rpoB gene sequencing highlights the prevalence of an E. miricola cluster over other Elizabethkingia species among UK cystic fibrosis patients

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.

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.

Effect of Intragenomic Sequence Heterogeneity among Multiple 16S rRNA Genes on Species Identification of Elizabethkingia

Accurate identification of Elizabethkingia species mostly requires the use of molecular techniques, and 16S rRNA gene sequencing is generally considered the method of choice. In this study, we evaluated the effect of intraspecific diversity among the multiple copies of the 16S rRNA gene on the accuracy of species identification in the genus Elizabethkingia. Sequences of 16S rRNA genes obtained from the 32 complete whole-genome sequences of Elizabethkingia deposited in GenBank and from 218 clinical isolates collected from 5 hospitals in Taiwan were analyzed. Four or five copies of 16S rRNA were identified in the Elizabethkingia species with complete genome sequences. The dissimilarity among the copies of the16S rRNA gene was <1% in all Elizabethkingia strains. E. meningoseptica demonstrated a significantly higher rate of nucleotide variations in the 16S rRNA than did E. anophelis (P = 0.011). Nucleotide alterations occurred more frequently in regions V2 and V6 than in other hypervariable regions (P < 0.001). E. meningoseptica, E. anophelis, and E. argenteiflava strains were clustered distinctly in the phylogenetic tree inferred from 16S rRNA genes, and the intragenomic variation of gene sequences had no profound effect on the classification of taxa. However, E. miricola, E. bruuniana, E. ursingii, and E. occulta were grouped closely in the phylogenetic analysis, and the variation among the multiple copies of the 16S rRNA in one E. ursingii strain affected species classification. Other marker genes may be required to supplement the species classification of closely related taxa in the genus Elizabethkingia. IMPORTANCE Incorrect identification of bacterial species would influence the epidemiology and clinical analysis of patients infected with Elizabethkingia. The results of the present study suggest that 16S rRNA gene sequencing should not be considered the gold standard for the accurate identification of Elizabethkingia species.

Epidemiology and Characteristics of Elizabethkingia spp. Infections in Southeast Asia

Elizabethkingia spp. is a ubiquitous pathogenic bacterium that has been identified as the causal agent for a variety of conditions such as meningitis, pneumonia, necrotizing fasciitis, endophthalmitis, and sepsis and is emerging as a global threat including in Southeast Asia. Elizabethkingia infections tend to be associated with high mortality rates (18.2–41%) and are mostly observed in neonates and immunocompromised patients. Difficulties in precisely identifying Elizabethkingia at the species level by traditional methods have hampered our understanding of this genus in human infections. In Southeast Asian countries, hospital outbreaks have usually been ascribed to E. meningoseptica, whereas in Singapore, E. anophelis was reported as the main Elizabethkingia spp. associated with hospital settings. Misidentification of Elizabethkingia spp. could, however, underestimate the number of cases attributed to the bacterium, as precise identification requires tools such as MALDI-TOF MS, and particularly whole-genome sequencing, which are not available in most hospital laboratories. Elizabethkingia spp. has an unusual antibiotic resistance pattern for a Gram-negative bacterium with a limited number of horizontal gene transfers, which suggests an intrinsic origin for its multidrug resistance. Efforts to prevent and further understand Elizabethkingia spp. infections and limit its spread must rise to this new challenge.

Elizabethkingia miricola Recovered from a Peritoneal Fluid Sample – A Clinical Case Report with Diagnostic Challenges

Background: Elizabethkingia spp. are Gram-negative, non-spore-forming bacteria that used to be rarely encountered but now they are of growing clinical significance. Furthermore, the diagnostic challenges to identification impede the complete elucidation of their epidemiology and association with human diseases. Case report: A 64-year-old man with liver cirrhosis due to alcohol abuse presented with fatigue, abdominal swelling, and bilateral scrotal edema. A peritoneal fluid sample was cultured and subject to a number of identification methods – API 20 NE (bioMerieux), automated Vitek-2 Compact (bioMerieux), MALDI-TOF MS (Vitek-MS, bioMerieux), and 16S rRNA gene sequencing. A final diagnosis of bacterascites was made on the basis of clinical, laboratory, and microbiological findings. Conclusion: To the best of our knowledge this is the first report of Elizabethkingia miricola being cultured from a peritoneal fluid sample in an immune-compromised host thus pointing to the emerging pathogenic role of the bacterium in patients with liver cirrhosis and ascites.  

