Elizabethkingia Infections in Humans: From Genomics to Clinics

Successfully treated case of meningitis caused by Elizabethkingia anophelis in an adult with fluoroquinolone-based treatment: A case report and literature review

Elizabethkingia anophelis, a Gram-negative bacillus, is a rare cause of adult meningitis with high mortality. Due to its resistance to most β-lactams including carbapenems and aminoglycosides, the standard treatment for meningitis remains undetermined. Herein, we report the first case of adult meningitis caused by E. anophelis after nasal endoscopic transnasal surgery. In our patient, E. anophelis colonized the respiratory tract without clinical evidence of pneumonia. Although an apparent cerebrospinal fluid leak was not identified, we believe that a minor leak following brain surgery was the entry site for E. anophelis. Levofloxacin resulted in rapid resolution of fever and headache. All previously reported cases of meningitis in adults treated with fluoroquinolones survived. We highlighted the importance of prompt identification of the strain and considering changing antimicrobial agents as necessary. Although regional susceptibility rates must be carefully considered, fluoroquinolones can be a viable treatment option for adult meningitis caused by fluoroquinolone-susceptible E. anophelis.

Cefiderocol-Resistant Elizabethkingia anophelis Bacteremia Following WATCHMAN Implantation: A Case Report and Review of the Literature

Elizabethkingia anophelis is an emerging pathogen associated with nosocomial and community outbreaks. Treatment of infection caused by E. anophelis is not well-defined given its extensive drug resistance profile, and infection carries a poor prognosis. E. anophelis is intrinsically resistant to many classes of antibiotics including carbapenems and polymyxins due to multiple resistance genes. Resistance to novel β-lactam/β-lactamase inhibitors has also been reported. The activity of cefiderocol (FDC) is unknown. Here, we describe a case of FDC-resistant E. anophelis bacteremia following WATCHMAN implantation. To our knowledge, this is the first reported case of FDC resistance amongst Elizabethkingia spp.

Epidemiological and genomic features of clinical isolates of the Elizabethkingia genus in Taizhou City, China

OBJECTIVE

Elizabethkingia species usually exhibit resistance to multiple antibiotics, and inappropriate antimicrobial therapy is a major cause of mortality in patients with Elizabethkingia infection. Our study aimed to comprehensively analyse and compare the genomic and clinical features of three Elizabethkingia species.

METHODS

Matrix-assisted laser desorption/ionization-time of flight mass spectrometry and whole-genome sequencing were used to identify 88 Elizabethkingia isolates from 88 patients in the past 6 y. Phylogenetic tree and Sankey diagram analysis were used to compare the strains with metallo-β-lactamase resistance genes and 49 Elizabethkingia miricola strains with evolutionary relationships.

RESULTS

The identified Elizabethkingia species included Elizabethkingia anophelis (65/88, 73.9%), Elizabethkingia meningoseptica (8/88, 9.1%), and E. miricola (15/88, 17.0%). Multivariate analysis showed that co-isolated with Pseudomonas aeruginosa (odds ratio: 40.83, 95% confidence interval: 3.05-546.29, P = 0.005) and antimicrobial exposure to carbapenems (odds ratio: 5.76, 95% confidence interval: 1.00-248.32, P = 0.050) were independent risk factors for in-hospital mortality. Whole-genome sequencing and phylogenetic tree analysis revealed all 88 strains with 22 BlaBlaB and 19 BlaGOB variants. In particular, the specific combinations of BlaB and GOB subtypes differed in three Elizabethkingia species. All Elizabethkingia species harboured drug-resistance genes adeF, vanT, and vanW and shared 32 virulence-associated genes. Global phylogenetic evolution of E. miricola showed a dispersal in Chinese clinical isolates and did not display outbreak possibility.

CONCLUSIONS

Variations in resistance and virulence genes are associated with the natural resistance and pathogenicity of Elizabethkingia. Increased genomic monitoring is recommended for a deeper understanding of the pathogenic mechanisms of Elizabethkingia spp.

Holy water not so holy: Potential source of Elizabethkingia pneumonia and bacteremia in an immunocompromised host

Elizabethkingia species are Gram-negative, glucose-non-fermenting bacilli predominantly found in soil and water, with Elizabethkingia anophelis increasingly recognized as a human pathogen. E. anophelis has also been reported in hospital outbreaks, suggesting the potential role of contaminated institutional water sources. Conventional microbiological methods often lead to misidentifying this pathogen for other members of the genus Elizabethkingia, suggesting a role for molecular methods for identification. We report a 67-year-old female who developed multiorgan failure requiring intensive care unit admission and mechanical ventilation while being treated with chemotherapy for Burkitt lymphoma. She developed pneumonia with Gram-negative bacilli isolated from her endotracheal aspirate culture, later identified as E. anophelis. She later developed bacteremia due to the same pathogen, which was confirmed by MALDI-TOF and whole genome sequencing. Waterborne transmission via holy water administration was postulated to be potential source of infection. Our case report highlights that E. anophelis may cause significant infection and should not be disregarded as contaminant, especially in immunosuppressed individuals. As a waterborne pathogen that may be brought into hospital environments, emphasis on educating family members, close nursing monitoring, and reporting of suspected, unsupervised manipulation of medical equipment should be undertaken to prevent contamination by this organism from outside sources.

Comprehensive investigation of Litsea cubeba antibacterial and antifungal activities across solid, liquid, and vapor phases against key human pathogens

The escalating global incidence of antimicrobial resistance poses a significant public health challenge. In response, exploring alternative antimicrobial agents, particularly derived from plants, becomes crucial to alleviate the selective pressure exerted by conventional antibiotics. The aim of this study was to characterize the composition of essential oil extracted from Litsea cubeba fruits and to evaluate its antimicrobial potential, along with its major compound, across solid, liquid, and vapor phases. The antimicrobial activity was assessed against a diverse range of human pathogenic Gram-positive bacteria (n = 8), Gram-negative bacteria (n = 34), filamentous fungi (n = 2), and yeast (n = 1). Disk diffusion, broth macrodilution, and vapor-phase diffusion methods were employed. This study found that all phases of L. cubeba essential oil and purified limonene exhibited broad-spectrum bactericidal and fungicidal activities (solid-phase: inhibition zone diameter (IZD) 19 mm vs 14 mm; liquid-phase: minimum inhibitory concentration (MIC) 2.0 mg/mL vs 4.0 mg/mL; vapor-phase: IZD 90 mm vs 45 mm), with superior efficacy against filamentous fungi and yeast compared to bacteria (solid-phase: IZD 90 mm vs 17.5 mm; liquid-phase: MIC 2.0 mg/mL vs 0.06 mg/mL; vapor-phase: IZD 90 mm vs 12.5 mm; all p-values<0.05). Among bacteria, solid-phase L. cubeba essential oil demonstrated increased activity against Staphylococcus saprophyticus and Acinetobacter Iwoffii whereas liquid-phase L. cubeba essential oil had optimal activity against Streptococcus agalactiae and Elizabethkingia meningoceptica. Notably, Trichophyton rubrum, Nannizzia gypsea, and Candida albicans displayed high susceptibility to all phases of L. cubeba essential oil. These findings highlight the potential activity of L. cubeba essential oil, across its various phases, as a promising alternative antimicrobial agent against medically significant pathogens, providing essential baseline information for further exploration and development of L. cubeba essential oil in the pursuit of combating antimicrobial resistance.

Rare or Unusual Non-Fermenting Gram-Negative Bacteria: Therapeutic Approach and Antibiotic Treatment Options

Non-fermenting Gram-negative bacteria (NFGNB) are a heterogeneous group of opportunistic pathogens increasingly associated with healthcare-associated infections. While Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia are well known, rarer species such as Burkholderia cepacia complex, Achromobacter spp., Chryseobacterium spp., Elizabethkingia spp., Ralstonia spp., and others pose emerging therapeutic challenges. Their intrinsic and acquired resistance mechanisms limit effective treatment options, making targeted therapy essential. Objectives: This narrative review summarizes the current understanding of rare and unusual NFGNB, their clinical significance, resistance profiles, and evidence-based therapeutic strategies. Methods: A literature review was conducted using PubMed, Scopus, and Web of Science to identify relevant studies on the epidemiology, antimicrobial resistance, and treatment approaches to rare NFGNB. Results: Rare NFGNB exhibits diverse resistance mechanisms, including β-lactamase production, efflux pumps, and porin modifications. Treatment selection depends on species-specific susceptibility patterns, but some cornerstones can be individuated. Novel β-lactam/β-lactamase inhibitors and combination therapy approaches are being explored for multidrug-resistant isolates. However, clinical data remain limited. Conclusions: The increasing incidence of rare NFGNB requires heightened awareness and a tailored therapeutic approach. Given the paucity of clinical guidelines, antimicrobial stewardship and susceptibility-guided treatment are crucial in optimizing patient outcomes.

