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See detailFourth Belgian multicentre survey of antibiotic susceptibility of anaerobic bacteria
Wybo, Ingrid; Van den Bossche; Soetens, Oriane et al

in Journal of Antimicrobial Chemotherapy (2014), 69

Objectives: To collect recent data on the susceptibility of anaerobes to antimicrobial agents with known activity against anaerobes, and to compare them with results from previous Belgian multicentre ... [more ▼]

Objectives: To collect recent data on the susceptibility of anaerobes to antimicrobial agents with known activity against anaerobes, and to compare them with results from previous Belgian multicentre studies. Methods: Four hundred and three strict anaerobic clinical isolates were prospectively collected from February 2011 to April 2012 in eight Belgian university hospitals. MICs were determined by one central laboratory for 11 antimicro- bial agents using Etest methodology. Results: According to EUCAST breakpoints, .90% of isolates were susceptible to amoxicillin/clavulanate (94%), piperacillin/tazobactam (91%), meropenem (96%), metronidazole (92%) and chloramphenicol (98%), but only 70% and 40% to clindamycin and penicillin, respectively. At CLSI recommended breakpoints, only 71% were sus- ceptible to moxifloxacin and 79% to cefoxitin. MIC50/MIC90 values for linezolid and for tigecycline were 1/4 and 0.5/ 4 mg/L, respectively. When compared with survey data from 2004, no major differences in susceptibility profiles were noticed. However, the susceptibility of Prevotella spp. and other Gram-negative bacilli to clindamycin decreased from 91% in 1993 – 94 and 82% in 2004 to 69% in this survey. Furthermore, the susceptibility of clostridia to moxifloxacin decreased from 88% in 2004 to 66% in 2011 – 12 and that of fusobacteria from 90% to 71%. Conclusions: Compared with previous surveys, little evolution was seen in susceptibility, except a decline in activity of clindamycin against Prevotella spp. and other Gram-negative bacteria, and of moxifloxacin against clostridia. Since resistance was detected to all antibiotics, susceptibility testing of anaerobic isolates is indicated in severe infections to confirm appropriateness of antimicrobial therapy. [less ▲]

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See detailPrevalence and mechanisms of resistance to carbapenems in Enterobacteriaceae
Huang, Te-Din; Berhin, Catherine; Glupczynski, Youri et al

in Journal of Antimicrobial Chemotherapy (2013), 68(8), 1832-7

Objectives: To determine the point prevalence of carbapenem-non-susceptible Enterobacteriaceae (CNSE) and carbapenemase-producing Enterobacteriaceae (CPE) isolates among hospitalized patients in Belgium ... [more ▼]

Objectives: To determine the point prevalence of carbapenem-non-susceptible Enterobacteriaceae (CNSE) and carbapenemase-producing Enterobacteriaceae (CPE) isolates among hospitalized patients in Belgium. Methods: Twenty-four hospital-based laboratories prospectively collected 200 non-duplicated Enterobacteriaceae isolates from clinical specimens of hospitalized patients over a 2 month period. All isolates were screened locally for decreased susceptibility to carbapenem drugs using a disc diffusion method according to CLSI interpretative criteria. CNSE strains were referred centrally for confirmation of carbapenemase by phenotypic and molecular testing. Results: From February to April 2012, 158 of the 4564 screened Enterobacteriaceae isolates were categorized as non-susceptible to carbapenems, resulting in a point prevalence of CNSE of 3.5% (95% CI: 2.9%–4.2%; range per centre: 0.5%–8.5%). Of the 125 referred CNSE isolates, 11 Klebsiella pneumoniae isolates [OXA-48 (n=7), KPC type (n=3) and NDM type (n=1)], 1 OXA-48-positive Escherichia coli isolate and 1 KPC-positive Klebsiella oxytoca isolate were detected in eight hospitals. None of the 72 carbapenem-non-susceptible Enterobacter spp. isolates were confirmed as CPE. The minimal estimated point prevalence of CPE isolates was 0.28% (13/ 4564; 95% CI: 0.13%–0.44%) overall (range per centre: 0%–1.5%). Conclusions: Despite the overall low prevalence of CNSE found in this study, the detection of CPE isolates in one-third of the participating centres raises concerns and highly suggests the spread and establishment of CPE in Belgian hospitals. [less ▲]

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See detailNovel fragments of clavulanate observed in the structure of the class A b-lactamase from Bacillus licheniformis BS3
Power, Pablo; Mercuri, Paola ULg; Herman, Raphaël ULg et al

in Journal of Antimicrobial Chemotherapy (2012), 67(10), 2379-2387

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See detailComparison of phenotypic and genotypic tropism determination in triple-class-experienced HIV patients eligible for maraviroc treatment.
Vandekerckhove, Linos; Verhofstede, Chris; Demecheleer, Els et al

in Journal of Antimicrobial Chemotherapy (2011), 66(2), 265-72

BACKGROUND: Determination of HIV-1 tropism is a pre-requisite to the use of CCR5 antagonists. This study evaluated the potential of population genotypic tropism tests (GTTs) in clinical practice, and the ... [more ▼]

