Genetic determinants of pOXA-48 plasmid maintenance and propagation in Escherichia coli.

Conjugative plasmids are the main drivers of antibiotic resistance dissemination contributing to the emergence and extensive spread of multidrug resistance clinical bacterial pathogens. pOXA-48 plasmids, belonging to the IncL group, emerge as the primary vehicle for carbapenem resistance in Enterobacteriaceae. Despite the problematic prevalence of pOXA-48, most research focus on epidemiology and genomics, leaving gaps in our understanding of the mechanisms behind its propagation.

Eravacycline: evaluation of susceptibility testing methods and activity against multidrug-resistant Enterobacterales and Acinetobacter.

Purpose: Eravacycline is a tetracycline approved for treating intra-abdominal infections caused by multidrug-resistant (MDR) bacteria. Our study aims to compare two methods for determining eravacycline MIC against Gram-negatives and to evaluate its in vitro activity compared with various antibiotics, particularly last-line agents.

Methods: We performed susceptibility testing of eravacycline against 275 consecutive MDR Gram-negative clinical isolates collected by the Belgian NRC.

Evaluation of Serum Biomarkers for Improved Diagnosis of Candidemia.

Background: Candidemia, associated with high morbidity and mortality, remains challenging to diagnose due to the limitations of blood cultures. Serological biomarkers offer faster detection, enabling earlier treatment and improving outcomes.

Methods: This study, conducted at CHU UCL Namur (August 2023-January 2025), evaluated three diagnostic biomarkers for candidemia: CAGTA IgG VirClia Monotest, Wako β-D-glucan test, and CandId OLM RT-PCR.

Diagnostic Value of Serum Biomarkers for Invasive Aspergillosis in Haematologic Patients.

Background: Invasive aspergillosis (IA) is a significant cause of morbidity and mortality in patients with haematological malignancies. Accurate diagnosis of IA is challenging due to non-specific symptoms and the impact of antifungal prophylaxis on biomarker sensitivity.

Methods: This retrospective study evaluated the diagnostic performance of three serum biomarkers: Galactomannan Ag VirClia Monotest (VirClia), Wako β-D-Glucan Test (Wako BDG), and MycoGENIE Real-Time PCR (MycoGENIE PCR).

Comparison of testing methods assessing the in vitro efficacy of the combination of aztreonam with avibactam on multidrug-resistant Gram-negative bacilli.

Background: Aztreonam-avibactam (ATM-AVI) combination shows promising effectiveness on most carbapenemase-producing Gram-negatives, yet standardized antibiotic susceptibility testing (AST) methods for evaluating the combination in clinical laboratories is lacking. We aimed to evaluate different ATM-AVI AST approaches.

Methods: 96 characterized carbapenem-resistant clinical isolates belonging to 9 Enterobacterales (EB; n = 80) and P.

Pseudomonasaeruginosa antimicrobial susceptibility profiles, resistance mechanisms and international clonal lineages: update from ESGARS-ESCMID/ISARPAE Group.

Scope: Pseudomonas aeruginosa, a ubiquitous opportunistic pathogen considered one of the paradigms of antimicrobial resistance, is among the main causes of hospital-acquired and chronic infections associated with significant morbidity and mortality. This growing threat results from the extraordinary capacity of P. aeruginosa to develop antimicrobial resistance through chromosomal mutations, the increasing prevalence of transferable resistance determinants (such as the carbapenemases and the extended-spectrum β-lactamases), and the global expansion of epidemic lineages.

Multicenter interlaboratory study of routine systems for the susceptibility testing of temocillin using a challenge panel of multidrug-resistant strains.

Accurate susceptibility result of temocillin (TMO) is important for treating infections caused by multidrug-resistant Enterobacterales. This multicenter study aimed to investigate the performance of routine temocillin testing assays against Enterobacterales challenging strains. Forty-seven selected clinical isolates were blindly analyzed by 12 Belgian laboratories using VITEK® 2 (n = 5) and BD Phoenix™ (n = 3) automated systems, ETEST® gradient strip (n = 3), and disk (3 brands) diffusion method (DD; n = 6) for temocillin susceptibility using standardized methodology.

