Differential Contribution of Hydrogen Metabolism to Proteus mirabilis Fitness during Single-Species and Polymicrobial Catheterized Urinary Tract Infection

Proteus mirabilis is a common uropathogen and a leading cause of catheter-associated urinary tract infections (CAUTIs), which are often polymicrobial. Through a genome-wide screen, we previously identified two [NiFe] hydrogenases as candidate fitness factors for P. mirabilis CAUTI: a Hyb-type Group 1c H2-uptake hydrogenase and a Hyf-type Group 4a H2-producing hydrogenase. In this study, we disrupted one gene of each system (hyfE and hybC) and also generated a double mutant to examine the contribution of flexible H2 metabolism to P. mirabilis growth and fitness in vitro and during experimental CAUTI. Since P. mirabilis is typically present as part of a polymicrobial community in the urinary tract, we also examined the impact of two common co-colonization partners, Providencia stuartii and Enterococcus faecalis, on the expression and contribution of each hydrogenase to fitness. Our data demonstrate that neither system alone is critical for P. mirabilis growth in vitro or fitness during experimental CAUTI. However, perturbation of flexible H2 metabolism in the ∆hybC∆hyfE double mutant decreased P. mirabilis fitness in vitro and during infection. The Hyf system alone contributed to the generation of proton motive force and swarming motility, but only during anaerobic conditions. Unexpectedly, both systems contributed to benzyl viologen reduction in TYET medium, and disruption of either system increased expression of the other. We further demonstrate that polymicrobial interactions with P. stuartii and E. faecalis alter the expression of Hyb and Hyf in vitro as well as the contribution of each system to P. mirabilis fitness during CAUTI.

An Integrative Approach to Study the Inhibition of Providencia vermicola FabD Using C2-Quaternary Indolinones

Background

The present study investigates the potential bioactivity of twelve experimentally designed C-2 quaternary indolinones against Providencia spp., a bacterial group of the Enterobacteriaceae family known to cause urinary tract infections. The study aims to provide insights into the bioactive properties of the investigated compounds and their potential use in developing novel treatments against Providencia spp. The experimental design of indolinones, combined with their unique chemical structure, makes them attractive candidates for further investigation. The results of this research may contribute to the development of novel therapeutic agents to combat Providencia spp. infections.

Methods

The synthesized indolinones (moL1-moL12) are evaluated to identify any superior activity, particularly focusing on moL12, which possesses aza functionality. The antimicrobial activities of all twelve compounds are tested in triplicates against six different Gram-positive and Gram-negative organisms, including P. vermicola (P<0.05). Computational methods have been employed to assess the pharmacokinetic properties of the compounds.

Results

Among the synthesized indolinones, moL12 exhibits superior activity compared to the other compounds with similar skeleton but different functional moieties. All six strains tested, including P. vermicola, demonstrated sensitivity to moL12. Computational studies support the pharmacokinetic properties of moL12, indicating acceptable absorption, distribution, metabolism, excretion, and toxicity characteristics.

Conclusion

Utilizing the PPI approach, we have identified a promising target, FabD, in Gram-negative bacteria. Our analysis has shown that moL12 exhibits significant potential in binding with FabD, thereby, might inhibit cell wall formation, and display superior antimicrobial activity compared to other compounds. Consequently, moL12 may be a potential therapeutic agent that could be used to combat urinary tract infections caused by Providencia spp. The findings of this research hold significant promise for the development of new and effective treatments for bacterial infections.

