scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Contributions of Antibiotic Penetration, Oxygen Limitation, and Low Metabolic Activity to Tolerance of Pseudomonas aeruginosa Biofilms to Ciprofloxacin and Tobramycin

01 Jan 2003-Antimicrobial Agents and Chemotherapy (American Society for Microbiology)-Vol. 47, Iss: 1, pp 317-323
TL;DR: Results show that oxygen limitation and low metabolic activity in the interior of the biofilm, not poor antibiotic penetration, are correlated with antibiotic tolerance of this P. aeruginosa biofilm system.
Abstract: The roles of slow antibiotic penetration, oxygen limitation, and low metabolic activity in the tolerance of Pseudomonas aeruginosa in biofilms to killing by antibiotics were investigated in vitro. Tobramycin and ciprofloxacin penetrated biofilms but failed to effectively kill the bacteria. Bacteria in colony biofilms survived prolonged exposure to either 10 μg of tobramycin ml−1or 1.0 μg of ciprofloxacin ml−1. After 100 h of antibiotic treatment, during which the colony biofilms were transferred to fresh antibiotic-containing plates every 24 h, the log reduction in viable cell numbers was only 0.49 ± 0.18 for tobramycin and 1.42 ± 0.03 for ciprofloxacin. Antibiotic permeation through colony biofilms, indicated by a diffusion cell bioassay, demonstrated that there was no acceleration in bacterial killing once the antibiotics penetrated the biofilms. These results suggested that limited antibiotic diffusion is not the primary protective mechanism for these biofilms. Transmission electron microscopic observations of antibiotic-affected cells showed lysed, vacuolated, and elongated cells exclusively near the air interface in antibiotic-treated biofilms, suggesting a role for oxygen limitation in protecting biofilm bacteria from antibiotics. To test this hypothesis, a microelectrode analysis was performed. The results demonstrated that oxygen penetrated 50 to 90 μm into the biofilm from the air interface. This oxic zone correlated to the region of the biofilm where an inducible green fluorescent protein was expressed, indicating that this was the active zone of bacterial metabolic activity. These results show that oxygen limitation and low metabolic activity in the interior of the biofilm, not poor antibiotic penetration, are correlated with antibiotic tolerance of this P. aeruginosa biofilm system.
Citations
More filters
Journal ArticleDOI
TL;DR: It is evident that biofilm formation is an ancient and integral component of the prokaryotic life cycle, and is a key factor for survival in diverse environments.
Abstract: Biofilms--matrix-enclosed microbial accretions that adhere to biological or non-biological surfaces--represent a significant and incompletely understood mode of growth for bacteria. Biofilm formation appears early in the fossil record (approximately 3.25 billion years ago) and is common throughout a diverse range of organisms in both the Archaea and Bacteria lineages, including the 'living fossils' in the most deeply dividing branches of the phylogenetic tree. It is evident that biofilm formation is an ancient and integral component of the prokaryotic life cycle, and is a key factor for survival in diverse environments. Recent advances show that biofilms are structurally complex, dynamic systems with attributes of both primordial multicellular organisms and multifaceted ecosystems. Biofilm formation represents a protected mode of growth that allows cells to survive in hostile environments and also disperse to colonize new niches. The implications of these survival and propagative mechanisms in the context of both the natural environment and infectious diseases are discussed in this review.

6,170 citations


Cites background from "Contributions of Antibiotic Penetra..."

  • ...The creation of starved, stationary phase dormant zones in biofilms seems to be a significant factor in the resistance of biofilm populations to antimicrobial...

    [...]

Journal ArticleDOI
TL;DR: Biofilms can be prevented by early aggressive antibiotic prophylaxis or therapy and they can be treated by chronic suppressive therapy and a promising strategy may be the use of enzymes that can dissolve the biofilm matrix as well as quorum-sensing inhibitors that increase biofilm susceptibility to antibiotics.

2,637 citations


Additional excerpts

  • ...of biofilms to aminoglycosides and ciprofloxacin (69)....

    [...]

Journal ArticleDOI
07 Sep 2007-Cell
TL;DR: The results suggest that all three major classes of bactericidal drugs can be potentiated by targeting bacterial systems that remediate hydroxyl radical damage, including proteins involved in triggering the DNA damage response, e.g., RecA.

2,420 citations


Cites background from "Contributions of Antibiotic Penetra..."

  • ...…the efficacy of quinolones in stationary phase can be enhanced by adding oxygen to a stationary-phase culture (Morrissey and Smith, 1994), and recent evidence suggests that metabolic activity and oxygen tension are important indicators of quinolone activity against biofilms (Walters et al., 2003)....

    [...]

  • ...Also, the efficacy of quinolones in stationary phase can be enhanced by adding oxygen to a stationary-phase culture (Morrissey and Smith, 1994), and recent evidence suggests that metabolic activity and oxygen tension are important indicators of quinolone activity against biofilms (Walters et al., 2003)....

    [...]