Susceptibility of Elizabethkingia spp. to commonly tested and novel antibiotics and concordance between broth microdilution and automated testing methods

OBJECTIVES

We aimed to determine susceptibilities of Elizabethkingia spp. to 25 commonly tested and 8 novel antibiotics, and to compare the performance of different susceptibility testing methods.

METHODS

Clinical isolates of Elizabethkingia spp., Chryseobacterium spp. and Flavobacterium spp. collected during 2002-18 (n = 210) in a nationwide surveillance programme in Taiwan were speciated by 16S rRNA sequencing. MICs were determined by broth microdilution. The broth microdilution results of 18 common antibiotics were compared with those obtained by the VITEK 2 automated system.

RESULTS

Among the Elizabethkingia spp. identified (n = 108), Elizabethkingia anophelis was the most prevalent (n = 90), followed by Elizabethkingia meningoseptica (n = 7) and Elizabethkingia miricola cluster [E. miricola (n = 6), Elizabethkingia bruuniana (n = 3) and Elizabethkingia ursingii (n = 2)]. Most isolates were recovered from respiratory or blood specimens from hospitalized, elderly patients. PFGE showed two major and several minor E. anophelis clones. All isolates were resistant to nearly all the tested β-lactams. Doxycycline, minocycline and trimethoprim/sulfamethoxazole inhibited >90% of Elizabethkingia spp. Rifampin inhibited E. meningoseptica (100%) and E. anophelis (81.1%). Fluoroquinolones and tigecycline were active against E. meningoseptica and E. miricola cluster isolates. Novel antibiotics, including imipenem/relebactam, meropenem/vaborbactam, ceftazidime/avibactam, cefepime/zidebactam, delafloxacin, eravacycline and omadacycline were ineffective but lascufloxacin inhibited half of Elizabethkingia spp. The very major discrepancy rates of VITEK 2 were >1.5% for ciprofloxacin, moxifloxacin and vancomycin. Major discrepancy rates were >3% for amikacin, tigecycline, piperacillin/tazobactam and trimethoprim/sulfamethoxazole.

CONCLUSIONS

MDR, absence of standard interpretation criteria and poor intermethod concordance necessitate working guidelines to facilitate future research of emerging Elizabethkingia spp.

A real-time PCR assay for detection of emerging infectious Elizabethkingia miricola

Elizabethkingia miricola, a Gram-negative bacillus, is emerging as a life-threatening pathogen in both humans and animals. However, no specific and rapid diagnostic method exists to detect E. miricola. Here, we established a real-time PCR assay for the rapid, sensitive, and specific detection of E. miricola with a wide dynamic range of 10⁸ copies/μL to 10² copies/μL. The detection limit of the real-time assay was 145 copies/μL, which was 100 times more sensitive than conventional PCR. All clinical isolates E. miricola from different host species yield very close Tm (80.25 ± 0.25 °C). Additionally, no cross-reaction or false positives were observed in the assay for non-target bacterial species. The performance of this assay was primarily assessed by testing frog tissue samples. Overall, our study provided a real-time PCR assay, which is a rapid, sensitive, and specific diagnostic method that could be used for early diagnosis and epidemiological investigation of E. miricola.

Elizabethkingia miricola bacteraemia in a haemodialysis patient

We report a case of catheter-associated Elizabethkingia miricola bacteraemia in a haemodialysis patient. The patient was a 73-year-old home haemodialysis patient who presented with a history of recurrent falls and fevers. Blood cultures grew Gram-negative bacilli identified by MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry 6903 MSP Library) and 16S rRNA gene sequencing as E. miricola. E. miricola is an emerging human pathogen and is multidrug-resistant, making the choice of antimicrobial therapy challenging. There are only a small number of case reports of human infection worldwide and this is the second reported case of catheter-related bacteraemia. It has also been found in the hospital environment in South Korea and is pathogenic in black-spotted frogs.

Molecular Characteristics and Antimicrobial Susceptibility Profiles of Elizabethkingia Clinical Isolates in Shanghai, China

Purpose

To investigate molecular characteristics and antimicrobial susceptibility profiles of clinical isolates of Elizabethkingia in Shanghai, China.

Methods

Elizabethkingia isolates were collected in a university-affiliated hospital in 2012–2015 and 2017–2018. They were re-identified to species level by 16S rRNA gene and species-specific gene sequencing. Antimicrobial susceptibility testing, screening for metallo-beta-lactamase production, identification of antimicrobial resistance genes and pulsed-field gel electrophoresis (PFGE) were performed.

