MBLs, Rather Than Efflux Pumps, Led to Carbapenem Resistance in Fosfomycin and Aztreonam/Avibactam Resistant Elizabethkingia anophelis

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.

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.

Mortality Risk and Antibiotic Therapy for Patients with Infections Caused by Elizabethkingia Species-A Meta-Analysis

Background and Objectives: Patients with infections caused by Elizabethkingia species require prompt identification and effective antibiotic treatment since these spp. are typically resistant to multiple antibiotics and variable susceptibility patterns. Understanding the mortality risk of this disease is difficult because of the relatively low incidence of infections caused by Elizabethkingia spp. and the lack of published systematic evaluations of the risk factors for mortality. The aim of the present study was to investigate risk factors for mortality in patients with infections caused by Elizabethkingia spp. by conducting a meta-analysis of existing studies on these infections. Materials and Methods: Studies comparing patients who died from infections caused by Elizabethkingia spp. with patients who survived were considered for inclusion. Studies that reported one or more risk factors for mortality were considered. Clinical predisposing variables, predisposing comorbidities, and clinical outcomes of antibiotic treatment were among the risk factors for mortality. Results: The meta-analysis included twenty studies with 990 patients, and 298 patients (30.1%) died. The following risk factors for mortality were identified: intensive care unit admission, the need for mechanical ventilation, immunosuppressive or steroid therapy use, pneumonia, comorbid liver disease, and the use of inappropriate antimicrobial therapy. Conclusions: The use of appropriate antimicrobial therapy is critical for the effective management of infections caused by Elizabethkingia spp. Antimicrobial susceptibility testing would be a more reliable means of guiding treatment. The identification of the best antimicrobial drugs is needed to ensure optimal treatment recommendations for treating Elizabethkingia-related infections.

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.

In vitro activity of cefiderocol and comparator antibiotics against multidrug-resistant non-fermenting Gram-negative bacilli

Background

This study evaluated the in vitro activity of cefiderocol, ceftazidime/avibactam, and aztreonam/avibactam against clinically important multidrug-resistant non-fermenting Gram-negative bacilli.

Methods

Bacteraemic isolates of 126 multidrug-resistant Acinetobacter baumannii (MDRAB), 110 imipenem-resistant Pseudamoas aeruginosa [including 14 difficult-to-treat resistant P. aeruginosa (DTRPA)], 45 beta-lactam-non-susceptible Burkholderia cepacia complex (BCC), 47 levofloxacin or trimethoprim/sulfamethoxazole-non-susceptible Stenotrophomonas maltophilia and 22 ciprofloxacin-non-susceptible Elizabethkingia spp. collected between 2019 and 2021 were subjected to MIC determination for cefiderocol, ceftazidime/avibactam and aztreonam/avibactam.

Results

The MIC50/90s of cefiderocol for drug-resistant A. baumannii, P. aeruginosa, BCC, S. maltophilia and Elizabethkingia spp. were 0.25/2, 0.25/1, ≤0.06/≤0.06, ≤0.06/0.25 and >32/>32 mg/L, respectively. Cefiderocol inhibited 94.4% (119/126) of MDRAB, 100% of imipenem-resistant P. aeruginosa, 100% of DTRPA and 100% of BCC at an MIC ≤4 mg/L, and 97.9% (46/47) of S. maltophilia at ≤1 mg/L. Ceftazidime/avibactam inhibited 76.4% (84/110) of imipenem-resistant P. aeruginosa, 21.4% (3/14) of DTRPA and 68.9% (31/45) of BCC at an MIC ≤8 mg/L. Aztreonam/avibactam had MIC50/90s of 16/>32, 8/16 and 4/8 mg/L for imipenem-resistant P. aeruginosa, BCC and S. maltophilia, respectively. At ≤8 mg/L, aztreonam/avibactam inhibited 7.1% (1/14) of DTRPA and 93.6% (44/47) of S. maltophilia isolates. Elizabethkingia spp. demonstrated high MICs for cefiderocol, ceftazidime/avibactam and aztreonam/avibactam, with all MIC50s and MIC90s > 32 mg/L.

