A Narrative Review of Experimental Assessment to Study Vascular Biomaterials Infections and Infectability

Objective: Many experimental studies have been conducted to evaluate vascular and endovascular graft infections (VGEIs) and infectability in order to elaborate strategies to prevent or to treat their occurrence. A systematic literature search was conducted to collect and summarise key features of infection and infectability assessment techniques in VGEI experimental models. Methods: The literature search was conducted using the Medline and Cochrane databases, with no limit on the date of publication, until 10 August 2021. Ex vivo, in vitro, and in vivo animal studies on VGEIs, published in English or French, were selected. Cross references retrieved from selected articles on PubMed database were also included in the search. Data were collected on the techniques and the protocols performed for vascular graft infection and infectability assessment. Results: A total of 243 studies were included in the review: 55 in vitro studies, 169 animal studies, 17 combining the two models, and two ex vivo studies. Many experimental techniques were performed, with a lot of protocol discrepancies. The main experiments conducted were bacterial culture, with (n = 82 studies) or without sonication (n = 120), histopathology (n = 69), scanning electron microscopy (n = 36), and graft diffusion tests (n = 28). These techniques were used to answer different research questions corresponding to different graft infection steps, such as microbial adhesion and/or viability, biofilm biomass or organisation, human cell reaction, or antimicrobial activity. Conclusion: Many experimental tools are available to study VGEIs, but to improve their reproducibility and scientific reliability research protocols must be standardised and include sonication of grafts before microbiological culture. Moreover, the key role of the biofilm in VGEI physiopathology must be taken into account in future studies

Analysis of the Phospholipid Profile of the Collection Strain PAO1 and Clinical Isolates of Pseudomonas aeruginosa in Relation to Their Attachment Capacity

Bacteria form multicellular and resistant structures named biofilms. Biofilm formation starts with the attachment phase, and the molecular actors involved in this phase, except adhesins, are poorly characterized. There is growing evidence that phospholipids are more than simple structural bricks. They are involved in bacterial adaptive physiology, but little is known about their role in biofilm formation. Here, we report a mass spectrometry analysis of the phospholipid (PL) profile of several strains of Pseudomonas aeruginosa isolated from cystic fibrosis patients. The aim of our study was to evaluate a possible link between the PL profile of a strain and its attachment phenotype. Our results showed that PL profile is strongly strain-dependent. The PL profile of P. aeruginosa PAO1, a collection strain, was different from those of 10 clinical isolates characterized either by a very low or a very high attachment capacity. We observed also that the clinical strain's PL profiles varied even more importantly between isolates. By comparing groups of strains having similar attachment capacities, we identified one PL, PE 18:1-18:1, as a potential molecular actor involved in attachment, the first step in biofilm formation. This PL represents a possible target in the fight against biofilms

<p>An unexpected case of <em>Bartonella alsatica</em> prosthetic vascular graft infection</p>

International audienceBartonella alsatica is a wild rabbit pathogen causing bacteremia rarely reported in humans, with only three cases published so far, including one lymphadenitis and two endocarditis cases. Here, we report the case of a 66-year-old man who suffered from acute renal failure due to a membranoproliferative glomerulonephritis. Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) showed diffuse FDG uptake around the aortobifemoral graft with no indication of infection. A white blood cell scan showed an accumulation of labeled neutrophils on the left femoral part of the graft. The patient underwent surgery and an abscess around the left iliac part of the graft was found intraoperatively. Intraoperative samples were all negative, but 16S rRNA gene-based PCR was positive, and the sequence was positioned among the Bartonella species cluster. Specific PCRs targeting groEL/hsp60, rpoB and gltA genes were performed and led to the identification of B. alsatica. Accordingly, indirect immunofluorescence serological analyses were positive for Bartonella henselae and Bartonella quintana. The patient had a history of regularly hunting wild rabbits. He was treated with 100 mg of doxycycline twice a day for six months and his renal function significantly improved with no sign of persistent infection. This case highlights the contribution of serology assays and molecular-based methods in prosthetic vascular graft infection diagnosis

Polymicrobial Infections Among Patients with Vascular Q Fever, France, 2004–2020

International audienceWe report 5 cases of vascular Q fever complicated by polymicrobial superinfection in patients who had no risk factors for acute Q fever. Q fever was diagnosed by serologic and molecular assays for Coxiella burnetii. We confirmed additional infections using conventional graft cultures

Limbic encephalitis as a relapse of Whipple’s disease with digestive involvement and spondylodiscitis

