A large multicenter Ralstonia pickettii outbreak in critically ill patients during the COVID-19 pandemic: Epidemiological and clinical characteristics of 66 cases

Objective

To describe a multicenter outbreak of R. pickettii that occurred in a large number of critically ill patients in a city in Colombia, during the COVID-19 pandemic.

Methods

In April 2021, the National Institute for Food and Drug Surveillance (INVIMA) reported an outbreak of R. pickettii infection associated with contaminated intravenous medications. The Municipal Health Department began collecting data for all cases identified by the hospitals and the results of microbiological studies. Medical records and death certificates of included cases were reviewed.

Results

Between March and May 2021, 66 cases of R. pickettii bloodstream infections from nine hospitals were documented. The median age of the patients was 60 years (IQR 51-72), and most of them had comorbidities (78.8%), mainly arterial hypertension and diabetes mellitus. At the time of the R. pickettii bloodstream infection, 89.4% had COVID-19, 86.4% were on mechanical ventilation, and 98.5% were receiving corticosteroids. The overall mortality was 81.8%. Nearly 60% of the deaths were related to R. pickettii bloodstream infections. R. pickettii was identified in the cultures from intravenous medications.

Conclusions

This large multicenter outbreak caused by intravenous medications contaminated with R. pickettii mainly affected critically ill COVID-19 patients. Mortality was high and largely related to R. pickettii bloodstream infection.

Genomic analysis of Ralstonia pickettii reveals the genetic features for potential pathogenicity and adaptive evolution in drinking water

Ralstonia pickettii, the most critical clinical pathogen of the genus Ralstonia, has been identified as a causative agent of numerous harmful infections. Additionally, Ralstonia pickettii demonstrates adaptability to extreme environmental conditions, such as those found in drinking water. In this study, we conducted a comprehensive genomic analysis to investigate the genomic characteristics related to potential pathogenicity and adaptive evolution in drinking water environments of Ralstonia pickettii. Through phylogenetic analysis and population genetic analysis, we divided Ralstonia pickettii into five Groups, two of which were associated with drinking water environments. The open pan-genome with a large and flexible gene repertoire indicated a high genetic plasticity. Significant differences in functional enrichment were observed between the core- and pan-genome of different groups. Diverse mobile genetic elements (MGEs), extensive genomic rearrangements, and horizontal gene transfer (HGT) events played a crucial role in generating genetic diversity. In drinking water environments, Ralstonia pickettii exhibited strong adaptability, and the acquisition of specific adaptive genes was potentially facilitated by genomic islands (GIs) and HGT. Furthermore, environmental pressures drove the adaptive evolution of Ralstonia pickettii, leading to the accumulation of unique mutations in key genes. These mutations may have a significant impact on various physiological functions, particularly carbon metabolism and energy metabolism. The presence of virulence-related elements associated with macromolecular secretion systems, virulence factors, and antimicrobial resistance indicated the potential pathogenicity of Ralstonia pickettii, making it capable of causing multiple nosocomial infections. This study provides comprehensive insights into the potential pathogenicity and adaptive evolution of Ralstonia pickettii in drinking water environments from a genomic perspective.

Ralstonia pickettii bloodstream infections with potential genomic link to internationally distributed contaminated saline solution, Germany, October 2023

Ralstonia pickettii is a Gram-negative rod which may cause invasive infections when they contaminate liquid medical products. After R. pickettii was detected in blood cultures and a stem cell product from three patients in a tertiary care hospital in Germany, whole genome sequencing of these three isolates and two water isolates from the environment was performed. Core genome multilocus sequence typing analysis showed that the three patient isolates were closely related and there was a large distance to the environmental isolates. In a genomic comparison, the patients' isolates were distantly related to an R. pickettii strain from a cluster in Australia suspected to be caused by contaminated saline produced in India, while all liquid medical products with a link to all patients were produced in Europe or the United States. Our data point towards an ongoing risk by an unknown common source that could be traced back to medical products contaminated with R. pickettii and potentially distributed worldwide. Investigating invasive R. pickettii infections, identifying and testing medical products administered to the patients and timely whole genome sequencing may help identify the exact source of this potentially global outbreak.