Genotypic Evolution of Klebsiella pneumoniae Sequence Type 512 during Ceftazidime/Avibactam, Meropenem/Vaborbactam, and Cefiderocol Treatment, Italy

In February 2022, a critically ill patient colonized with a carbapenem-resistant K. pneumoniae producing KPC-3 and VIM-1 carbapenemases was hospitalized for SARS-CoV-2 in the intensive care unit of Policlinico Umberto I hospital in Rome, Italy. During 95 days of hospitalization, ceftazidime/avibactam, meropenem/vaborbactam, and cefiderocol were administered consecutively to treat 3 respiratory tract infections sustained by different bacterial agents. Those therapies altered the resistome of K. pneumoniae sequence type 512 colonizing or infecting the patient during the hospitalization period. In vivo evolution of the K. pneumoniae sequence type 512 resistome occurred through plasmid loss, outer membrane porin alteration, and a nonsense mutation in the cirA siderophore gene, resulting in high levels of cefiderocol resistance. Cross-selection can occur between K. pneumoniae and treatments prescribed for other infective agents. K. pneumoniae can stably colonize a patient, and antimicrobial-selective pressure can promote progressive K. pneumoniae resistome evolution, indicating a substantial public health threat.

Genome-Based Retrospective Analysis of a Providencia stuartii Outbreak in Rome, Italy: Broad Spectrum IncC Plasmids Spread the NDM Carbapenemase within the Hospital

Providencia stuartii is a member of the Morganellaceae family, notorious for its intrinsic resistance to several antibiotics, including last-resort drugs such as colistin and tigecycline. Between February and March 2022, a four-patient outbreak sustained by P. stuartii occurred in a hospital in Rome. Phenotypic analyses defined these strains as eXtensively Drug-Resistant (XDR). Whole-genome sequencing was performed on the representative P. stuartii strains and resulted in fully closed genomes and plasmids. The genomes were highly related phylogenetically and encoded various virulence factors, including fimbrial clusters. The XDR phenotype was primarily driven by the presence of the bla_NDM-1 metallo-β-lactamase alongside the rmtC 16S rRNA methyltransferase, conferring resistance to most β-lactams and every aminoglycoside, respectively. These genes were found on an IncC plasmid that was highly related to an NDM-IncC plasmid retrieved from a ST15 Klebsiella pneumoniae strain circulating in the same hospital two years earlier. Given its ability to acquire resistance plasmids and its intrinsic resistance mechanisms, P. stuartii is a formidable pathogen. The emergence of XDR P. stuartii strains poses a significant public health threat. It is essential to monitor the spread of these strains and develop new strategies for their control and treatment.

AadA36, a novel chromosomal aminoglycoside nucleotidyltransferase from a clinical isolate of Providencia stuartii

In this study, we characterized a novel chromosome-encoded aminoglycoside nucleotidyltransferase (ANT), AadA36, from the Providencia stuartii strain P14 isolated from the sputum specimen of a burn patient at a hospital in Wenzhou, China. Among the functionally characterized ANTs, AadA36 shared the highest amino acid sequence identity of 51.91% with AadA14. The whole genome of P. stuartii P14 consisted of one chromosome and two plasmids (designated pP14-166 and pP14-114). A total of 19 genes with ≥80% similarity with functionally characterized antimicrobial resistance genes (ARGs) were identified in the whole genome, including aminoglycosides [aac(2')-Ia, aph(6)-Id, aph(3″)-Ib, aac(6')-Ib, ant(3″)-IIa, aph(3')-Ia], β-lactams (bla _CMY-2 and bla _OXA-10) and so on. Antimicrobial susceptibility testing showed that the aadA36 gene conferred specific resistance to spectinomycin and streptomycin, and the minimum inhibitory concentration (MIC) of these antimicrobials increased 128- and 64-fold compared with the control strain. The kinetic parameters of AadA36 were consistent with the MIC data of spectinomycin and streptomycin, with k_cat /K_m ratios of (1.07 ± 2.23) × 10⁴ M^-1 s^-1 and (8.96 ± 1.01) × 10³ M^-1 s^-1, respectively. The identification of a novel aminoglycoside resistance gene will help us further understand the complexity of the resistance mechanisms and provide deep insights into the dissemination of resistance genes in the microbial population.