Results

Among 52 Elizabethkingia isolates, E. anophelis was the most prevalent species (67.3%), followed by E. meningoseptica (26.9%). High carriage rates of bla_CME, bla_BlaB and bla_GOB genes were consistent with the poor in vitro activity of most β-lactams including carbapenems. Nevertheless, β-lactamase inhibitors increased susceptibility rates significantly for cefoperazone and piperacillin. Susceptibility rates for minocycline, tigecycline, rifampin and levofloxacin were 100%, 78.8%, 76.9% and 71.2%, respectively. Ser83Ile or Ser83Arg substitution in the DNA gyrase A unit was associated with resistance to fluoroquinolones. MIC₅₀/MIC₉₀ values of vancomycin and linezolid were 16/16 mg/L and 16/32 mg/L, respectively. Molecular typing showed twenty-one different types of PFGE and more than one indistinguishable isolates were observed in each of the eight subtypes.

Conclusion

Tetracyclines, tigecycline, β-lactam/β-lactamase inhibitor combinations, rifampin and fluoroquinolones demonstrated high rates of in vitro activity against clinical isolates of Elizabethkingia. Both genetic diversity and clonality were observed from this health-care facility. Our report provides potential alternative treatment options for Elizabethkingia infections.

Whole-genome analysis of the potentially zoonotic Elizabethkingia miricola FL160902 with two new chromosomal MBL gene variants

Objectives

Elizabethkingia is an emerging life-threatening pathogen in both humans and animals. We describe the whole-genome analysis of an Elizabethkingia miricola strain isolated from a diseased frog in China and investigate the molecular mechanism of carbapenem resistance in this pathogen.

Methods

WGS of E. miricola FL160902 was performed using single-molecule, real-time technology. A phylogenetic tree was generated by SNP analysis, comparing the genome of our strain with other E. miricola isolates of amphibian and human origins. Antimicrobial resistance genes and virulence-related genes were identified using the Comprehensive Antibiotic Resistance Database (CARD) and the Virulence Factor Database (VFDB). Two putative carbapenemase genes were expressed in Escherichia coli to evaluate their contribution to antimicrobial resistance.

Results

The genome of E. miricola FL160902 consists of a 4 249 586 bp circular chromosome with 27 putative resistance genes and 38 predicted virulence-associated genes. Comparative genomic analysis demonstrated that the E. miricola strains of human and amphibian origins have similar virulence-associated gene profiles. In addition, all the amphibian isolates clustered together with one of the human isolates in the phylogenetic analysis. WGS revealed the presence of two novel MBL genes, designated blaBlaB-16 and blaGOB-19. Cloning of blaBlaB-16 and blaGOB-19 into E. coli DH5α resulted in increased MICs of most β-lactams, including imipenem, meropenem and ampicillin.

Conclusions

We identified two chromosomal MBL gene variants, named blaBlaB-16 and blaGOB-19 in an amphibian E. miricola isolate, which was considered potentially zoonotic based on phylogenetic analysis and virulence-associated gene comparison. This study highlights the importance of E. miricola as a potential zoonotic pathogen and a reservoir of MDR genes.

Elizabethkingia Infections in Humans: From Genomics to Clinics

The genus Elizabethkingia has recently emerged as a cause of life-threatening infections in humans, particularly in immunocompromised patients. Several new species in the genus Elizabethkingia have been proposed in the last decade. Numerous studies have indicated that Elizabethkingia anophelis, rather than Elizabethkingia meningoseptica, is the most prevalent pathogen in this genus. Matrix-assisted laser desorption/ionization–time of flight mass spectrometry systems with an extended spectrum database could reliably identify E. anophelis and E. meningoseptica, but they are unable to distinguish the remaining species. Precise species identification relies on molecular techniques, such as housekeeping gene sequencing and whole-genome sequencing. These microorganisms are usually susceptible to minocycline but resistant to most β-lactams, β-lactam/β-lactam inhibitors, carbapenems, and aminoglycosides. They often exhibit variable susceptibility to piperacillin, piperacillin-tazobactam, fluoroquinolones, and trimethoprim-sulfamethoxazole. Accordingly, treatment should be guided by antimicrobial susceptibility testing. Target gene mutations are markedly associated with fluoroquinolone resistance. Knowledge on the genomic characteristics provides valuable insights into in these emerging pathogens.