Identification of Elizabethkingia species by MALDI-TOF MS proteotyping

Elizabethkingia species, isolated from clinical and environmental samples, are emerging opportunistic bacterial pathogens with a high mortality rate in clinical settings worldwide. Taxonomically, Elizabethkingia comprises seven species: E. anophelis, E. argenteiflava, E. bruuniana, E. meningoseptica, E. miricola, E. ursingii, and E. occulta. In this study, we identified useful biomarker proteins, including ribosomal L29, L30, S21, and the YtxH domain-containing proteins, for distinguishing Elizabethkingia species using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiles. Evaluation of 29 clinical and environmental Elizabethkingia strains revealed that these species could be separated by MALDI-TOF MS profiles into six groups-E. anophelis, E. argenteiflava, E. bruuniana/E. miricola, E. meningoseptica, E. ursingii, and E. occulta-based on the four biomarker protein peaks. This study demonstrates the potential of routine MALDI-TOF MS -based examination methods for the early detection of Elizabethkingia species in clinical laboratories.

IMPORTANCE

Elizabethkingia species are groups of emerging opportunistic bacterial pathogens with a high mortality rate, causing healthcare-associated outbreaks worldwide. Rapid identification of Elizabethkingia species is important becausethese species show intrinsically carbapenem resistance and there are few data for using appropriate antibiotics. Until now, only whole-genome sequencing could accurately identify the seven Elizabethkingia species. Therefore, establishing rapid and accurate identification methods for Elizabethkingia species in clinical laboratories is vital. In this study, we developed new methods for identifying Elizabethkingia species using four biomarker protein peaks-ribosomal L29, L30, S21, and the YtxH domain-containing proteins by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) proteotyping. This study demonstrates the potential of routine MALDI-TOF MS -based laboratory examination for the early identification of Elizabethkingia species.

Elizabethkingia meningoseptica in Dubai, United Arab Emirates: A 7-year multicenter study

BACKGROUND

Elizabethkingia meningoseptica (E. meningoseptica) is a gram-negative bacillus. Widely distributed in nature, it poses a significant threat as a nosocomial pathogen, particularly affecting immunocompromised neonates and the elderly.

METHODS

This study aimed to describe the antimicrobial susceptibility and outcomes of E. meningoseptica infections over seven years in United Arab Emirates. A retrospective chart review study was conducted at four hospitals that are part of Dubai Academic Health Corporation.

RESULTS

A total of 23 cases were observed during the study, 21 (91%) of which exhibited multidrug resistance. More than half of the cases required intensive care and mechanical ventilation (n = 13, 57%). The in-hospital mortality rate was 38% (n = 5) in adults and 20% (n = 2) in pediatrics.

CONCLUSIONS

E. meningoseptica is a significant nosocomial pathogen with high antibiotic resistance, posing severe risks to immunocompromised pediatric and adult patients. Effective management of E. meningoseptica requires vigilant monitoring, comprehensive control, and targeted therapies.

Clinical presentation and outcomes of bloodstream infection with intrinsically carbapenem-resistant non-fermenting gram-negative organisms: Stenotrophomonas maltophilia, Elizabethkingia spp. and Chryseobacterium spp. in Singapore, from 2012 to 2024

BACKGROUND

Bloodstream infections with the non-fermenting Gram-negative organisms Stenotrophomonas maltophilia, Elizabethkingia spp. or Chryseobacterium spp. are observed in nosocomial settings. Comparative description of their clinical presentation, microbiological characteristics, treatment options and outcomes remain to be investigated.

METHODS

We performed a retrospective single-centre analysis of bloodstream infections with the abovementioned three organisms from 1 Jan 2012 to 30 Jun 2024.

RESULTS

A total of 349 distinct encounters (from 322 unique patients) were identified with bacteraemia. Stenotrophomonas maltophilia was the commonest (197/349, 56.4%), followed by Elizabethkingia spp. (127/349, 36.4%) and Chryseobacterium spp. (25/349, 7.2%). Prior carbapenem exposure was observed in 59.9% of cases. The majority were related to central lines (58.2%). Most cases were nosocomial in onset (82.5%), and a third were from the intensive care unit (32.1%). A significant proportion of our Stenotrophomonas maltophilia (32.8%) and Chryseobacterium spp. (22.7%) isolates were resistant to levofloxacin, while a majority of the organisms retained susceptibility to trimethoprim-sulfamethoxazole (TMP-SMX) and minocycline. Dual antibiotics were used in a minority of encounters (23/349, 6.6%). Mortality was high across infections with the three organisms, but highest amongst those with Stenotrophomonas maltophilia bacteraemia (41.6%), followed by Elizabethkingia spp. (29.9%) and Chryseobacterium spp. (20.0%).

CONCLUSIONS

Stenotrophomonas, Elizabethkingia or Chryseobacterium spp bacteraemia was associated with significant mortality. Most cases were nosocomial in acquisition, with prior carbapenem exposure or indwelling central catheters. Fluoroquinolone resistance was common for Stenotrophomonas maltophilia and Chryseobacterium spp., but less prevalent in Elizabethkingia spp., while TMP-SMX and minocycline retained susceptibility. Monitoring these trends would be critical in guiding empiric therapy for these organisms.

Chemotactic Activity of Products of Elizabethkingia anophelis Derived from Aedes albopictus against RAW264 Murine Macrophage Cell Line

Dengue viruses enter the dermal macrophages derived from other tissues following a bite from an infected mosquito. We examined the chemotactic activity of factors derived from the dengue vector mosquito Aedes albopictus on a RAW264 murine macrophage cell line. We found that Elizabethkingia anophelis isolated from the mosquitoes exhibits migration-inducing activity in RAW264 cells. The active substances that induce the chemotactic movement were extracted using ethyl acetate. Chemotactic activity was noted in several of the fractions isolated using reverse-phase chromatography, suggesting that multiple components were responsible for this activity. Next, we isolated three bacterial colonies from wild A. albopictus mosquitoes collected from Toyama Park (Tokyo, Japan). The bacterial 16S rRNA gene sequences shared homology with that of Lonsdalea quercina. These bacteria also exhibited migration-inducing activity in RAW264 cells. The migration-inducing activity of the bacteria in mosquitoes may be a novel aspect of mosquito-mediated viral infections.

Biochemical properties and substrate specificity of GOB-38 in Elizabethkingia anophelis

The novel pathogen, Elizabethkingia anophelis, has gained attention due to its high mortality rates and drug resistance facilitated by its inherent metallo-β-lactamases (MBLs) genes. This study successfully identified and outlined the functions of the B3-Q MBLs variant, GOB-38, in a clinical sample of E. anophelis. The T7 expression system was employed to stimulate the expression of recombinant protein in Escherichia coli, followed by an analysis of the biochemical properties of purified GOB-38. Our findings indicate that the enzyme GOB-38 displays a wide range of substrates, including broad-spectrum penicillins, 1-4 generation cephalosporins, and carbapenems, potentially contributing to in vitro drug resistance in E. coli through a cloning mechanism. It is important to highlight that GOB-38 exhibits a distinct active site composition compared to GOB-1/18, featuring hydrophilic amino acids Thr51 and Glu141 at both ends of its active center instead of hydrophobic alanine, potentially indicating a preference for imipenem. Furthermore, the co-isolation of Acinetobacter baumannii and E. anophelis, two opportunistic pathogens, from a single lung infection is noteworthy. Our in vitro co-culture experiments suggest that E. anophelis, carrying two MBL genes, may have the ability to transfer carbapenem resistance to other bacterial species through co-infection.