Socialization of Providencia stuartii Enables Resistance to Environmental Insults

Providencia stuartii is a highly social pathogen responsible for nosocomial chronic urinary tract infections. The bacterium indeed forms floating communities of cells (FCC) besides and prior-to canonical surface-attached biofilms (SAB). Within P. stuartii FCC, cells are riveted one to another owing to by self-interactions between its porins, viz. Omp-Pst1 and Omp-Pst2. In pathophysiological conditions, P. stuartii is principally exposed to high concentrations of urea, ammonia, bicarbonate, creatinine and to large variations of pH, questioning how these environmental cues affect socialization, and whether formation of SAB and FCC protects cells against those. Results from our investigations indicate that FCC and SAB can both form in the urinary tract, endowing cells with increased resistance and fitness. They additionally show that while Omp-Pst1 is the main gateway allowing penetration of urea, bicarbonate and ammonia into the periplasm, expression of Omp-Pst2 enables resistance to them.

Targeting Biofilm of MDR Providencia stuartii by Phages Using a Catheter Model

Providencia spp. are emerging pathogens mainly in nosocomial infections. Providencia stuartii in particular is involved in urinary tract infections and contributes significantly to the high incidence of biofilm-formation in catheterized patients. Furthermore, recent reports suggested a role for multiple drug resistant (MDR) P. stuartii in hospital-associated outbreaks which leads to excessive complications resulting in challenging treatments. Phage therapy is currently one of the most promising solutions to combat antibiotic-resistant infections. However, the number of available phages targeting Providencia spp. is extremely limited, restricting the use of phage therapy in such cases. In the present study, we describe the isolation and characterization of 17 lytic and temperate bacteriophages targeting clinical isolates of Providencia spp. as part of the Israeli Phage Bank (IPB). These phages, isolated from sewage samples, were evaluated for host range activity and effectively eradicated 95% of the tested bacterial strains isolated from different geographic locations and displaying a wide range of antibiotic resistance. Their lytic activity is demonstrated on agar plates, planktonic cultures, and biofilm formed in a catheter model. The results suggest that these bacteriophages can potentially be used for treatment of antibiotic-resistant Providencia spp. infections in general and of urinary tract infections in particular.

Clinical and drug resistance characteristics of Providencia stuartii infections in 76 patients

OBJECTIVES

To investigate the clinical and drug resistance characteristics of Providencia stuartii infections in the Huainan region of Anhui and provide a reference for the clinical selection of antimicrobial agents.

METHODS

This single-center retrospective analysis included 76 patients with P. stuartii infection in Huainan during the period from October 2018 to March 2020. The hospital department in which the patients were treated and the drug susceptibility characteristics of the P. stuartii isolates were recorded.

RESULTS

Among the 76 patients, the lung was the most common site of infection, and intensive care unit was the main hospital department. Extended spectrum beta-lactamase screening revealed expression by all 76 isolates of P. stuartii. Of the 76 isolates, 92.1% exhibited multiple drug resistance or extensive drug resistance. P. stuartii isolates were sensitive to cefepime and imipenem, but not to other beta-lactam antibiotics. Twenty isolates were resistant to all 21 types of antibiotics. Of the 20 patients infected with extensively drug-resistant isolates, nine (45%) died.

CONCLUSIONS

Drug resistance is increasing in P. stuartii. The antimicrobial agent imipenem may be effective for treatment of P. stuartii infections. Fluoroquinolones, aminoglycosides, and fourth-generation cephalosporins are suitable options for antibiotic therapy.

Application of Arjuna (Terminalia arjuna) seed biochar in hybrid treatment system for the bioremediation of Congo red dye

In the present study, a hybrid treatment system (biological and ozonation) was developed and used in the decolorization of Congo red (CR) dye. The biological treatment was performed in packed bed bioreactor (PBBR) containing Arjuna (Terminalia Arjuna) seeds biochar immobilized with Providencia stuartii, whereas ozonation was carried out in an ozone reactor. The process variables such as temperature, process time, and inoculum size were optimized and found to be 30 °C, 2 48 h, and 3 × 10⁵ CFU/mL, respectively with 92.0 ± 5.0% of dye decolorization. Furthermore, biologically treated effluent was subject to ozone treatment for the decolorization of the remaining CR dye. The hybrid approach reveals almost complete decolorization of Congo red (CR) dye. The kinetic study of microbial growth was examined by Monod model. In addition, the cost analysis estimation for the removal of CR dye was done, and removal per liter was found to be economic.

