Serodiagnosis of Mycobacterium abscessus complex infection in cystic fibrosis

Early signs of pulmonary disease with Mycobacterium abscessus complex (MABSC) can be missed in patients with cystic fibrosis (CF). A serological method could help stratify patients according to risk. The objective of this study was to test the diagnostic accuracy of a novel method for investigating IgG activity against MABSC. A prospective study of all patients attending the Copenhagen CF Centre was conducted by culturing for MABSC during a 22-month period and then screening patients with an anti-MABSC IgG ELISA. Culture-positive patients had stored serum examined for antibody kinetics before and after culture conversion. 307 patients had 3480 respiratory samples cultured and were then tested with the anti-MABSC IgG ELISA. Patients with MABSC pulmonary disease had median anti-MABSC IgG levels six-fold higher than patients with no history of infection (434 versus 64 ELISA units; p<0.001). The test sensitivity was 95% (95% CI 74–99%) and the specificity was 73% (95% CI 67–78%). A diagnostic algorithm was constructed to stratify patients according to risk. The test accurately identified patients with pulmonary disease caused by MABSC and was suited to be used as a complement to mycobacterial culture

Complete Genome Sequence of the Cystic Fibrosis Pathogen Achromobacter xylosoxidans NH44784-1996 Complies with Important Pathogenic Phenotypes

Achromobacter xylosoxidans is an environmental opportunistic pathogen, which infects an increasing number of immunocompromised patients. In this study we combined genomic analysis of a clinical isolated A. xylosoxidans strain with phenotypic investigations of its important pathogenic features. We present a complete assembly of the genome of A. xylosoxidans NH44784-1996, an isolate from a cystic fibrosis patient obtained in 1996. The genome of A. xylosoxidans NH44784-1996 contains approximately 7 million base pairs with 6390 potential protein-coding sequences. We identified several features that render it an opportunistic human pathogen, We found genes involved in anaerobic growth and the pgaABCD operon encoding the biofilm adhesin poly-?-1,6-N-acetyl-D-glucosamin. Furthermore, the genome contains a range of antibiotic resistance genes coding efflux pump systems and antibiotic modifying enzymes. In vitro studies of A. xylosoxidans NH44784-1996 confirmed the genomic evidence for its ability to form biofilms, anaerobic growth via denitrification, and resistance to a broad range of antibiotics. Our investigation enables further studies of the functionality of important identified genes contributing to the pathogenicity of A. xylosoxidans and thereby improves our understanding and ability to treat this emerging pathogen

Fructooligosacharides Reduce Pseudomonas aeruginosa PAO1 Pathogenicity through Distinct Mechanisms

Pseudomonas aeruginosa is ubiquitously present in the environment and acts as an opportunistic pathogen on humans, animals and plants. We report here the effects of the prebiotic polysaccharide inulin and its hydrolysed form FOS on this bacterium. FOS was found to inhibit bacterial growth of strain PAO1, while inulin did not affect growth rate or yield in a significant manner. Inulin stimulated biofilm formation, whereas a dramatic reduction of the biofilm formation was observed in the presence of FOS. Similar opposing effects were observed for bacterial motility, where FOS inhibited the swarming and twitching behaviour whereas inulin caused its stimulation. In co-cultures with eukaryotic cells (macrophages) FOS and, to a lesser extent, inulin reduced the secretion of the inflammatory cytokines IL-6, IL-10 and TNF- a . Western blot experiments indicated that the effects mediated by FOS in macrophages are associated with a decreased activation of the NF- k B pathway. Since FOS and inulin stimulate pathway activation in the absence of bacteria, the FOS mediated effect is likely to be of indirect nature, such as via a reduction of bacterial virulence. Further, this modulatory effect is observed also with the highly virulent ptxS mutated strain. Co-culture experiments of P. aeruginosa with IEC18 eukaryotic cells showed that FOS reduces the concentration of the major virulence factor, exotoxin A, suggesting that this is a possible mechanism for the reduction of pathogenicity. The potential of these compounds as components of antibacterial and anti-inflammatory cocktails is discussed.The authors acknowledge financial support from FEDER funds and Fondo Social Europeo through grants from the Spanish Ministry of Economy and Competitiveness (grants SAF2011-22922, SAF2011-22812) the Andalusian regional government Junta de Andalucía (grant CVI-7335) and the Centre of Networked Biomedical Research on Hepatic and Digestive Diseases (CIBERehd) which is funded by the Carlos III Health Institute and the Ramón Areces Foundation, Spain