The effect of bacteria addition on DDT biodegradation by BROWN-ROT fungus Gloeophyllum trabeum

DDT (1,1,1-trichloro-2,2 bis(4-chlorophenyl) ethane) is a synthetic insecticide that has several negative effects on the environment and humans. Therefore, determining an effective method to reduce DDT may give a beneficial impact. Brown-rot fungus, Gloeophyllum trabeum, is well known to have the ability to degrade DDT, even though it might require long-term remediation. In this study, the effect of the addition of bacteria on the biodegradation of DDT by G. trabeum had been investigated. Bacillus subtilis, Pseudomonas aeruginosa, and Ralstonia pickettii were screened for the bacteria which the volume of bacteria at 1, 3, 5, and 10 mL and the time range of addition of bacteria on days 0, 1, 3, and 5. The addition of B. subtilis, P. aeruginosa, and R. pickettii bacteria into the G. trabeum culture increased DDT biodegradation to approximately 62.02; 74.66; and 75.72%, respectively, in which G. trabeum was only able to degrade DDT by 54.52% for 7 days of incubation. R. pickettii enhanced the degradation process, in which the addition of 10 mL of this bacterium at day 1 possessed the highest value of 92.41% within 7 days of incubation. DDD was detected to be a product metabolite through a dechlorination reaction. This study indicated that mixed cultures of G. trabeum and R. pickettii can be used to degrade DDT.

The Microbial and Metabolic Signatures of Patients with Stable Coronary Artery Disease

Growing evidence indicates an association between gut dysbiosis and coronary artery disease (CAD). However, the underlying mechanisms relevant to stable CAD (SCAD) pathogenesis, based on microbe-host metabolism interactions, are poorly explored. Here, we constructed a quasi-paired cohort based on the metabolic background of metagenomic samples by the propensity score matching (PSM) principle. Compared to healthy controls (HCs), gut microbiome disturbances were observed in SCAD patients, accompanied by differences in serum metabolome, mainly including elevated acylcarnitine and decreased unsaturated fatty acids in SCAD patients, which implicated the reduced cardiac fatty acid oxidation. Moreover, we identified Ralstonia pickettii as the core strain responsible for impaired microbial homeostasis in SCAD patientsm and may be partly responsible for the decrease of host unsaturated fatty acid levels. These findings highlight the importance of unsaturated fatty acids, R. pickettii, and their interaction in the pathogenesis of SCAD. IMPORTANCE Stable coronary artery disease (SCAD) is an early stage of CAD development. It is important to understand the pathogenesis of SCAD and find out the possible prevention and control targets for delaying the progression of CAD. We observed reduced levels of unsaturated fatty acids (USFAs) in SCAD patients. However, the reduced USFAs may be related to Ralstonia Pickettii, which was the core strain responsible for the impaired gut microbial function in SCAD patients, and further affected the host's cardiovascular health by altering amino acids, vitamin B metabolism, and LPS biosynthesis. These findings not only emphasized the importance of USFAs for cardiovascular health, but also R. Pickettii for maintaining microbial function homeostasis. More importantly, our study revealed, for the first time, that enriched R. Pickettii might be responsible for the reduced USFAs in SCAD patients, which adds new evidence on the role of altered gut microbiota for SCAD formation.

[Rapid identification of Ralstonia pickettii using PCR-nucleic acid test strips]

OBJECTIVE

To develop a method for rapid detection of Ralstonia pickettii in water for pharmaceutical purpose using PCR-nucleic acid test strips.

METHODS

The genomic DNA of Ralstonia pickettii was extracted by boiling method. A pair of specific primers targeting the 16S rDNA with FITC and biotin labeling of the 5' ends was designed and cloned into competent E. coli DH5α cells. The nucleic acid test strips were assembled, and the workload of streptavidin labeled with colloidal gold and antibody concentration in the reaction system was optimized. After verification of the reaction mechanism and assessment of the test sensitivity, specificity and stability, the test strip was used for detecting 7 known strains of Ralstonia pickettii detected in pharmaceutical water, and an evolutionary tree was constructed to analyze the source of contamination.