Anthocyanins in Blueberries Grown in Hot Climate Exert Strong Antioxidant Activity and May Be Effective against Urinary Tract Bacteria

Anthocyanins are extensively studied for their health-related properties, including antibacterial activity against urinary tract infections (UTI). Among common fruits, blueberries, with their remarkable antioxidant capacity, are one of the richest sources. Anthocyanin-rich extracts were obtained from four varieties: Snowchaser, Star, Stella Blue and Cristina Blue, grown in the hot climate of Southern Spain. Their total anthocyanins contents (TAC) were determined spectrophotometrically, and the anthocyanin profile by ultra high performance liquid chromatography—tandem mass spectrometer (UHPLC-MS/MS). Their antioxidant activity was assessed by oxygen radical absorbance capacity (ORAC) assay, while antibacterial activity against strains isolated from UTI patients was assessed in vitro, helping to select the varieties with the highest bioactive potential. Star showed the highest TAC and antioxidant activity (1663 ± 159 mg of cyanidin-3-O-glucoside (cy-3-O-glu) equivalents/100 g fresh weight (FW), 6345 ± 601 μmol Trolox equivalents (TE)/100 g FW, respectively), followed by Cristina Blue, Stella Blue and Snowchaser. As far as we know, this is the first time that cyanidin-3-rutinoside has been identified in blueberries. The extracts inhibited all the tested strains, MICs ranging from 0.4 mg/mL (for Stella Blue extract against UTI P. aeruginosa) to 9.5 mg/mL (for all extracts against UTI K. pneumoniae ssp. pneumoniae). This is the first study that assessed in vitro the antibacterial activity of blueberries against Klebsiella pneumoniae, Providencia stuartii and Micrococcus spp. strains isolated from UTI.

Transposon Insertion Site Sequencing of Providencia stuartii: Essential Genes, Fitness Factors for Catheter-Associated Urinary Tract Infection, and the Impact of Polymicrobial Infection on Fitness Requirements

Providencia stuartii is a common cause of polymicrobial catheter-associated urinary tract infection (CAUTI), and yet literature describing the molecular mechanisms of its pathogenesis is limited. To identify factors important for colonization during single-species infection and during polymicrobial infection with a common cocolonizer, Proteus mirabilis, we created a saturating library of ∼50,000 transposon mutants and conducted transposon insertion site sequencing (Tn-Seq) in a murine model of CAUTI. P. stuartii strain BE2467 carries 4,398 genes, 521 of which were identified as essential for growth in laboratory medium and therefore could not be assessed for contribution to infection. Using an input/output fold change cutoff value of 20 and P values of <0.05, 340 genes were identified as important for establishing single-species infection only and 63 genes as uniquely important for polymicrobial infection with P. mirabilis, and 168 genes contributed to both single-species and coinfection. Seven mutants were constructed for experimental validation of the primary screen that corresponded to flagella (fliC mutant), twin arginine translocation (tatC), an ATP-dependent protease (clpP), d-alanine-d-alanine ligase (ddlA), type 3 secretion (yscI and sopB), and type VI secretion (impJ). Infection-specific phenotypes validated 6/7 (86%) mutants during direct cochallenge with wild-type P. stuartii and 3/5 (60%) mutants during coinfection with P. mirabilis, for a combined validation rate of 9/12 (75%). Tn-Seq therefore successfully identified genes that contribute to fitness of P. stuartii within the urinary tract, determined the impact of coinfection on fitness requirements, and added to the identification of a collection of genes that may contribute to fitness of multiple urinary tract pathogens.IMPORTANCE Providencia stuartii is a common cause of polymicrobial catheter-associated urinary tract infections (CAUTIs), particularly during long-term catheterization. However, little is known regarding the pathogenesis of this organism. Using transposon insertion site sequencing (Tn-Seq), we performed a global assessment of P. stuartii fitness factors for CAUTI while simultaneously determining how coinfection with another pathogen alters fitness requirements. This approach provides four important contributions to the field: (i) the first global estimation of P. stuartii genes essential for growth in laboratory medium, (ii) identification of novel fitness factors for P. stuartii colonization of the catheterized urinary tract, (iii) identification of core fitness factors for both single-species and polymicrobial CAUTI, and (iv) assessment of conservation of fitness factors between common uropathogens. Genomewide assessment of the fitness requirements for common uropathogens during single-species and polymicrobial CAUTI thus elucidates complex interactions that contribute to disease severity and will uncover conserved targets for therapeutic intervention.

