Search

With the increase of infections due to multidrug resistant bacterial pathogens and the shortage of antimicrobial molecules with novel targets, interest in bacteriophages as a therapeutic option has regained much attraction. Before the launch of future clinical trials, in vitro studies are required to better evaluate the efficacies and potential pitfalls of such therapies. Here we studied in an ex vivo human airway epithelial cell line model the efficacy of phage and ciprofloxacin alone and in combination to treat infection by Pseudomonas aeruginosa. The Calu-3 cell line and the isogenic CFTR knock down cell line (cftr-) infected apically with P. aeruginosa strain PAO1 showed a progressive reduction in transepithelial resistance during 24 h. Administration at 6 h p.i. of single phage, phage cocktails or ciprofloxacin alone prevented epithelial layer destruction at 24 h p.i. Bacterial regrowth, due to phage resistant mutants harboring mutations in LPS synthesis genes, occurred thereafter both in vitro and ex vivo. However, co-administration of two phages combined with ciprofloxacin efficiently prevented PAO1 regrowth and maintained epithelial cell integrity at 72 p.i. The phage/ciprofloxacin treatment did not induce an inflammatory response in the tested cell lines as determined by nanoString® gene expression analysis. We conclude that combination of phage and ciprofloxacin efficiently protects wild type and cftr- epithelial cells from infection by P. aeruginosa and emergence of phage resistant mutants without inducing an inflammatory response. Hence, phage-antibiotic combination should be a safe and promising anti-Pseudomonas therapy for future clinical trials potentially including cystic fibrosis patients.

Background: Ecthyma gangrenosum (EG) are necrotic lesions that develop in the context of Pseudomonas aeruginosa bacteremia. Isolated reports describe EG in the setting of non-Pseudomonal infections. In a patient with EG, initial blood cultures showed Escherichia coli, and almost occulted P. aeruginosa bacteremia. Based on the clinical picture we suspected preponderant P. aeruginosa bacteremia, outgrown by concomitant low-grade E. coli bacteremia in the blood culture vials.Methods: We performed quantitative polymerase chain reaction (PCR) assays with specific primers for P. aeruginosa and E. coli on blood collected at the same time for blood cultures. We also performed quantitative cultures of the strains isolated from the patient’s blood.Results: Quantitative PCR showed that there were 1.5 × 10E7 copies/milliliter (ml) of P. aeruginosa DNA, whereas the quantity of E. coli DNA was below the detection limit of 2 × 10E4 copies/ml. We estimated that there was at least 1000 times more P. aeruginosa than E. coli. Quantitative cultures showed that E. coli grew faster than P. aeruginosa.Conclusion: Our patient with EG had preponderant P. aeruginosa bacteremia, that was almost occulted by concomitant low-grade E. coli bacteremia. Quantitative PCR was complementary to blood cultures in the final microbiological diagnosis, and proved beneficial in establishing the etiology of EG. This may question the existence of non-Pseudomonal EG, and also shows that blood culture results do not always reflect an “exact picture” of what happens in the patient’s blood at the time of sampling. This case illustrates the importance of communication between the clinician and the microbiology laboratory to ensure best possible results.

Background: Lung transplantation (LT) is a recognized treatment for end-stage pulmonary disease. Bacteria from the recipient nasopharynx seed the new lungs leading to infections and allograft damage. Understanding the characteristics and topological variations of the microbiota may be important to apprehend the pathophysiology of allograft dysfunction. Objectives: To examine the characteristics and relationship of bacterial compositions between conducting and respiratory zones of the allograft. Methods: We performed 16S rRNA gene sequencing on bronchial aspirates (BAs) and bronchoalveolar lavages (BALs) collected in pairs in 19 patients at several time-points post-LT. Results: The respiratory zone was characterized independently of the time post-LT by a higher bacterial richness than the conducting zone (p=0.041). The phyla Firmicutes and Proteobacteria dominated both sampling zones, with an inverse correlation between these two phyla (Spearman r=–0.830). Samples of the same pair, as well as pairs from the same individual clustered together (Pseudo-F=3.8652, p

A series of complex stilbene dimers have been generated through biotransformation of resveratrol, pterostilbene, and the mixture of both using the enzymatic secretome of Botrytis cinerea Pers. The process starts with achiral molecules and results in the generation of complex molecules with multiple chiral carbons. So far, we have been studying these compounds in the form of enantiomeric mixtures. In the present study, we isolated the enantiomers to determine their absolute configuration and assess if the stereochemistry could impact their biological properties. Eight compounds were selected for this study, corresponding to the main scaffolds generated (pallidol, leachianol, restrytisol and acyclic dimers) and the most active compounds (trans-δ-viniferin derivatives) against a methicillin-resistant strain of Staphylococcus aureus (MRSA). To isolate these enantiomers and determine their absolute configuration, a chiral HPLC-PDA analysis was performed. The analysis was achieved on a high-performance liquid chromatography system equipped with a chiral column. For each compound, the corresponding enantiomeric pair was obtained with high purity. The absolute configuration of each enantiomer was determined by comparison of experimental and calculated electronic circular dichroism (ECD). The antibacterial activities of the four trans-δ-viniferin derivatives against two S. aureus strains were evaluated.