Frédéric Laurent

Mycobacterium setense sp. nov., a Mycobacterium fortuitum-group organism isolated from a patient with soft tissue infection and osteitis

A Gram-positive, rod-shaped acid-fast bacterium was isolated from a patient with a post-traumatic chronic skin abscess associated with osteitis. Morphological analysis, 16S rRNA, hsp65, sodA and rpoB gene sequence analysis, cell-wall fatty acid and mycolic acid composition analyses and biochemical tests showed that the isolate, designated ABO-M06(T), belonged to the genus Mycobacterium. Its phenotype was unique and genetic and phylogenetic findings suggest that strain ABO-M06(T) represents a novel species within the Mycobacterium fortuitum group. The name Mycobacterium setense sp. nov. is proposed for this novel species, with the type strain ABO-M06(T) (=CIP 109395(T)=DSM 45070(T)).

Evidence for Human Adaptation and Foodborne Transmission of Livestock-Associated Methicillin-Resistant Staphylococcus aureus

We investigated the evolution and epidemiology of a novel livestock-associated methicillin-resistant Staphylococcus aureus strain, which colonizes and infects urban-dwelling Danes even without a Danish animal reservoir. Genetic evidence suggests both poultry and human adaptation, with poultry meat implicated as a probable source.

Antimicrobial Activity against Intraosteoblastic Staphylococcus aureus

ABSTRACT Although Staphylococcus aureus persistence in osteoblasts, partly as small-colony variants (SCVs), can contribute to bone and joint infection (BJI) relapses, the intracellular activity of antimicrobials is not currently considered in the choice of treatment strategies for BJI. Here, antistaphylococcal antimicrobials were evaluated for their intraosteoblastic activity and their impact on the intracellular emergence of SCVs in an ex vivo osteoblast infection model. Osteoblastic MG63 cells were infected for 2 h with HG001 S. aureus. After killing the remaining extracellular bacteria with lysostaphin, infected cells were incubated for 24 h with antimicrobials at the intraosseous concentrations reached with standard therapeutic doses. Intracellular bacteria and SCVs were then quantified by plating cell lysates. A bactericidal effect was observed with fosfomycin, linezolid, tigecycline, oxacillin, rifampin, ofloxacin, and clindamycin, with reductions in the intracellular inocula of −2.5, −3.1, −3.9, −4.2, −4.9, −4.9, and −5.2 log10 CFU/100,000 cells, respectively (P < 10−4). Conversely, a bacteriostatic effect was observed with ceftaroline and teicoplanin, whereas vancomycin and daptomycin had no significant impact on intracellular bacterial growth. Ofloxacin, daptomycin, and vancomycin significantly limited intracellular SCV emergence. Overall, ofloxacin was the only molecule to combine an excellent intracellular activity while limiting the emergence of SCVs. These data provide a basis for refining the choice of antibiotics to prioritise in the management of BJI, justifying the combination of a fluoroquinolone for its intracellular activity with an anti-biofilm molecule, such as rifampin.

Population pharmacokinetics and probability of target attainment of ertapenem administered by subcutaneous or intravenous route in patients with bone and joint infection

Background Ertapenem is a therapeutic option in patients with Gram-negative bone and joint infection (BJI). The subcutaneous (sc) route of administration is convenient in the outpatient setting and has shown favourable pharmacokinetics (PK), but available data on ertapenem are limited. Objectives To perform population PK analysis and pharmacokinetic/pharmacodynamic (PK/PD) simulation of ertapenem administered by the intravenous (iv) or sc route to patients with BJI. Patients and methods This was a retrospective analysis of PK data collected in patients with BJI who received iv or sc ertapenem. Measured ertapenem concentrations were analysed with a non-parametric population approach. Then, simulations were performed based on the final model to investigate the influence of ertapenem route of administration, dosage and renal function on the probability of achieving a pharmacodynamic (PD) target, defined as the percentage of time for which free plasma concentrations of ertapenem remained above the MIC (fT>MIC) of 40%. Results Forty-six PK profiles (13 with iv and 33 with sc ertapenem) with a total of 133 concentrations from 31 subjects were available for the analysis. A two-compartment model with linear sc absorption and linear elimination best fitted the data. Creatinine clearance was found to significantly influence ertapenem plasma clearance. Simulations showed that twice daily dosing, sc administration and renal impairment were associated with an increase in fT>MIC and target attainment. Conclusions Our results indicate that 1 g of ertapenem administered twice daily, by the iv or sc route, may optimize ertapenem exposure and achievement of PK/PD targets in patients with BJI.

Reactivation of Clostridium tertium bone infection 30 years after the Iran-Iraq war.

