Is transmission electron microscopy (TEM) a promising approach for qualitative and quantitative investigations of polymyxin B and miconazole interactions with cellular and subcellular structures of Staphylococcus pseudintermedius , Escherichia coli , Pseudomonas aeruginosa and Malassezia pachydermatis ?

Voget, Michael; Lorenz, Dorothea; Lieber-Tenorio, Elisabeth; Hauck, Rüdiger; Meyer, Michael T.; Cieslicki, M.

doi:10.1016/j.vetmic.2015.10.002

Cited by 10 publications

(8 citation statements)

References 27 publications

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“…Therefore, the mode of action of the plant extracts may be by causing apoptosis directly or indirectly. The changes are similar to those observed in previous studies with silver ion [5], polymyxin-B and miconazole [18], as well as honey [19] on E. coli. In a related study, exposure of pathogenic E. coli to cranberry extracts caused morphological damage such as cellular deformation, breakage of cell wall and membrane, condensation of cellular material, and presence of large amounts of cytoplasmic material and membrane debris in the cell's surrounding environment [20].…”

Section: Gas Chromatography-mass Spectroscopy Analysis Of Plant Extractssupporting

confidence: 89%

The ultrastructural damage caused by Eugenia zeyheri and Syzygium legatii acetone leaf extracts on pathogenic Escherichia coli

et al. 2020

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Background: Antibiotics are commonly added to livestock feeds in sub-therapeutic doses as growth promoters and for prophylaxis against pathogenic microbes, especially those implicated in diarrhoea. While this practice has improved livestock production, it is a major cause of antimicrobial resistance in microbes affecting livestock and humans. This has led to the banning of prophylactic antibiotic use in animals in many countries. To compensate for this, alternatives have been sought from natural sources such as plants. While many studies have reported the antimicrobial activity of medicinal plants with potential for use as phytogenic/botanical feed additives, little information exists on their mode of action. This study is based on our earlier work and describes ultrastructural damage induced by acetone crude leaf extracts of Syzygium legatii and Eugenia zeyheri (Myrtaceae) active against diarrhoeagenic E. coli of swine origin using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fluorescent microscopy (FM). Gas chromatography/mass spectrometry (GC-MS) was used to investigate the chemical composition of plant extracts. Results: The extracts damaged the internal and external anatomy of the cytoplasmic membrane and inner structure at a concentration of 0.04 mg/mL. Extracts also led to an increased influx of propidium iodide into treated bacterial cells suggesting compromised cellular integrity and cellular damage. Non-polar compounds such as αamyrin, friedelan-3-one, lupeol, and β-sitosterol were abundant in the extracts. Conclusions: The extracts of S. legatii and E. zeyheri caused ultrastructural damage to E. coli cells characterized by altered external and internal morphology. These observations may assist in elucidating the mode of action of the extracts.

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Section: Gas Chromatography-mass Spectroscopy Analysis Of Plant Extractssupporting

confidence: 89%

The ultrastructural damage caused by Eugenia zeyheri and Syzygium legatii acetone leaf extracts on pathogenic Escherichia coli

et al. 2020

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“…Although there is no clear evidence of membrane disruption, the leaflets of bacterial cell envelope cannot be distinguished. The same trend has already been observed for colistin (Nguyen et al, 2021) and Polymyxin B (Voget et al, 2015), two antimicrobials which also target the outer membrane.…”

Section: Effect Of Biocides On Cell Structure and Morphologysupporting

confidence: 79%

A Multi-Purpose Approach to the Mechanisms of Action of Two Biocides (Benzalkonium Chloride and Dibromonitrilopropionamide): Discussion of Pseudomonas fluorescens’ Viability and Death