Conclusion

Cefiderocol may serve as an alternative treatment for multidrug-resistant A. baumannii, P. aeruginosa, BCC and S. maltophilia when other antibiotics have been ineffective or intolerable. The role of ceftazidime/avibactam and aztreonam/avibactam in the management of BCC or S. maltophilia infections warrants further investigation.

Elizabethkingia meningoseptica Outbreak in NICU: An Observational Study on a Debilitating Neuroinfection in Neonates

BACKGROUND

Elizabethkingia meningoseptica is an emerging nosocomial pathogen implicated in neonatal sepsis with high mortality and morbidities. However, there is very limited data regarding the characteristics as well as outcomes following this infection, particularly in developing countries.

METHODS

We conducted a retrospective observational study of all infants with culture-positive Elizabethkingia sepsis as part of an outbreak, to study their clinical and epidemiological characteristics, as well as their antimicrobial susceptibility patterns, using a structured proforma from the neonatal intensive care unit database. Analysis was done using descriptive statistics and predictors of mortality and hydrocephalus were also identified.

RESULTS

Of the 21 neonates enrolled, 9 (42.9%) were male, with a mean gestational age and birth weight of 31.7 ± 3.4 weeks and 1320 ± 364 g, respectively. The median (interquartile range) age of onset of illness was 7 (5-12) days. The overall mortality rate was 23.8%, and among survivors, 50% had neurologic complications requiring intervention. Vancomycin and ciprofloxacin were the most used antibiotics for treatment in our series, with a median duration of 26 (17-38) days. On univariate analysis, shock at presentation was significantly associated with increased mortality (P = 0.04) while, seizures (P = 0.04) and elevated cerebrospinal fluid protein levels (P = 0 .01) at onset of illness predicted progressive hydrocephalus in surviving neonates.

CONCLUSION

E. meningoseptica sepsis is associated with high morbidity and mortality. Early diagnosis and prompt initiation of appropriate antibiotics are critical for improving survival and neurodevelopmental outcomes. Though isolation of the organism by environmental surveillance is always not possible, with proper infection control measures, the infection can be controlled.

Emerging infections in vulnerable hosts: Stenotrophomonas maltophilia and Elizabethkingia anophelis

PURPOSE OF REVIEW

This systematic review aimed to explore the recent trends in the epidemiology, risk factors, and antimicrobial susceptibility of two emerging opportunistic pathogens, Stenotrophomonas maltophilia and Elizabethkingia anophelis .

RECENT FINDINGS

Since 2020, numerous outbreaks of S. maltophilia and E. anophelis have been reported worldwide. Most of these outbreaks have been associated with healthcare facilities, although one outbreak caused by E. anophelis in France was considered a community-associated infection. In terms of antimicrobial susceptibility, trimethoprim/sulfamethoxazole (TMP-SMZ), levofloxacin, and minocycline have exhibited good efficacy against S. maltophilia . Additionally, cefiderocol and a combination of aztreonam and avibactam have shown promising results in in vitro susceptibility testing. For E. anophelis , there is currently no consensus on the optimal treatment. Although some studies have reported good efficacy with rifampin, TMP-SMZ, piperacillin/tazobactam, and cefoperazone/sulbactam, minocycline had the most favourable in vitro susceptibility rates. Cefiderocol may serve as an alternative due to its low minimum inhibitory concentration (MIC) against E. anophelis . The role of vancomycin in treatment is still uncertain, although several successful cases with vancomycin treatment, even with high MIC values, have been reported.

SUMMARY

Immunocompromised patients are particularly vulnerable to infections caused by S. maltophilia and E. anophelis , but the optimal treatment strategy remains inconclusive. Further research is necessary to determine the most effective use of conventional and novel antimicrobial agents in combatting these multidrug-resistant pathogens.

Phylogenomics analysis of multidrug-resistant Elizabethkingia anophelis in industrial wastewater treatment plant

AIMS

This study investigated the phylogenetic relatedness of multidrug-resistant Elizabethkingia anophelis recovered from an industrial wastewater treatment plant (WWTPi).

