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Introduction: Linezolid is a last-resort antibiotic for infections caused by multidrug-resistant microorganisms. It is widely used for off-label indications and for longer than recommended treatment durations, exposing patients at higher risk of adverse drug reactions (ADRs), notably thrombocytopenia. This study aimed to investigate ADR incidence and risk factors, identify thrombocytopenia-related trough levels based on treatment duration, and evaluate the performance of predictive scores for ADR development. Methods: Adult in- and outpatients undergoing linezolid therapy were enrolled in three hospitals and ADRs and linezolid trough levels prospectively monitored over time. A population pharmacokinetic (pop-PK model) was used to estimate trough levels for blood samples collected at varying times. Results: A multivariate analysis based on 63 treatments identified treatment duration ≥10 days and trough levels >8 mg/L as independent risk factors of developing thrombocytopenia, with high trough values correlated with impaired renal function. Five patients treated for >28 days did not develop thrombocytopenia but maintained trough values in the target range (<8 mg/L). The Buzelé predictive score, which combines an age-adjusted Charlson comorbidity index with treatment duration, demonstrated 77% specificity and 67% sensitivity to predict the risk of ADR. Conclusion: Our work supports the necessity of establishing guidelines for dose adjustment in patients with renal insufficiency and the systematic use of TDM in patients at-risk in order to keep trough values ≤8 mg/L. The Buzelé predictive score (if ≥7) may help to detect these at-risk patients, and pop-PK models can estimate trough levels based on plasma samples collected at varying times, reducing the logistical burden of TDM in clinical practice., SCOPUS: ar.j, info:eu-repo/semantics/published

In Belgium, linezolid is indicated for pneumonia and skin and soft tissue infections, but is more broadly used, due to its oral bioavailability and activity against multiresistant organisms. This could increase the risk of adverse drug reactions (ADR), notably hematological disorders (anemia, thrombocytopenia), neuropathy, or lactic acidosis. We analyzed linezolid clinical use in relationship with occurrence of ADR in Belgian hospitals and highlighted risk factors associated with the development of thrombocytopenia. A retrospective analysis of electronic medical records and laboratory tests of adult patients treated with linezolid in four Belgian hospitals in 2016 allowed the collection of ADR for 248 linezolid treatments. Only 19.7% of indications were in-label. ADR included 43 thrombocytopenia, 17 anemia, 4 neuropathies, and 4 increases in lactatemia. In a multi-variate analysis, risk factors of thrombocytopenia were a treatment duration > 10 days, a glomerular filtration rate < 60 mL/min, and a Charlson index ≥ 4. Off-label use of linezolid is frequent in Belgium, and ADR more frequent than reported in the summary of product characteristics, but not statistically associated with any indication. This high prevalence of ADR could be related to a high proportion of patients presenting risk factors in our population, highlighting the importance of detecting them prospectively

Background: The aim of this study was to identify predictors of insufficient beta-lactam concentrations in patients undergoing extracorporeal membrane oxygenation (ECMO). Methods: Retrospective analysis of all patients receiving ECMO support and treated with ceftazidime or cefepime (CEF), piperacillin/tazobactam (TZP), or meropenem (MEM). Trough drug concentrations (Cmin) were measured before the subsequent dose, according to the decision of the attending physi-cian. Insufficient drug concentrations were identified if Cmin was below the clinical breakpoint of Pseudomonas aeruginosa. Results: A total of 222 Cmin (CEF, n = 41; TZP, n = 85; MEM, n = 96) from 110 patients were included; insufficient concentrations were observed in 26 (12%) antibiotic assess-ments; 21 (81%) of those occurred during MEM therapy. Insufficient Cmin were associated with a shorter time from initiation of antibiotics to measurement, a lower single dose of antibiotic, a higher creatinine clearance (CrCL), lower sequential organ failure assessment (SOFA) scores, and less use of continuous renal replacement therapy (CRRT) when compared to others. Conclusions: Insufficient broad-spectrum beta-lactam concentrations were observed in 12% of drug measurement during ECMO therapy. Higher than recommended drug regimens could be considered in the very early phase of therapy and in those patients with augmented renal clearance and with less severe organ dysfunction., SCOPUS: ar.j, info:eu-repo/semantics/published