In vitro activities of imipenem, vancomycin, and rifampicin against clinical Elizabethkingia species producing BlaB and GOB metallo-beta-lactamases

Elizabethkingia genus is emerging in hospitals and resistant to multiple antibiotics. The intrinsic imipenem resistance of Elizabethkingia genus is related to two chromosome-encoded metallo-beta-lactamases (MBLs), BlaB and GOB. This study was aimed to investigate the in vitro activity of imipenem, vancomycin, and rifampicin in clinical Elizabethkingia species. The distribution and heterogeneity of MBLs responsible for imipenem resistance were also evaluated. A total of 167 Elizabethkingia isolates from different patients were collected, including E. anophelis (142), E. meningoseptica (11), and E. miricola (14). All isolates were evaluated by the broth microdilution assay, ethylenediaminetetraacetic acid (EDTA) combination disk test, and EDTA-based microdilution test. The characteristics of BlaB and GOB were evaluated in phylogenetic analysis and heterologous expression experiments. Most of the isolates were susceptible to rifampin (94%), whereas none of the isolates were susceptible to imipenem. Vancomycin showed intermediate effectiveness. EDTA could reduce 4 folds or more minimum inhibitory concentrations (MICs) of imipenem in 105 isolates (62.9%). Of the isolates, the amino acid sequences of BlaB and GOB were divided into 22 and 25 different types, respectively. Phylogenetic analysis showed BlaB and GOB are species-specific proteins. Furthermore, GOB and BlaB from E. anophelis showed higher imipenem hydrolysis efficiency than those from the other two species. Rifampicin remained the most active agent in the current study. The mechanism of Elizabethkingia resistance to imipenem primarily stemmed from MBLs but other mechanisms could also exist, which requires further investigation.

A Real-Time Multiplex PCR Assay for Detection of Elizabethkingia Species and Differentiation between Elizabethkingia anophelis and E. meningoseptica

Nosocomial infections of Elizabethkingia species can have fatal outcomes if not identified and treated properly. The current diagnostic tools available require culture and isolation, which can extend the reporting time and delay treatment. Using comparative genomics, we developed an efficient multiplex real-time PCR for the simultaneous detection of all known species of Elizabethkingia, as well as differentiating the two most commonly reported species, Elizabethkingia anophelis and Elizabethkingia meningoseptica.

The draft genomes of Elizabethkingia anophelis of equine origin are genetically similar to three isolates from human clinical specimens

We report the isolation and characterization of two Elizabethkingia anophelis strains (OSUVM-1 and OSUVM-2) isolated from sources associated with horses in Oklahoma. Both strains appeared susceptible to fluoroquinolones and demonstrated high MICs to all cell wall active antimicrobials including vancomycin, along with aminoglycosides, fusidic acid, chloramphenicol, and tetracycline. Typical of the Elizabethkingia, both draft genomes contained multiple copies of β-lactamase genes as well as genes predicted to function in antimicrobial efflux. Phylogenetic analysis of the draft genomes revealed that OSUVM-1 and OSUVM-2 differ by only 6 SNPs and are in a clade with 3 strains of Elizabethkingia anophelis that were responsible for human infections. These findings therefore raise the possibility that Elizabethkingia might have the potential to move between humans and animals in a manner similar to known zoonotic pathogens.

Multicentre study evaluating matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of clinically isolated Elizabethkingia species and analysis of antimicrobial susceptibility

OBJECTIVES

Rapid identification of Elizabethkingia species is essential because these species show variations in antibiotic susceptibility and clinical outcomes. Many recent inaccuracies in Elizabethkingia identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) have been noted. Accordingly, in this study, we evaluated the use of MALDI-TOF MS with an amended database to identify isolates of Elizabethkingia anophelis, E. miricola and E. meningoseptica. We then investigated the antimicrobial susceptibility of Elizabethkingia.

METHODS

MALDI-TOF MS spectra were acquired from formic acid extracts overlaid with α-cyano-4-hydroxycinnamic acid matrix on target slides in linear positive ion mode for m/z 2000 to 20 000 Da. Spectra were analysed and SuperSpectra were created with SARAMIS premium software. 16S rRNA gene sequencing was used as the reference standard for species identification. Antibiotic susceptibility was assessed by broth microdilution.

RESULTS

A total of 103 E. anophelis, 21 E. miricola and 11 E. meningoseptica isolates were used to calculate the average spectra and exclude common peaks. SuperSpectra were added to the SARAMIS taxonomy database; all validation results were correct, even for isolates not included in SuperSpectra. Confirmation by direct colony formation was also performed. Overall, the positive predictive value of SuperSpectra was 100% for all isolates. E. miricola (77%, 17/22) was more susceptible to levofloxacin than E. anophelis (16%, 17/105). Doxycycline and minocycline were effective against all Elizabethkingia species.

CONCLUSIONS

Spectral analysis software identified significant species-specific peaks to create reference masses for efficient and accurate identification of Elizabethkingia species, providing accurate information for clinical treatment of Elizabethkingia infections.