Antimicrobial Susceptibility Patterns and Antimicrobial Therapy of Infections Caused by Elizabethkingia Species

Background and Objectives: Elizabethkingia species have become significant sources of infections acquired in hospital settings and are commonly linked to high mortality rates. Antimicrobial resistance can be influenced by Elizabethkingia species, geographical location, antimicrobial susceptibility testing methods, and the time of bacterial isolation. There are distinct antimicrobial susceptibility patterns among species, and the investigation into potential antibiotic susceptibility variations among species is beneficial. There is no guidance on the treatment of Elizabethkingia species infections in the literature. Consequently, the purpose of this review was to elaborate on the antimicrobial susceptibility patterns of Elizabethkingia species through a scoping review of existing studies on the antibiograms of the Elizabethkingia species and on the illness caused by Elizabethkingia species. Materials and Methods: A comprehensive literature search in PubMed and Web of Science between 1 January 2000 and 30 April 2024 identified all studies, including those that examined antimicrobial susceptibility patterns and antimicrobial therapy of infections caused by Elizabethkingia species. I considered studies on antimicrobial susceptibility testing for Elizabethkingia species in which only broth microdilution methods and agar dilution methods were used. Results: The sensitivity levels of Elizabethkingia meningoseptica to piperacillin-tazobactam (5-100%), ciprofloxacin (0-43.4%), levofloxacin (30-81.8%), trimethoprim-sulfamethoxazole (0-100%), tigecycline (15-100%), minocycline (60-100%), and rifampicin (94-100%) varied. The sensitivity levels of Elizabethkingia anophelis to piperacillin-tazobactam (3.3-93.3%), ciprofloxacin (1-75%), levofloxacin (12-100%), trimethoprim-sulfamethoxazole (1.02-96.7%), tigecycline (0-52.2%), minocycline (97.5-100%), and rifampicin (20.5-96%) varied. The sensitivity levels of Elizabethkingia miricola to piperacillin-tazobactam (41.6-94.0%), ciprofloxacin (14-75%), levofloxacin (77.0-100%), trimethoprim-sulfamethoxazole (18.0-100%), tigecycline (50%), minocycline (100%), and rifampicin (66-85.7%) varied. Conclusions: The majority of the isolates of Elizabethkingia species were susceptible to minocycline and rifampin. This issue requires professional knowledge integration and treatment recommendations.

capD deletion in the Elizabethkingia miricola capsular locus leads to capsule production deficiency and reduced virulence

Elizabethkingia miricola is a multidrug-resistant pathogen that can cause life-threatening infections in immunocompromised humans and outbreaks in amphibians. However, the specific virulence factors of this microorganism have not been described. In this study, we identified the polysaccharide biosynthesis protein-encoding gene capD, which is located in the conserved region of the Wzy-dependent capsule synthesis gene cluster in the E. miricola strain FL160902, and investigated its role in the pathogenesis of E. miricola. Our results revealed that the capD deletion strain (ΔcapD) lost its typical encapsulated structure, with a 45% reduction in cell wall thickness. CapD affects wza expression in the capsule polysaccharide synthesis pathway. Furthermore, the survival rates were significantly reduced in ΔcapD in response to complement-mediated killing, desiccation stress, and macrophage phagocytosis, whereas biofilm formation, surface hydrophobicity, and adherence to both endothelial and epithelial cells were increased. Additionally, the deletion of capD sharply attenuated the virulence of E. miricola in a frog infection model. Complementation of the capD gene restored the biological properties and virulence to wild-type levels. Overall, these findings suggest that CapD contributes to polysaccharide synthesis and plays a crucial role in the pathogenesis of E. miricola.

Combination Therapy of Trimethoprim-Sulfamethoxazole (TMP-SMZ) and Eravacycline for Treating Elizabethkingia anophelis-Induced Pulmonary Infections: A Case Report

Elizabethkingia anophelis is an opportunistic pathogen that causes serious life-threatening infections. In this report, we describe a case of pulmonary infection caused by E. anophelis in a young female patient, following cardiac surgery, which was successfully treated with a combination of trimethoprim-sulfamethoxazole (TMP-SMZ) and eravacycline. Additionally, this report provides a summary of high-risk factors for E. anophelis infection, clinical manifestations, and therapeutic options. Given the high degree of antimicrobial drug resistance of the organism and the fact that inappropriate empirical antimicrobial therapy constitutes a risk factor for mortality, our case serves as a valuable reference for similar cases, highlighting potential strategies for effective management.

Large-scale genomic analysis of Elizabethkingia anophelis

The recent emergence of Elizabethkingia anophelis as a human pathogen is a major concern for global public health. This organism has the potential to cause severe infections and has inherent antimicrobial resistance. The potential for widespread outbreaks and rapid global spread highlights the critical importance of understanding the biology and transmission dynamics of this infectious agent. We performed a large-scale analysis of available 540 E. anophelis, including one novel strain isolated from raw milk and sequenced in this study. Pan-genome analysis revealed an open and diverse pan-genome in this species, characterized by the presence of many accessory genes. This suggests that the species has a high level of adaptability and can thrive in a variety of environments. Phylogenetic analysis has also revealed a complex population structure, with limited source-lineage correlation. We identified diverse antimicrobial resistance factors, including core-genome and accessory ones often associated with mobile genetic elements within specific lineages. Mobilome analysis revealed a dynamic landscape primarily composed of genetic islands, integrative and conjugative elements, prophage elements, and small portion of plasmids emphasizing a complex mechanism of horizontal gene transfer. Our study underscores the adaptability of E. anophelis, characterized by a diverse range of antimicrobial resistance genes, putative virulence factors, and genes enhancing fitness. This adaptability is also supported by the organism's ability to acquire genetic material through horizontal gene transfer, primarily facilitated by mobile genetic elements such as integrative and conjugative elements (ICEs). The potential for rapid evolution of this emerging pathogen poses a significant challenge to public health efforts.

A Rare Case of Infective Endocarditis with Recurrent Fever Caused by Elizabethkingia anophelis

Background

Elizabethkingia anophelis, an opportunistic pathogen that can cause infections in multiple parts of the human body, has multiple drug resistance and a high mortality rate. However, there have been few reports of infective endocarditis (IE) caused by Elizabethkingia anophelis, which means that diagnosis and treatment face challenges that cannot be ignored. Rapid and accurate identification and drug sensitivity results are needed to make timely treatment adjustments.

Case Presentation

An 81-year-old man presented with recurrent fever and increased infection index for more than a month. Based on his clinical symptoms, infection index, reduplicative blood cultures, and results of transesophageal echocardiography, he was ultimately diagnosed with infective endocarditis caused by Elizabethkingia anophelis. The patient had a favorable outcome with a 6-week course of intravenous antibiotic therapy.

Conclusion

This is a rare and successfully cured case of IE caused by the pathogen of Elizabethkingia anophelis, which is difficult not only in diagnosis but also in treatment. This case provides a certain referential significance to the treatment of Elizabethkingia anophelis-caused IE in clinical practice.

Prevalence and characterization of an integrative and conjugative element carrying tet(X) gene in Elizabethkingia meningoseptica

OBJECTIVES

To investigate the tet(X) gene, a determinant of tigecycline resistance, in the emerging pathogen Elizabethkingia meningoseptica and its association with an integrative and conjugative element (ICE).

METHODS

All E. meningoseptica genomes from the National Center for Biotechnology Information (n = 87) were retrieved and annotated for resistome searches using the CARD database. A phylogenic analysis was performed based on the E. meningoseptica core genome. The ICE was identified through comparative genomics with other ICEs occurring in Elizabethkingia spp.

RESULTS

Phylogenetic analysis revealed E. meningoseptica genomes from six countries distributed across different lineages, some of which persisted for years. The common resistome of these genomes included blaBlaB, blaCME, blaGOB, ranA/B, aadS, and catB (genes associated with resistance to β-lactams, aminoglycosides, and chloramphenicol). Some genomes also presented additional resistance genes (dfrA, ereD, blaVEB, aadS, and tet(X)). Interestingly, tet(X) and aadS were located in an ICE of 49 769 bp (ICEEmSQ101), which was fully obtained from the E. meningoseptica SQ101 genome. We also showed evidence that the other 27 genomes harboured this ICE. The distribution of ICEEmSQ101, carrying tet(X), was restricted to a single Chinese lineage.

CONCLUSIONS

The tet(X) gene is not prevalent in the species E. meningoseptica, as previously stated for the genus Elizabethkingia, since it is present only in a single Chinese lineage. We identified that several E. meningoseptica genomes harboured an ICE that mobilized the Elizabethkingia tet(X) gene and exhibited characteristics similar to the ICEs of other Flavobacteria, which would favour their transmission in this bacterial family.

Epidemiology, clinical profiles, and antimicrobial susceptibility of Elizabethkingia meningoseptica infections: Insights from a tertiary care hospital in Saudi Arabia

OBJECTIVES

To investigate the incidence rate, clinical characteristics across different age groups, antimicrobial susceptibility, and outcomes of Elizabethkingia meningoseptica (E. meningoseptica) infections.