BACKGROUND: Determination of HIV-1 tropism is a pre-requisite to the use of CCR5 antagonists. This study evaluated the potential of population genotypic tropism tests (GTTs) in clinical practice, and the correlation with phenotypic tropism tests (PTTs) in patients accessing routine HIV care. METHODS: Forty-nine consecutive plasma samples for which an original Trofile(TM) assay was performed were obtained from triple-class-experienced patients in need of a therapy change. Viral tropism was defined as the consensus of three or more tropism calls obtained from the combination of two independent population PTT assays (Trofile Biosciences, San Francisco, CA, USA, and Virco, Beerse, Belgium), population GTTs and GTTs based on ultra-deep sequencing. If no consensus was reached, a clonal PTT was performed in order to finalize the tropism call. This two-step approach allowed the definition of a reference tropism call. RESULTS: According to the reference tropism result, 35/49 samples were CCR5 tropic (R5) (patients eligible for maraviroc treatment) and 14/49 were assigned as non-R5 tropic. The non-R5 samples [patients not eligible for maraviroc treatment according to the FDA/European Medicines Agency (EMEA) label] group included both the CXCR4 (X4) samples and the dual and mixed CCR5/CXCR4 (R5/X4) samples. Compared with Trofile(TM) population PTTs, population GTTs showed a higher sensitivity (97%) and a higher negative predictive value (91%), but almost equal specificity and an equal positive predictive value. CONCLUSIONS: In line with recent reports from clinical trial data, our data support the use of population genotypic tropism testing as a tool for tropism determination before the start of maraviroc. [less ▲]

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See detailA Tripeptide Deletion in the Class C beta-Lactamase FOX-4 Enzyme Impairs Cefoxitin Hydrolysis and Slightly Increases Susceptibility to beta-Lactamase Inhibitors
Mallo, Susana; Pérez-Llarena, Francisco J.; Kerff, Frédéric ULg et al

in Journal of Antimicrobial Chemotherapy (2010), 65(6), 1187-94

OBJECTIVES: A natural variant of the AmpC enzyme from Escherichia coli HKY28 with a tripeptide deletion (Gly-286/Ser-287/Asp-288) was recently described. The isolate produced an inhibitor-sensitive AmpC ... [more ▼]

OBJECTIVES: A natural variant of the AmpC enzyme from Escherichia coli HKY28 with a tripeptide deletion (Gly-286/Ser-287/Asp-288) was recently described. The isolate produced an inhibitor-sensitive AmpC beta-lactamase variant that also conferred higher than usual levels of resistance to ceftazidime in the E. coli host. To demonstrate whether this is true in other class C beta-lactamase enzymes, we deleted the equivalent tripeptide in the FOX-4 plasmid-mediated class C beta-lactamase. METHODS: By site-directed mutagenesis, we deleted the tripeptide Gly-306/Asn-307/Ser-308 of FOX-4, thus generating FOX-4(DeltaGNS). The enzymes (FOX-4 wild-type and DeltaGNS) were purified and kinetic parameters (kcat, Km, kcat/Km) as well as IC50 values of several beta-lactams were assessed. Modelling studies were also performed. RESULTS: FOX-4(DeltaGNS) did not increase the catalytic efficiency towards ceftazidime, although it conferred a slight increase in the susceptibility to beta-lactamase inhibitors. There was also a noteworthy decrease in the cefoxitin MIC with the FOX-4(DeltaGNS) mutant (from 512 to 16 mg/L) as well as a 10-fold decrease in kcat/Km towards imipenem, which revealed specific structural features. CONCLUSIONS: Although deletions in the R2-loop are able to extend the substrate spectrum of class C enzymes, the present results do not confirm this hypothesis in FOX-4. The FOX-4 R2 site would already be wide enough to accommodate antibiotic molecules, and thus any amino acid replacement or deletion at this location would not affect the hydrolytic efficiency towards beta-lactams and would have a less drastic effect on the susceptibility to beta-lactamase inhibitors. [less ▲]

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See detailRole of changes in the L3 loop of the active site in the evolution of enzymatic activity of VIM-type metallo-beta-lactamases.
Merino, Maria; Perez-Llarena, Francisco J; Kerff, Frédéric ULg et al

in Journal of Antimicrobial Chemotherapy (2010), 65(9), 1950-4

OBJECTIVES: The new metallo-beta-lactamase VIM-13 has been recently characterized. In comparison with the VIM-1 enzyme, VIM-13 showed 19 amino acid differences, 2 of which were located in the active site ... [more ▼]