Dissemination of NDM-1 carbapenemase-producer Providencia stuartii strains in Romanian hospitals: a multicentre study

Several Romanian hospitals have noted increasing isolation of Providencia stuartii strains in recent years, with an alarming rate of carbapenem resistance. In order to provide molecular epidemiological data regarding their dissemination, 77 P. stuartii strains collected from five hospitals located in different regions of Romania were analysed. All strains harboured IncA/C plasmid, and 67 carried the blaNDM-1 gene. Six clonal clusters were differentiated by pulsed-field gel electrophoresis. The predominant subtype was found in all five hospitals. Our study highlights the need for efficient infection-control measures, the optimization of antibiotic use and the targeted surveillance for carbapenemase-producing P. stuartii.

d-Serine Degradation by Proteus mirabilis Contributes to Fitness during Single-Species and Polymicrobial Catheter-Associated Urinary Tract Infection

Urinary tract infections are among the most common health care-associated infections worldwide, the majority of which involve a urinary catheter (CAUTI). Our recent investigation of CAUTIs in nursing home residents identified Proteus mirabilis, Enterococcus species, and Escherichia coli as the three most common organisms. These infections are also often polymicrobial, and we identified Morganella morganii, Enterococcus species, and Providencia stuartii as being more prevalent during polymicrobial CAUTI than single-species infection. Our research therefore focuses on identifying “core” fitness factors that are highly conserved in P. mirabilis and that contribute to infection regardless of the presence of these other organisms. In this study, we determined that the ability to degrade d-serine, the most abundant d-amino acid in urine and serum, strongly contributes to P. mirabilis fitness within the urinary tract, even when competing for nutrients with another organism. d-Serine uptake and degradation therefore represent potential targets for disruption of P. mirabilis infections.

Proteus mirabilis is a common cause of catheter-associated urinary tract infection (CAUTI) and secondary bacteremia, which are frequently polymicrobial. We previously utilized transposon insertion-site sequencing (Tn-Seq) to identify novel fitness factors for colonization of the catheterized urinary tract during single-species and polymicrobial infection, revealing numerous metabolic pathways that may contribute to P. mirabilis fitness regardless of the presence of other cocolonizing organisms. One such “core” fitness factor was d-serine utilization. In this study, we generated isogenic mutants in d-serine dehydratase (dsdA), d-serine permease (dsdX), and the divergently transcribed activator of the operon (dsdC) to characterize d-serine utilization in P. mirabilis and explore the contribution of this pathway to fitness during single-species and polymicrobial infection. P. mirabilis was capable of utilizing either d- or l-serine as a sole carbon or nitrogen source, and dsdA, dsdX, and dsdC were each specifically required for d-serine degradation. This capability was highly conserved among P. mirabilis isolates, although not universal among uropathogens: Escherichia coli and Morganella morganii utilized d-serine, while Providencia stuartii and Enterococcus faecalis did not. d-Serine utilization did not contribute to P. mirabilis growth in urine ex vivo during a 6-h time course but significantly contributed to fitness during single-species and polymicrobial CAUTI during a 96-h time course, regardless of d-serine utilization by the coinfecting isolate. d-Serine utilization also contributed to secondary bacteremia during CAUTI as well as survival in a direct bacteremia model. Thus, we propose d-serine utilization as a core fitness factor in P. mirabilis and a possible target for disruption of infection.