METHODS

A retrospective analysis was carried out to include 66 cases with confirmed E. meningoseptica cultures from sterile samples between January 2014 and June 2022 at King Faisal Specialist Hospital and Research Centre in Riyadh, Saudi Arabia.

RESULTS

A total of 66 cases were identified, with an incidence rate of 0.3 per 1000 admissions. Most cases were hospital-acquired (80.3%), primarily in critical care areas. All patients had underlying diseases, with respiratory (40.9%) and cardiovascular (39.4%) diseases being the most common. Minocycline showed the highest susceptibility (96.0%), followed by trimethoprim/sulfamethoxazole (77.0%), whereas tobramycin and colistin were fully resistant. The in-hospital mortality rate was 34.8%, whereas the 28-day mortality rate was 22.7%. Clinical characteristics across age groups showed a higher prevalence of cardiovascular disease in pediatrics than in adults, whereas exposure to mechanical ventilation, immunosuppressive therapy, previous infection, anemia, and in-hospital mortality were reported more frequently in adults (p<0.05).

CONCLUSION

Our study provides valuable insights into E. meningoseptica infection in Saudi Arabia, emphasizing the importance of robust infection control measures. Incidence and mortality rates align with global trends. Variations in clinical characteristics across age groups highlight the importance of tailored treatments based on patient demographics and underlying comorbidities.

Identification of novel Tet(X6)-Tet(X2) recombinant variant in Elizabethkingia meningoseptica from a bullfrog farm and downstream river in China

Introduction

The dissemination of strains producing tetracyclines monooxygenase Tet(X) from breeding farms to the natural environment poses a potential threat to public health.

Methods

Antimicrobial susceptibility testing and WGS were performed to identify resistance phenotypes and genotypes. Cloning experiments, sequence alignment, and homology modeling were used to characterize the function and formation mechanisms of the recombinant variant. The mobilization potential of Tet(X) was assessed by collinearity analysis, conjugation experiments, and phylogenetic analysis.

Results

Three tet(X)-producing Elizabethkingia meningoseptica strains were isolated from bullfrog breeding ponds, the sewage outlet, and downstream river in Zhejiang Province, China. These strains carry a novel Tet(X) variant, differing from Tet(X6) by seven residues, and possess the ability to degrade tetracyclines. Interestingly, the novel Tet(X) is a recombinant variant formed by homologous recombination of Tet(X6) and the C-terminal of Tet(X2). Further analysis revealed that Tet(X6) formed several Tet(X) variants, including Tet(X5), through homologous recombination. The novel tet(X) gene is located on a circularizable integrative and conjugative element (ICEEmeChn3), with ISwz1 participating in the recombination of its multi-drug resistance region, potentially facilitating the mobilization and recombination of tet(X) in early hosts. These three strains were clonally transmitted and shared a close genetic relationship (SNP < 62) with a clinically-sourced strain isolated from the same province.

Discussion

To our knowledge, this is the first report of homologous recombination between Tet(X) variants with differing activities. These clonal strains provide evidence of the transmission of tet(X)-positive strains from aquaculture sewage to the natural environment, highlighting the need to strengthen the monitoring and management of this emerging farming model.

The individual contributions of blaB, blaGOB and blaCME on MICs of β-lactams in Elizabethkingia anophelis

BACKGROUND

The blaB, blaGOB and blaCME genes are thought to confer β-lactam resistance to Elizabethkingia anophelis, based on experiments conducted primarily on Escherichia coli.

OBJECTIVES

To determine the individual contributions of β-lactamase genes to increased MICs in E. anophelis and to assess their impact on the in vivo efficacy of carbapenem therapy.

METHODS

Scarless gene deletion of one or more β-lactamase gene(s) was performed in three clinical E. anophelis isolates. MICs were determined by broth microdilution. Hydrolytic activity and expressions of β-lactamase genes were measured by an enzymatic assay and quantitative RT-PCR, respectively. In vivo efficacy was determined using Galleria mellonella and murine thigh infection models.

RESULTS

The presence of blaB resulted in >16-fold increases, while blaGOB caused 4-16-fold increases of carbapenem MICs. Hydrolysis of carbapenems was highest in lysates of blaB-positive strains, possibly due to the constitutionally higher expression of blaB. Imipenem was ineffective against blaB-positive isolates in vivo in terms of improvement of the survival of wax moth larvae and reduction of murine bacterial load. The deletion of blaB restored the efficacy of imipenem. The blaB gene was also responsible for a >4-fold increase of ampicillin/sulbactam and piperacillin/tazobactam MICs. The presence of blaCME, but not blaB or blaGOB, increased the MICs of ceftazidime and cefepime by 8-16- and 4-8-fold, respectively.

CONCLUSIONS

The constitutionally and highly expressed blaB gene in E. anophelis was responsible for increased MICs of carbapenems and led to their poor in vivo efficacy. blaCME increased the MICs of ceftazidime and cefepime.

Clinical Characteristics and Risk Factors for Infection and Death in Critically Ill Patients with Pulmonary Infection with Elizabethkingia Spp

Purpose

Elizabethkingia spp. infections have recently increased, and they are difficult to treat because of intrinsic antimicrobial resistance. This study aimed to investigate the clinical characteristics of patients with pulmonary infection with Elizabethkingia spp. and reveal the risk factors for infection and death.

Patients and Methods

In this retrospective case-control study, patients were divided into infection and control groups based on the bacterial identification results. Patients in the infection group were further divided into survival and death groups according to their hospital outcomes. Clinical characteristics between different groups were compared. We further analyzed antimicrobial susceptibility testing results of the isolated strains.

Results

A total of the 316 patients were divided into infection (n = 79), 23 of whom died, and control (n = 237) groups. Multivariate logistic regression analysis showed that glucocorticoid consumption (OR: 2.35; 95% CI: 1.14-4.81; P = 0.02), endotracheal intubation (OR: 3.74; 95% CI: 1.62-8.64; P = 0.002), and colistin exposure (OR: 2.50; 95% CI: 1.01-6.29; P = 0.046) were significantly associated with pulmonary infection with Elizabethkingia spp. Advanced age (OR: 1.07, 95% CI: 1.00-1.15; P = 0.046), high acute physiology and chronic health evaluation (APACHE) II score (OR: 1.21; 95% CI: 1.01-1.45; P = 0.037), and low albumin level (OR: 0.73, 95% CI: 0.56-0.96; P = 0.025) were significantly associated with in-hospital mortality of infected patients. Elizabethkingia spp. was highly resistant to cephalosporins, carbapenems, macrolides, and aminoglycoside, and was sensitive to fluoroquinolones, minocycline, and co-trimoxazole in vitro.

Conclusion

Glucocorticoid consumption, tracheal intubation, and colistin exposure were associated with pulmonary infection with Elizabethkingia spp. for critically ill patients. Patients with advanced age, high APACHE II score, and low albumin level had higher risk of death from infection.

Central Line-Associated Bloodstream Infection Due to Elizabethkingia anophelis: Case Report and Literature Review on Pediatric Infections

Elizabethkingia anophelis is an opportunistic pathogen causing lifethreatening infections in humans, particularly in immunocompromised patients, neonates and the elderly. We report a case of central line-associated bloodstream infection by E. anophelis in a 2.5-year-old girl with acute lymphoblastic leukemia successfully treated with a combination of piperacillin/tazobactam and amikacin. The literature was also reviewed on pediatric infections caused by E. anophelis, focusing on clinical manifestations, underlying medical conditions, treatment and outcome. Accurate identification with MALDI-TOF, or using molecular techniques, is of the utmost importance because treatment and prognosis differ depending on the species. Considering that E. anophelis is multiresistant to antibiotics and that inappropriate antimicrobial therapy is an independent risk factor for mortality, the early, accurate identification of bacterial species and prompt effective treatment are essential to achieve optimal therapeutic outcomes.

In vitro induction and selection of fluoroquinolone-resistant mutants in Elizabethkingia anophelis

For 29 parent strains, recognized by pulsed-field gel electrophoresis, the MICs multiplied significantly in the ciprofloxacin group than levofloxacin group, following the first and third induction cycle. Ser83Arg in GyrA was the most common site of mutations. No mutation in ParC nor ParE was identified in the selected mutants.

