE; and (4) the class II integron harbouring dfrA1, sat2, and aadA1. CONCLUSION: This study reported the whole genome sequence of MDR P. mirabilis PM1162 and the genetic context of its ARGs. This comprehensive genomic analysis of MDR P. mirabilis PM1162 provides a deeper understanding of its MDR mechanism and elucidates the horizontal spread of its ARGs, thus providing a basis for the containment and treatment of the bacteria.

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.

Construction of an Ordered Transposon Library for Uropathogenic Proteus mirabilis HI4320.

Ordered transposon libraries are a valuable resource for many bacterial species, especially those with difficult methods for generating targeted genetic mutations. Here, we present the construction of an ordered transposon library for the bacterial urinary tract pathogen Proteus mirabilis strain HI4320. This library will facilitate future studies into P. mirabilis biology. For large experimental screens, it may be used to overcome bottleneck constraints and avoid biased outcomes resulting from gene length. For smaller studies, the library allows sidestepping the laborious construction of single targeted mutants. This library, containing 18,432 wells, was condensed into a smaller library containing 1,728 mutants. Each selected mutant had a single transposon insertion in an open reading frame, covering 45% of predicted genes encoded by P. mirabilis HI4320. This coverage was lower than expected and was due both to library wells with no mapped insertions and a surprisingly high proportion of mixed clones and multiple transposon insertion events. We offer recommendations for improving future library construction and suggestions for how to use this P. mirabilis library resource. IMPORTANCE Ordered libraries facilitate large genetic screens by guaranteeing high genomic coverage with a minimal number of mutants, and they can save time and effort by reducing the need to construct targeted mutations. This resource is now available for P. mirabilis, a common and complicating agent of catheter-associated urinary tract infection. We also present obstacles encountered during library construction with the goal to aid others who would like to construct ordered transposon libraries in other species.

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.

A Phage Cocktail To Control Surface Colonization by Proteus mirabilis in Catheter-Associated Urinary Tract Infections.

Proteus mirabilis is a biofilm-forming bacterium and one of the most common causes of catheter-associated urinary tract infections (CAUTIs). The rapid spread of multidrug-resistant P. mirabilis represents a severe threat to management of nosocomial infections. This study aimed to isolate a potent phage cocktail and assess its potential to control urinary tract infections caused by biofilm-forming P. mirabilis. Two lytic phages, Isf-Pm1 and Isf-Pm2, were isolated and characterized by proteome analysis, transmission electron microscopy, and whole-genome sequencing. The host range and effect of the phage cocktail to reduce the biofilm formation were assessed by a cell adhesion assay in Vero cells and a phantom bladder model. The samples treated with the phage cocktail showed a significant reduction (65%) in the biofilm mass. Anti-quorum sensing and quantitative real-time PCR assays were also used to assess the amounts of transcription of genes involved in quorum sensing and biofilm formation. Furthermore, the phage-treated samples showed a downregulation of genes involved in the biofilm formation. In conclusion, these results highlight the efficacy of two isolated phages to control the biofilms produced by P. mirabilis CAUTIs. IMPORTANCE The rapid spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacterial strains and biofilm formation of bacteria have severely restricted the use of antibiotics and become a challenging issue in hospitals. Therefore, there is a necessity for alternative or complementary treatment measures, such as the use of virulent bacteriophages (phages), as effective therapeutic strategies.

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.

Bacteriological Study of Urinary Tract Infections among Pregnant Women in Al Samawa City of Iraq.

Pregnancy causes some changes in pregnant women due to mechanical and hormonal changes that lead to ureteral dilatation and urinary stasis which in turn contribute to an increased risk of developing urinary tract infection (UTI). This study aimed to determine the frequency of urinary tract infections among pregnant women in Samawa city, Iraq, and examine the isolated organisms. In total, 210 and 55 urine samples were collected from pregnant and non-pregnant women with clinical signs and symptoms of UTI who were hospitalized in the Obstetric and Pediatric Hospital in Samawa, Iraq, respectively. The data collected from each woman included their age, gestational period, parity, level of education, and residence. The frequency of urinary tract infections among the studied woman was 86%. Escherichia coli (38.6%), staphylococcus aureus (20.4%), and Proteus mirabilis (12.7%) were the most frequently isolated bacteria in the current study. According to the recorded data in this study, 86% of the infections in pregnant women occurred in the age group of 25-34 years (52.4%) and the 3rd trimester of pregnancy (49.1%). On the other hand, the results revealed that the infection rate in women with one to three pregnancies was 50.2% more than non-pregnant women. The findings of the current study showed that the highest rate of infection was observed in women who were in the age range of 25-34 years (52.4%). This can be explained by the fact that women often experience the highest reproductive activity during this period. In fact, in this period of life, women are most prone to sexual activity which predisposes them to the introduction of microorganisms to the urinary tract which causes infection. The recorded data showed that UTI became more prevalent with the progress of pregnancy, accounting for 49.1% of infections occurring in the third trimester of pregnancy. Parity and frequent pregnancies are other factors that account for 50.2% of UTI. The prevalence of UTI in women with 1 to 3 children was 58.5%. Moreover, the rate of UTI was 61.3% among pregnant women who attended the antenatal care unit, which was the highest risk of UTI among the pregnant participants. In the non-pregnant women, the prevalence of UTI was 50.2 at the age range of 6-12 years. Based on the obtained results, pregnant women were more vulnerable to renal infection. On the other hand, the concurrence of UTI was positively influenced by sexual activity and pregnancy.

Association of Proteus mirabilis and Providencia stuartii Infections with Diabetes.

Background and Objectives: Proteus and Providencia are related genera of opportunistic pathogens belonging to the Morganellaceae family, often a cause of infections in the immunocompromised hosts, such as diabetic patients. Their clinical significance has increased due to their intrinsic resistance to polymyxins, which is often associated with acquired resistance mechanisms. In this study we evaluated the infections caused by Proteus mirabilis and Providencia stuartii in two groups of patients, with diabetes (group 1) and without diabetes (group 2) admitted to the intensive care unit and surgical wards. The infections were investigated in terms of infection type, risk factors, clinical course, predictive factors for unfavourable outcomes and antibiotic resistance profile. Materials and Methods: An observational, retrospective, cross-sectional study was conducted, comprising all patients infected with these pathogens. Bacterial identification and antibiotic sensitivity testing were performed using the Vitek2C automated system. Results: Comparison of the two groups showed that the statistically significant common infectious risk factors were found less frequently among diabetic patients when compared with non-diabetic patients, and that antimicrobial resistance was significantly lower in the diabetic patient group. However, survival rates did not differ between the two groups, drawing attention to the implications of diabetes as comorbidity. Additionally, with regard to the antibiotic resistance profile, 38.89% of P. stuartii strains isolated from diabetic patients belonged to the difficult-to-treat (DTR) phenotype, contributing to the severity of these infections compared with those caused by P. mirabilis, of which 32% were wild type strains and 0% were DTR phenotype. The DTR/extended spectrum beta-lactamase producing P. stuartii isolates more than doubled the risk of mortality, while the presence of nasogastric nutrition tripled the risk. Conclusions: P. stuartii infections that occurred in diabetic patients proved to be more difficult to treat, the majority of them being healthcare-associated bacteremias.

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.