METHODS AND RESULTS

The wastewater samples were plated in brain heart infusion agar (4 mg/L ceftazidime, 8 mg/L meropenem, and 2 mg/L polimixin). Four isolates recovered from four stages of WWTPi (influent, aeration, decantation, and treated effluent) were identified and evaluated of susceptibility profiles in the VITEK 2 system. These strains identified as E. meningoseptica were confirmed to be E. anophelis by whole genomic sequencing (Miseq-Illumina) and showed antimicrobial resistance genes of β-lactams, aminoglycosides, and tetracycline's classes. The ribosomal multilocus sequence typing showed that they belong to the rST 65620 together with clinical strains. The phylogenomic tree revealed the similarity of our strains to those belonging to sublineage 11 and the single nucleotide polymorphism analysis confirmed that they belong to a single clade.

CONCLUSIONS

To the best of our knowledge, this is the first study reporting the persistence of multidrug-resistant E. anophelis sublineage 11 along the wastewater treatment.

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.

Rarely Encountered Gram-Negative Rods and Lung Transplant Recipients: A Narrative Review

The respiratory tract of lung transplant recipients (LTR) is likely to be colonized with non-fermentative Gram-negative rods. As a consequence of the improvements in molecular sequencing and taxonomy, an increasing number of bacterial species have been described. We performed a review of the literature of bacterial infections in LTR involving non-fermentative Gram-negative rods with exclusion of Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Achromobacter spp. and Burkholderia spp. Overall, non-fermenting GNR were recovered from 17 LTR involving the following genera: Acetobacter, Bordetella, Chryseobacterium, Elizabethkinga, Inquilinus, and Pandoraea. We then discuss the issues raised by these bacteria, including detection and identification, antimicrobial resistance, pathogenesis, and cross-transmission.

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.

Characterization of a Novel Pathogen in Immunocompromised Patients: Elizabethkingia anophelis-Exploring the Scope of Resistance to Contemporary Antimicrobial Agents and β-lactamase Inhibitors

Background

Elizabethkingia anophelis is an emerging Gram-negative nonlactose fermenter in the health care setting, where it causes life-threatening infections in immunocompromised patients. We aimed to characterize the molecular mechanisms of antimicrobial resistance and evaluate the utility of contemporary antibiotics with the intent to offer targeted therapy against an uncommonly encountered pathogen.

Methods

Whole-genome sequencing (WGS) was conducted to accurately identify isolate species and elucidate the determinants of β-lactam resistance. Antimicrobial susceptibility testing was performed using broth microdilution and disk diffusion assays. To assess the functional contribution of the major metallo-β-lactamase (MBL) encoding genes to the resistance profile, bla _BlaB was cloned into pBCSK(-) phagemid vector and transformed into Escherichia coli DH10B.

Results

WGS identified the organism as E. anophelis. MBL genes bla _BlaB-1 and bla _GOB-26 were identified, in addition to bla _CME-2, which encodes for an extended-spectrum β-lactamase (ESBL). Plasmids were not detected. The isolate was nonsusceptible to all commonly available β-lactams, carbapenems, newer β-lactam β-lactamase inhibitor combinations, and to the combination of aztreonam (ATM) with ceftazidime-avibactam (CAZ-AVI). Susceptibility to the novel siderophore cephalosporin cefiderocol was determined. A BlaB-1 transformant E. coli DH10B isolate was obtained and demonstrated increased minimum inhibitory concentrations to cephalosporins, carbapenems, and CAZ-AVI, but not ATM.

Conclusions

Using WGS, we accurately identified and characterized an extensively drug-resistant E. anophelis in an immunocompromised patient. Rapid evaluation of the genetic background can guide accurate susceptibility testing to better inform antimicrobial therapy selection.

Clinical Profile and Outcome of Neonates with Elizabethkingia Sepsis

Elizabethkingia, an emerging nosocomial pathogen is a gram-negative bacillus causing NICU outbreaks. This case series from a tertiary care hospital, South India describes the clinical profile and outcome of 92 neonates with culture-positive elizabethkingia sepsis over a period of 2 y. Elizabethkingia sepsis predominantly affected preterm neonates and the common clinical features were respiratory distress, apnea, and poor feeding. Meningitis was noted in 68% and mortality was 12%. Antimicrobial susceptibility testing showed that elizabethkingia was susceptible to minocycline and levofloxacin.