Elizabethkingia anophelis MSU001 Isolated from Anopheles stephensi: Molecular Characterization and Comparative Genome Analysis

Elizabethkingia anophelis MSU001, isolated from Anopheles stephensi in the laboratory, was characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-ToF/MS), biochemical testing, and genome sequencing. Average nucleotide identity analysis revealed 99% identity with the type species E. anophelis R26. Phylogenetic placement showed that it formed a clade with other mosquito-associated strains and departed from a clade of clinical isolates. Comparative genome analyses further showed that it shared at least 98.6% of genes with mosquito-associated isolates (except E. anophelis As1), while it shared at most 88.8% of common genes with clinical isolates. Metabolites from MSU001 significantly inhibited growth of E. coli but not the mosquito gut symbionts Serratia marcescens and Asaia sp. W12. Insect-associated E. anophelis carried unique glycoside hydrolase (GH) and auxiliary activities (AAs) encoding genes distinct from those of clinical isolates, indicating their potential role in reshaping chitin structure and other components involved in larval development or formation of the peritrophic matrix. Like other Elizabethkingia, MSU001 also carried abundant genes encoding two-component system proteins (51), transcription factor proteins (188), and DNA-binding proteins (13). E. anophelis MSU001 contains a repertoire of antibiotic resistance genes and several virulence factors. Its potential for opportunistic infections in humans should be further evaluated prior to implementation as a paratransgenesis agent (by transgenesis of a symbiont of the vector).

Outbreaks of Elizabethkingia miricola Caused Fatal Meningitis-Like Disease in Cultured Bullfrogs

Elizabethkingia miricola is an emerging nosocomial pathogen responsible for meningitis, sepsis, urinary tract infection, pneumonia, and joint infection in humans. These pathogens were also reported to be causal agents for meningitis-like disease in cultured frogs, which displayed high infectivity, mortality, and significant loss. In July 2023, 10 outbreaks of infectious meningitis-like disease in bullfrogs occurred in Tangshan area. To determine the causal agent, 70 diseased frogs from 10 farms were collected for etiological identification. Gram-negative bacilli were isolated from the brain and liver of sick bullfrogs and identified as members of E. miricola by biochemical characterization and 16S rRNA sequencing analysis. A total of 42 strains of E. miricola were isolated and further determined as the etiological agent by reproducing neurological symptoms and deaths in an artificial infection test. A representative isolate, HBTS-1, was picked up for the pathogenicity test, and the data showed that this stain was highly pathogenic to bullfrogs with an LD50 of 3.7 × 105 CFU. Notably, the isolate also showed high pathogenicity to 5-day-old suckling mice, with an LD50 of 3.1 × 106 CFU, indicating its potential threat to mammals. Moreover, all the 42 E. miricola isolates showed resistance to multiple antibotics without an apparent inhibition zone observed in the test, making the choice of antimicrobial therapy challenging. These novel findings prioritized E. miricola as an important zoonotic agent, which may provide a reference for human medicine.

Clinical manifestations, antimicrobial resistance and genomic feature analysis of multidrug-resistant Elizabethkingia strains

BACKGROUND

Elizabethkingia is emerging as an opportunistic pathogen in humans. The aim of this study was to investigate the clinical epidemiology, antimicrobial susceptibility, virulence factors, and genome features of Elizabethkingia spp.

METHODS

Clinical data from 71 patients who were diagnosed with Elizabethkingia-induced pneumonia and bacteremia between August 2019 and September 2021 were analyzed. Whole-genome sequencing was performed on seven isolates, and the results were compared with a dataset of 83 available Elizabethkingia genomes. Genomic features, Kyoto Encyclopedia of Genes and Genomes (KEGG) results and clusters of orthologous groups (COGs) were analyzed.

RESULTS

The mean age of the patients was 56.9 ± 20.7 years, and the in-hospital mortality rate was 29.6% (21/71). Elizabethkingia strains were obtained mainly from intensive care units (36.6%, 26/71) and emergency departments (32.4%, 23/71). The majority of the strains were isolated from respiratory tract specimens (85.9%, 61/71). All patients had a history of broad-spectrum antimicrobial exposure. Hospitalization for invasive mechanical ventilation or catheter insertion was found to be a risk factor for infection. The isolates displayed a high rate of resistance to cephalosporins and carbapenems, but all were susceptible to minocycline and colistin. Genomic analysis identified five β-lactamase genes (blaGOB, blaBlaB, blaCME, blaOXA, and blaTEM) responsible for β-lactam resistance and virulence genes involved in stress adaptation (ureB/G, katA/B, and clpP), adherence (groEL, tufA, and htpB) and immune modulation (gmd, tviB, cps4J, wbtIL, cap8E/D/G, and rfbC). Functional analysis of the COGs revealed that "metabolism" constituted the largest category within the core genome, while "information storage and processing" was predominant in both the accessory and unique genomes. The unique genes in our 7 strains were mostly enriched in KEGG pathways related to microRNAs in cancer, drug resistance (β-lactam and vancomycin), ABC transporters, biological metabolism and biosynthesis, and nucleotide excision repair mechanisms.

CONCLUSION

The Elizabethkingia genus exhibits multidrug resistance and carries carbapenemase genes. This study presents a comparative genomic analysis of Elizabethkingia, providing knowledge that facilitates a better understanding of this microorganism.

Opportunistic Elizabethkingia miricola Infections in Intensive Care Unit, Spain

In 2021, we identified a cluster of Elizabethkingia miricola cases in an intensive care unit in Spain. Because E. miricola is not considered a special surveillance agent in Spain, whole-genome sequencing was not performed. The bacterial source was not identified. All Elizabethkingia species should be listed as special surveillance bacteria.

Characterization of an outbreak caused by Elizabethkingia miricola using Fourier-transform infrared (FTIR) spectroscopy

Fourier-transform infrared (FTIR) spectroscopy has the potential to be used for bacterial typing and outbreak characterization. We evaluated FTIR for the characterization of an outbreak caused by Elizabethkingia miricola. During the 2020-2021 period, 26 isolates (23 clinical and 3 environmental) were collected and analyzed by FTIR (IR Biotyper) and core-genome MLST (cgMLST), in addition to antimicrobial susceptibility testing. FTIR spectroscopy and cgMLST showed that 22 of the isolates were related to the outbreak, including the environmental samples, with only one discordance between both methods. Then, FTIR is useful for E. miricola typing and can be easily implemented in the laboratory.

Probability of outbreaks and cross-border dissemination of the emerging pathogen: a genomic survey of Elizabethkingia meningoseptica

IMPORTANCE

Elizabethkingia meningoseptica is an emerging infectious agent associated with life-threatening infections in immunocompromised individuals. However, there are limited data available on the genomic features of E. meningoseptica. This study aims to characterize the geographical distribution, phylogenetic evolution, pathogenesis, and transmission of this bacterium. A systematic analysis of the E. meningoseptica genome revealed that a common ancestor of this bacterium existed 90 years ago. The evolutionary history showed no significant relationship with the sample source, origin, or region, despite the presence of genetic diversity. Whole genome sequencing data also demonstrated that E. meningoseptica bacteria possess inherent resistance and pathogenicity, enabling them to spread within the same hospital and even across borders. This study highlights the potential for E. meningoseptica to cause severe nosocomial outbreaks and horizontal transmission between countries worldwide. The available evidence is crucial for the development of evidence-based public health policies to prevent global outbreaks caused by emerging pathogens.

A case of Elizabethkingia meningoseptica septicemia

A 82-year-old man was admitted to hospital with fever, unresponsiveness, elevated hypersensitive C-reactive protein and neutrophile granulocyte. Ceftriaxone was administrated by intravenous dripping in the emergency room, but the effect was not satisfactory. Following his admission to the ward, cefoperazone sulbactam were given. Elizabethkingia meningoseptica was identified by blood culture and further confirmed by 16S rRNA sequencing. The lumbar puncture showed that cerebrospinal fluid pressure was 80 mmH2O (1 mmH2O=0.0098 kPa) and biochemical results were normal. After 11 days of cefoperazone sulbactam treatment, the patient was discharged with negative blood culture. The hypersensitive C-reactive protein and neutrophile granulocyte had also declined. The patient received levofloxacin tablets for anti-infection treatment for 14 d after discharge. No signs of infection were observed in three months' following up.

Peritoneal dialysis-associated peritonitis with Elizabethkingia miricola

Peritoneal dialysis (PD)-associated peritonitis is linked to increased mortality rates and transfer to haemodialysis or PD discontinuation. Rare and emerging pathogens can pose challenges in management. We present the first case of PD peritonitis caused by Elizabethkingia miricola through direct contamination, which was successfully treated with intraperitoneal and oral antibiotics.