IMPORTANCE Urinary tract infections are among the most common health care-associated infections worldwide, the majority of which involve a urinary catheter (CAUTI). Our recent investigation of CAUTIs in nursing home residents identified Proteus mirabilis, Enterococcus species, and Escherichia coli as the three most common organisms. These infections are also often polymicrobial, and we identified Morganella morganii, Enterococcus species, and Providencia stuartii as being more prevalent during polymicrobial CAUTI than single-species infection. Our research therefore focuses on identifying “core” fitness factors that are highly conserved in P. mirabilis and that contribute to infection regardless of the presence of these other organisms. In this study, we determined that the ability to degrade d-serine, the most abundant d-amino acid in urine and serum, strongly contributes to P. mirabilis fitness within the urinary tract, even when competing for nutrients with another organism. d-Serine uptake and degradation therefore represent potential targets for disruption of P. mirabilis infections.

First report of carbapenem-resistant Providencia stuartii in Saudi Arabia

We present the case of 31-year-old man who developed hospital-acquired pneumonia in the intensive care unit. Pathogens were identified to be carbapenem-resistant isolates of Providencia stuartii and Klebsiella pneumoniae. The patient was treated with an extended infusion of double-dose meropenem (targeting the carbapenem-resistant P. stuartii) and colistin (targeting the carbapenem-resistant K. pneumoniae) for 2 weeks. The patient's disease responded well to the prescribed regimen; his chest X-ray became normal, and all other signs of infection subsided. To our knowledge, this is the first description of the emergence of carbapenem-resistant P. stuartii due to AmpC hyperproduction in Saudi Arabia.

Immuno-informatics driven proteome-wide investigation revealed novel peptide-based vaccine targets against emerging multiple drug resistant Providencia stuartii

The bacterium Providencia stuartii, is associated with urinary tract infections and is the most common cause of purple urine bag syndrome. The increasing multi-drug resistance pattern shown by the pathogen and lack of licensed vaccines make treatment of infections caused by P. stuartii challenging. As vaccinology data against the pathogen is scarce, an in silico proteome based Reverse Vaccinology (RV) protocol, in combination with subtractive proteomics is introduced in this work to screen potential vaccine candidates against P. stuartii. The analysis identified three potential vaccine candidates for designing broad-spectrum and strain-specific peptide vaccines: FimD4, FimD6, and FimD8. These proteins are essential for pathogen survival, localized in the outer membrane, virulent, and antigenic in nature. Immunoproteomic tools mapped surface exposed and non-allergenic 9mer B-cell derived T-cell antigenic epitopes for the proteins. The epitopes also show stable and rich interactions with the most predominant HLA allele (DRB1*0101) in the human population. Metabolic pathway annotation of the proteins indicated that fimbrial biogenesis outer membrane usher protein (FimD6) is the most suitable candidate for vaccine design, due to its involvement in several significant pathways. These pathways include: the bacterial secretion system, two-component system, β-lactam resistance, and cationic antimicrobial peptide pathways. The predicted epitopes may provide a basis for designing a peptide-based vaccine against P. stuartii.

The Pathogenic Potential of Proteus mirabilis Is Enhanced by Other Uropathogens during Polymicrobial Urinary Tract Infection

Urinary catheter use is prevalent in health care settings, and polymicrobial colonization by urease-positive organisms, such as Proteus mirabilis and Providencia stuartii, commonly occurs with long-term catheterization. We previously demonstrated that coinfection with P. mirabilis and P. stuartii increased overall urease activity in vitro and disease severity in a model of urinary tract infection (UTI). In this study, we expanded these findings to a murine model of catheter-associated UTI (CAUTI), delineated the contribution of enhanced urease activity to coinfection pathogenesis, and screened for enhanced urease activity with other common CAUTI pathogens. In the UTI model, mice coinfected with the two species exhibited higher urine pH values, urolithiasis, bacteremia, and more pronounced tissue damage and inflammation compared to the findings for mice infected with a single species, despite having a similar bacterial burden within the urinary tract. The presence of P. stuartii, regardless of urease production by this organism, was sufficient to enhance P. mirabilis urease activity and increase disease severity, and enhanced urease activity was the predominant factor driving tissue damage and the dissemination of both organisms to the bloodstream during coinfection. These findings were largely recapitulated in the CAUTI model. Other uropathogens also enhanced P. mirabilis urease activity in vitro, including recent clinical isolates of Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, and Pseudomonas aeruginosa We therefore conclude that the underlying mechanism of enhanced urease activity may represent a widespread target for limiting the detrimental consequences of polymicrobial catheter colonization, particularly by P. mirabilis and other urease-positive bacteria.

