(1-3)-␤-D-Glucan (BG) reactivity was tested in serum samples from 28 patients with human immunodeficiency virus infection or a hematological malignancy and Pneumocystis jirovecii pneumonia (PCP) and 28 control patients. The sensitivity and specificity of BG detection with the Fungitell assay for PCP were 100 and 96.4%, respectively, using a cutoff value of 100 pg/ml. Serum BG testing looks promising for the noninvasive diagnosis of PCP. Our data suggest that a higher cutoff value for the diagnosis of PCP than for the diagnosis of invasive aspergillosis or candidiasis could be used safely and will improve the specificity of the test.

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OXA-427 is a new class D carbapenemase encountered in different species of in a Belgian hospital. To study the dispersal of this gene, we performed a comparative analysis of two plasmids containing the gene, isolated from a strain and an complex strain. The two IncA/C2 plasmids containing share the same backbone; in the strain, however, this plasmid is cointegrated into an IncFIb plasmid, forming a 321-kb megaplasmid with multiple multiresistance regions.

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. A proposal to harmonize reporting of test results was drafted by the National Reference Centre (NRC) UZ/KU Leuven, distinguishing four categories of positivity based on RNA copies/mL. Pre-quantified control material was shipped to 124 laboratories with instructions to setup a standard curve to define thresholds per assay. For each assay, the mean Ct value and corresponding standard deviation was calculated per target gene, for the three concentrations (107, 105 and 103 copies/mL) that determine the classification. The results of 17 assays are summarized. This harmonization effort allowed to ensure that all Belgian laboratories would report positive PCR results in the same semi-quantitative manner to clinicians and to the national database which feeds contact tracing interventions.

f Identification of the causative pathogen of infective endocarditis (IE) is crucial for adequate management and therapy. A broadrange PCR-electrospray ionization mass spectrometry (PCR-ESI-MS) technique was compared with broad-spectrum 16S rRNA PCR and amplicon sequencing (16S rRNA PCR) for the detection of bacterial pathogens in 40 heart valves obtained from 34 definite infective endocarditis patients according to the modified Duke criteria and six nonendocarditis patients. Concordance between the two molecular techniques was 98% for being positive or negative, 97% for concordant identification up to the genus level, and 77% for concordant identification up to the species level. Sensitivity for detecting the causative pathogen (up to the genus level) in excised heart valves was 88% for 16S rRNA PCR and 85% for PCR-ESI-MS; the specificity was 83% for both methods. The two molecular techniques were significantly more sensitive than valve culture (18%) and accurately identified bacteria in excised heart valves. In eight patients with culture-negative IE, the following results were obtained: concordant detection of Coxiella burnetii (n ‫؍‬ 2), Streptococcus gallolyticus (n ‫؍‬ 1), Propionibacterium acnes (n ‫؍‬ 1), and viridans group streptococci (n ‫؍‬ 1) by both molecular tests, detection of P. acnes by PCR-ESI-MS whereas the 16S rRNA PCR was negative (n ‫؍‬ 1), and a false-negative result by both molecular techniques (n ‫؍‬ 2). In one case of IE caused by viridans streptococci, PCR-ESI-MS was positive for Enterococcus spp. The advantages of PCR-ESI-MS compared to 16S rRNA PCR are its automated workflow and shorter turnaround times. Diagnosis of infective endocarditis (IE) remains challenging. A multidisciplinary approach by microbiologists, infectiologists, surgeons, and cardiologists is needed for adequate management. Identification of the pathogen is crucial for selecting appropriate antimicrobial therapy (1-4). According to the modified Duke criteria, positive blood cultures (BCs) remain the cornerstone of the microbiological diagnosis of IE (4). Three sets of BCs, taken before starting antimicrobial therapy, detect 96% to 98% of bacteremia (5, 6). Unfortunately, BCs are negative in 2% to 31% of IE patients due to prior antimicrobial therapy or fastidious (Brucella spp., fungi) or intracellular (Coxiella burnetii, Bartonella spp., or Tropheryma whipplei) microorganisms, resulting in obscured diagnoses (7-9). During the last decade, molecular techniques performed directly on excised heart valves have emerged. Broad-range PCR, targeting the 16S rRNA gene, followed by subsequent sequencing of the amplicon proved to be superior to the culture of excised valves (VC) (8, 10-12). The sensitivity and specificity of 16S rRNA PCR for detecting the causative microorganism ranged from 61% to 90% and 97% to 100%, respectively, whereas the sensitivity and specificity of VC ranged from 23% to 31% and 67% to 87%, respectively (10-12). The use of different or no criteria for defining the definite microbiological cause of IE ...

The emergence of the SARS-CoV-2 Omicron variant, characterized by a significant antigenic diversity compared to the previous Delta variant, had led to a decrease in antibody efficacy in both convalescent and vaccinees sera resulting in high number of reinfections and breakthrough cases worldwide. However, to date, reinfections are defined by the ECDC as two positive tests >/= 60 days apart, influencing retesting policies after an initial positive test in several European countries. In our manuscript, we illustrate by a clinical case supplemental by epidemiological data that early reinfections do occur within 60 days especially in young, unvaccinated individuals. In older patient groups, unvaccinated and patients with a basic vaccination scheme are more vulnerable to reinfections compared to patients who received a first booster vaccine. For this reason, we consider that the duration of protection offered by a previous infection should be reconsidered, in particular when a shift between consecutive SARS-CoV-2 variants occurs.

Background: Changes in serotype distribution have been described after the switch from the 13-valent pneumococcal conjugate vaccine (PCV13) to the 10-valent pneumococcal conjugate vaccine (PCV10) in Belgium. Aim: To describe serotype's invasive disease potential and the detailed evolution of serotype distribution and antimicrobial susceptibility of pneumococcal isolates (carriage and IPD) in children up to 30 months of age over a period during and after the vaccine switch (2015)(2016)(2017)(2018). Methods: S. pneumoniae strains isolated from the nasopharynx of healthy children attending day-care centres (DCCs) and strains from normally sterile sites of children with IPD were serotyped (Quellungreaction) and antimicrobial susceptibility testing was performed. Invasive disease potential was defined as the serotype-specific odds ratio (OR). Results: The highly invasive (OR > 1) serotypes 12F, 1, 3, 24A/B/F, 33F, 19A, and 9N were not frequently carried (<7.5% of carriage strains). Different serotypes dominated in carriage (23B, 23A, 11A, 15B) versus IPD (12F, 19A, 10A, 33F). PCV13 vaccine serotypes increased in carriage (5.4% (25/463) in period 1 vs 10.3% (69/668) in period 3) and in IPD (7.3% (8/110 in period 1 vs 23.9% (34/142) in period 3) due to an increase (p < 0.01) in serotype 19A. The penicillin non-susceptibility of 19A was lower (p = 0.02) in carriage (6.8%) than in IPD (23.5%). Erythromycin and tetracycline non-susceptibility were more frequent (p < 0.01) in IPD (26.0%; 23.0%) compared to carriage strains (18.2%; 14.5%) and penicillin nonsusceptibility increased over the three year study period (carriage: 13.4%, 19.8%, 18.5%, p = 0.05; IPD: 11.8%, 15.0%, 20.4%, p = 0.02). Conclusion:Only some of the serotypes with high invasive disease potential (serotype 1, 3, 19A) in Belgium are included in PCV10 and/or PCV13. This reinforces the need for continuous monitoring, both in healthy children as in children with IPD, to better understand the dynamics of pneumococcal disease, to optimise the composition and implementation of PCVs.