WS02.6 Increased bactericidal activity of colistin on Pseudomonas aeruginosa biofilms in anaerobic conditions

Kolpen, Mette; Appeldorff, Cecilie F.; Brandt, S.; Mousavi, Nabi; Kragh, Kasper Nørskov; Bjarnsholt, Thomas; Ciofu, Oana; Høiby, Niels; Jensen, Peter Østrup

doi:10.1016/s1569-1993(15)30012-6

Cited by 7 publications

(10 citation statements)

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“…To estimate the acid production of the lactobacilli and the effect of pH on Candida growth, pH was measured with a pH microelectrode (pH-25; Unisense A/S, Århus, Denmark) using a modification of a previously described procedure [ 24 ] in selected plates from the abovementioned agar overlay interference test. A reference electrode was used to establish a reference potential against the pH microelectrode (ref-100, Unisense A/S).…”

Section: Methodsmentioning

confidence: 99%

Probiotic Lactobacillus reuteri has antifungal effects on oral Candida species in vitro

Jørgensen

Kragelund

Jensen

et al. 2017

Journal of Oral Microbiology

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Background: An alternative approach for managing Candida infections in the oral cavity by modulating the oral microbiota with probiotic bacteria has been proposed. Objective: The aim was to investigate the antifungal potential of the probiotic bacterium Lactobacillus reuteri (DSM 17938 and ATCC PTA 5289) against six oral Candida species (C. albicans, C. glabrata, C. krusei, C. tropicalis, C. dubliniensis, and C. parapsilosis). Design: The lactobacilli were tested for their ability to co-aggregate with and inhibit the growth of the yeasts assessed by spectrophotometry and the agar overlay inhibition assay. Additionally, the pH was evaluated with microsensors, and the production of hydrogen peroxide (H2O2) by the lactobacilli was verified. Results: Both L. reuteri strains showed co-aggregation abilities with the yeasts. The lactobacilli almost completely inhibited the growth of C. albicans and C. parapsilosis, but did not affect C. krusei. Statistically significant differences in co-aggregation and growth inhibition capacities between the two L. reuteri strains were observed (p<0.001). The pH measurements suggested that C. krusei can resist the acids produced by the lactobacilli. Conclusions: L. reuteri exhibited antifungal properties against five of the six most common oral Candida species. Further, the results reconfirms that the probiotic capacity of L. reuteri is strain specific.

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Section: Methodsmentioning

confidence: 99%

Probiotic Lactobacillus reuteri has antifungal effects on oral Candida species in vitro

Jørgensen

Kragelund

Jensen

et al. 2017

Journal of Oral Microbiology

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“…Regarding the real biofilm environment, recently, a flow cell model was used to mimic a catheter‐associated biofilm infection by S. aureus through pre‐coating the channels with human blood and creating microfluidic conditions with the peristaltic pump . Similarly, the reproduction in vitro of the conditions in the CF lung are attempted by using artificial sputum media and microaerophilic atmosphere for biofilm growth as a more realistic environment in which to study antimicrobial susceptibility. Likewise, further development of models that allow applying susceptibility studies to mixed/multispecies biofilms will be another step to mimic real‐life circumstances of biofilm‐driven infections .…”

Section: In Vitro and In Vivo Endpoints To Assess Antimicrobial Activmentioning

confidence: 99%

Antibiotic treatment of biofilm infections

Ciofu

Rojo-Molinero²,

Macià³

et al. 2017

APMIS

335

259

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Bacterial biofilms are associated with a wide range of infections, from those related to exogenous devices, such as catheters or prosthetic joints, to chronic tissue infections such as those occurring in the lungs of cystic fibrosis patients. Biofilms are recalcitrant to antibiotic treatment due to multiple tolerance mechanisms (phenotypic resistance). This causes persistence of biofilm infections in spite of antibiotic exposure which predisposes to antibiotic resistance development (genetic resistance). Understanding the interplay between phenotypic and genetic resistance mechanisms acting on biofilms, as well as appreciating the diversity of environmental conditions of biofilm infections which influence the effect of antibiotics are required in order to optimize the antibiotic treatment of biofilm infections. Here, we review the current knowledge on phenotypic and genetic resistance in biofilms and describe the potential strategies for the antibiotic treatment of biofilm infections. Of note is the optimization of PK/PD parameters in biofilms, high-dose topical treatments, combined and sequential/alternate therapies or the use antibiotic adjuvants.

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“…In contrast, the bactericidal activity of colistin on P. aeruginosa does not require the formation of toxic levels of ROS from O 2 , and the bactericidal activity of colistin is actually enhanced in the absence of O 2 . The bactericidal activity of colistin mainly depends on its interaction with lipopolysaccharides (LPSs) within the outer bacterial membrane .…”

Section: Effects Of the Chemical Microenvironment On Bacterial Suscepmentioning

confidence: 99%

Microenvironmental characteristics and physiology of biofilms in chronic infections of CF patients are strongly affected by the host immune response

Jensen

Kolpen

Kragh

et al. 2017

APMIS

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Jensen PØ, Kolpen M, Kragh KN, K€ uhl M. Microenvironmental characteristics and physiology of biofilms in chronic infections of CF patients are strongly affected by the host immune response. APMIS 2017; 125: 276-288.In vitro studies of Pseudomonas aeruginosa and other pathogenic bacteria in biofilm aggregates have yielded detailed insight into their potential growth modes and metabolic flexibility under exposure to gradients of substrate and electron acceptor. However, the growth pattern of P. aeruginosa in chronic lung infections of cystic fibrosis (CF) patients is very different from what is observed in vitro, for example, in biofilms grown in flow chambers. Dense in vitro biofilms of P. aeruginosa exhibit rapid O 2 depletion within <50-100 lm due to their own aerobic metabolism. In contrast, in vivo investigations show that P. aeruginosa persists in the chronically infected CF lung as relatively small cell aggregates that are surrounded by numerous PMNs, where the activity of PMNs is the major cause of O 2 depletion rendering the P. aeruginosa aggregates anoxic. High levels of nitrate and nitrite enable P. aeruginosa to persist fueled by denitrification in the PMN-surrounded biofilm aggregates. This configuration creates a potentially long-term stable ecological niche for P. aeruginosa in the CF lung, which is largely governed by slow growth and anaerobic metabolism and enables persistence and resilience of this pathogen even under the recurring aggressive antimicrobial treatments of CF patients. As similar slow growth of other CF pathogens has recently been observed in endobronchial secretions, there is now a clear need for better in vitro models that simulate such in vivo growth patterns and anoxic microenvironments in order to help unravel the efficiency of existing or new antimicrobials targeting anaerobic metabolism in P. aeruginosa and other CF pathogens. We also advocate that host immune responses such as PMN-driven O 2 depletion play a central role in the formation of anoxic microniches governing bacterial persistence in other chronic infections such as chronic wounds.

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WS02.6 Increased bactericidal activity of colistin on Pseudomonas aeruginosa biofilms in anaerobic conditions

Cited by 7 publications

References 0 publications

Probiotic Lactobacillus reuteri has antifungal effects on oral Candida species in vitro

Probiotic Lactobacillus reuteri has antifungal effects on oral Candida species in vitro

Antibiotic treatment of biofilm infections

Microenvironmental characteristics and physiology of biofilms in chronic infections of CF patients are strongly affected by the host immune response

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