Requiring Reconsideration of Differences of Aeromonas Infections Between Extra-Intestinal and Intestinal in Hospitalized Patients

Purpose

The purpose of this study is to examine the variations between extra-intestinal and intestinal infections of Aeromonas in terms of strain types, risk factors, drug susceptibility results, and the distribution of drug resistance and virulence genes.

Patients and Methods

A total of 188 Aeromonas strains were identified to the species level using housekeeping genes (rpoD, gyrB, and gyrA). The risk factors for Aeromonas extra-intestinal and intestinal infection, as well as mortality, were retrospectively examined in this study. The broth microdilution method was used to investigate the antimicrobial susceptibility profiles. Touchdown polymerase chain reaction (PCR) assays and DNA sequencing were employed to confirm virulence and the presence of drug resistance genes.

Results

The housekeeping genes identified 188 strains into 7 species. Extra-intestinal isolates generally contained A. caviae and A. hydrophila, while intestinal were A. veronii (p=0.0001). Extra-intestinal infections (158/188) were the main type and accounted for 24/27 of all fatalities. Malignant tumors, hepatobiliary diseases, anemia, and hypoproteinemia were linked to infections. Poor results were associated with septic shock. Using the broth microdilution method, over 80% isolates were susceptible to most antimicrobials, except for ceftazidime (79.8%) and ceftriaxone (69.7%). Except for imipenem, intestinal strains were more susceptible to other medications than extra-intestinal. Using touch-down polymerase chain reaction testing and DNA sequencing, 6 strains, 31 strains, and a strain only had bla _TEM, bla _CphA, and bla _VIM, respectively. Two Aeromonas hydrophila each possessed bla _CphA+ bla _CTXM-M-9, and bla _CphA + bla _CTX-M-1 + bla _{CTX-M-15-like} + bla _TEM; two Aeromonas caviae each possessed bla _NDM + bla _CTX-M-1 +bla _{CTX-M-15-like} + bla _TEM, and bla _NDM + bla _TEM. Thirty-four of the 42 strains mentioned above were isolated from extra-intestinal. Act, aexT, and ascF-G, were in intestinal more frequently, but alt, hlyA, ela, and lip were in extra-intestinal more frequently.

Conclusion

Aeromonas inside and outside intestinal differed in their clinical characteristics, drug susceptibility, drug resistance and virulence genes.

Accurate Identification and Virulence Detection of Aeromonas: a Single-Center Retrospective Study on the Clinical Features and Outcomes Associated with Aeromonas Bacteremia in Southwestern China

In this study, Aeromonas spp. were re-identified, and the clinical aspects associated with Aeromonas bacteremia, as well as drug resistance and virulence genes, were elucidated. A total of 188 isolates were classified into 7 Aeromonas spp. using housekeeping gene sequencing, which was the standard to assess the accuracy of the VITEK MALDI-TOF system and the VITEK2 Compact system. The VITEK MS system and housekeeping gene sequencing had a 39.89% clear coincidence rate, whereas the VITEK2 Compact system and the standard had a 2.13% coincidence rate. Aeromonas bacteremia was associated with septic shock, hematologic malignancy, and post-hepatitic cirrhosis. Hematological malignancy, hypoproteinemia, systemic steroid use, central venous catheterization, and virulence genes act and ast were linked to poor outcomes. Aeromonas bacteremia had a 37.5% mortality rate; however, differences in mortality rates among Aeromonas spp. were observed. According to the broth microdilution method, over 90% of isolates were sensitive to most antimicrobials, except ceftriaxone (83.33%) and imipenem (83.33%). Polymerase chain reaction and DNA sequencing verified the presence of drug resistance genes; bla_CphA was detected in 3 isolates, while bla_NDM-1 was found in one isolate. In summary, common methods for identifying Aeromonas spp. are ineffective. Immunocompromised patients have a higher risk of infection and mortality. Furthermore, carbapenem resistance is a serious problem.