International audienc

Néphrologie & Thérapeutique

La population de patients traités par hémodialyse sur cathéter est fragile, à risque infectieux important. La bactériémie liée au cathéter d’hémodialyse est l’une des complications les plus graves, dont l’incidence augmente chaque année, en lien avec une hausse de l’utilisation des cathéters comme abord vasculaire. Cependant, le diagnostic clinique et microbiologique reste difficile. La mise en place de l’antibiothérapie probabiliste se base sur des recommandations anciennes qui préconisent d’associer une molécule visant le Staphylococcus aureus méticillino-résistant, ainsi qu’une bêtalactamine active sur P. aeruginosa, mais également d’adapter ce traitement probabiliste en réalisant un recueil microbiologique à l’échelle locale, ce qui est rarement réalisé. Dans notre centre d’hémodialyse du CHU de Bordeaux, une analyse de la répartition bactériologique des bactériémies liées au cathéter d’hémodialyse sur la période 2018–2020 a permis de proposer, en accord avec les infectiologues, un protocole d’antibiothérapie probabiliste adaptée. Cette démarche nous a permis de constater une incidence faible de méticillino-résistance des Staphylocoques, une incidence nulle de Staphylocoque après un délai de pose du cathéter de plus de 6 mois, aucun Pseudomonas multirésistant et un très faible pourcentage d’entérobactérie résistant aux céphalosporines. La mise à jour régulière de l’épidémiologie microbiologique des bactériémies liées aux cathéters d’hémodialyse, associée à un partenariat avec l’équipe d’infectiologie dans son centre d’hémodialyse, permettant une adaptation de l’antibiothérapie probabiliste, paraît avoir une bonne faisabilité et, à long terme, favoriser la préservation de l’écologie microbienne à l’échelle individuelle et collective pour la population de patients traités par hémodialyse.Patients in hemodialysis on central venous catheter as vascular access are at risk of infections. Catheter-related bloodstream infection is one of the most serious catheter-complications in hemodialysis patients. Its clinical and microbiological diagnosis is challenging. The implementation of empiric antibiotic therapy is based on old recommendations proposing the combination of a molecule targeting methicillin-resistant Staphylococcus aureus and a betalactamin active on P. aeruginosa, and also adapting this probabilistic treatment by carrying out a microbiological register on a local scale, which is rarely done. In our hemodialysis center at Bordeaux University Hospital, an analysis of the microorganisms causing all catheter-related bloodstream infection over the period 2018–2020 enabled us to propose, in agreement with the infectious disease specialists, an adapted probabilistic antibiotic therapy protocol. This approach allowed us to observe a low incidence of meticillinoresistance of Staphylococcus. For catheters inserted more than 6 months ago, we observed no Staphylococcus, no multi-resistant Pseudomonas, and only 2% of Enterobacteria resistant to cephalosporins. A frequent updating of the microbiological epidemiology of catheter-related bloodstream infection, in partnership with the infectious diseases team in each hemodialysis center, allowing an adaptation of the probabilistic antibiotic therapy, and seems to have a good feasibility. This strategy might favor the preservation of microbial ecology on an individual and collective scale in maintenance hemodialysis patients

Retrospective multicentric study on Campylobacter spp. bacteremia in France: the Campylobacteremia study

International audienceAbstract Background Campylobacter spp. bacteremia is a severe infection. A nationwide 5-year retrospective study was conducted to characterize its clinical features and prognostic factors. Methods Patients diagnosed with Campylobacter spp. bacteremia in 37 French hospitals participating in the surveillance network of the National Reference Center for Campylobacter and Helicobacter were included from January 1, 2015, to December 31, 2019. The goal was to analyze the effects of a delay of appropriate antibiotic therapy and other risk factors on 30-day mortality, antibiotic resistance, patient characteristics and prognosis according to the Campylobacter species. Findings Among the 592 patients, Campylobacter jejuni and Campylobacter fetus were the most commonly identified species (42.9 and 42.6%, respectively). The patients were elderly (median age 68 years), and most had underlying conditions, mainly immunodepression (43.4%), hematologic malignancies (25.9%), solid neoplasms (23%) and diabetes (22.3%). C. jejuni and Campylobacter coli were associated with gastrointestinal signs, and C. fetus was associated with secondary localizations. Among the 80 patients (13.5%) with secondary localizations, 12 had endocarditis, 38 vascular, 24 osteo-articular and 9 ascitic fluid infections. The thirty-day mortality rate was 11.7%, and an appropriate antibiotic treatment was independently associated with 30-day survival (odds ratio [OR]=0.47, 95% CI [0.24–0.93], p=0.03). The median efficient therapy initiation delay was quite short (2 days, IQR [0–4]) but it had no significant impact on 30-day mortality (p=0.78). Interpretation Campylobacter spp. bacteremia mainly occurred in elderly immunocompromised individuals with variable clinical presentations according to the species involved. Appropriate antimicrobial therapy was associated with improved 30-day survival

Multicenter Retrospective Study of Vascular Infections and Endocarditis Caused by Campylobacter spp., France

The incidence of campylobacteriosis has substantially increased over the past decade, notably in France. Secondary localizations complicating invasive infections are poorly described. We aimed to describe vascular infection or endocarditis caused by Campylobacter spp. We included 57 patients from a nationwide 5-year retrospective study on Campylobacter spp. bacteremia conducted in France; 44 patients had vascular infections, 12 had endocarditis, and 1 had both conditions. Campylobacter fetus was the most frequently involved species (83%). Antibiotic treatment involved a β-lactam monotherapy (54%) or was combined with a fluoroquinolone or an aminoglycoside (44%). The mortality rate was 25%. Relapse occurred in 8% of cases and was associated with delayed initiation of an efficient antimicrobial therapy after the first symptoms, diabetes, and coexistence of an osteoarticular location. Cardiovascular Campylobacter spp. infections are associated with a high mortality rate. Systematically searching for those localizations in cases of C. fetus bacteremia may be warranted