Minimal requirements for ISO15189 validation and accreditation of three next generation sequencing procedures for SARS-CoV-2 surveillance in clinical setting.

Rapid and recurrent breakthroughs of new SARS-CoV-2 strains (variants) have prompted public health authorities worldwide to set up surveillance networks to monitor the circulation of variants of concern. The use of next-generation sequencing technologies has raised the need for quality control assessment as required in clinical laboratories. The present study is the first to propose a validation guide for SARS-CoV-2 typing using three different NGS methods fulfilling ISO15189 standards.

Development of Nanobodies as Theranostic Agents against CMY-2-Like Class C β-Lactamases.

Three soluble single-domain fragments derived from the unique variable region of camelid heavy-chain antibodies (VHHs) against the CMY-2 β-lactamase behaved as inhibitors. The structure of the complex VHH cAb(254)/CMY-2 showed that the epitope is close to the active site and that the CDR3 of the VHH protrudes into the catalytic site. The β-lactamase inhibition pattern followed a mixed profile with a predominant noncompetitive component.

Structural and Biochemical Features of OXA-517: a Carbapenem and Expanded-Spectrum Cephalosporin Hydrolyzing OXA-48 Variant.

OXA-48-producing Enterobacterales have now widely disseminated throughout the world. Several variants have now been reported, differing by just a few amino-acid substitutions or deletions, mostly in the region of the loop β5-β6. As OXA-48 hydrolyzes carbapenems but lacks significant expanded-spectrum cephalosporin (ESC) hydrolytic activity, ESCs were suggested as a therapeutic option.

In vitro Activity of Cefiderocol and Comparators against Carbapenem-Resistant Gram-Negative Pathogens from France and Belgium.

Infections with carbapenem-resistant (CR) Gram-negative (GN) pathogens have increased in many countries worldwide, leaving only few therapeutic options. Cefiderocol (CFDC) is approved in Europe for the treatment of aerobic GN infections in adults with limited treatment options. This study evaluated the in vitro activity of cefiderocol and comparators against multidrug-resistant (MDR) bacteria including meropenem-resistant (MR) or pandrug-resistant (PR) GN clinical isolates from France and Belgium.

Nationwide Harmonization Effort for Semi-Quantitative Reporting of SARS-CoV-2 PCR Test Results in Belgium.

From early 2020, a high demand for SARS-CoV-2 tests was driven by several testing indications, including asymptomatic cases, resulting in the massive roll-out of PCR assays to combat the pandemic. Considering the dynamic of viral shedding during the course of infection, the demand to report cycle threshold (Ct) values rapidly emerged. As Ct values can be affected by a number of factors, we considered that harmonization of semi-quantitative PCR results across laboratories would avoid potential divergent interpretations, particularly in the absence of clinical or serological information.

Characterization of hypervirulent Klebsiella pneumoniae isolates in Belgium.

Hypervirulent Klebsiella pneumoniae (hvKp) raised concern worldwide. We studied 22 hvKp clinical invasive isolates referred to the Belgian national reference laboratory between 2014 and 2020. Sixty-four percent of the isolates expressed K2 capsular serotype and belonged to 7 different MLST lineages, while 32% expressed K1 (all belonging to ST23) and were associated with liver abscesses.

Multicentre interlaboratory analysis of routine susceptibility testing with a challenge panel of resistant strains.

Objectives: In order to elaborate a new national challenge panel of resistant Gram-negative bacilli and Gram-positive cocci strains for the validation of routine antimicrobial susceptibility testing (AST) methods, an interlaboratory evaluation was organised.