OBJECTIVES: The new metallo-beta-lactamase VIM-13 has been recently characterized. In comparison with the VIM-1 enzyme, VIM-13 showed 19 amino acid differences, 2 of which were located in the active site centre. The main objective of the present study was to assess whether differences between VIM-1 and VIM-13 beta-lactamases in the active site, at His224Leu and Ser228Arg, are necessary and sufficient to explain the microbiological and biochemical differences between the two enzymes. METHODS: Single mutants VIM-13 (Leu224His) and VIM-13 (Arg228Ser) and double mutant VIM-13 (Leu224His, Arg228Ser) were created by site-directed mutagenesis with the bla(VIM-13) gene as template. VIM-1, VIM-13 and VIM-13 (Leu224His, Arg228Ser) were purified by affinity chromatography, and kinetic parameters for these enzymes were obtained with ceftazidime, cefepime and ampicillin. RESULTS: Ceftazidime and cefepime MICs (mg/L) for Escherichia coli TG1 expressing VIM-1, VIM-13, VIM-13 (Leu224His), VIM-13 (Arg228Ser) and VIM-13 (Leu224His, Arg228Ser) were >256 and 64, 6 and 4, 8 and 1, >256 and 8, and >256 and 48, respectively. VIM-1, VIM-13 and VIM-13 (Leu224His, Arg228Ser) revealed k(cat)/K(m) values (M(-1)s(-1)) for ceftazidime of 3.7 E(4), 1.9 E(4) and 10 E(4), respectively, and revealed k(cat)/K(m) values for cefepime of 3.5 E(5), 3 E(4) and 1.5 E(5), respectively. CONCLUSIONS: Overall, the results showed that the two residues located in the L3 loop are sufficient to confer the substrate specificity of each enzyme, thus highlighting the importance of the L3 loop of the active site in the evolution of VIM-type metallo-beta-lactamases. [less ▲]

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See detailThird Belgian multicentre survey of antibiotic susceptibility of anaerobic bacteria
Wybo, Ingrid; Piérard, Denis ULg; Verschraegen, Inge et al

in Journal of Antimicrobial Chemotherapy (2007), 59(1), 132-139

Objectives: To collect recent data on the susceptibility of anaerobes and to compare them with results from previous studies. Methods: Four hundred and forty-three anaerobic clinical isolates from various ... [more ▼]

Objectives: To collect recent data on the susceptibility of anaerobes and to compare them with results from previous studies. Methods: Four hundred and forty-three anaerobic clinical isolates from various body sites were prospectively collected from October 2003 to February 2005 in nine Belgian hospitals. MICs were determined for nine anti-anaerobic and three recently developed antibiotics. Results: Most Gram-negative bacilli except Fusobacterium spp. were resistant to penicillin. Piperacillin/tazobactam, metronidazole, chloramphenicol, meropenem and amoxicillin/clavulanic acid were very active against all groups, but only 86% of Bacteroides fragilis group strains were susceptible to the latter. Cefoxitin, cefotetan and clindamycin were less active. In particular, only 62%, 52% and 48% of B. fragilis group strains were susceptible, respectively. Clindamycin shows a continuing decrease in activity, as 83% were still susceptible in 1987 and 66% in 1993-94. Anti-anaerobic activity of the new antibiotics is interesting, with MIC50 and MIC90 of 1 and > 32 mg/L for moxifloxacin, 2 and 4 mg/L for linezolid and 0.5 and 8 mg/L for tigecycline. Conclusions: The susceptibility of anaerobic bacteria remains stable in Belgium, except for clindamycin, which shows a continuous decrease in activity. However, for each of the tested antibiotics, at least a few resistant organisms were detected. Consequently, for severe infections involving anaerobic bacteria, it could be advisable to perform microbiological testing instead of relying on known susceptibility profiles. Periodically monitoring background susceptibility remains necessary to guide empirical therapy. [less ▲]

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See detailDescription of In116, the first blaCTX-M-2-containing complex class 1 integron found in Morganella morganii isolates from Buenos Aires, Argentina
Power, pablo; Galleni, Moreno ULg; Di Conza, José et al

in Journal of Antimicrobial Chemotherapy (2005), 55(4), 461-465

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See detailIs it necessary to change the classification of ß-lactamases?
Frère, Jean-Marie ULg; Galleni, Moreno ULg; Bush, Karen et al

in Journal of Antimicrobial Chemotherapy (2005), 55(6), 1051-1053

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See detailIn Vitro Comparison of the Antimycotic Activity of a Miconazole-Hp-Beta-Cyclodextrin Solution with a Miconazole Surfactant Solution
Piel, Géraldine ULg; Hayette, Marie-Pierre ULg; Pavoni, Ermanno et al

in Journal of Antimicrobial Chemotherapy (2001), 48(1), 83-7

The antimycotic activity of a new parenteral solution containing miconazole was compared with that of a marketed solution (Daktarin IV solution). This solution has been withdrawn from the Belgian market ... [more ▼]

