Global Proteome Profiling Reveals Drug-Resistant Traits in Elizabethkingia meningoseptica: An Opportunistic Nosocomial Pathogen

Emerging Prevalence and Clinical Features of Elizabethkingia meningoseptica Infection in Southwest China: A 9-Year Retrospective Study and Systematic Review

Background

Elizabethkingia meningoseptica infections have gradually emerged as life-threatening nosocomial infections worldwide, accompanied by increasing incidence, multidrug resistance and poor outcomes. However, the epidemiology and clinical features of E. meningoseptica infection are still limited in mainland China.

Methods

Patients with E. meningoseptica infections from 2011 to 2019 in southwestern China were retrospectively analyzed. The clinical features, infection patterns and outcomes were extracted from medical records and analyzed. A comprehensive systematic review was performed in accordance with PRISMA guidelines from conception to August 23, 2021.

Results

Ninety-two patients were ultimately included, with the prevalence rapidly rising from 0 in 2011 to 0.19 per 1000 inpatients in 2019. A total of 93.48% of E. meningoseptica isolates were multidrug resistant, including 100% resistance to carbapenem. Furthermore, 75% of E. meningoseptica infections were concomitant with other pathogens. The mortality of our cohort was 36.96%, with risk factors for mechanical ventilation (OR=9.51, P=0.004), male sex (OR=0.27, P=0.031) and more concomitant pathogens. After propensity score matching, central venous catheters, exposure to carbapenem and antifungal drugs, and underlying tumors were associated with E. meningoseptica infection. Sixteen articles were also summarized, with reported mortality rates ranging from 11.0% to 66.6%. Blood and respiratory tract were the common sources. Piperacillin/tazobactam, trimethoprim/sulfamethoxazole, fluoroquinolone and minocycline were the most sensitive antibiotics. Inappropriate antibiotic treatment was the most commonly reported risk factor for mortality.

Conclusion

Nosocomial infection with E. meningoseptica has become an emerging problem with high mortality in southwestern China. Inappropriate antibiotic treatment and central venous catheters are risk factors for infection and death and should receive adequate attention.

Structural characterization of a GNAT family acetyltransferase from Elizabethkingia anophelis bound to acetyl-CoA reveals a new dimeric interface

General control non-repressible 5 (GCN5)-related N-acetyltransferases (GNATs) catalyse the acetylation of a diverse range of substrates, thereby orchestrating a variety of biological processes within prokaryotes and eukaryotes. GNAT enzymes can catalyze the transfer of an acetyl group from acetyl coenzyme A to substrates such as aminoglycoside antibiotics, amino acids, polyamines, peptides, vitamins, catecholamines, and large macromolecules including proteins. Although GNATs generally exhibit low to moderate sequence identity, they share a conserved catalytic fold and conserved structural motifs. In this current study we characterize the high-resolution X-ray crystallographic structure of a GNAT enzyme bound with acetyl-CoA from Elizabethkingia anophelis, an important multi-drug resistant bacterium. The tertiary structure is comprised of six α-helices and nine β-strands, and is similar with other GNATs. We identify a new and uncharacterized GNAT dimer interface, which is conserved in at least two other unpublished GNAT structures. This suggests that GNAT enzymes can form at least five different types of dimers, in addition to a range of other oligomers including trimer, tetramer, hexamer, and dodecamer assemblies. The high-resolution structure presented in this study is suitable for future in-silico docking and structure–activity relationship studies.

MetaFS: Performance assessment of biomarker discovery in metaproteomics

Metaproteomics suffers from the issues of dimensionality and sparsity. Data reduction methods can maximally identify the relevant subset of significant differential features and reduce data redundancy. Feature selection (FS) methods were applied to obtain the significant differential subset. So far, a variety of feature selection methods have been developed for metaproteomic study. However, due to FS's performance depended heavily on the data characteristics of a given research, the well-suitable feature selection method must be carefully selected to obtain the reproducible differential proteins. Moreover, it is critical to evaluate the performance of each FS method according to comprehensive criteria, because the single criterion is not sufficient to reflect the overall performance of the FS method. Therefore, we developed an online tool named MetaFS, which provided 13 types of FS methods and conducted the comprehensive evaluation on the complex FS methods using four widely accepted and independent criteria. Furthermore, the function and reliability of MetaFS were systematically tested and validated via two case studies. In sum, MetaFS could be a distinguished tool for discovering the overall well-performed FS method for selecting the potential biomarkers in microbiome studies. The online tool is freely available at https://idrblab.org/metafs/.

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.