Getting off tract: contributions of intraorgan microbiota to cancer in extraintestinal organs

The gastrointestinal ecosystem has received the most attention when examining the contributions of the human microbiome to health and disease. This concentration of effort is logical due to the overwhelming abundance of microbes in the gut coupled with the relative ease of sampling compared with other organs. However, the intestines are intimately connected to multiple extraintestinal organs, providing an opportunity for homeostatic microbial colonisation and pathogenesis in organs traditionally thought to be sterile or only transiently harbouring microbiota. These habitats are challenging to sample, and their low microbial biomass among large amounts of host tissue can make study challenging. Nevertheless, recent findings have shown that many extraintestinal organs that are intimately linked to the gut harbour stable microbiomes, which are colonised from the gut in selective manners and have highlighted not just the influence of the bacteriome but that of the mycobiome and virome on oncogenesis and health.

Successful Eradication of a Highly Resistant Elizabethkingia anophelis Species in a Premature Neonate With Bacteremia and Meningitis

Elizabethkingia anophelis is a Gram-negative bacillus that can exhibit highly resistant phenotypes against most antibiotics with evidence of efficacy and safety in the neonatal population. Given the limited antimicrobial options, clinicians may be forced into challenging treatment scenarios when faced with central nervous system infections in premature neonates caused by E. anophelis . We report a case of successful treatment of hospital-acquired meningitis and bacteremia caused by E. anophelis at 11 days of life in a male infant born at 29 weeks, 1 day gestation and birth weight of 1.41 kg. Therapy consisted of vancomycin, dose adjusted to maintain goal troughs of 15-20 mg/L, and rifampin 10 mg/kg/dose every 12 hours, with ciprofloxacin 15 mg/kg/dose every 12 hours and trimethoprim/sulfamethoxazole 5 mg/kg/dose every 12 hours added due to antimicrobial susceptibilities and unsatisfactory response, for a total of 21 days. Following initiation of this multidrug regimen, repeat cultures were negative, laboratory parameters improved [with exception of elevated cerebrospinal fluid (CSF) white blood cell count], the patient remained otherwise stable, and there were no adverse effects noted from therapy. Complications after treatment included the requirement of bilateral hearing aids and the development of hydrocephalus necessitating ventriculoperitoneal shunt placement. To our knowledge, we report the first case of meningitis in a premature neonate initially identified as E. anophelis in the United States treated with this regimen which led to successful microbiologic eradication with no antimicrobial safety concerns.

In Vitro and In Vivo Antimicrobial Activities of Vancomycin and Rifampin against Elizabethkingia anophelis

Elizabethkingia anophelis has emerged as a critical human pathogen, and a number of isolated reports have described the successful treatment of Elizabethkingia infections with vancomycin, a drug that is typically used to target Gram-positive bacteria. This study employed in vitro broth microdilution checkerboard and time-kill assays, as well as in vivo zebrafish animal models to evaluate the individual and combination antimicrobial effects of vancomycin and rifampin against E. anophelis. The minimum inhibitory concentration ranges of vancomycin and rifampin against 167 isolates of E. anophelis were 16-256 mg/L and 0.06-128 mg/L, respectively. The checkerboard assay results revealed a synergistic effect between vancomycin and rifampin in 16.8% (28/167) of the isolates. Time-kill assays were implemented for 66 isolates, and the two-drug combination had a synergistic interaction in 57 (86.4%) isolates. In vivo zebrafish studies revealed that treatment with vancomycin monotherapy, rifampin monotherapy, or vancomycin-rifampin combination therapy yielded a higher survival rate than the control group treatment with 0.9% saline. The results of this study support the use of vancomycin to treat E. anophelis infections.

Immune Activation and Inflammatory Response Mediated by the NOD/Toll-like Receptor Signaling Pathway-The Potential Mechanism of Bullfrog (Lithobates catesbeiana) Meningitis Caused by Elizabethkingia miricola

Elizabethkingia miricola is an emerging opportunistic pathogen that is highly pathogenic in both immunocompromised humans and animals. Once the disease occurs, treatment can be very difficult. Therefore, a deep understanding of the pathological mechanism of Elizabethkingia miricola is the key to the prevention and control of the disease. In this study, we isolated the pathogenic bacteria from bullfrogs with dark skin color, weak limbs, wryneck, and cataracts. Via subsequent morphological observations and a 16S rRNA gene sequence analysis, the pathogen was identified as Elizabethkingia miricola. The histopathological and transmission electron microscopy analysis revealed that the brain was the main target organ. Therefore, brain samples from diseased and healthy bullfrogs were used for the RNA-Seq analysis. The comparative transcriptome analysis revealed that the diseased bullfrog brain was characterized by the immune activation and inflammatory response, which were mediated by the "NOD-like receptor signaling pathway" and the "Toll-like receptor signaling pathway". We also performed qRT-PCR to examine the expression profile of inflammation-related genes, which further verified the reliability of our transcriptome data. Based on the above results, it was concluded that the NOD/Toll-like receptor-related networks that dominate the immune activation and inflammatory response were activated in the brain of Elizabethkingia miricola-infected bullfrogs. This study contributes to the search for therapeutic targets for bullfrog meningitis and provides basic information for establishing effective measures to prevent and control bullfrog meningitis.

Multiomics reveal human umbilical cord mesenchymal stem cells improving acute lung injury via the lung-gut axis

BACKGROUND

Acute lung injury (ALI) and its final severe stage, acute respiratory distress syndrome, are associated with high morbidity and mortality rates in patients due to the lack of effective specific treatments. Gut microbiota homeostasis, including that in ALI, is important for human health. Evidence suggests that the gut microbiota improves lung injury through the lung-gut axis. Human umbilical cord mesenchymal cells (HUC-MSCs) have attractive prospects for ALI treatment. This study hypothesized that HUC-MSCs improve ALI via the lung-gut microflora.

AIM

To explore the effects of HUC-MSCs on lipopolysaccharide (LPS)-induced ALI in mice and the involvement of the lung-gut axis in this process.

METHODS

C57BL/6 mice were randomly divided into four groups (18 rats per group): Sham, sham + HUC-MSCs, LPS, and LPS + HUC-MSCs. ALI was induced in mice by intraperitoneal injections of LPS (10 mg/kg). After 6 h, mice were intervened with 0.5 mL phosphate buffered saline (PBS) containing 1 × 106 HUC-MSCs by intraperitoneal injections. For the negative control, 100 mL 0.9% NaCl and 0.5 mL PBS were used. Bronchoalveolar lavage fluid (BALF) was obtained from anesthetized mice, and their blood, lungs, ileum, and feces were obtained by an aseptic technique following CO2 euthanasia. Wright's staining, enzyme-linked immunosorbent assay, hematoxylin-eosin staining, Evans blue dye leakage assay, immunohistochemistry, fluorescence in situ hybridization, western blot, 16S rDNA sequencing, and non-targeted metabolomics were used to observe the effect of HUC-MSCs on ALI mice, and the involvement of the lung-gut axis in this process was explored. One-way analysis of variance with post-hoc Tukey's test, independent-sample Student's t-test, Wilcoxon rank-sum test, and Pearson correlation analysis were used for statistical analyses.

RESULTS

HUC-MSCs were observed to improve pulmonary edema and lung and ileal injury, and decrease mononuclear cell and neutrophil counts, protein concentrations in BALF and inflammatory cytokine levels in the serum, lung, and ileum of ALI mice. Especially, HUC-MSCs decreased Evans blue concentration and Toll-like receptor 4, myeloid differentiation factor 88, p-nuclear factor kappa-B (NF-κB)/NF-κB, and p-inhibitor α of NF-κB (p-IκBα)/IκBα expression levels in the lung, and raised the pulmonary vascular endothelial-cadherin, zonula occludens-1 (ZO-1), and occludin levels and ileal ZO-1, claudin-1, and occludin expression levels. HUC-MSCs improved gut and BALF microbial homeostases. The number of pathogenic bacteria decreased in the BALF of ALI mice treated with HUC-MSCs. Concurrently, the abundances of Oscillospira and Coprococcus in the feces of HUS-MSC-treated ALI mice were significantly increased. In addition, Lactobacillus, Bacteroides, and unidentified_Rikenellaceae genera appeared in both feces and BALF. Moreover, this study performed metabolomic analysis on the lung tissue and identified five upregulated metabolites and 11 downregulated metabolites in the LPS + MSC group compared to the LPS group, which were related to the purine metabolism and the taste transduction signaling pathways. Therefore, an intrinsic link between lung metabolite levels and BALF flora homeostasis was established.