RESULTS

The genomic DNA extracted by boiling method had a purity between 1.8 and 2.0, and the PCR products showed a 100% similarity of with Ralstonia pickettii 16S rDNA registered in GenBank. Using the colloidal gold amplification principle, in every 100 μL colloidal gold solution, 3.5 μL streptavidin was added; the detection line on nitrocellulose membrane was 2.0 mg·mL-1 anti FITC antibody, and the quality control line was 1.2 mg · mL-1 biotinylated BSA, and they generate a red band after binding with positive amplification product. Specificity test of the assembled test strip yielded consistent result with agarose gel electrophoresis without cross reaction with Acinetobacter, Aeromonas, Pseudomonas, or Leclercia adecarboxylata. Sensitivity test of the strip showed a lower detection limit for DNA concentration of 10-5 ng/μL, with a sensitivity 1000 times that of agarose gel electrophoresis. The test strip still had good performance after storage for 3, 6, 9 and 12 months.

CONCLUSION

We successfully developed a PCR-nucleic acid test strip for convenient and cost-effective detection of Ralstonia pickettii with good specificity and sensitivity and low cost to facilitate daily monitoring of pharmaceutical water contaminations.

A Case of Ralstonia pickettii Bloodstream Infection and the Growing Problem of Healthcare Associated Infections in Frail Older Adults

Frailty is a clinically measurable state of vulnerability to developing increased dependency and/or mortality when exposed to a stressor. Chronic diseases, aggressive treatments, antibiotic overuse, microbiota changes, immune senescence, and increased use of medical devices and implants (i.e., central lines and catheters) expose modern patients to healthcare-associated infections (HAIs), multidrug-resistant bacteria, and new and unusual opportunistic pathogens. Older adults are among the main victims of HAIs and are associated with high costs, disability, morbidity, and mortality. Ralstonia pickettii is an emerging opportunistic pathogen that causes rare nosocomial infections in frail individuals. Herein, we present a case of bloodstream infection caused by R. pickettii in an 88-year-old woman with a relatively mild course. In addition to describing this unusual finding, this report discusses the problem of HAIs in older adults. Older age, comorbidities, and hospital admissions were among the main risk factors for HAIs. Adherence to guidelines, training, auditing, and surveillance is crucial for reducing the burden of HAIs in acute settings. Furthermore, avoiding incongruous hospitalizations would have positive implications both for preventing HAIs and improving patient quality of life.

An outbreak of Ralstonia pickettii bloodstream infection and clinical outcomes

INTRODUCTION

Ralstonia pickettii infections are rare and may be mistaken for other bacteria. This study aims to report a hospital outbreak of R. pickettii at a tertiary hospital, which was initially misidentified as Ralstonia insidiosa, along with its clinical consequences.

METHODOLOGY

A bacteraemia outbreak occurred between August 14 and October 4, 2019, infecting 22 patients admitted to diverse intensive care units. All isolates were identified with the use of the automated VITEK 2 Compact system and were then subjected to a microbial identification system, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Bacterial identification and genomic DNA typing was made using pulsed-field gel electrophoresis. Investigation covered all potential sources of the outbreak.

RESULTS

An index patient and five additional patients developed fever while receiving care. Blood cultures of these patients yielded R. insidiosa by the VITEK 2 Compact system. Culture isolates were then submitted to a reference centre for confirmation by the MALDI-TOF MS system, where the bacterium turned out to be R. pickettii. No pathogen was isolated in the commercial products except for three samples of unopened sterile distilled water. Despite its discontinuation, 16 new cases were identified, in which blood cultures grew R. pickettii by the MALDI-TOF MS system. Attempts to uncover the source of the outbreak failed. Clinical manifestation was confined to fever in all the patients.

CONCLUSIONS

During this outbreak, R. pickettii infections ran a relatively mild course without clinical deterioration or mortality, possibly due to low virulence.