Proteomic Network of Antibiotic-Induced Outer Membrane Vesicles Released by Extensively Drug-Resistant Elizabethkingia anophelis

Elizabethkingia anophelis, a nonfermenting Gram-negative bacterium, causes life-threatening health care-associated infections. E. anophelis harbors multidrug resistance (MDR) genes and is intrinsically resistant to various classes of antibiotics. Outer membrane vesicles (OMVs) are secreted by Gram-negative bacteria and contain materials involved in bacterial survival and pathogenesis. OMVs specialize and tailor their functions by carrying different components to challenging environments and allowing communication with other microorganisms or hosts. In this study, we sought to understand the characteristics of E. anophelis OMVs under different antibiotic stress conditions. An extensively drug-resistant clinical isolate, E. anophelis C08, was exposed to multiple antibiotics in vitro, and its OMVs were characterized using nanoparticle tracking analysis, transmission electron microscopy, and proteomic analysis. Protein functionality analysis showed that the OMVs were predominantly involved in metabolism, survival, defense, and antibiotic resistance processes, such as the Rag/Sus family, the chaperonin GroEL, prenyltransferase, and an HmuY family protein. Additionally, a protein-protein interaction network demonstrated that OMVs from imipenem-treated E. anophelis showed significant enrichments in the outer membrane, adenyl nucleotide binding, serine-type peptidase activity, the glycosyl compound metabolic process, and cation binding proteins. Collectively, the OMV proteome expression profile indicates that the role of OMVs is immunologically relevant and related to bacterial survival in antibiotic stress environments rather than representing a resistance point. IMPORTANCE Elizabethkingia anophelis is a bacterium often associated with nosocomial infection. This study demonstrated that imipenem-induced E. anophelis outer membrane vesicles (OMVs) are immunologically relevant and crucial for bacterial survival under antibiotic stress conditions rather than being a source of antibiotic resistance. Furthermore, this is the first study to discuss the protein-protein interaction network of the OMVs released by E. anophelis, especially under antibiotic stress. Our findings provide important insights into clinical antibiotic stewardship.

Biofilm formation and antibiotic sensitivity in Elizabethkingia anophelis

Elizabethkingia anophelis has recently gained global attention and is emerging as a cause of life-threatening nosocomial infections. The present study aimed to investigate the association between antimicrobial resistance and the ability to form biofilm among E. anophelis isolated from hospitalized patients in China. Over 10 years, a total of 197 non-duplicate E. anophelis strains were collected. Antibiotic susceptibility was determined by the standard agar dilution method as a reference assay according to the Clinical and Laboratory Standards Institute. The biofilm formation ability was assessed using a culture microtiter plate method, which was determined using a crystal violet assay. Culture plate results were cross-checked by scanning electron microscopy imaging analysis. Among the 197 isolates, all were multidrug-resistant, and 20 were extensively drug-resistant. Clinical E. anophelis showed high resistance to current antibiotics, and 99% of the isolates were resistant to at least seven antibiotics. The resistance rate for aztreonam, ceftazidime, imipenem, meropenem, trimethoprim-sulfamethoxazole, cefepime, and tetracycline was high as 100%, 99%, 99%, 99%, 99%, 95%, and 90%, respectively. However, the isolates exhibited the highest susceptibility to minocycline (100%), doxycycline (96%), and rifampin (94%). The biofilm formation results revealed that all strains could form biofilm. Among them, the proportions of strong, medium, and weak biofilm-forming strains were 41%, 42%, and 17%, respectively. Furthermore, the strains forming strong or moderate biofilm presented a statistically significant higher resistance than the weak formers (p < 0.05), especially for piperacillin, piperacillin-tazobactam, cefepime, amikacin, and ciprofloxacin. Although E. anophelis was notoriously resistant to large antibiotics, minocycline, doxycycline, and rifampin showed potent activity against this pathogen. The data in the present report revealed a positive association between biofilm formation and antibiotic resistance, which will provide a foundation for improved therapeutic strategies against E. anophelis infections in the future.