CONCLUSION

This study suggests that HUM-MSCs attenuate ALI by redefining the gut and lung microbiota.

Review on infection control strategies to minimize outbreaks of the emerging pathogen Elizabethkingia anophelis

BACKGROUND

Elizabethkingia anophelis is a multi-drug resistant emerging opportunistic pathogen with a high mortality rate, causing healthcare-associated outbreaks worldwide.

METHODS

We report a case of E. anophelis pleuritis, resulting from transmission through lung transplantation, followed by a literature review of outbreak reports and strategies to minimize E. anophelis transmission in healthcare settings.

RESULTS

From 1990 to August 2022, 14 confirmed E. anophelis outbreak cohorts and 21 cohorts with suspected E. anophelis outbreaks were reported in literature. A total of 80 scientific reports with recommendations on diagnostics and infection control measures were included and summarized in our study.

CONCLUSION

Strategies to prevent and reduce spread of E. anophelis include water-free patient rooms, adequate hygiene and disinfection practices, and optimized diagnostic techniques for screening, identification and molecular typing.

The First Reported Case of Elizabethkingia anophelis From Nepal

Elizabethkingia anophelis, a gram-negative bacillus belonging to the Flavobacteriaceae family, is found in various environmental sources and has been associated with community and hospital outbreaks. Correct identification is crucial, guided by advanced genomic techniques, i.e., matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system with an updated database. The case fatality rate, ranging from 24 to 60%, underscores the need for timely recognition and appropriate management. Additionally, Elizabethkingia presents a challenge due to its recent discovery, misidentification history, and drug resistance. Here, we present a case of fatal infection in a 30-year-old male, who presented with pneumonia. It gradually progressed and ultimately proved fatal underscoring the virulence of the pathogen involved. It was a diagnostic challenge as it likely is the first reported instance of Elizabethkingia anophelis infection from Nepal.

Validation of 16S rRNA and Complete rpoB Gene Sequence Analysis for the Identification of Elizabethkingia Species

Bacteria in the genus Elizabethkingia have emerged as a cause of life-threatening infections in humans. However, accurate species identification of these pathogens relies on molecular techniques. We aimed to evaluate the accuracy of 16S rRNA and complete RNA polymerase β-subunit (rpoB) gene sequences in identifying Elizabethkingia species. A total of 173 Elizabethkingia strains with whole-genome sequences in GenBank were included. The 16S rRNA gene and rpoB gene sequences from the same Elizabethkingia strains were examined. Of the 41 E. meningoseptica strains, all exhibited >99.5% 16S rRNA similarity to its type strain. Only 83% of the 99 E. anophelis strains shared >99.5% 16S rRNA gene similarity with its type strain. All strains of E. meningoseptica and E. anophelis formed a cluster distinct from the other Elizabethkingia species in the 16S rRNA and rpoB gene phylogenetic trees. The polymorphisms of 16S rRNA gene sequences are not sufficient for constructing a phylogenetic tree to discriminate species in the E. miricola cluster (E. miricola, E. bruuniana, E. occulta, and E. ursingii). The complete rpoB gene phylogenetic tree clearly delineates all strains of Elizabethkingia species. The complete rpoB gene sequencing could be a useful complementary phylogenetic marker for the accurate identification of Elizabethkingia species.

Development and application of a dose-response model for Elizabethkingia spp

Elizabethkingia spp. are common environmental pathogens responsible for infections in more vulnerable populations. Although the exposure routes of concern are not well understood, some hospital-associated outbreaks have indicated possible waterborne transmission. In order to facilitate quantitative microbial risk assessment (QMRA) for Elizabethkingia spp., this study fit dose-response models to frog and mice datasets that evaluated intramuscular and intraperitoneal exposure to Elizabethkingia spp. The frog datasets could be pooled, and the exact beta-Poisson model was the best fitting model with optimized parameters α  = 0.52 and β = 86,351. Using the exact beta-Poisson model, the dose of Elizabethkingia miricola resulting in a 50% morbidity response (LD50) was estimated to be approximately 237,000 CFU. The model developed herein was used to estimate the probability of infection for a hospital patient under a modeled exposure scenario involving a contaminated medical device and reported Elizabethkingia spp. concentrations isolated from hospital sinks after an outbreak. The median exposure dose was approximately 3 CFU/insertion event, and the corresponding median risk of infection was 3.4E-05. The median risk estimated in this case study was lower than the 3% attack rate observed in a previous outbreak, however, there are noted gaps pertaining to the possible concentrations of Elizabethkingia spp. in tap water and the most likely exposure routes. This is the first dose-response model developed for Elizabethkingia spp. thus enabling future risk assessments to help determine levels of risk and potential effective risk management strategies.

Identification and pathogenicity of multidrug-resistant Elizabethkingia miricola isolated from farmed American bullfrogs Rana catesbeiana in China with in vitro screening of herbal antimicrobial agents

OBJECTIVE

In 2021, an outbreak of an infectious disease characterized by torticollis, cataracts, and neurological disorders caused massive mortality in farmed American bullfrogs Rana catesbeiana in Hubei province, China. We identified the causal agent in this outbreak, characterized its pathogenicity, and screened candidate antimicrobial agents for future disease control.

METHODS

Bacterium was isolated from the diseased American bullfrogs and identified based on biochemical tests, sequence analyses (16S ribosomal RNA; DNA gyrase subunit B), and experimental challenge. Furthermore, antibiotic sensitivity of the isolated strain was detected with Kirby-Bauer paper diffusion method, and the antibacterial activity of 60 traditional Chinese herbal extracts against the isolated strain was evaluated by agar disc diffusion and broth dilution assays.

RESULT

We identified Elizabathkingia miricola strain FB210601 as the causative agent of this disease. The isolated E. miricola strain FB210601 exhibited extensive antibiotic resistance to all tested quinolones, β-lactam antibiotics, and aminoglycosides. Eight herbal extracts exhibited excellent antimicrobial activity against E. miricola FB210601, especially Caesalpinia sappan and Rhus chinensis, with minimal inhibitory concentrations less than 0.2 mg/mL. Additionally, the combined effects of two-component herbal mixtures containing C. sappan or R. chinensis were greater than those of the individual extracts.

CONCLUSION

Our results provide a reference for understanding the pathogenesis of Elizabethkingia infection in frogs. Furthermore, this study will aid in the application of herbal extracts for protection against infections caused by multidrug-resistant Elizabathkingia in the future.

Microbial landscapes of the rhizosphere soils and roots of Luffa cylindrica plant associated with Meloidogyne incognita

Introduction

The root-knot nematodes (RKN), especially Meloidogyne spp., are globally emerging harmful animals for many agricultural crops.

Methods

To explore microbial agents for biological control of these nematodes, the microbial communities of the rhizosphere soils and roots of sponge gourd (Luffa cylindrica) infected and non-infected by M. incognita nematodes, were investigated using culture-dependent and -independent methods.

Results

Thirty-two culturable bacterial and eight fungal species, along with 10,561 bacterial and 2,427 fungal operational taxonomic units (OTUs), were identified. Nine culturable bacterial species, 955 bacterial and 701 fungal OTUs were shared in both four groups. More culturable bacterial and fungal isolates were detected from the uninfected soils and roots than from the infected soils and roots (except no fungi detected from the uninfected roots), and among all samples, nine bacterial species (Arthrobacter sp., Bacillus sp., Burkholderia ambifaria, Enterobacteriaceae sp., Fictibacillus barbaricus, Microbacterium sp., Micrococcaceae sp., Rhizobiaceae sp., and Serratia sp.) were shared, with Arthrobacter sp. and Bacillus sp. being dominant. Pseudomonas nitroreducens was exclusively present in the infested soils, while Mammaliicoccus sciuri, Microbacterium azadirachtae, and Priestia sp., together with Mucor irregularis, Penicillium sp., P. commune, and Sordariomycetes sp. were found only in the uninfected soils. Cupriavidus metallidurans, Gordonia sp., Streptomyces viridobrunneus, and Terribacillus sp. were only in the uninfected roots while Aspergillus sp. only in infected roots. After M. incognita infestation, 319 bacterial OTUs (such as Chryseobacterium) and 171 fungal OTUs (such as Spizellomyces) were increased in rhizosphere soils, while 181 bacterial OTUs (such as Pasteuria) and 166 fungal OTUs (such as Exophiala) rose their abundance in plant roots. Meanwhile, much more decreased bacterial or fungal OTUs were identified from rhizosphere soils rather than from plant roots, exhibiting the protective effects of host plant on endophytes. Among the detected bacterial isolates, Streptomyces sp. TR27 was discovered to exhibit nematocidal activity, and B. amyloliquefaciens, Bacillus sp. P35, and M. azadirachtae to show repellent potentials for the second stage M. incognita juveniles, which can be used to develop RKN bio-control agents.