Non-occupational post-exposure prophylaxis (nPEP) is a public health instrument in HIV prevention. Treatment efficacy depends on round the clock availability, adequate prescription, drug efficacy and treatment adherence. Efforts should be made to achieve the most adequate treatment prescription and highest treatment retention for patients exposed to HIV. This thesis investigated treatment prescription, determinants of treatment completion and a strategy to improve treatment completion in a mixed population from a tertiary HIV reference. We showed that adherence to nPEP guidelines is 98.8% in emergency physicians prescribing nPEP round the clock in the emergency department. A low treatment adherence of 60% was identified by this study and strategies to improve it were searched. A second study identified independent determinants of adherence such as men who have sex with men (MSM) sexual orientation (OR, 1.40; 95%CI,1.04–1.90), being a native Belgian (OR, 1.50; 95%CI, 1.18–1.90), older age (OR, 1.02; 95%CI, 1.01–1.04), being a sexual assault survivor (OR, 0.59; 95%CI, 0.38–0.91), having had a previous nPEP treatment (OR, 1.44; 95%CI, 1.02–2.02), consultation during daytime (OR, 1.35; 95%CI, 1.07–1.70) and coverage from a health insurance (OR, 2.11; 95%CI, 1.58–2.89). A third study evaluated how a single tablet regimen of emtricitabine/tenofovir disoproxil fumarate plus cobicistat-boosted elvitegravir (OR 1.62; 95%CI, 1.08-2.42; p=0.019), as well as psychological support (OR: 3.13, 95%CI: 2.00–4.17, p<0.001), increase treatment completion rates in nPEP in sexual assault victims when compared to older regimens or absence of psychological support. We conclude that a system relying on emergency physicians to prescribe PEP is accurate, that determinants of low completion rates should be addressed during consultation and follow-up, that psychological support should be offered to all sexual assault victims and that a modern single tablet regimen should be preferred for nPEP, Doctorat en Sciences médicales (Médecine), info:eu-repo/semantics/nonPublished

Background and Aims: Infection is a major driver of mortality in patients with advanced alcohol-associated liver disease (ALD). The epidemiology and clinical course of patients infected with life-threatening forms of ALD, including severe alcohol-associated hepatitis (sAH) and decompensated alcohol-associated cirrhosis (DAC), and specific risk factors for infection remain mostly unknown. Approach and Results: In this observational study, we assessed all infectious episodes occurring within a 90-day period from diagnosis in all consecutive patients with biopsy-proven sAH (modified Maddrey’s discriminant function ≥ 32, Model for End-Stage Liver Disease [MELD] ≥ 18) and DAC (MELD ≥ 18) without alcohol-associated hepatitis in our tertiary hospital between 2003 and 2016. A total of 207 patients were included: 139 with sAH and 68 with DAC. One hundred seventeen (84%) patients with sAH and 41 (60%) patients with DAC experienced at least one infection episode at 90 days (P < 0.001). In multivariable analysis, factors associated with the development of infection were the presence of sAH and baseline MELD score. Bacterial infections represented the most common infection in the two groups, and only the MELD score was independently associated with the occurrence of bacterial infection. In both groups, pneumonia was the most prevalent bacterial infection, and gram-negative bacilli were the main pathogens. Invasive fungal infections (IFI) occurred in 20 (14.5%) patients with sAH and 3 (4.5%) with patients with DAC (P < 0.05). Multivariable regression showed that younger age, higher MELD, and corticosteroid therapy were independently associated with IFI. The 90-day cumulative incidence of death in patients infected with sAH and patients infected with DAC was 46% and 41.5%, respectively (P = 0.43). Conclusions: Patients with sAH are more susceptible to develop infection than those with DAC. In life-threatening forms of ALD, patients who were infected share a similar mortality rate., SCOPUS: ar.j, info:eu-repo/semantics/published

In Belgium, linezolid is indicated for pneumonia and skin and soft tissue infections, but is more broadly used, due to its oral bioavailability and activity against multiresistant organisms. This could increase the risk of adverse drug reactions (ADR), notably hematological disorders (anemia, thrombocytopenia), neuropathy, or lactic acidosis. We analyzed linezolid clinical use in relationship with occurrence of ADR in Belgian hospitals and highlighted risk factors associated with the development of thrombocytopenia. A retrospective analysis of electronic medical records and laboratory tests of adult patients treated with linezolid in four Belgian hospitals in 2016 allowed the collection of ADR for 248 linezolid treatments. Only 19.7% of indications were in-label. ADR included 43 thrombocytopenia, 17 anemia, 4 neuropathies, and 4 increases in lactatemia. In a multivariate analysis, risk factors of thrombocytopenia were a treatment duration > 10 days, a glomerular filtration rate < 60 mL/min, and a Charlson index ≥ 4. Off-label use of linezolid is frequent in Belgium, and ADR more frequent than reported in the summary of product characteristics, but not statistically associated with any indication. This high prevalence of ADR could be related to a high proportion of patients presenting risk factors in our population, highlighting the importance of detecting them prospectively., SCOPUS: ar.j, info:eu-repo/semantics/published