The Evolutionary Trend and Genomic Features of an Emerging Lineage of Elizabethkingia anophelis Strains in Taiwan

The incidence of Elizabethkingia anophelis bacteremia increased significantly in a tertiary hospital, Changhua Christian Hospital (CCH) since 2013. The infection density was 1.3 and 8.1 cases per 100,000 patient-days between 2005 and 2012 and 2013 and 2020, respectively (P < 0.05). During an outbreak investigation, a specific lineage of E. anophelis strains was identified by the pulsed-field gel electrophoresis analysis. To evaluate the evolution of the specific E. anophelis lineage, whole-genome sequencing was performed, and unique genomic features (GRs) were determined by comparative genomic analysis. The specific E. anophelis lineage was novel compared to worldwide strains ever reported by cg-MLST phylogenic and whole-genome comparative analysis. Multiplex PCR using primers designed from unique GRs were performed for prevalence screening among isolates from the CCH and nationwide isolates from the Taiwan surveillance of Antimicrobial Resistance (TSAR) Program. The proportion of the specific E. anophelis lineage increased from 7.9% (3/38) during 2005-2012 to 89.2% (223/250) during 2013-2020 (P < 0.05). Although E. anophelis usually confers resistance to multiple antibiotics with limited therapeutic options, the E. anophelis strains in the specific lineage had higher ciprofloxacin resistance (100% [226/226] versus 27.4% [17/62], P < 0.05) and was associated with a higher 14-day mortality rates (33.2% [37/226] versus 16.1% [10/62], P < 0.05) than other strains at CCH. A similarly increasing trend was also found in the national TSAR program during 2002-2018 (p for trend <0.05). We concluded that a novel lineage of E. anophelis strains has emerged dominantly in Taiwan. The genomic features are important for further investigations of epidemiology, resistance, virulence, and appropriate treatment.

IMPORTANCEElizabethkingia anophelis is an emerging multidrug resistant pathogen caused several global outbreaks recently. E. anophelis was frequently misidentified as E. meningoseptica in the past by conventional culture methods; therefore, the prevalence was often underestimated. Through revised identification, an increasing trend of E. anophelis infection was noted in a tertiary hospital and a dominant lineage of strains was recognized by genotyping. To our best knowledge, the dominant lineage of E. anophelis is novel in comparison to other worldwide strains by whole-genome comparative analysis and several unique genomic regions were found. The whole-genome sequencing data also demonstrated multiple putative virulence factors and genes associated with multidrug resistance. In our study, we identified a specially evolved E. anophelis in Taiwan with increasing nationwide dominance. This study will assist in further epidemiology surveillance and developing corresponsive infection control policies to restrain it potential of global dissemination.

The Revival of Aztreonam in Combination with Avibactam against Metallo-β-Lactamase-Producing Gram-Negatives: A Systematic Review of In Vitro Studies and Clinical Cases

Infections caused by metallo-β-lactamase (MBL)-producing Enterobacterales and Pseudomonas are increasingly reported worldwide and are usually associated with high mortality rates (>30%). Neither standard therapy nor consensus for the management of these infections exist. Aztreonam, an old β-lactam antibiotic, is not hydrolyzed by MBLs. However, since many MBL-producing strains co-produce enzymes that could hydrolyze aztreonam (e.g., AmpC, ESBL), a robust β-lactamase inhibitor such as avibactam could be given as a partner drug. We performed a systematic review including 35 in vitro and 18 in vivo studies on the combination aztreonam + avibactam for infections sustained by MBL-producing Gram-negatives. In vitro data on 2209 Gram-negatives were available, showing the high antimicrobial activity of aztreonam (MIC ≤ 4 mg/L when combined with avibactam) in 80% of MBL-producing Enterobacterales, 85% of Stenotrophomonas and 6% of MBL-producing Pseudomonas. Clinical data were available for 94 patients: 83% of them had bloodstream infections. Clinical resolution within 30 days was reported in 80% of infected patients. Analyzing only patients with bloodstream infections (64 patients), death occurred in 19% of patients treated with aztreonam + ceftazidime/avibactam. The combination aztreonam + avibactam appears to be a promising option against MBL-producing bacteria (especially Enterobacterales, much less for Pseudomonas) while waiting for new antimicrobials.