The antimycotic activity of a new parenteral solution containing miconazole was compared with that of a marketed solution (Daktarin IV solution). This solution has been withdrawn from the Belgian market, probably because of toxic effects related to the presence of polyoxyl 35 castor oil. We propose a new formulation containing miconazole (10 mg/mL) (like the marketed solution), in combination with hydroxypropyl-beta-cyclodextrin and lactic acid. The MICs of these two solutions were determined by a broth microdilution method (based on NCCLS guidelines) for 67 yeasts and 50 filamentous fungi isolates. This study shows that the MICs obtained with these two solutions are not significantly different. [less ▲]

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See detailAntimicrobial susceptilities of Campylobacter strains isolated from food animals in Belgium.
Van Looveren, M.; Daube, Georges ULg; De Zutter, L. et al

in Journal of Antimicrobial Chemotherapy (2001), 48

Afin d’assurer une transparence tout le long de la chaîne de transformation de la viande, il faut disposer d’un système de traçabilité performant. La traçabilité administative montre des limites que ... [more ▼]

Afin d’assurer une transparence tout le long de la chaîne de transformation de la viande, il faut disposer d’un système de traçabilité performant. La traçabilité administative montre des limites que l’utilisation de marqueurs génétiques pourrait surmonter. Le génome de chaque individu possède des différences de séquences, à la base du polymorphisme génétique, dont les marqueurs génétiques sont les témoins. Parmi ceux-ci, deux classes semblent s’imposer en matière de traçabilité : les microsatellites et les polymorphismes simple nucléotide. Les microsatellites sont caractérisés par un degré de polymorphisme important avec de nombreux allèles pour un même locus. De plus, leur détection se fait directement par amplification itérative. Techniquement, le problème se pose lors de la détection simultanée de plusieurs microsatellites où le patron obtenu est difficile à interpréter. Les polymorphismes simple nucléotide sont répresentés par des mutations ponctuelles dans la séquence nucléotidique. Ils sont fréquents, stables, répartis de façon aléatoire et généralement bialléliques. La détection se fait soit par hybridation sur des biopuces, soit par spectrométrie de masse ou par d’autres techniques facilement automatisables. Cette automatisation est nécessaire pour pouvoir tester un grand nombre de polymorphismes simultanément sur un grand nombre d’échantillons, permettant ainsi de diminuer les coûts. L’avantage majeur des polymophismes simple nucléotide est le signal binaire obtenu, son désavantage est le caractère population- spécifique de ce type de marqueur. [less ▲]

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See detailIntraconzole versus amphotericin B plus nystatin in the prophylaxis of fungal infections in neutropenic cancer patients
Boogaerts, Marc; Maertens, Johan; van Hoof, Achiel et al

in Journal of Antimicrobial Chemotherapy (2001), 48

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See detailHow should zoster trials be conducted?
Wood, M. J.; Balfour, Hank; Beutner, Karl et al

in Journal of Antimicrobial Chemotherapy (1995), 36(6), 1089-1101

In 1994, an international group of interested clinicians and biostatisticians met to discuss the design of clinical trials in herpes tester. They agreed that trials in herpes tester should have ... [more ▼]

In 1994, an international group of interested clinicians and biostatisticians met to discuss the design of clinical trials in herpes tester. They agreed that trials in herpes tester should have prospectively agreed definitions of all outcome measures and plans for data analysis. In immunocompetent individuals, in whom pain is the major outcome measure, trials should only include patients over the age of 50 years, and for those recruited within 72 fi of rash onset, should be designed to demonstrate superiority of any new therapy over existing antivirals. The primary endpoint should be time to cessation of pain for at least 4 weeks and, for the purposes of statistical analysis of its duration, the pain associated with herpes tester ought to be considered as a continuum. All other variables, including the incidence of post-herpetic neuralgia and effects upon quality of life should be considered as secondary end-points. Evaluation of treatment effects on primary endpoints should be based upon an intent-to-treat (ITT) analysis and subgroup analysis should be used only to support the findings of the ITT analysis. These elements of good study design should be borne in mind in the evaluation of current and future trails of antiviral drugs in herpes zoster. [less ▲]

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See detailAllergic cross-reaction of teicoplanin and vancomycin
Grek, V.; Andrien, F.; Collignon, J. et al

in Journal of Antimicrobial Chemotherapy (1991), 28

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