Antimicrobial susceptibility profile of clinically relevant Bacteroides, Phocaeicola, Parabacteroides and Prevotella species, isolated by eight laboratories in the Netherlands.

OBJECTIVES: Recently, reports on antimicrobial-resistant Bacteroides and Prevotella isolates have increased in the Netherlands. This urged the need for a surveillance study on the antimicrobial susceptibility profile of Bacteroides, Phocaeicola, Parabacteroides and Prevotella isolates consecutively isolated from human clinical specimens at eight different Dutch laboratories. METHODS: Each laboratory collected 20-25 Bacteroides (including Phocaeicola and Parabacteroides) and 10-15 Prevotella isolates for 3 months. At the national reference laboratory, the MICs of amoxicillin, amoxicillin/clavulanic acid, piperacillin/tazobactam, meropenem, imipenem, metronidazole, clindamycin, tetracycline and moxifloxacin were determined using agar dilution. Isolates with a high MIC of metronidazole or a carbapenem, or harbouring cfiA, were subjected to WGS. RESULTS: Bacteroides thetaiotaomicron/faecis isolates had the highest MIC90 values, whereas Bacteroides fragilis had the lowest MIC90 values for amoxicillin/clavulanic acid, piperacillin/tazobactam, meropenem, imipenem and moxifloxacin. The antimicrobial profiles of the different Prevotella species were similar, except for amoxicillin, for which the MIC50 ranged from 0.125 to 16 mg/L for Prevotella bivia and Prevotella buccae, respectively. Three isolates with high metronidazole MICs were sequenced, of which one Bacteroides thetaiotaomicron isolate harboured a plasmid-located nimE gene and a Prevotella melaninogenica isolate harboured a nimA gene chromosomally.Five Bacteroides isolates harboured a cfiA gene and three had an IS element upstream, resulting in high MICs of carbapenems. The other two isolates harboured no IS element upstream of the cfiA gene and had low MICs of carbapenems. CONCLUSIONS: Variations in resistance between species were observed. To combat emerging resistance in anaerobes, monitoring resistance and conducting surveillance are essential.

Characterization of mobile genetic elements in multidrug-resistant Bacteroides fragilis isolates from different hospitals in the Netherlands.

OBJECTIVES: Five human clinical multidrug-resistant (MDR) Bacteroides fragilis isolates, including resistance to meropenem and metronidazole, were recovered at different hospitals in the Netherlands between 2014 and 2020 and sent to the anaerobic reference laboratory for full characterization. METHODS: Isolates were recovered from a variety of clinical specimens from patients with unrelated backgrounds. Long- and short-read sequencing was performed, followed by a hybrid assembly to study the presence of mobile genetic elements (MGEs) and antimicrobial resistance genes (ARGs). RESULTS: A cfxA gene was present on a transposon (Tn) similar to Tn4555 in two isolates. In two isolates a novel Tn was present with the cfxA gene. Four isolates harbored a nimE gene, located on a pBFS01_2 plasmid. One isolate contained a novel plasmid carrying a nimA gene with IS1168. The tetQ gene was present on novel conjugative transposons (CTns) belonging to the CTnDOT family. Two isolates harbored a novel plasmid with tetQ. Other ARGs in these isolates, but not on an MGE, were: cfiA, ermF, mef(EN2), and sul2. ARGs harboured differed between isolates and corresponded with the observed phenotypic resistance. CONCLUSIONS: Novel CTns, Tns, and plasmids were encountered in the five MDR B. fragilis isolates, complementing our knowledge on MDR and horizontal gene transfer in anaerobic bacteria.

Clinically unsuspected orthopedic implants during S. aureus bacteremia do not require additional diagnostic work-up.

PURPOSE: To assess the likelihood of occult infection in patients with clinically unsuspected orthopedic implants during Staphylococcus aureus bacteremia (SAB). METHODS: In a retrospective study in two Dutch hospitals, we included all patients with SAB between 2013 and 2020 with one or more orthopedic implants in whom [18F]FDG-PET/CT was performed. The primary outcome was the percentage of patients who had an orthopedic implant-related infection by S. aureus. We also compared clinical parameters in patients with clinically suspected and unsuspected implants. RESULTS: Fifty-five of 191 (29%) orthopedic implants in 118 SAB patients included had clinical signs of infection. Of all 136 unsuspected implants, 5 (3%, all arthroplasties), showed increased [18F]FDG uptake around the prosthesis on [18F]FDG-PET/CT. The clinical course of these patients without clinically overt infection or relapse of bacteremia during follow-up of a median of 48 months (range 0-48), however, argued against prosthetic joint infection. CONCLUSION: Although orthopedic implants are evidently a risk factor for metastatic infection during SAB, the absence of clinical symptoms obviate the need of additional investigations or prolonged antibiotic treatment.

The impact of implementing an endocarditis team in comparison to the classic heart team in a tertiary referral centre.

BACKGROUND: Infective endocarditis (IE) is a complex disease for which the European Society of Cardiology guideline recommends a dedicated multidisciplinary endocarditis team (ET) approach since 2015. It is currently unknown whether this ET approach is beneficial compared to a classic heart team approach including bedside consultation by an infectious disease specialist in Western Europe. METHODS: This retrospective single centre, observational cohort study was conducted at the Radboudumc, a tertiary referral centre in the Netherlands. Consecutive patients treated for IE were included from September 2017 to September 2018 before implementation of a dedicated ET and from May 2019 to May 2020 afterwards. RESULTS: In total, 90 IE patients (45 patients before and 45 patients after the implementation of the ET) were included. No significant differences were found in diagnostic workup, surgical treatment (surgery performed 69% vs. 71%, p = 0.82), time to surgery because of an urgent indication (median 4 vs. 6 days, p = 0.82), in-hospital complications (53% vs. 67%, p = 0.20), and 6-month mortality (11% vs. 13%, p = 0.75) between IE patients treated before and after the implementation of the ET. CONCLUSION: Formalization of the recommended multidisciplinary endocarditis team might not significantly improve the complication rate nor the short term outcome.