Papers by Philippe Moreillon
Microbial Drug Resistance, 2000
ABSTRACT
The expression of Staphylococcus aureus adhesins in Lactococcus lactis identified clumping factor... more The expression of Staphylococcus aureus adhesins in Lactococcus lactis identified clumping factor A (ClfA) and fibronectin-binding protein A (FnBPA) as critical for valve colonization in rats with experimental endocarditis. This study further analyzed their role in disease evolution. Infected animals were followed for 3 d. ClfA-positive lactococci successfully colonized damaged valves, but were spontaneously eradicated over 48 h. In contrast, FnBPA-positive lactococci progressively increased bacterial titers in vegetations and spleens. At imaging, ClfA-positive lactococci were restricted to the vegetations, whereas FnBPA-positive lactococci also invaded the adjacent endothelium. This reflected the capacity of FnBPA to trigger cell internalization in vitro. Because FnBPA carries both fibrinogen- and fibronectin-binding domains, we tested the role of these functionalities by deleting the fibrinogen-binding domain of FnBPA and supplementing it with the fibrinogen-binding domain of ClfA...
PloS one, 2018
The recent rise of multidrug-resistant Gram-negative bacteria represents a serious threat to publ... more The recent rise of multidrug-resistant Gram-negative bacteria represents a serious threat to public health and makes the search for novel effective alternatives to antibiotics a compelling need. Bacteriophage (Phage) lysins are enzymes that hydrolyze the cell wall of bacteria and represent a promising alternative to tackle this ever-increasing problem. Despite their use is believed to be restricted to Gram-positive bacteria, recent findings have shown that they can also be used against Gram-negative bacteria. By using a phage genome-based screening approach, we identified and characterized a novel lysin, PlyE146, encoded by an Escherichia coli prophage and with a predicted molecular mass of ca. 17 kDa. PlyE146 is composed of a C-terminal cationic peptide and a N-terminal N-acetylmuramidase domain. Histidine-tagged PlyE146 was overexpressed from a plasmid in Lactococcus lactis NZ9000 and purified by NI-NTA chromatography. PlyE146 exhibited in vitro optimal bactericidal activity again...
International Journal of Antimicrobial Agents
Quinupristin/dalfopristin and -lactams interact positively against methicillin-resistant Staphyl... more Quinupristin/dalfopristin and -lactams interact positively against methicillin-resistant Staphylococcus aureus (MRSA). The effect extends to other inhibitors of protein synthesis, but not to inhibitors of polynucleotide synthesis or assembly, or to Q/D plus non--lactam cell wall inhibitors. Moreover, electron microscopy studies have correlated this effect with a thickened cell wall. In this study, we sought to determine whether inhibitors of protein synthesis might produce a specific peptidoglycan muropeptide signature that would correlate with their positive -lactam interaction. The muropeptides of six S. aureus isolates (three methicillin-susceptible and three MRSA) were analysed using high-performance liquid chromatography and mass spectrometry. Exposure to 0.25 the minimum inhibitory concentration of inhibitors of protein synthesis consistently produced three main alterations irrespective of methicillin resistance: (i) an increase in peak 12 (a cyclic dimer of glycine-containing disaccharide-tetrapeptide); (ii) an increase in poorly resolved late-eluting materials; and (iii) a decrease in peak 1 (a disaccharidepentapeptide). Eventually, the rate of autolysis was also decreased, supporting the structural alteration of the peptidoglycan. Other drug classes did not produce these anomalies. An increase in peak 12 was also observed in staphylococci treated with fosfomycin, which decreases expression of the native penicillin-binding protein (PBP) 2 and 4. Parallel blockage of normal PBPs with -lactams abolished the anomalies, indicating that they resulted from altered function of native PBPs. This underlines the potential of inhibiting both protein synthesis and transpeptidation simultaneously and suggests that such a drug combination strategy might be efficaciously exploited.