Case report: Providencia stuartii conjunctivitis

Purpose

The purpose of this study is to report a case of Providencia stuartii conjunctivitis.

Methods

This study is a retrospective chart review of a patient with persistent conjunctivitis.

Results

We report the first case of P. stuartii conjunctivitis. Our patient was an elderly man living in a nursing home who was likely immunocompromised from longstanding diabetes mellitus. A conjunctival swab culture was able to identify the infecting bacteria and its antibiotic susceptibility. The conjunctivitis was successfully treated with vancomycin drops and oral sulfamethoxazole and trimethoprim.

Discussion

P. stuartii is an increasingly common bacterium found in the urine of immunocompromised nursing home residents with indwelling Foley catheters. While it has rarely been found to cause ocular infections, P. stuartii may be suspected in elderly, immunocompromised nursing home residents.

Septicemia in an Indian Rhesus Macaque (Macaca mulatta) associated with Providencia stuartii

Providencia stuartii (P. stuartii) is an opportunistic pathogen and major concern in urinary catheter-related infections in human medicine. Here we report P. stuartii-induced septicemia in an eighteen-year-old, female India-origin Rhesus macaque with multiple traumatic wounds. The animal had neutrophilic leukocytosis, necrosuppurative meningoencephalitis, hypophysitis and bronchopneumonia with vasculitis, thrombosis, and clusters of extracellular Gram-negative bacilli. P. stuartii was isolated from the lesions of the brain and lung and confirmed by PCR and sequencing. To the authors' knowledge, this is the first case of septicemia associated with P. stuartii in a non-human primate.

Laboratory investigation of a suspected outbreak caused by Providencia stuartii with intermediate resistance to imipenem at a long-term care facility

BACKGROUND

Providencia stuartii survives well in natural environment and often causes opportunistic infection in residents of long-term care facilities (LTCFs). Clinical isolates of P. stuartii are usually resistant to multiple antibiotics. The bacterium is also naturally resistant to colistin and tigecycline. Treatment of infections caused by carbapenem-resistant P. stuartii is challenging.

METHODS

During a 15-month period in 2013-2014, four isolates (P1, P2, and P3B/P3U) of P. stuartii showing intermediate resistance to imipenem were identified at a regional hospital in southern Taiwan. They were identified from three patients (P1-P3) transferred from the same LTCF for the treatment of the infection. Pulsed-field gel electrophoresis was used to genotype the isolates. Resistance genes/plasmids and outer membrane proteins were investigated by polymerase chain reaction and sequence analysis.

RESULTS

Isolates P1 and P3B/P3U demonstrated similar pulsotypes. All isolates were found to have resistance genes (bla_CMY-2, qnrD1, aac(6')-Ib-cr) carried on nonconjugative IncA/C plasmids of different sizes. A single point mutation was identified in the chromosomal gyrA (Ser83Ile) and parC (Ser84Ile) genes of all isolates. Various point mutations and insertion/deletion changes were found in their major outer membrane protein gene ompPst1.

CONCLUSIONS

Isolates of similar pulsotypes could appear after 15 months and caused urosepsis in another resident of the same LTCF. The bacterium may have persisted in the environment and caused opportunistic infection. As LTCF residents are usually vulnerable to infections, surveillance of multidrug-resistant organisms and infection control intervention that have been established in acute-care hospitals to control infections by resistant organisms are apparently as essential in LTCFs.

