V. Dubée - Academia.edu (original) (raw)
Papers by V. Dubée
La Revue de Médecine Interne, 2013
Journal des Anti-infectieux, 2012
ABSTRACT Background Although spinal fusion surgery has become a common procedure, there are few d... more ABSTRACT Background Although spinal fusion surgery has become a common procedure, there are few data about surgical site infections (SSI) following instrumented spinal surgery. Methods Systematic literature review. Results SSI affect 2 to 5% of patients undergoing instrumented spinal surgery. Diabetes, obesity, malnutrition and longer operations are risk factors for SSI, whereas anterior approach and cervical operations are associated with a low risk. Prognosis and clinical expression of SSI depend on the infection's extension and on the delay between surgery and first symptoms. Superficial infections should be treated with debridement surgery and a short-course of antibiotic therapy. Deep early-onset infections, occurring within 30 days after initial surgery, are most often caused by Staphylococcus aureus or Enterobacteriaceae, and are frequently associated with bacteraemia. Such infections may be treated with prompt surgical debridement with implant retention, combined with a 3-month course of antibiotics. More than 80% of patients treated along these modalities are cured of their infection. Late-onset infections are generally caused by low virulent bacteria. While most authors agree on the need for implant removal for late-onset SSI, optimal length of antibiotic therapy remains controversial. Conclusion SSI following instrumented spinal surgery present specific therapeutic challenges. Optimal management of these infections should take into account the delay between implant placement and infection's onset.
Biomolecular NMR Assignments, 2013
Penicillin-binding proteins were long considered as the only peptidoglycan cross-linking enzymes ... more Penicillin-binding proteins were long considered as the only peptidoglycan cross-linking enzymes and one of the main targets of b-lactam antibiotics. A new class of transpeptidases, the L,D-transpeptidases, has emerged in the last decade. In most Gram-negative and Gram-positive bacteria, these enzymes generally have nonessential roles in peptidoglycan synthesis. In some clostridiae and mycobacteria, such as Mycobacterium tuberculosis, they are nevertheless responsible for the major peptidoglycan crosslinking pathway. L,D-Transpeptidases are thus considered as appealing new targets for the development of innovative therapeutic approaches. Carbapenems are currently investigated in this perspective as they are active on extensively drug-resistant M. tuberculosis and represent the only b-lactam class inhibiting L,D-transpeptidases. The molecular basis of the enzyme selectivity for carbapenems nevertheless remains an open question. Here we present the backbone and side-chain 1 H, 13 C, 15 N NMR assignments of the catalytic domain of Enterococcus faecium L,D-transpeptidase before and after acylation with the carbapenem ertapenem, as a prerequisite for further structural and functional studies.
PLoS ONE, 2013
Active-site serine D,D-transpeptidases belonging to the penicillin-binding protein family (PBPs) ... more Active-site serine D,D-transpeptidases belonging to the penicillin-binding protein family (PBPs) have been considered for a long time as essential for peptidoglycan cross-linking in all bacteria. However, bypass of the PBPs by an L,D-transpeptidase (Ldt fm ) conveys high-level resistance to b-lactams of the penam class in Enterococcus faecium with a minimal inhibitory concentration (MIC) of ampicillin .2,000 mg/ml. Unexpectedly, Ldt fm does not confer resistance to b-lactams of the carbapenem class (imipenem MIC = 0.5 mg/ml) whereas cephems display residual activity (ceftriaxone MIC = 128 mg/ml). Mass spectrometry, fluorescence kinetics, and NMR chemical shift perturbation experiments were performed to explore the basis for this specificity and identify b-lactam features that are critical for efficient L,D-transpeptidase inactivation. We show that imipenem, ceftriaxone, and ampicillin acylate Ldt fm by formation of a thioester bond between the active-site cysteine and the b-lactam-ring carbonyl. However, slow acylation and slow acylenzyme hydrolysis resulted in partial Ldt fm inactivation by ampicillin and ceftriaxone. For ampicillin, Ldt fm acylation was followed by rupture of the C 5 -C 6 bond of the b-lactam ring and formation of a secondary acylenzyme prone to hydrolysis. The saturable step of the catalytic cycle was the reversible formation of a tetrahedral intermediate (oxyanion) without significant accumulation of a non-covalent complex. In agreement, a derivative of Ldt fm blocked in acylation bound ertapenem (a carbapenem), ceftriaxone, and ampicillin with similar low affinities. Thus, oxyanion and acylenzyme stabilization are both critical for rapid L,D-transpeptidase inactivation and antibacterial activity. These results pave the way for optimization of the b-lactam scaffold for L,D-transpeptidaseinactivation. Citation: Triboulet S, Dubée V, Lecoq L, Bougault C, Mainardi J-L, et al. (2013) Kinetic Features of L,D-Transpeptidase Inactivation Critical for b-Lactam Antibacterial Activity. PLoS ONE 8(7): e67831.