Ralstonia pickettii bacteremia in a cardiac surgery patient in Belgrade, Serbia

Ralstonia pickettii is an opportunistic bacterium found in the water environment with an increasing incidence as a nosocomial pathogen. The objectives of this study were to describe R. pickettii bacteremia in a cardiac surgery patient and to evaluate its ability to grow in a saline solution and to form biofilm. The patient in this study underwent mitral and aortic valve replacement surgery with two aortocoronary bypasses. She developed signs of respiratory and renal failure, therefore hemodialysis was started. After 25 days in an intensive care unit, the patient had recurrent episodes of fever with signs of bacteremia. R. pickettii was identified from blood cultures by MALDI-TOF MS. Antimicrobial susceptibility testing was performed using disc diffusion and broth microdilution methods in accordance with EUCAST methodology and results were interpreted following clinical breakpoints for Pseudomonas spp. The isolate was susceptible to all tested antimicrobial agents except aminoglycosides and colistin. Survival of R. pickettii was analyzed in saline solution with four different starting concentrations at 25 °C and 37 °C for six days. Biofilm capacity was tested using the microtiter plate method. R. pickettii showed substantial growth in saline solution, with starting concentration of 2 CFU ml-1 reaching 107 CFU ml-1 after six days. There was no significant difference between growth at 25 °C and 37 °C. This indicates that storage of contaminated solutions at room temperature can enhance the count of R. pickettii. Our strain did not show the capacity to form biofilm. The patient responded well to adequate treatment with ceftazidime, and after 48 days in ICU she was discharged to convalesce.

Synergistic interaction of a consortium of the brown-rot fungus Fomitopsis pinicola and the bacterium Ralstonia pickettii for DDT biodegradation

1,1,1-Trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) is a toxic and recalcitrant pesticide that has been greatly used to eradicate malaria mosquitos since the 1940s. However, the US Environmental Protection Agency banned and classified DDT as priority pollutants due to its negative impact on wildlife and human health. Considering its negative effects, it is necessary to develop effective methods of DDT degradation. A synergistic interaction of a consortium consisting of the brown-rot fungus Fomitopsis pinicola and the bacterium Ralstonia pickettii was adopted to degrade DDT. For the microbial consortia, F. pinicola was mixed with R. pickettii at 1, 3, 5, 7 and 10 ml (1 ml ≈ 1.44 × 1013 CFU) in a potato dextrose broth (PDB) medium to degrade DDT throughout the seven days incubation period. The degradation of DDT by only the fungus F. pinicola was roughly 42%, while by only R. pickettii was 31%. The addition of 3 ml of R. pickettii into F. pinicola culture presented appropriate optimization for efficient DDT degradation at roughly 61%. The DDT transformation pathway by co-inoculation of F. pinicola and R. pickettii showed that DDT was converted to 1,1-dichloro-2,2-bis(4-chlorophenyl) ethane (DDD), further transformed to 1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene (DDE), and then ultimately transformed to 1-chloro-2,2-bis(4-chlorophenyl) ethylene (DDMU). These metabolites are less toxic than DDT. This research showed that R. picketti synergistically interacts with F. pinicola by enhancing DDT degradation.

Evaluating changes to Ralstonia pickettii in high-purity water to guide selection of potential calibration materials for online water bioburden analyzers

Online water bioburden analyzers (OWBAs) can provide real-time feedback on viable bacteria in high-purity water (HPW) systems for pharmaceutical manufacturers. To calibrate and validate OWBAs, which detect bacteria using scattered light and bacterial autofluorescence, standards are needed that mimic the characteristics of bacteria in HPW. To guide selection of potential standards, e.g., fluorescent microspheres, a relevant bacterial contaminant, Ralstonia pickettii, was characterized for size, count, viability, and autofluorescence after exposure for 24 h to HPW or a nutrient environment. The cells exposed to HPW showed smaller sizes, with lower counts and autofluorescence intensities, but similar spectral features. The cell characteristics are discussed in comparison with a set of fluorescent microspheres, considering factors relevant to OWBAs. These studies suggest that fluorescent microspheres should be relatively small (< 1 µm diameter) and dim, while covering a broad emission range from ≈ (420 to 600) nm to best mimic the representative R. pickettii.

