Distribution of Achromobacter Species in 12 French Cystic Fibrosis Centers in 2020 by a Retrospective MALDI-TOF MS Spectrum Analysis.

Achromobacter spp. are nonfermenting Gram-negative bacilli mainly studied among cystic fibrosis (CF) patients. The identification of the 19 species within the genus is time-consuming (nrdA-sequencing), thus data concerning the distribution of the species are limited to specific studies. Recently, we built a database using MALDI-TOF mass spectrometry (MS) (Bruker) that allows rapid and accurate species identification and detection of the multiresistant epidemic clones: A. xylosoxidans ST137 spreading among CF patients in various French and Belgium centers, and A. ruhlandii DES in Denmark. Here, we first assessed whether species identification could be achieved with our database solely by analysis of MS spectra without availability of isolates. Then, we conducted a multicentric study describing the distribution of Achromobacter species and of the clone ST137 among French CF centers. We collected and analyzed with our local database the spectra of Achromobacter isolates from 193 patients (528 samples) from 12 centers during 2020. In total, our approach enabled to conclude for 502/528 samples (95.1%), corresponding to 181 patients. Eleven species were detected, only five being involved in chronic colonization, A. xylosoxidans (86.4%), A. insuavis (9.1%), A. mucicolens (2.3%), A. marplatensis (1.1%) and A. genogroup 3 (1.1%). This study confirmed the high prevalence of A. xylosoxidans in chronic colonizations and the circulation of the clone A. xylosoxidans ST137 in France: four patients in two centers. The present study is the first to report the distribution of Achromobacter species from CF patients samples using retrospective MALDI-TOF/MS data. This easy approach could enable future large-scale epidemiological studies.

In vitro activity of novel anti-MRSA cephalosporins and comparator antimicrobial agents against staphylococci involved in prosthetic joint infections.

OBJECTIVES: Ceftaroline and ceftobiprole are new parenteral cephalosporins with potent activity against methicillin-resistant (MR) staphylococci, which are the leading cause of prosthetic joint infections (PJIs). The aim of this study was to determine and compare the in vitro activities of both molecules against staphylococcal isolates recovered from clinically documented PJIs. METHODS: A collection of 200 non-duplicate clinical isolates [100 Staphylococcus aureus and 100 coagulase-negative staphylococci (CoNS), including 19 and 27 MR isolates, respectively] was studied. Minimum inhibitory concentrations (MICs) of oxacillin, ceftaroline, ceftobiprole, vancomycin, teicoplanin, clindamycin, levofloxacin, linezolid and daptomycin were determined by the broth microdilution method. Bactericidal activity (at 4× MIC) of ceftaroline, ceftobiprole, vancomycin, teicoplanin, linezolid and daptomycin was assessed by time-kill assay. RESULTS: Among the S. aureus isolates, 100% were susceptible to ceftaroline (MIC50/90, 0.25/0.5µg/mL) and 98% were susceptible to ceftobiprole (MIC50/90, 0.5/1µg/mL), regardless of their methicillin resistance. The two ceftobiprole-non-susceptible strains (including one MRSA) showed MICs at 4mg/L. Against CoNS isolates, ceftaroline and ceftobiprole exhibited in vitro potency with MIC50/90 values at 0.06/0.25µg/mL and 0.25/1µg/mL, respectively. At 4× MIC, ceftaroline and ceftobiprole showed rapid and marked bactericidal activity against both S. aureus and CoNS (after 24/12h and 12/6h of incubation, respectively), whilst none of the other molecules tested had a bactericidal effect by 24h. CONCLUSIONS: This study showed that ceftaroline and ceftobiprole have excellent in vitro activity against clinical isolates of staphylococci involved in PJIs. These molecules may therefore represent promising alternatives for the treatment of such infections.

A case of hypercalcemia Indications for 1,25-dihydroxyvitamin D prescription.

Circulating vitamin D is found in various forms: 25-hydroxyvitamin D or calcidiol, majority circulating form, is a "pro-hormon" which will be converted to 1,25-dihydroxyvitamin D or calcitriol, hormone corresponding to vitamin D active form. While determination of 25-hydroxyvitamin D serum levels reflects vitamin D status of patients, determination of 1,25-dihydroxyvitamin D serum level is only indicated in rare cases of suspected hypersensitivity vitamin D in children or of sarcoidosis in adults. There are too many confusion between these two vitamin forms, resulting in inappropriate prescription of 1,25-dihydroxyvitamin D. Here, we describe a case of hypersensitivity to vitamin D by mutation of CYP24A1. We propose to review the interest of 1,25-dihydroxyvitamin D assay in different pathologies, to describe the assay techniques and remind the good prescribing practices of this parameter.