The Journal of infectious diseases, Mar 1, 2017
Increasing antibiotic resistance warrants therapeutic alternatives. Here we investigated the effi... more Increasing antibiotic resistance warrants therapeutic alternatives. Here we investigated the efficacy of bacteriophage-therapy (phage) alone or combined with antibiotics against experimental endocarditis (EE) due to Pseudomonas aeruginosa, an archetype of difficult-to-treat infection. In vitro fibrin clots and rats with aortic EE were treated with an antipseudomonas phage cocktail alone or combined with ciprofloxacin. Phage pharmacology, therapeutic efficacy, and resistance were determined. In vitro, single-dose phage therapy killed 7 log colony-forming units (CFUs)/g of fibrin clots in 6 hours. Phage-resistant mutants regrew after 24 hours but were prevented by combination with ciprofloxacin (2.5 × minimum inhibitory concentration). In vivo, single-dose phage therapy killed 2.5 log CFUs/g of vegetations in 6 hours (P < .001 vs untreated controls) and was comparable with ciprofloxacin monotherapy. Moreover, phage/ciprofloxacin combinations were highly synergistic, killing >6 l...
Infection and Immunity, 2016
Streptococcus gordonii and related species of oral viridans group streptococci (VGS) are common e... more Streptococcus gordonii and related species of oral viridans group streptococci (VGS) are common etiological agents of infective endocarditis (IE). We explored vaccination as a strategy to prevent VGS-IE, using a novel antigen-presenting system based on non-genetically modified Lactococcus lactis displaying vaccinogens on its surface. Hsa and PadA are surface-located S. gordonii proteins implicated in platelet adhesion and aggregation, which are key steps in the pathogenesis of IE. This function makes them ideal targets for vaccination against VGS-IE. In the present study, we report the use of nonliving L. lactis displaying at its surface the N-terminal region of Hsa or PadA by means of the cell wall binding domain of Lactobacillus casei A2 phage lysine LysA2 (Hsa-LysA2 and PadA-LysA2, respectively) and investigation of their ability to elicit antibodies in rats and to protect them from S. gordonii experimental IE. Immunized and control animals with catheter-induced sterile aortic va...
Revue Medicale De La Suisse Romande, 2004
The Journal of Infectious Diseases, 1988
Seventy percent of clinical isolates of penicillin-resistant pneumococci also exhibit defective l... more Seventy percent of clinical isolates of penicillin-resistant pneumococci also exhibit defective lysis when treated with penicillin exceeding the minimal inhibitory concentration (MIC). To provide a possible explanation for the frequent association of these two traits, we exposed penicillin-susceptible pneumococci to two kinds of antibiotic pressures in the laboratory. Treatment of cultures with cycles of high concentrations of penicillin (20 X MIC) followed by growth of the survivors in drug-free medium selected for lysis-defective mutants that died only slowly during antibiotic treatment but had unchanged MICs. Exposure to sustained, low levels of penicillin produced resistant mutants, with elevated MICs, that lysed normally with penicillin. We suggest that the cyclic antibiotic exposure generally used in the clinical setting may select primarily for enhanced survival. From these survivors a second type of antibiotic exposure--sustained antibiotic concentrations just above the MIC (concentrations that may be restricted to the tail-end trough of a dosing interval)--selects for penicillin-resistant mutants.