A case of persistent bacteraemia by Ralstonia mannitolilytica and Ralstonia pickettii in an intensive care unit

The Ralstonia spp. genus is a group of non-fermentative, Gram-negative bacteria often resistant to many antibiotics, which are emerging as opportunistic pathogens frequently associated with infections in hospital settings. We present herein a case of combined R. pickettii and R. mannitolilytica persisting and relapsing bacteraemia, possibly caused by a septic arterial thrombosis secondary to the rupture of an internal carotid artery aneurysm. Microbiology studies showed that both Ralstonia isolates produced biofilm and carried class D oxacillinase genes. When confronted with infections caused by members of the Ralstonia genus, identification to the species level is crucial for correct clinical management, as the two species show different antibiotic susceptibility patterns.

Identification of a tyrosine switch in copper-haem nitrite reductases

There are few cases where tyrosine has been shown to be involved in catalysis or the control of catalysis despite its ability to carry out chemistry at much higher potentials (1 V versus NHE). Here, it is shown that a tyrosine that blocks the hydrophobic substrate-entry channel in copper-haem nitrite reductases can be activated like a switch by the treatment of crystals of Ralstonia pickettii nitrite reductase (RpNiR) with nitric oxide (NO) (-0.8 ± 0.2 V). Treatment with NO results in an opening of the channel originating from the rotation of Tyr323 away from AspCAT97. Remarkably, the structure of a catalytic copper-deficient enzyme also shows Tyr323 in the closed position despite the absence of type 2 copper (T2Cu), clearly demonstrating that the status of Tyr323 is not controlled by T2Cu or its redox chemistry. It is also shown that the activation by NO is not through binding to haem. It is proposed that activation of the Tyr323 switch is controlled by NO through proton abstraction from tyrosine and the formation of HNO. The insight gained here for the use of tyrosine as a switch in catalysis has wider implications for catalysis in biology.

Seasonal variation in the biocontrol efficiency of bacterial wilt is driven by temperature-mediated changes in bacterial competitive interactions

Microbe-based biocontrol applications hold the potential to become an efficient way to control plant pathogen disease outbreaks in the future. However, their efficiency is still very variable, which could be due to their sensitivity to the abiotic environmental conditions.Here, we assessed how environmental temperature variation correlates with ability of Ralstonia pickettii, an endophytic bacterial biocontrol agent, to suppress the Ralstonia solanacearum pathogen during different tomato crop seasons in China.We found that suppression of the pathogen was highest when the seasonal mean temperatures were around 20 °C and rapidly decreased with increasing mean crop season temperatures. Interestingly, low levels of disease incidence did not correlate with low pathogen or high biocontrol agent absolute densities. Instead, the biocontrol to pathogen density ratio was a more important predictor of disease incidence levels between different crop seasons. To understand this mechanistically, we measured the growth and strength of competition between the biocontrol agent and the pathogen over a naturally occurring temperature gradient in vitro. We found that the biocontrol strain grew relatively faster at low temperature ranges, and the pathogen at high temperature ranges, and that similar to field experiments, pathogen suppression peaked at 20 °C.Together, our results suggest that temperature-mediated changes in the strength of bacterial competition could potentially explain the variable R. solanacearum biocontrol outcomes between different crop seasons in China. Synthesis and applications. Our results suggest that abiotic environmental conditions, such as temperature, can affect the efficacy of biocontrol applications. Thus, in order to develop more consistent biocontrol applications in the future, we might need to find and isolate bacterial strains that can retain their functionality regardless of the changing environmental conditions.

Sonication contribution to identifying prosthetic joint infection with Ralstonia pickettii: a case report and review of the literature

Background

In the context of an increase number of primary and revision total hip and total knee arthroplasty performed yearly, an increased risk of complication is expected. Prosthetic joint infection (PJI) remains the most common and feared arthroplasty complication. Ralstonia pickettii is a Gram-negative bacterium, that has also been identified in biofilms. It remains an extremely rare cause of PJI. There is no report of an identification of R. pickettii on an extracted spacer loaded with antibiotic.