Emergence of a pandrug-resistant VIM-1-producing Providencia stuartii clonal strain causing an outbreak in a Greek intensive care unit

Here we describe an outbreak caused by a pandrug-resistant Providencia stuartii strain involving 15 critically ill patients in a Greek intensive care unit (ICU) during September-November 2011. All isolates harboured the blaVIM-1 gene and a class 1 integron structure of 1913 bp as well as blaSHV-5 and blaTEM-1. Pulsed-field gel electrophoresis (PFGE) demonstrated that isolates from all 15 patients belonged to a single P. stuartii clonal type. As all of the infected patients were hospitalised during overlapping time periods, horizontal intra-ICU transmission was considered as the main route for the dissemination of the outbreak strain. The outbreak ended following reinforcement of infection control measures, including implementation of additional barrier precautions for infected patients.

First characterization of a Providencia stuartii clinical isolate from a Tunisian intensive care unit coproducing VEB-1-a, OXA-2, qnrA6 and aac(6')-Ib-cr determinants

A clinical Providencia stuartii isolate SM662 was recovered from a patient hospitalized in the intensive care unit at the Military hospital, Tunisia. This isolate was resistant to penicillins, cephalosporins, aminoglycosides and fluoroquinolones. A marked in vitro synergy between ceftazidime or cefotaxime and amoxicillin–clavulanic acid on Mueller-Hinton agar plates suggested the presence of an extended-spectrum-β-lactamase. In addition, an unusual synergy was found between cefepime or aztreonam, and cefoxitin or imipenem on a double disk synergy test suggesting a VEB-type extended-spectrum-β-lactamase. The characterization of β-lactamases and associated resistance genes was performed by isoelectric focusing, polymerase chain reaction and nucleotide sequencing. Two β-lactamases bands with pI values of 5.4 and 7.7, which were matched to TEM-1, VEB-1-a and OXA-2-like β-lactamases were detected. The bla_VEB-1-a gene was found to be associated with complex genetic structures, including Re elements. These β-lactamases were not transferred by electroporation or conjugation experiments to the transconjugants and electroporants. Hybridization methods showed that the extended-spectrum-β-lactamase encoding gene may have a chromosomal localization. The isolate SM662 produced the quinolone resistance determinants qnrA6 and aac(6′)-Ib-cr which were successfully transferred. The detection of an associated chromosomal quinolone resistance revealed the presence of a gyrA mutation at codon 83 (Ser83Ile). This is the first report of the linkage VEB-1-a/OXA-2-like in P. stuartii associated with the description of qnrA6 and aac(6′)-Ib-cr genes in this isolate.

Increased incidence of urolithiasis and bacteremia during Proteus mirabilis and Providencia stuartii coinfection due to synergistic induction of urease activity

BACKGROUND

Catheter-associated urinary tract infections (CaUTIs) are the most common hospital-acquired infections worldwide and are frequently polymicrobial. The urease-positive species Proteus mirabilis and Providencia stuartii are two of the leading causes of CaUTIs and commonly co-colonize catheters. These species can also cause urolithiasis and bacteremia. However, the impact of coinfection on these complications has never been addressed experimentally.

METHODS

A mouse model of ascending UTI was utilized to determine the impact of coinfection on colonization, urolithiasis, and bacteremia. Mice were infected with P. mirabilis or a urease mutant, P. stuartii, or a combination of these organisms. In vitro experiments were conducted to assess growth dynamics and impact of co-culture on urease activity.

RESULTS

Coinfection resulted in a bacterial load similar to monospecies infection but with increased incidence of urolithiasis and bacteremia. These complications were urease-dependent as they were not observed during coinfection with a P. mirabilis urease mutant. Furthermore, total urease activity was increased during co-culture.

CONCLUSIONS

We conclude that P. mirabilis and P. stuartii coinfection promotes urolithiasis and bacteremia in a urease-dependent manner, at least in part through synergistic induction of urease activity. These data provide a possible explanation for the high incidence of bacteremia resulting from polymicrobial CaUTI.