Clinical Microbiology and Infection, 2013
The in vitro activity of cefoxitin and imipenem was compared for 43 strains of the Mycobacterium ... more The in vitro activity of cefoxitin and imipenem was compared for 43 strains of the Mycobacterium abscessus complex, mostly isolated from cystic fibrosis patients. The MICs of imipenem were lower than those of cefoxitin, although the number of imipenemresistant strains was higher according to the CLSI breakpoints.
Clinical Microbiology and Infection, 2013
Few data are available on treatment and outcome of methicillin-resistant (MR) staphylococcal pros... more Few data are available on treatment and outcome of methicillin-resistant (MR) staphylococcal prosthetic joint infections. Vancomycin remains the treatment of choice for these infections, but its efficacy and safety in bone-and-joint infections are insufficiently documented. We conducted a prospective cohort study on 60 patients treated between November 2002 and December 2008 for chronic MR staphylococcal (44 S. epidermidis, nine other coagulase-negative Staphylococcus and seven S. aureus) prosthetic hip infections (PHIs). Twenty-two patients had previously undergone surgery for their PHI and 21 had previously received antibiotics. All patients had surgery (exchange arthroplasty for 58 patients, resection arthroplasty for two) and received an antibiotic regimen combining high-dose continuous intravenous vancomycin infusion (target serum concentration 30-40 mg/L) with another antibiotic for 6 weeks, followed by an additional 6 weeks of oral intake. Two years after surgery, infection was considered cured in 41 (68%) patients and only two relapses occurred after one-stage exchange arthroplasty. Nineteen (32%) patients experienced nephrotoxicity that was generally mild (RIFLE class R for 14 patients, class I for four patients and class F for one patient) and most often reversible. Continuous high-dose intravenous vancomycin combination therapy is an effective, feasible and reasonably safe treatment of chronic MR staphylococcal PHI.
Antimicrobial Agents and Chemotherapy, 2011
The mechanisms of antibiotic-induced cell death are poorly understood despite the critical role o... more The mechanisms of antibiotic-induced cell death are poorly understood despite the critical role of the bactericidal activities of antibiotics for successful treatment of severe infections. These mechanisms include irreversible damaging of macromolecules by reactive oxygen species and bacteriolysis mediated by peptidoglycan hydrolases (autolysins). We have assessed the contribution of the second mechanism by using an autolysindeficient mutant of Enterococcus faecalis and shown that it contributes to amoxicillin-induced cell lysis only at a high bacterial density.
![Research paper thumbnail of [Hypophosphatemia complicated with neurological manifestations during hematopoietic reconstitution]](https://attachments.academia-assets.com/42642808/thumbnails/1.jpg)
](La Revue de médecine interne / fondée ... par la Société nationale francaise de médecine interne, 2012
We report the case of a 52-year-old woman who developed neurological manifestations secondary to ... more We report the case of a 52-year-old woman who developed neurological manifestations secondary to severe hypophosphatemia during hematopoietic reconstitution after induction for acute lymphoblastic leukemia. A high cellular uptake of phosphate may be seen in situations with a rapid cell proliferation such as hematopoietic reconstitution, and phosphatemia should be carefully monitored in such situations.
La Revue de Médecine Interne, 2013
Journal des Anti-infectieux, 2012
ABSTRACT Background Although spinal fusion surgery has become a common procedure, there are few d... more ABSTRACT Background Although spinal fusion surgery has become a common procedure, there are few data about surgical site infections (SSI) following instrumented spinal surgery. Methods Systematic literature review. Results SSI affect 2 to 5% of patients undergoing instrumented spinal surgery. Diabetes, obesity, malnutrition and longer operations are risk factors for SSI, whereas anterior approach and cervical operations are associated with a low risk. Prognosis and clinical expression of SSI depend on the infection's extension and on the delay between surgery and first symptoms. Superficial infections should be treated with debridement surgery and a short-course of antibiotic therapy. Deep early-onset infections, occurring within 30 days after initial surgery, are most often caused by Staphylococcus aureus or Enterobacteriaceae, and are frequently associated with bacteraemia. Such infections may be treated with prompt surgical debridement with implant retention, combined with a 3-month course of antibiotics. More than 80% of patients treated along these modalities are cured of their infection. Late-onset infections are generally caused by low virulent bacteria. While most authors agree on the need for implant removal for late-onset SSI, optimal length of antibiotic therapy remains controversial. Conclusion SSI following instrumented spinal surgery present specific therapeutic challenges. Optimal management of these infections should take into account the delay between implant placement and infection's onset.
Biomolecular NMR Assignments, 2013
Penicillin-binding proteins were long considered as the only peptidoglycan cross-linking enzymes ... more Penicillin-binding proteins were long considered as the only peptidoglycan cross-linking enzymes and one of the main targets of b-lactam antibiotics. A new class of transpeptidases, the L,D-transpeptidases, has emerged in the last decade. In most Gram-negative and Gram-positive bacteria, these enzymes generally have nonessential roles in peptidoglycan synthesis. In some clostridiae and mycobacteria, such as Mycobacterium tuberculosis, they are nevertheless responsible for the major peptidoglycan crosslinking pathway. L,D-Transpeptidases are thus considered as appealing new targets for the development of innovative therapeutic approaches. Carbapenems are currently investigated in this perspective as they are active on extensively drug-resistant M. tuberculosis and represent the only b-lactam class inhibiting L,D-transpeptidases. The molecular basis of the enzyme selectivity for carbapenems nevertheless remains an open question. Here we present the backbone and side-chain 1 H, 13 C, 15 N NMR assignments of the catalytic domain of Enterococcus faecium L,D-transpeptidase before and after acylation with the carbapenem ertapenem, as a prerequisite for further structural and functional studies.
PLoS ONE, 2013
Active-site serine D,D-transpeptidases belonging to the penicillin-binding protein family (PBPs) ... more Active-site serine D,D-transpeptidases belonging to the penicillin-binding protein family (PBPs) have been considered for a long time as essential for peptidoglycan cross-linking in all bacteria. However, bypass of the PBPs by an L,D-transpeptidase (Ldt fm ) conveys high-level resistance to b-lactams of the penam class in Enterococcus faecium with a minimal inhibitory concentration (MIC) of ampicillin .2,000 mg/ml. Unexpectedly, Ldt fm does not confer resistance to b-lactams of the carbapenem class (imipenem MIC = 0.5 mg/ml) whereas cephems display residual activity (ceftriaxone MIC = 128 mg/ml). Mass spectrometry, fluorescence kinetics, and NMR chemical shift perturbation experiments were performed to explore the basis for this specificity and identify b-lactam features that are critical for efficient L,D-transpeptidase inactivation. We show that imipenem, ceftriaxone, and ampicillin acylate Ldt fm by formation of a thioester bond between the active-site cysteine and the b-lactam-ring carbonyl. However, slow acylation and slow acylenzyme hydrolysis resulted in partial Ldt fm inactivation by ampicillin and ceftriaxone. For ampicillin, Ldt fm acylation was followed by rupture of the C 5 -C 6 bond of the b-lactam ring and formation of a secondary acylenzyme prone to hydrolysis. The saturable step of the catalytic cycle was the reversible formation of a tetrahedral intermediate (oxyanion) without significant accumulation of a non-covalent complex. In agreement, a derivative of Ldt fm blocked in acylation bound ertapenem (a carbapenem), ceftriaxone, and ampicillin with similar low affinities. Thus, oxyanion and acylenzyme stabilization are both critical for rapid L,D-transpeptidase inactivation and antibacterial activity. These results pave the way for optimization of the b-lactam scaffold for L,D-transpeptidaseinactivation. Citation: Triboulet S, Dubée V, Lecoq L, Bougault C, Mainardi J-L, et al. (2013) Kinetic Features of L,D-Transpeptidase Inactivation Critical for b-Lactam Antibacterial Activity. PLoS ONE 8(7): e67831.