Case presentation

We present the case of an 83-years-old Caucasian male patient, that underwent a right cemented total hip replacement surgery. The patient is diagnosed with an early PJI with no isolated microorganism. A debridement and change of mobile parts is performed. At the beginning of 2016, the patient in readmitted into the Orthopedic Department for sever, right abdominal and groin pain and elevated serum erythrocyte sedimentation rate and C-reactive protein. A joint aspiration is performed with a negative microbiological examination. A two-stage exchange with long interval management is adopted, and a preformed spacer loaded with gentamicin was implanted. In July 2016, based on the proinflammatory markers evolution, a shift a three-stage exchange strategy is decided. In September 2016, a debridement, and changing of the preformed spacer loaded with gentamicin with another was carried out. Bacteriological examination of the tissues sampled intraoperatively was positive for Pseudomonas aeruginosa. From the sonication fluid, no bacteria were isolated on culture or identified using the bbFISH assay. During the hospitalization period, the patient received i.v. ceftazidime 3x2g/day and p.o. ciprofloxacin 2x750mg/day, antibiotic therapy that was continued after discharge with p.o. ciprofloxacin 2x750mg/day for 6 weeks. In February 2017, a reimplantation of a revision prosthesis is performed. The retrieved spacer is sonicated, and after 4 days of incubation of the sonication fluid, R. pickettii is isolated. A long term antibiotic therapy with cotrimoxazole being prescribed.

Conclusions

Bacteria culture of sonication fluid remains the gold standard in diagnosing prosthetic joint infections. R. pickettii remains an extremely rare cause of prosthetic joint infection. Optimal management of R. pickettii prosthetic joint infections of has not been established.

An outbreak of Ralstonia pickettii endophthalmitis following intravitreal methotrexate injection

Purpose

To report an outbreak of endophthalmitis in three eyes of two patients following intravitreal methotrexate, caused by Ralstonia pickettii.

Design

Retrospective, noncomparative, consecutive case series.

Methods

Medical records and microbiology results of two patients who presented with acute endophthalmitis following intravitreal methotrexate injection in November 2013 were reviewed.

Results

Following intravitreal injections, the patients experienced pain and decrease in vision in the affected eye within 24 hours of receiving intravitreal methotrexate injection. The presenting visual acuity in case 1 was 20/50 in the left eye. The presenting visual acuity in case 2 was hand motions in the right eye and counting fingers at 1 m in the left eye. Both the patients received methotrexate prepared in the same manufacturing facility. Both the patients underwent vitreous biopsy and intravitreal injection of vancomycin 1 mg/0.1 mL, amikacin 400 µg/0.1 mL, and dexamethasone 400 µg/0.1 mL. Microbiology cultures from vitreous, and used and unused vials of methotrexate from the same batch grew R. pickettii. After 8 months of follow-up, both the patients had visual acuity 20/60 or better.

Conclusion

R. pickettii can be rarely associated with outbreak of endophthalmitis. Timely intervention can be associated with good visual outcome in such patients.

Non-fermentative gram-negative bacteria in hospital tap water and water used for haemodialysis and bronchoscope flushing: prevalence and distribution of antibiotic resistant strains

This study provides a detailed description of the distribution of non-fermentative gram-negative bacteria (NFGNB) collected in water sources (tap water and water used for haemodialysis and bronchoscope flushing) from different wards of a tertiary care hospital. The aim is to identify risk practices for patients or to alert clinicians to the possible contamination of environment and medical devices. The resistance profile of NFGNB environmental isolates has shown that more than half (55.56%) of the strains isolated were resistant to one or more antibiotics tested in different antimicrobial categories. In particular, 38.89% of these strains were multidrug resistant (MDR) and 16.67% were extensively drug resistant (XDR). The most prevalent bacterial species recovered in water samples were Pseudomonas aeruginosa, Pseudomonas fluorescens, Ralstonia pickettii and Stenotrophomonas maltophilia. Analysis of antibiotic resistance rates has shown remarkable differences between Pseudomonadaceae (P. aeruginosa and P. fluorescens) and emerging pathogens, such as S. maltophilia and R. pickettii. Multidrug resistance can be relatively common among nosocomial isolates of P. aeruginosa, which represent the large majority of clinical isolates; moreover, our findings highlight that the emergent antibiotic resistant opportunistic pathogens, such as R. pickettii and S. maltophilia, isolated from hospital environments could be potentially more dangerous than other more known waterborne pathogens, if not subjected to surveillance to direct the decontamination procedures.