A phase 3, multi-center, multinational, randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of levofloxacin inhalation solution (APT-1026) in stable cystic fibrosis patients

Rationale For patients with cystic fibrosis (CF), the use of inhaled antibiotics has become standard of care to suppress chronic Pseudomonas airways infection. There are limited antibiotic options formulated and approved for inhaled use and antibiotic efficacies attenuate over time, making additional inhaled antibiotic classes desirable. APT-1026 (levofloxacin inhalation solution, LIS) is a fluoroquinolone in development for management of chronic P. aeruginosa airways infection in patients with CF. Objectives To compare the safety and efficacy of a 28-day course of treatment with LIS 240 mg or placebo BID in persons ≥ 12 years old with CF and chronic P. aeruginosa infection. Methods A multinational, randomized (2:1), double-blinded study of LIS and placebo over 28 days in CF patients ≥ 12 years with chronic P. aeruginosa infection. Time to exacerbation was the primary endpoint. FEV1 (% predicted) and patient-reported quality of life were among secondary endpoints. Main results Baseline demographics for 330 subjects (LIS = 220) were similar although significantly more patients randomized to LIS had experienced multiple exacerbations in the year prior to study entry. There was no statistically significant difference in protocol-defined pulmonary exacerbations between treatment arms. Relative change in FEV1% predicted from baseline was significantly greater for patients randomized to LIS compared to those randomized to placebo (mean difference 1.31%, p = 0.01 [95% CI 0.27, 2.34%]). LIS was well-tolerated, with dysguesia the most frequent adverse event. Conclusions LIS did not demonstrate a difference in time to next exacerbation when compared to placebo. Reasons for this result are discussed but may be due to an imbalance in the frequency of prior pulmonary exacerbations between the two groups. An improvement in FEV1 (% predicted) at 28 days was observed and LIS was well tolerated. LIS is safe and has a potential role in the management of CF patients with chronic P. aeruginosa

A phase 3, open-label, randomized trial to evaluate the safety and efficacy of levofloxacin inhalation solution (APT-1026) versus tobramycin inhalation solution in stable cystic fibrosis patients

Background: Inhaled antibiotics are standard of care for persons with cystic fibrosis (CF) and chronic Pseudomonas aeruginosa airway infection. APT-1026 (levofloxacin inhalation solution, LIS) is fluoroquinolone in development. We compared the safety and efficacy of LIS to tobramycin inhalation solution (TIS) in persons ≥12 years old with CF and chronic P. aeruginosa infection. Methods: This multinational, randomized (2:1), non-inferiority study compared LIS and TIS over three 28-day on/off cycles. Day 28 FEV1 % predicted change was the primary endpoint. Time to exacerbation and patient-reported quality of life superiority were among secondary endpoints. Results: Baseline demographics for 282 subjects were comparable. Non-inferiority was demonstrated (1.86% predicted mean FEV1 difference [95% CI −0.66 to 4.39%]). LIS was well-tolerated, with dysguesia (taste distortion) the most frequent adverse event. Conclusions: LIS is a safe and effective therapy for the management of CF patients with chronic P. aeruginosa

Evaluation of anti-biofilm activity of acidic amino acids and synergy with ciprofloxacin on Staphylococcus aureus biofilms