Journal ArticleDOI
TL;DR: The processes that generate chemical gradients inBiofilms, the genetic and physiological responses of the bacteria as they adapt to these gradients and the techniques that can be used to visualize and measure the microscale physiological heterogeneities of bacteria in biofilms are discussed.
Abstract: Biofilms contain bacterial cells that are in a wide range of physiological states. Within a biofilm population, cells with diverse genotypes and phenotypes that express distinct metabolic pathways, stress responses and other specific biological activities are juxtaposed. The mechanisms that contribute to this genetic and physiological heterogeneity include microscale chemical gradients, adaptation to local environmental conditions, stochastic gene expression and the genotypic variation that occurs through mutation and selection. Here, we discuss the processes that generate chemical gradients in biofilms, the genetic and physiological responses of the bacteria as they adapt to these gradients and the techniques that can be used to visualize and measure the microscale physiological heterogeneities of bacteria in biofilms.

1,953 citations


Cites methods from "Contributions of Antibiotic Penetra..."

  • ...Another strategy for visualizing patterns of protein synthetic activity is to use an inducible GFP construc...

    [...]

Journal ArticleDOI
TL;DR: Current concepts of biofilm tolerance are reviewed with special emphasis on the role of the biofilm matrix and the physiology ofBiofilm-embedded cells, and the heterogeneity in metabolic and reproductive activity within a biofilm correlates with a non-uniform susceptibility of enclosed bacteria.

1,730 citations

References
More filters
Book
01 Jan 1992
TL;DR: The most widely read reference in the water industry, Water Industry Reference as discussed by the authors, is a comprehensive reference tool for water analysis methods that covers all aspects of USEPA-approved water analysis.
Abstract: Set your standards with these standard methods. This is it: the most widely read publication in the water industry, your all-inclusive reference tool. This comprehensive reference covers all aspects of USEPA-approved water analysis methods. More than 400 methods - all detailed step-by-step; 8 vibrant, full-color pages of aquatic algae illustrations; Never-before-seen figures that will help users with toxicity testing and the identification of apparatus used in the methods; Over 300 superbly illustrated figures; A new analytical tool for a number of inorganic nonmetals; Improved coverage of data evaluation, sample preservation, and reagant water; And much more!

78,324 citations

Journal ArticleDOI
21 May 1999-Science
TL;DR: Improvements in understanding of the genetic and molecular basis of bacterial community behavior point to therapeutic targets that may provide a means for the control of biofilm infections.
Abstract: Bacteria that attach to surfaces aggregate in a hydrated polymeric matrix of their own synthesis to form biofilms. Formation of these sessile communities and their inherent resistance to antimicrobial agents are at the root of many persistent and chronic bacterial infections. Studies of biofilms have revealed differentiated, structured groups of cells with community properties. Recent advances in our understanding of the genetic and molecular basis of bacterial community behavior point to therapeutic targets that may provide a means for the control of biofilm infections.

11,162 citations


"Contributions of Antibiotic Penetra..." refers background in this paper

  • ...One explanation for the chronic nature of some infections involving the opportunistic pathogen Pseudomonas aeruginosa is that this organism is adept at forming biofilms in which the bacteria are protected from host defenses and from killing by antibiotics (6)....

    [...]

Journal ArticleDOI
TL;DR: The features of biofilm infections are summarized, the emerging mechanisms of resistance are reviewed, and potential therapies are discussed.

4,116 citations


"Contributions of Antibiotic Penetra..." refers background in this paper

  • ...The protection of bacteria growing in biofilms from antibiotics probably depends on multiple factors (3, 19, 27, 28)....

    [...]

Journal ArticleDOI
TL;DR: Results demonstrate that the potentially lethal function specified by fragment B of RK2 is not necessary for replication and that at least one trans-acting function is directly involved in RK 2 replication.
Abstract: pRK212.2, a derivative of the broad host range plasmid RK2, contains two EcoRI cleavage fragments, A and B, neither of which can replicate by itself in Escherichia coli. Fragment A (41.7 kilobases), but not fragment B (14.4 kilobases), can be cloned by insertion into the unrelated plasmids mini-F and ColE1. Fragment B contains the origin of replication and the ampicillin-resistance determinant of RK2. Transformation of E. coli cells containing the mini-F-fragment A hybrid plasmid with fragment B DNA results in the recircularization and replication of fragment B as a nonmobilizable plasmid (pRK2067) with the copy number and incompatibility properties of RK2. Fragment B cannot be cloned in the absence of fragment A because the latter fragment suppresses a function, specified by fragment B, that results in loss of host cell viability. A small segment (2.4 kilobases) of fragment B that contains the RK2 origin of replication but no longer affects host cell growth in the absence of fragment A had been cloned previously by insertion into a ColE1 plasmid. This hybrid plasmid, designated pRK256, will replicate in E. coli polA mutants only when a fragment A-bearing helper plasmid is present. These results demonstrate that the potentially lethal function specified by fragment B of RK2 is not necessary for replication and that at least one trans-acting function is directly involved in RK2 replication.

3,295 citations


"Contributions of Antibiotic Penetra..." refers background in this paper

  • ...aeruginosa by triparental mating with the conjugation helper plasmid pRK2013 (11)....

    [...]

PatentDOI
17 Aug 1998-Gene
TL;DR: In this article, three classes of GFP mutants having single excitation maxima around 488 nm are shown to be brighter than wild-type GFP following 488-nm excitation.

3,093 citations