Effect of Divalent Cation Concentrations on the Antibiotic Susceptibilities of Nonfermenters Other than
            <i>Pseudomonas aeruginosa</i>

Fass, Robert J.; Barnishan, Jean

doi:10.1128/aac.16.4.434

Cited by 22 publications

(10 citation statements)

References 17 publications

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“…The explanation for this is that cationic molecules are more suited to disrupting the outer-membrane lipolysaccharide in P. aeruginosa than in E. coli probably due to the greater role of divalent cations in the former case. It is thought that cationic molecules displace Ca ++ and Mg ++ and thereby weakening the outer structure (36). …”

Section: Discussionmentioning

confidence: 99%

Innovative cationic fullerenes as broad-spectrum light-activated antimicrobials

Huang

Terakawa

Zhiyentayev

et al. 2010

Nanomedicine: Nanotechnology, Biology and Medicine

108

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Photodynamic inactivation (PDI) is a rapidly developing antimicrobial technology which combines a non-toxic photoactivatable dye or photosensitizer (PS) in combination with harmless visible light of the correct wavelength to excite the dye to its reactive triplet state that will then generate reactive oxygen species (ROS) that are highly toxic to cells. Buckminsterfullerenes are closed-cage molecules entirely composed of sp2 hybridized carbon atoms and although their main absorption is in the UV, they also absorb visible light and have a long-lived triplet state. When C60 fullerene is derivatized with cationic functional groups it forms molecules that are more water-soluble and can mediate PDT efficiently upon illumination, and moreover cationic fullerenes can selectively bind to microbial cells. In this report we describe the synthesis and characterization of several new cationic fullerenes. Their relative effectiveness as broad-spectrum antimicrobial photosensitizers against Gram-positive, Gram-negative bacteria, and a fungal yeast was determined by quantitative structure function relationships.

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Section: Discussionmentioning

confidence: 99%

Innovative cationic fullerenes as broad-spectrum light-activated antimicrobials

Huang

Terakawa

Zhiyentayev

et al. 2010

Nanomedicine: Nanotechnology, Biology and Medicine

108

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“…For example, bioluminescence assays need not depend on the use of gentamicin to kill extracellular bacteria or eukaryotic cell lysis to report intracellular "gentamicin-protected" bacteria. This allows studies on bacteria intrinsically resistant to gentamicin or enables analysis in growth conditions that compromise gentamicin activity (eg, acidic pH or divalent cation concentrations 34 ) while also allowing assays in which gentamicin-mediated effects on eukaryotic phenotypes are a concern. 35,36 Our assay had similarities to other techniques for assessing bacterial invasion, such as direct observation of internalized bacteria following Giemsa staining 37 or direct observation of gfp-labeled bacteria within eukaryotic cells via fluorescent microscopy 30 or fluorescence-activated cell sorter (FACS) analysis.…”

Section: Discussionmentioning

confidence: 99%

Stably Integrated luxCDABE for Assessment of Salmonella Invasion Kinetics

Flentie

Gammon

et al. 2008

Mol Imaging

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Salmonella Typhimurium is a common cause of gastroenteritis in humans and also localizes to neoplastic tumors in animals. Invasion of specific eukaryotic cells is a key mechanism of Salmonella interactions with host tissues. Early stages of gastrointestinal cell invasion are mediated by a Salmonella type III secretion system, powered by the adenosine triphosphatase invC. The aim of this work was to characterize the invC dependence of invasion kinetics into disparate eukaryotic cells traditionally used as models of gut epithelium or neoplasms. Thus, a nondestructive real-time assay was developed to report eukaryotic cell invasion kinetics using lux+ Salmonella that contain chromosomally integrated luxCDABE genes. Bioluminescence-based invasion assays using lux+ Salmonella exhibited inoculum dose-response correlation, distinguished invasion-competent from invasion-incompetent Salmonella, and discriminated relative Salmonella invasiveness in accordance with environmental conditions that induce invasion gene expression. In standard gentamicin protection assays, bioluminescence from lux+ Salmonella correlated with recovery of colony-forming units of internalized bacteria and could be visualized by bioluminescence microscopy. Furthermore, this assay distinguished invasion-competent from invasion-incompetent bacteria independent of gentamicin treatment in real time. Bioluminescence reported Salmonella invasion of disparate eukaryotic cell lines, including neoplastic melanoma, colon adenocarcinoma, and glioma cell lines used in animal models of malignancy. In each case, Salmonella invasion of eukaryotic cells was invC dependent.

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“…DISCUSSION Since the early work with streptomycin in the 1940s, the ionic composition of the culture medium has been shown to influence measurement of susceptibility to aminoglycoside antibiotics (5). Although the drug susceptibility of many species of bacteria has been shown to be affected by the ionic composition of the test medium, variability is greatest with P. aeruginosa (7). The cation composition of both broth and agar has been reported to influence the susceptibility of P. aeruginosa to aminoglycosides and colistin (4,10,11,14,23).…”

Section: Resultsmentioning

confidence: 99%

Effect of calcium, magnesium, and zinc on ticarcillin and tobramycin alone and in combination against Pseudomonas aeruginosa

Zuravleff¹,

Yu²,

Yee³

et al. 1982

Antimicrob Agents Chemother

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Correlation between in vitro and in vivo test results for synergy between carboxypenicillins and aminoglycosides against Pseudomonas aeruginosa is poor. Although the divalent cation content of culture media is known to affect aminoglycoside susceptibility testing for P. aeruginosa, this effect of divalent cations has not been examined for synergy testing of carboxypenicillin-aminoglycoside interaction against P. aeruginosa. The minimal inhibitory concentrations (MICs) of tobramycin and ticarcillin and the interaction of these drugs in combination were studied by a microtitration method for 36 strains of P. aeruginosa in Mueller-Hinton broth with varying supplements of calcium, magnesium, and zinc. Boston, Mass., abstr. no. 1071) studied the efficacy of ticarcillin and tobramycin, singly and in combination, in a guinea pig model for P. aeruginosa bacteremia; they were unable to show an improvement in survival with combinations demonstrated to be synergistic in vitro against strains of Pseudomonas, as compared to a single-drug therapy. The results of in vitro studies examining the interaction between carboxypenicillin and aminoglycosides against P. aeruginosa are not easily compared. This is due to several reasons. First, the definition of synergy varies from study to study. Second, the divalent cation content of the culture media, which will affect aminoglycoside susceptibility (18,22,23), can also vary from study to study; unfortunately, the cation content is not even reported in a number of synergy studies of P. aeruginosa. We wondered whether some of the discrepancies in the literature concerning penicillin and aminoglycoside synergy might be due to differences in divalent cation content of the test media. To our knowledge the effect of divalent cations on the synergistic interaction of carboxypenicillins and aminoglycosides has not been systematically evaluated. We sought to do so by testing the interaction between ticarcillin and tobramycin against 36 clinical isolates of P. aeruginosa in 12 cation-defined media.

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Effect of Divalent Cation Concentrations on the Antibiotic Susceptibilities of Nonfermenters Other than Pseudomonas aeruginosa

Cited by 22 publications

References 17 publications

Innovative cationic fullerenes as broad-spectrum light-activated antimicrobials

Innovative cationic fullerenes as broad-spectrum light-activated antimicrobials

Stably Integrated luxCDABE for Assessment of Salmonella Invasion Kinetics

Effect of calcium, magnesium, and zinc on ticarcillin and tobramycin alone and in combination against Pseudomonas aeruginosa

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