OBJECTIVES: To assess the prevalence of intra-hospital mortality and associated risk factors in older people aged 75+, admitted with blood stream infections (BSI). DESIGN: Single center retrospective study performed in an 850-bed of the academic hospital of the Université Libre de Bruxelles. SETTING AND PARTICIPANTS: From January 2015 to December 2017, all inpatients over 75 years old admitted with BSI were included. MEASURES: Demographical, clinical and microbiological data were collected. RESULTS: 212 patients were included: median age was 82 [79-85] years and 60 % were female. The in-hospital mortality rate was 19%. The majority of microorganisms were Gram-negative strains, of which Escherichia coli was the most common, and urinary tract infection was the most common origin of BSI. Compared to patients who survived, the non-survivor group had a higher SOFA score (6 versus 3, p<0.0001), a higher comorbidity score (5 versus 4, p<0.0001), more respiratory tract infections (28 vs 6 %, p < 0.0001) and fungal infections (5 vs 1 %, p = 0.033), bedridden status (60 vs 25 %, p < 0.0001), and healthcare related infections (60 vs 40 %, p = 0.019). Using Cox multivariable regression analysis, only SOFA score was independently associated with mortality (HR 1.75 [95%IC 1.52-2.03], p<0.0001). CONCLUSIONS AND IMPLICATIONS: BSI in older people are severe infections associated with a significant in-hospital mortality. Severity of clinical presentation at onset remains the most important predictor of mortality for BSI in older people. BSI originating from respiratory source and bedridden patients are at greater risk of intra-hospital mortality. Further prospective studies are needed to confirm these results., SCOPUS: ar.j, info:eu-repo/semantics/published

Colistin, used as a last resort drug, has a narrow therapeutic range that justifies therapeutic drug monitoring. Few data are available in the literature concerning the in vivo unbound fraction of colistin. The objectives of this study were to develop a method to isolate unbound colistin in clinical samples by ultrafiltration and to quantify it. The association between unbound colistin and biological parameters (total protein, albumin, alpha-1-acid glycoprotein, and creatinine) was investigated. The measured ranges were 0.036-7.160 mg/L for colistin A and 0.064-9.630 mg/L for colistin B. The process of isolation and determination of unbound colistin was applied to clinical samples (n=30) within 40 minutes and no non-specific binding was observed during the ultracentrifugation step. The median unbound fractions of colistin measured were 34.3% (12.8%-51.0%) and 53.4% (27.0%-77.8%) for colistin A and colistin B, respectively. High inter-individual biological variation of binding was observed for colistin A and B which was not explained by the biochemical parameters studied. The method developed could be useful to improve outcomes for patients.

Infections are the second leading cause of death for patients with end-stage renal disease (ESRD). Temocillin, a beta-lactam antimicrobial agent, is an interesting therapeutic option for Gram-negative infections. However, temocillin pharmacokinetic (PK) data in the haemodialysis population is limited, and data on its dialysability with contemporary haemodialysers is inexistent. This thesis is in three parts. The first focuses on the development and validation of an analytical method for the quantification of temocillin concentrations in human serum. In the second, temocillin PK is characterised in the ESRD population based on data from a study conducted in a Belgian hospital. The licensed dosage regimens were found to be far below target, leading to an update of the Summary of Product Characteristics. Finally, population PK methodologies were used to investigate the performance of clinically practical dosing regimens and their ability to achieve set PK/PD targets. Model-based Monte Carlo simulations lead to an improved temocillin dosage regimen applicable in routine clinical practice and likely to meet contemporary treatment targets for this patient population. More generally, this thesis addresses the current need, acknowledged by regulatory bodies, to study PK/PD relationships for 'old-revived' antibiotics such as temocillin, including in specific patient populations for whom data is lacking. This thesis provides such data for ESRD patients and makes concrete propositions on how to optimise treatment in this population., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2019

Colistin, used as a last-resort drug, has a narrow therapeutic range that justifies therapeutic drug monitoring. Few data are available in the literature regarding the in vivo unbound fraction of colistin. The objectives of this study were to develop a method to isolate unbound colistin in clinical samples by ultrafiltration and to quantify it. The association between unbound colistin and biological parameters (total protein, albumin, alpha-1-acid glycoprotein and creatinine) was investigated. The measured ranges were 0.036–7.160 mg/L for colistin A and 0.064–9.630 mg/L for colistin B. The process of isolation and determination of unbound colistin was applied to clinical samples (n = 30) within 40 min and no non-specific binding was observed during the ultracentrifugation step. The median unbound fractions of colistin measured were 34.3% (12.8–51.0%) and 53.4% (27.0–77.8%) for colistin A and B, respectively. High interindividual biological variation of binding was observed for colistin A and B that was not explained by the biochemical parameters studied. The method developed could be useful to improve outcomes for patients., SCOPUS: ar.j, info:eu-repo/semantics/published