Infection and Immunity, 2005
Isogenic Staphylococcus aureus strains with different capacities to produce B activity were analy... more Isogenic Staphylococcus aureus strains with different capacities to produce B activity were analyzed for their ability to attach to fibrinogen-or fibronectin-coated surfaces or platelet-fibrin clots and to cause endocarditis in rats. In comparison to the B-deficient strain, BB255, which harbors an rsbU mutation, both rsbUcomplemented and B-overproducing derivatives exhibited at least five times greater attachment to fibrinogenand fibronectin-coated surfaces and showed increased adherence to platelet-fibrin clots. No differences in adherence were seen between BB255 and a ⌬rsbUVWsigB isogen. Northern blotting analyses revealed that transcription of clfA, encoding fibrinogen-binding protein clumping factor A, and fnbA, encoding fibronectinbinding protein A, were positively influenced by B. B overproduction resulted in a statistically significant increase in positive spleen cultures and enhanced bacterial densities in both the aortic vegetations and spleens at 16 h postinoculation. In contrast, at 72 h postinoculation, tissues infected with the B overproducer had lower bacterial densities than did those infected with BB255. These results suggest that although B appears to increase the adhesion of S. aureus to various host cell-matrix proteins in vitro, it has limited effect on pathogenesis in the rat endocarditis model. B appears to have a transient enhancing effect on bacterial density in the early stages of infection that is lost during progression. Staphylococcus aureus is a major human pathogen with the capacity to cause a broad spectrum of diseases including native and prosthetic valve endocarditis (34). Its ability to colonize vascular tissue is thought to occur via ligand-adhesin interactions between the organism's surface determinants and host proteins at sites of endovascular injuries and prosthetic materials (8, 11, 14, 40). S. aureus expresses a variety of distinct surface proteins, termed MSCRAMMs (for "microbial surface components recognizing adhesive matrix molecules"), which allow the pathogen to bind to host extracellular matrix proteins and establish a focus of infection (17, 21, 38, 43). Among the MSCRAMMs are the clumping factors ClfA and ClfB (35, 36, 37, 42), which modulate bacterial adhesion to fibrinogen, and the fibronectin-binding proteins FnbA and FnbB, which mediate binding to fibronectin (15, 16, 17, 26) and to a lesser extent fibrinogen (53). Fibrinogen is a large (340-kDa) protein found predominantly in blood. It is also the most abundant host protein in endothelial lesions (13), as well as the major blood protein deposited on newly implanted biomaterials (52). Fibronectin is a dimeric glycoprotein, which forms a significant component of the conditioning layer that coats many implanted medical devices such as heart valves and catheters.
Antimicrobial agents and chemotherapy, Sep 27, 2016
In this study, silver/copper (Ag/Cu)-coated catheters were investigated for their efficacy in pre... more In this study, silver/copper (Ag/Cu)-coated catheters were investigated for their efficacy in preventing methicillin-resistant Staphylococcus aureus (MRSA) infection in vitro and in vivoAg and Cu were sputtered (67/33% atomic ratio) on polyurethane catheters by Direct Current Magnetron Sputtering. In vitro, Ag/Cu-coated and uncoated catheters were immersed in PBS or rat plasma and exposed to 10(4)-10(8) CFU/ml of MRSA ATCC 43300. In vivo, Ag/Cu-coated and uncoated catheters were placed in the jugular vein of rats. Close by, MRSA (10(7) CFU/ml) was inoculated in the tail vein. Catheters were removed 48 h later and cultured.In vitro, Ag/Cu-coated catheters pre-incubated in PBS and exposed to 10(4)-10(7) CFU/ml, prevented the adherence of MRSA (0-12% colonization) compared to uncoated catheters (50-100% colonization; P< 0.005), Ag/Cu-coated catheters retained their activity (0-20% colonization) when pre-incubated in rat plasma while colonization of uncoated catheters increased (83-1...
Revue Medicale Suisse, 2006
Curr Opin Pharmacol, 2005
Methicillin-resistant Staphylococcus aureus (MRSA) have developed resistance to virtually all non... more Methicillin-resistant Staphylococcus aureus (MRSA) have developed resistance to virtually all non-experimental antibiotics. They are intrinsically resistant to β-lactams by virtue of newly acquired low-affinity penicillin-binding protein 2A (PBP2A). Because PBP2A can build the wall when other PBPs are blocked by β-lactams, designing β-lactams capable of blocking this additional target should help solve the issue. Older molecules including penicillin G, amoxicillin and ampicillin had relatively good PBP2A affinities, and successfully treated experimental endocarditis caused by MRSA, provided that the bacterial penicillinase could be inhibited. Newer anti-PBP2A β-lactams with over 10-fold greater PBP2A affinities and low minimal inhibitory concentrations were developed, primarily in the cephem and carbapenem classes. They are also very resistant to penicillinase. Most have demonstrated anti-MRSA activity in animal models of infection, and two — the carbapenem CS-023 and the cephalosporin ceftopibrole medocaril — have proceeded to Phase II and Phase III clinical evaluation. Thus, clinically useful anti-MRSA β-lactams are imminent.
Revista Espa De Cardiologia, Dec 1, 2009
Antimicrobial Agents and Chemotherapy, 1990
Revue Medicale De La Suisse Romande, 2000
Schweizerische Medizinische Wochenschrift, Jul 1, 2000
Medecine Et Hygiene, 1996
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Papers by Philippe Moreillon