Clostridium tertium could be responsible forlate metal fragment bone and joint infection.LateC. tertium metal fragment bone and joint infections requires a multidisciplinary management. Late C. tertium metal fragment bone and joint infections requires metal extraction and prolonged antimicrobial therapy for healin.

Post-traumatic chronic bone and joint infection caused by Butyricimonas spp, and treated with high doses of ertapenem administered subcutaneously in a 30-year-old obese man

An obese but otherwise healthy 30-year-old man presented with septic pseudarthrosis following a post-traumatic open radial fracture. Three months earlier, the patient had been involved in a truck accident and suffered a distal open radial fracture associated with compartment syndrome (figure 1A). Primary management consisted of wound debridement, fasciotomy, stabilisation with external fixation and antibiotic prophylaxis with amoxicillin-clavulanate. The wound healed after 1 month (figure 1B). Due to pseudarthrosis (figure 1C, D), the patient returned to the operating room for internal fixation. He did not have fever, and there was no local sign of inflammation and no fistula; …

A steam-based method to investigate biofilm

Biofilm has become a major topic of interest in medical, food, industrial, and environmental bacteriology. To be relevant, investigation of biofilm behavior requires effective and reliable techniques. We present herein a simple and robust method, adapted from the microplate technique, in which steam is used as a soft washing method to preserve biofilm integrity and to improve reproducibility of biofilm quantification. The kinetics of steam washing indicated that the method is adapted to remove both planktonic bacteria and excess crystal violet (CV) staining for S. aureus, S. epidermidis, S. carnosus, P. aeruginosa, and E. coli biofilm. Confocal laser scanning microscopy confirmed that steam washing preserved the integrity of the biofilm better than pipette-based washing. We also investigated the measurement of the turbidity of biofilm resuspended in phosphate-buffered saline (PBS) as an alternative to staining with CV. This approach allows the discrimination of biofilm producer strains from non-biofilm producer strains in a way similar to CV staining, and subsequently permits quantification of viable bacteria present in biofilm by culture enumeration from the same well. Biofilm quantification using steam washing and PBS turbidity reduced the technical time needed, and data were highly reproducible.

Prolonged Cefoxitin Infusion Using Mobile Elastomeric Infusors In Outpatients With Bone And Joint Infection

We reviewed all outpatients with bone and joint infection treated with cefoxitin in continuous intravenous infusion using mobile elastomeric infusors in our regional reference center between 2014 and 2017. The stability of cefoxitin provides an interesting and well-tolerated alternative for continuous infusion in outpatients with polymicrobial bone and joint infection.

Diagnostic de l’infection d’une plaie chronique et principes de traitement

Les plaies chroniques representent un probleme clinique frequent dont la prise en charge est mal codifiee. La colonisation bacterienne est systematique, et peut evoluer vers une infection dont le diagnostic est parfois difficile. Les situations urgentes, severes ou complexes, telles que les dermohypodermites bacteriennes necrosantes et les osteites de contiguite, doivent etre connues et recherchees systematiquement. La documentation microbiologique est complexe, l’indication et la nature des prelevements devant etre de qualite pour permettre de faire la part entre la flore colonisante et celle responsable de l’infection. La prise en charge doit etre pluridisciplinaire, incluant soins locaux, debridement chirurgical, antibiotherapie adaptee, et gestion systematique des pathologies sous-jacentes ainsi que des facteurs etiologiques, incluant diabete et insuffisances vasculaires. Les formes les plus complexes doivent etre gerees en centre de reference.

Tigecycline-based prolonged salvage therapy in patients presenting with complex bone and joint infection

OBJECTIVES To assess the clinical experience of tigecycline-based salvage therapy in patients presenting with Bone and Joint Infections (BJI). PATIENTS AND METHODS Multicenter retrospective cohort study in France and Turkey (2007-2014). RESULTS Thirty-six patients (age 58.2±17.8 years; 21 men) were included. The most frequently isolated bacteria were Enterobacteriaceae and staphylococci. Tigecycline (50mg BID, mainly in combination (69.4%), mean duration of 58 days) was indicated for multidrug resistance (90.6%) and/or previous antibiotic intolerance (36.1%), and/or as second- or third-line therapy (69.4%). Six patients (16.7%) experienced early treatment discontinuation for adverse event (4 severe vomiting, 1 pancreatitis, 1 asymptomatic lipase increase). Clinical success was observed in 23 of 30 assessable patients who completed the tigecycline therapy (mean follow-up: 54.1±57.7 weeks). CONCLUSION Prolonged tigecycline-based therapy could be an alternative in patients presenting with BJI requiring salvage therapy, especially if multidrug-resistant Enterobacteriaceae and/or staphylococci are involved.