Introduction: Immunocompromised patients infected with influenza exhibit prolonged viral shedding and higher risk of resistance. Optimized treatment strategies are needed to reduce the risk of antiviral resistance. This phase IIIb, randomized, double-blind study (NCT00545532) evaluated conventional-dose or double-dose oseltamivir for the treatment of influenza in immunocompromised patients. Methods: Patients with primary or secondary immunodeficiency and influenza infection were randomized 1:1 to receive conventional-dose oseltamivir (75 mg adolescents/adults [≥ 13 years]; 30–75 mg by body weight in children [1–12 years]) or double-dose oseltamivir (150 or 60–150 mg, respectively), twice daily for an extended period of 10 days. Nasal/throat swabs were taken for virology assessments at all study visits. Co-primary endpoints were safety/tolerability and viral resistance. Secondary endpoints included time to symptom alleviation (TTSA) and time to cessation of viral shedding (TTCVS). Results: Of 228 patients enrolled between February 2008 and May 2017, 215 (199 adults) were evaluable for safety, 167 (151 adults) for efficacy, and 152 (138 adults) for resistance. Fewer patients experienced an adverse event (AE) in the conventional-dose group (50.5%) versus the double-dose group (59.1%). The most frequently reported AEs were nausea, diarrhea, vomiting, and headache. Fifteen patients had post-baseline resistance, more commonly in the conventional-dose group (n = 12) than in the double-dose group (n = 3). In adults, median TTSA was similar between arms, while median TTCVS was longer with conventional dosing. Conclusions: Oseltamivir was well tolerated, with a trend toward better safety/tolerability for conventional dosing versus double dosing. Resistance rates were higher with conventional dosing in this immunocompromised patient population. Trial Registration: ClinicalTrials.gov identifier: NCT00545532. Funding: F. Hoffmann-La Roche Ltd., SCOPUS: ar.j, info:eu-repo/semantics/published

Urinary tract infection is the most common infection among kidney transplant recipients (KTRs). Many transplant physicians fear that host compromise will allow low-virulence strains to cause pyelonephritis in KTRs, so they often treat asymptomatic bacteriuria with antibiotics. Identification of the host/microbe factors that determine the clinical presentation (i.e. pyelonephritis versus asymptomatic bacteriuria) once an Escherichia coli strain enters a KTRs bladder could inform management decisions., info:eu-repo/semantics/published

Les gastroentérites aiguës (GEA) représentent un lourd fardeau pour la population pédiatrique. Elles sont responsables d’une mortalité importante, particulièrement chez les enfants de moins de 5 ans dans les pays à faibles revenus, et ont un impact socio-économique non négligeable dans les pays à hauts revenus. La prévalence des différents entéropathogènes potentiellement impliqués dans les GEA varie selon les études, dépendamment de la technique diagnostique utilisée, de la population étudiée – âge des patients, co-morbidités, situation géographique et socio-économique – et du moment où l’étude a été réalisée.Campylobacter est l’un des pathogènes entériques majeurs dans les pays à hauts revenus. Les espèces Campylobacter jejuni et coli sont les plus fréquemment retrouvées par les méthodes de culture sur des milieux sélectifs utilisées en routine dans la plupart des laboratoires de microbiologie. Cependant l’utilisation d’autres méthodes, comme la technique « de filtration » ou les techniques de PCR, permet de mettre en évidence d’autres campylobacters tels que Campylobacter concisus dont le rôle dans les GEA est sujet à controverse.Dans ce contexte, l’objectif général de ce travail de thèse est l’amélioration de la prise en charge diagnostique des GEA en pédiatrie à Bruxelles. Cet objectif se détaille en deux sousobjectifs: d’abord une étude de prévalence des entéropathogènes - et potentiels entéropathogènes -, ensuite une amélioration de techniques diagnostiques. Ces éléments sont détaillés ci-dessous.La première partie de ce travail nous a permis de recruter deux groupes de patients :l’un atteint de GEA (185 cas) et l’autre asymptomatique (179 témoins), mais comparables notamment en termes d’âge, de fréquentation de la crèche ou de l’école, de vaccination contre rotavirus, et de traitement par antibiotique. Au vu des techniques diagnostiques utilisées dans notre étude, Campylobacter jejuni-coli était le principal reponsable de GEA dans notre population (14% des c, Doctorat en Sciences médicales (Médecine), info:eu-repo/semantics/nonPublished