Clinical Microbiology and Infection, 2013
The in vitro activity of cefoxitin and imipenem was compared for 43 strains of the Mycobacterium ... more The in vitro activity of cefoxitin and imipenem was compared for 43 strains of the Mycobacterium abscessus complex, mostly isolated from cystic fibrosis patients. The MICs of imipenem were lower than those of cefoxitin, although the number of imipenemresistant strains was higher according to the CLSI breakpoints.
Clinical Microbiology and Infection, 2013
Few data are available on treatment and outcome of methicillin-resistant (MR) staphylococcal pros... more Few data are available on treatment and outcome of methicillin-resistant (MR) staphylococcal prosthetic joint infections. Vancomycin remains the treatment of choice for these infections, but its efficacy and safety in bone-and-joint infections are insufficiently documented. We conducted a prospective cohort study on 60 patients treated between November 2002 and December 2008 for chronic MR staphylococcal (44 S. epidermidis, nine other coagulase-negative Staphylococcus and seven S. aureus) prosthetic hip infections (PHIs). Twenty-two patients had previously undergone surgery for their PHI and 21 had previously received antibiotics. All patients had surgery (exchange arthroplasty for 58 patients, resection arthroplasty for two) and received an antibiotic regimen combining high-dose continuous intravenous vancomycin infusion (target serum concentration 30-40 mg/L) with another antibiotic for 6 weeks, followed by an additional 6 weeks of oral intake. Two years after surgery, infection was considered cured in 41 (68%) patients and only two relapses occurred after one-stage exchange arthroplasty. Nineteen (32%) patients experienced nephrotoxicity that was generally mild (RIFLE class R for 14 patients, class I for four patients and class F for one patient) and most often reversible. Continuous high-dose intravenous vancomycin combination therapy is an effective, feasible and reasonably safe treatment of chronic MR staphylococcal PHI.
Antimicrobial Agents and Chemotherapy, 2011
The mechanisms of antibiotic-induced cell death are poorly understood despite the critical role o... more The mechanisms of antibiotic-induced cell death are poorly understood despite the critical role of the bactericidal activities of antibiotics for successful treatment of severe infections. These mechanisms include irreversible damaging of macromolecules by reactive oxygen species and bacteriolysis mediated by peptidoglycan hydrolases (autolysins). We have assessed the contribution of the second mechanism by using an autolysindeficient mutant of Enterococcus faecalis and shown that it contributes to amoxicillin-induced cell lysis only at a high bacterial density.
La Revue de médecine interne / fondée ... par la Société nationale francaise de médecine interne, 2012
We report the case of a 52-year-old woman who developed neurological manifestations secondary to ... more We report the case of a 52-year-old woman who developed neurological manifestations secondary to severe hypophosphatemia during hematopoietic reconstitution after induction for acute lymphoblastic leukemia. A high cellular uptake of phosphate may be seen in situations with a rapid cell proliferation such as hematopoietic reconstitution, and phosphatemia should be carefully monitored in such situations.