Methods: The results of 12 well-characterised multidrug-resistant strains tested by nine laboratories using local disk diffusion (DD) and automated AST (AUST) methods were compared with the reference broth microdilution method.

Results: Overall categorical agreement ranged from 70% to 100% both for DD and AUST and was >90% for all but one strain for all antibiotics.

Detection and Characterization of VIM-52, a New Variant of VIM-1 from a Klebsiella pneumoniae Clinical Isolate.

Over the last two decades, antimicrobial resistance has become a global health problem. In Gram-negative bacteria, metallo-β-lactamases (MBLs), which inactivate virtually all β-lactams, increasingly contribute to this phenomenon. The aim of this study is to characterize VIM-52, a His224Arg variant of VIM-1, identified in a Klebsiella pneumoniae clinical isolate.

Rapid COVID-19 antigenic tests: Usefulness of a modified method for diagnosis.

The current reliable recommended test for coronavirus disease 2019 (COVID-19) diagnosis is quantitative reverse-transcription polymerase chain reaction (RT-qPCR). Rapid antigen test devices could be useful as they are less expensive, faster without the need of specialized laboratories to perform the test. We report the performances of two rapid immunochromatographic antigen testing devices compared with RT-qPCR for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection in nasopharyngeal samples.

Multicenter study of automated systems for colistin susceptibility testing.

Purpose: Broth microdilution (BMD) stays as the reference testing method for determination of antimicrobial susceptibility testing (AST) to colistin and is considered essential for patient management and for monitoring of colistin resistance. This multicenter study aimed to evaluate the performance of automated systems for colistin AST among Enterobacterales as an alternative for BMD since the majority of laboratories use automated systems as first-line method.

Methods: Twenty colistin resistant (COL-R) including 10 MCR producers and 10 colistin-susceptible (COL-S) Enterobacterales isolates were blindly tested for colistin susceptibility with the routine automated AST systems used by 8 laboratories (3 with BD Phoenix, 3 with Vitek2 and 2 with MicroScan).

SARS-CoV-2 Detection for Diagnosis Purposes in the Setting of a Molecular Biology Research Lab.

The emergence of the SARS-CoV-2 virus and the exponential growth of COVID-19 cases have created a major crisis for public health systems. The critical identification of contagious asymptomatic carriers requires the isolation of viral nucleic acids, reverse transcription, and amplification by PCR. However, the shortage of specific proprietary reagents or the lack of automated platforms have seriously hampered diagnostic throughput in many countries.

Development of an NGS-Based Workflow for Improved Monitoring of Circulating Plasmids in Support of Risk Assessment of Antimicrobial Resistance Gene Dissemination.

Antimicrobial resistance (AMR) is one of the most prominent public health threats. AMR genes localized on plasmids can be easily transferred between bacterial isolates by horizontal gene transfer, thereby contributing to the spread of AMR. Next-generation sequencing (NGS) technologies are ideal for the detection of AMR genes; however, reliable reconstruction of plasmids is still a challenge due to large repetitive regions.

Severe influenza/respiratory syncytial virus infections and hospital antimicrobial stewardship opportunities: impact of a 4-year surveillance including molecular diagnosis.

Objective: To assess the prevalence of influenza and respiratory syncytial virus (RSV) in adults hospitalized for a respiratory infection in the winter months and to evaluate the impact of a viral diagnosis on empirical antimicrobial management (antibiotics and antivirals).

Design: Observational cohort study.

Setting: Acute-care university hospital.

A single Proteus mirabilis lineage from human and animal sources: a hidden reservoir of OXA-23 or OXA-58 carbapenemases in Enterobacterales.

In Enterobacterales, the most common carbapenemases are Ambler's class A (KPC-like), class B (NDM-, VIM- or IMP-like) or class D (OXA-48-like) enzymes. This study describes the characterization of twenty-four OXA-23 or OXA-58 producing-Proteus mirabilis isolates recovered from human and veterinary samples from France and Belgium. Twenty-two P.