Acidic amino acids, aspartic acid (Asp) and glutamic acid (Glu) can enhance the solubility of many poorly soluble drugs including ciprofloxacin (Cip). One of the mechanisms of resistance within a biofilm is retardation of drug diffusion due to poor penetration across the matrix. To overcome this challenge, this work set to investigate novel counter ion approach with acidic amino acids, which we hypothesised will disrupt the biofilm matrix as well as simultaneously improve drug effectiveness. The anti-biofilm activity of D-Asp and D-Glu was studied on Staphylococcus aureus biofilms. Synergistic effect of combining D-amino acids with Cip was also investigated as a strategy to overcome anti-microbial resistance in these biofilms. Interestingly at equimolar combinations, D-Asp and D-Glu were able to significantly disperse (at 20 mM and 40 mM) established biofilms and inhibit (at 10 mM, 20 mM and 40 mM) new biofilm formation in the absence of an antibiotic. Moreover, our study confirmed L-amino acids also exhibit anti-biofilm activity. The synergistic effect of acidic amino acids with Cip was observed at lower concentration ranges (<40 mM amino acids and <90.54 µM, respectively), which resulted in 96.89% (inhibition) and 97.60% (dispersal) reduction in CFU with exposure to 40 mM amino acids. Confocal imaging indicated that the amino acids disrupt the honeycomb-like extracellular DNA (eDNA) meshwork whilst also preventing its formation

Utilization and control of ecological interactions in polymicrobial infections and community-based microbial cell factories

Microbial activities are most often shaped by interactions between co-existing microbes within mixed-species communities. Dissection of the molecular mechanisms of species interactions within communities is a central issue in microbial ecology, and our ability to engineer and control microbial communities depends, to a large extent, on our knowledge of these interactions. This review highlights the recent advances regarding molecular characterization of microbe-microbe interactions that modulate community structure, activity, and stability, and aims to illustrate how these findings have helped us reach an engineering-level understanding of microbial communities in relation to both human health and industrial biotechnology

Deciphering the contribution of biofilm to the pathogenesis of peritoneal dialysis infections: characterization and microbial behaviour on dialysis fluids

Infections are major complications in peritoneal dialysis (PD) with a multifactorial etiology that comprises patient, microbial and dialytic factors. This study aimed at investigating the contribution of microbial biofilms on PD catheters to recalcitrant infections and their interplay with PD related-factors. A prospective observational study was performed on 47 patients attending Centro Hospitalar of Porto and Vila Nova de Gaia/Espinho to whom the catheter was removed due to infectious (n = 16) and non-infectious causes (n = 31). Microbial density on the catheter was assessed by culture methods and the isolated microorganisms identified by matrix-assisted laser desorption/ionization time-of-flight intact cell mass spectrometry. The effect of conventional and three biocompatible PD solutions on 16 Coagulase Negative Staphylococci (CNS) and 10 Pseudomonas aeruginosa strains planktonic growth and biofilm formation was evaluated. Cultures were positive in 87.5% of the catheters removed due infectious and 90.3% removed due to non-infectious causes. However, microbial yields were higher on the cuffs of catheters removed due to infection vs. non-infection. Staphylococci (CNS and Staphylococcus aureus) and P. aeruginosa were the predominant species: 32% and 20% in the infection and 43.3% and 22.7% in the non-infection group, respectively. In general, PD solutions had a detrimental effect on planktonic CNS and P. aeruginosa strains growth. All strains formed biofilms in the presence of PD solutions. The solutions had a more detrimental effect on P. aeruginosa than CNS strains. No major differences were observed between conventional and biocompatible solutions, although in icodextrin solution biofilm biomass was lower than in bicarbonate/lactate solution. Overall, we show that microbial biofilm is universal in PD catheters with the subclinical menace of Staphylococci and P. aeruginosa. Cuffs colonization may significantly contribute to infection. PD solutions differentially impact microbial species. This knowledge is important for the development of infection diagnosis, treatment and preventive strategies.This work received support from a Sociedade Portuguesa de Nefrologia (http://www.spnefro.pt) research grant to AR and a Fundação para a Ciência e Tecnologia (http://www.fct.pt) post doc grant (SFRH/BPD/73663/2010) to MM. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript