No abstract

Omadacycline is an aminomethylcycline antibiotic with in vitro activity against pathogens causing community-acquired bacterial pneumonia (CABP). This study investigated the activity of omadacycline against Legionella pneumophila strains isolated between 1995 and 2014 from nosocomial or community-acquired respiratory infections. Omadacycline exhibited extracellular activity similar to comparator antibiotics; intracellular penetrance was found by day 3 of omadacycline exposure. These results support the utility of omadacycline as an effective antibiotic for the treatment of CABP caused by L. pneumophila.

b GSK1322322, a novel peptide deformylase inhibitor currently in development as an oral and intravenous agent for the treatment of hospitalized community-acquired bacterial pneumonia, showed poor in vitro activity against a panel of 50 Legionella pneumophila strains, with MICs ranging from 1 to 16 g/ml and an MIC 90 of 16 g/ml, but very potent intracellular activity, with the minimum extracellular concentrations capable of inhibiting intracellular proliferation (MIECs) ranging from 0.12 to 2 g/ml and 98% of the strains being inhibited by concentrations of <1 g/ml.T he opportunistic Gram-negative bacterium Legionella pneumophila, which can grow free living or as a facultative intracellular organism in amoebae or human alveolar macrophages, is the major causative agent of Legionnaires' disease, a severe form of pneumonia (1). Although at least 15 serogroups have been identified, L. pneumophila serogroup 1 accounts for more than 80% of the cases worldwide (2). Except in the event of a Legionnaires' disease outbreak, L. pneumophila is treated empirically as part of the therapy used for hospitalized pneumonia, and given the severity of the disease, it is important to ensure that the antibacterial agent to be utilized shows good activity against this pathogen. GSK1322322 is a novel peptide deformylase (PDF) inhibitor with good safety and pharmacokinetic properties (3-5) and is currently in phase II development as an oral and intravenous agent for the treatment of hospitalized community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections. GSK1322322 has demonstrated good antibacterial activity against other causative agents of bacterial pneumonia, such as Streptococcus pneumoniae, Staphylococcus aureus, and Haemophilus influenzae (6), so it was therefore important to investigate its potency against this atypical pathogen.In order to assess the in vitro activity of GSK1322322, we performed susceptibility studies against 50 L. pneumophila strains: 25 from serogroup 1 and 5 each from serogroups 2, 3, 4, 5, and 6. L. pneumophila isolates were collected from 1992 to 2013, mostly from the human respiratory tract, and grown on buffered charcoal yeast extract (BCYE) agar to produce pure cultures. MIC endpoints were determined by broth microdilution according to Clinical and Laboratory Standards Institute (CLSI) guidelines (7). MIC plates, containing approximately 5 ϫ 10 5 CFU/ml in buffered yeast extract (BYE) broth (with Legionella BCYE growth supplement), were incubated at 35°C in aerobic conditions for 48 h. The MIC was defined as the lowest concentration of antimicrobial agent that completely inhibited visible growth after the appropriate incubation time.GSK1322322 showed variable activities against this panel of 50 L. pneumophila strains, with MICs ranging from 1 to 16 g/ml and MIC 50 and MIC 90 values of 8 and 16 g/ml, respectively (Table 1). No significant differences were observed in the activities of GSK1322322 against strains from different serogroups; 8 g/ml was the most frequent MIC ...

Au Québec, le conopholis d’Amérique (Conopholis americana [L.] Wallr.) est une plante parasite des racines du chêne rouge (Quercus rubra L.). Désignée espèce vulnérable au Québec, cette plante est beaucoup plus rare que son hôte et se restreint à quelques versants de collines exposés au sud. À la suite de la découverte d’une population totalisant près de 2 000 tiges dans la région de Rawdon, 2 hypothèses ont été explorées pour tenter d’expliquer la répartition de l’espèce, soit : 1) des inventaires insuffisants, 2) la qualité de l’habitat. Selon les résultats obtenus, aucune de ces hypothèses n’apparaît satisfaisante. Des facteurs aléatoires, comme la dispersion par l’ours noir ou le cerf de Virginie, pourraient être en cause.