2022

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Biocides are widely used in water treatment for microbiological control. The rise of antimicrobial resistance and the need to assure properly managed water systems require a better understanding of the mechanisms of action of biocides and of their impact on cell’s viability as a function of dosage concentrations. The present work addresses these two aspects regarding the biocides benzalkonium chloride (BAC) and dibromonitrilopropionamide (DBNPA)—two biocides commonly found in the water treatment industry. For that, the following parameters were studied: culturability, membrane integrity, metabolic activity, cellular energy, and the structure and morphology of cells. Also, to assess cell’s death, a reliable positive control, consisting of cells killed by autoclave (dead cells), was introduced. The results confirmed that BAC is a lytic biocide and DBNPA a moderate electrophilic one. Furthermore, the comparison between cells exposed to the biocides’ minimum bactericidal concentrations (MBCs) and autoclaved cells revealed that other viability parameters should be taken into consideration as “death indicators.” The present work also shows that only for the concentrations above the MBC the viability indicators reached values statistically similar to the ones observed for the autoclaved cells (considered to be definitively dead). Finally, the importance of considering the biocide mechanism of action in the definition of the viability parameter to use in the viable but non-culturable (VBNC) determination is discussed.

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“…These results were similar to what was observed for polymyxin B. 41 Similar to miconazole, the antibacterial activity of clotrimazole has been recently demonstrated in vitro against 50 clinical isolates of S pseudintermedius (MRSP = 25 and MSSS = 25). 42 In that study, the authors were able to show an MIC 90 of 1 µg/mL for all the isolates, independently from their MR status.…”

Section: Azolessupporting

confidence: 86%

“…However, the direct antibacterial activity of miconazole on S pseudintermedius, Escherichia coli, and Pseudomonas aeruginosa has been recently assessed via transmission electron microscopy. 41 In that study, the authors were able to show that miconazole, at 5 µg/mL, is able to alter bacterial membrane permeability as demonstrated by a significant decrease in size of the S pseudintermedius and P aeruginosa, and an increase in size of E coli. These results were similar to what was observed for polymyxin B.…”

Section: Azolesmentioning

confidence: 93%

“…This need for new antimicrobials has been dictated by the possibility of the insurgence of antimicrobial resistance to compounds like chlorhexidine. 14,18,41 Resistance to antiseptic agents is associated with the expression of multidrug efflux pump genes (eg, qacA, qacB, and smr). However, such genes have not been identified in a cohort of 100 isolates of multidrug-resistant S pseudintermedius (MDRSP) in Japan.…”

Section: New/alternative Topical Therapiesmentioning

confidence: 99%

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Topical therapy for canine pyoderma: what is new?

Santoro

2023

javma

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Antimicrobial-resistant cutaneous infections are increasing in veterinary medicine. The use of systemic antibiotics should be limited to severe cases of pyoderma to decrease the microbial pressure and selection for multidrug-resistant bacteria. Topical antimicrobials with a low-resistance profile, such as chlorhexidine, benzoyl peroxide, and ethyl lactate have been used for decades in veterinary dermatology. However, new alternatives have been explored in the past decade. The goal of this review is to summarize the current knowledge on the antibacterial efficacy and clinical use, when reported, of “classic” and new treatment options for topically treating canine pyoderma. This review is intended to fill the gap from previous systematic reviews published in veterinary dermatology a decade ago. The studies reported in this review emphasize the need and desire for alternatives to the classic topical antimicrobials used in veterinary medicine to significantly reduce the use of systemic antibiotics in the spirit of appropriate antimicrobial stewardship.

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Cited by 10 publications

References 27 publications

The ultrastructural damage caused by Eugenia zeyheri and Syzygium legatii acetone leaf extracts on pathogenic Escherichia coli

The ultrastructural damage caused by Eugenia zeyheri and Syzygium legatii acetone leaf extracts on pathogenic Escherichia coli

A Multi-Purpose Approach to the Mechanisms of Action of Two Biocides (Benzalkonium Chloride and Dibromonitrilopropionamide): Discussion of Pseudomonas fluorescens’ Viability and Death

Topical therapy for canine pyoderma: what is new?

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