Discussion

These findings provided insights into the interactions among root-knot nematodes, host plants, and microorganisms, which will inspire explorations of novel nematicides.

Microbiological Characterization and Clinical Facets of Elizabethkingia Bloodstream Infections in a Tertiary Care Hospital of Eastern India

Purpose

Elizabethkingia is an emerging non-fermenting Gram-negative bacillus (NFGNB) causing bloodstream infections (BSI) associated with high mortality. It demonstrates a unique antimicrobial profile in showing susceptibility to antimicrobials effective against Gram-positive bacteria. This study was undertaken to determine the overall frequency of Elizabethkingia BSI, associated risk factors, microbiological susceptibility, and clonal relationship of Elizabethkingia isolates using Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR).

Patients and Methods

Elizabethkingia isolates obtained from the blood culture of admitted patients (August 2020-December 2021) were identified by the VITEK 2 system and subjected to an antimicrobial susceptibility test by standard procedures. Demographics, co-morbidities, risk factors for survival, and outcome were summarized and analyzed by Chi-square test, Kaplan-Meier curve, and Cox regression. Clonal relatedness between Elizabethkingia isolates was analyzed using ERIC‑PCR fingerprinting with the "PAST: Paleontological statistics software package".

Results

Of 13,747 blood samples received during the study period, 13.59% were culture positive, and 14.60% were NFGNBs. The frequency of Elizabethkingia spp. among all NFGNBs in BSI was 29.30%, and the overall prevalence in BSI was 4.21%. In patients with Elizabethkingia BSI, Foley's catheter was present in 81.25% of the cases. 100% susceptibility was observed to linezolid, followed by vancomycin (98.75%) and chloramphenicol (89.5%). The 30-day mortality rate in the patients of Elizabethkingia BSI was 26.25%. The Presence of COVID-19, pneumonia, diabetes mellitus (DM), mechanical ventilation (MV), and prior antibiotics were significantly different (p<0.05) between the survival and death groups. ERIC-PCR profile dendrogram of Elizabethkingia isolates showed ten major clusters indicating high genetic diversity.

Conclusion

Elizabethkingia was responsible for one-third of NFGNB BSI in a single-center study, with approximately 26% of 30-day all-cause mortality. Most isolates were susceptible to linezolid, vancomycin, and chloramphenicol. COVID-19 was the most significant risk factor associated with mortality. ERIC-PCR of Elizabethkingia isolates exhibited high genetic diversity.

Genomic and phylogenetic characterization of Elizabethkingia anophelis strains: The first two cases of life-threatening infection in Japan

OBJECTIVE

Elizabethkingia anophelis causes meningitis, bloodstream infections, and respiratory infections in immunocompromised individuals. We examined two E. anophelis strains isolated from the first life-threatening cases caused by this species in Japan to determine the phylogenetic origin and genomic features of them.

METHODS

We performed whole genome-based analysis to clarify the genetic relationship for the two strains (EK0004 and EK0079) and Elizabethkingia sp. strains isolated from worldwide and to characterize the genomic features such as the prevalence of virulence- and antimicrobial resistance (AMR)-related genes.

PATIENTS

A 29-year-old man with hepatosplenic T-cell lymphoma and a 52-year-old man with systemic lupus erythematosus developed fatal bacteremia and meningitis due to E. anophelis, respectively.

RESULTS

Two strains, EK0004 and EK0079, were genetically different but most closely related to the strains isolated from the largest outbreak in Wisconsin, USA from 2015 to 2016, and the strain isolated from cerebrospinal fluid of a patient in Florida, USA in 1982, respectively. The two strains contained AMR-related genes such as those encoding for an extended-spectrum β-lactamase and multiple metallo-β-lactamases and several virulence-related genes such as capsular polysaccharide synthesis gene clusters.

CONCLUSIONS

Although further functional analyses are required to understand the virulence of these clones, these finding suggests that enough caution of E. anophelis infection in immunocompromised patients is required since the number of infections by this species is increasing outside Japan.

Natural occurrences and characterization of Elizabethkingia miricola infection in cultured bullfrogs (Rana catesbeiana)

Introduction

The bacterium Elizabethkingia miricola is a multispecies pathogen associated with meningitis-like disease that has been isolated from several amphibian species, including the bullfrog, but this is the first isolation in Guangxi. In the present study, the dominant bacteria were isolated from the brains of five bullfrogs with meningitis-like disease on a South China farm in Guangxi.

Methods

The NFEM01 isolate was identified by Gram staining; morphological observations; 16S rRNA, rpoB, and mutT-based phylogenetic tree analysis; and physiochemical characterization and was subjected to drug sensitivity and artificial infection testing.

Results and discussion

As a result of identification, the NFEM01 strain was found to be E. miricola. An artificial infection experiment revealed that NFEM01 infected bullfrogs and could cause symptoms of typical meningitis-like disease. As a result of the bacterial drug sensitivity test, NFEM01 is highly sensitive to mequindox, rifampicin, enrofloxacin, nitrofural, and oxytetracycline and there was strong resistance to gentamicin, florfenicol, neomycin, penicillin, amoxicillin, doxycycline, and sulfamonomethoxine. This study provides a reference to further study the pathogenesis mechanism of E. miricola-induced bullfrog meningitislike disease and its prevention and treatment.

Bullfrogs (Lithobates catesbeianus) as a Potential Source of Foodborne Disease

In Mexico, bullfrogs (Lithobates catesbeianus) are produced as gourmet food. However, bullfrogs can be carriers of pathogens because the frogs' preferred living conditions occur in stagnant water. The present study aimed to identify bacteria that cause foodborne diseases or are associated with human diseases. For molecular identification, based on the sequential analysis by 16S rRNA or rpoD was conducted on all isolates obtained from bullfrog. A total of 91 bacterial isolates were obtained from bullfrogs; 14 genera and 23 species were identified, including Acinetobacter johnsonii 16.5%; Aeromonas media 14.3%; Aeromonas veronii 13.2%; Providencia rettgeri 7.7%; Citrobacter freundii 6.6%; Aeromonas caviae 4.4%; Aeromonas hydrophila and Elizabethkingia ursingii 3.3%; Pseudomonas stutzeri, Raoultella ornithinolytica, and Shewanella putrefaciens 2.2%; Acinetobacter guillouiae, Acinetobacter pseudolwoffii, Citrobacter portucalensis, Citrobacter werkmanii, Edwardsiella anguillarum, Klebsiella michiganensis, Kluyvera intermedia, Kocuria rosea, Myroides odoratimimus, Myroides odoratus, Proteus sp., and Proteus hauseri 1.1%. In this study, 49.4% of the isolates obtained cause foodborne disease, 19.8% are bacteria that play an important role in the spoilage of food, 5.5% of isolates have nosocomial significance, 13.2% of bacteria are considered to be pollutants of the ecosystem, and in the case of A. salmonicida and Edwardsiella anguillarum (12.1%) to have a negative impact on aquaculture. Acinetobacter pseudolwoffii and Citrobacter portucalensis have not been reported to cause disease. Lastly of these isolates, 97.8% (89/91) can cause disease by food consumption or by direct contact for immunocompromised persons. The presence of these bacteria in bullfrogs represents a significant problem for human health. There is evidence that these microorganisms are pathogenic and frogs may also be reservoirs.

Treatment Failure Due to Adaptive Resistance Mechanisms in a Severe and Complicated Bloodstream Infection Due to Elizabethkingia meningoseptica

Elizabethkingia meningoseptica is an uncommonly encountered multidrug-resistant gram-negative bacterium that causes infections primarily among vulnerable hosts. A true opportunistic pathogen, its ability to cause severe sepsis and complicated infection in selected patients has been noted. Very limited preclinical and clinical data exist with regard to suitable therapeutic options. In this study, we present the case of prolonged bloodstream and central nervous system infection due to E. meningoseptica treated with dose-optimized combination antibiotic therapy, with evidence of microbiological (including development of adaptive resistance mechanisms) and clinical failure.