In Vitro Effect of Copper (I) Complex [Cu(NN1)2](ClO4) on Vibrio harveyi BB170 Biofilm Formation

Biofilm formation in pathogenic bacteria is an important factor of resistance to antimicrobial treatments, allowing them to survive for a long time in their hosts. In the search for new antibiofilm agents, in this work we report the activity of a copper (I) complex, [Cu(NN1)2]ClO4, synthesized with Cu (I) and NN1, an imine ligand 6-((quinolin-2-ylmethylene)amino)-2H-chromen-2-one, a derivate of natural compound coumarin. The antibacterial and antibiofilm capacity was evaluated in Vibrio harveyi BB170 used as model bacteria. Antibacterial activity was measured in vitro by minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and half-maximal inhibitory concentration (IC50) determination. Antibiofilm capacity of copper (I) complex was analyzed by different concentrations of IC50 values. The results showed that the sub-IC50 concentration, 12.6 µg/mL of the copper (I) complex, was able to reduce biofilm formation by more than 75%, and bacterial viability was reduced by 50%. Inverted and confocal laser scanning microscopy showed that the [Cu(NN1)2]ClO4 complex affected the biofilm structure. Therefore, the copper (I) complex is effective as an antibiofilm compound in V. harveyi BB170.

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Bacterial lipopolysaccharides variably modulate in vitro biofilm formation of Candida species

Journal of Medical Microbiology ◽

10.1099/jmm.0.021832-0 ◽

2010 ◽

Vol 59 (10) ◽

pp. 1225-1234 ◽

Cited By ~ 51

Author(s):

H. M. H. N. Bandara ◽

O. L. T. Lam ◽

R. M. Watt ◽

L. J. Jin ◽

L. P. Samaranayake

Keyword(s):

Biofilm Formation ◽

Laser Scanning ◽

Significant Inhibition ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Dependent Manner ◽

Bacterial Lipopolysaccharides ◽

Species Specific ◽

Biofilm Development

The objective of this study was to evaluate the effect of the bacterial endotoxin LPS on Candida biofilm formation in vitro. The effect of the LPS of Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens and Salmonella typhimurium on six different species of Candida, comprising Candida albicans ATCC 90028, Candida glabrata ATCC 90030, Candida krusei ATCC 6258, Candida tropicalis ATCC 13803, Candida parapsilosis ATCC 22019 and Candida dubliniensis MYA 646, was studied using a standard biofilm assay. The metabolic activity of in vitro Candida biofilms treated with LPS at 90 min, 24 h and 48 h was quantified by XTT reduction assay. Viable biofilm-forming cells were qualitatively analysed using confocal laser scanning microscopy (CLSM), while scanning electron microscopy (SEM) was employed to visualize the biofilm structure. Initially, adhesion of C. albicans was significantly stimulated by Pseudomonas and Klebsiella LPS. A significant inhibition of Candida adhesion was noted for the following combinations: C. glabrata with Pseudomonas LPS, C. tropicalis with Serratia LPS, and C. glabrata, C. parapsilosis or C. dubliniensis with Salmonella LPS (P<0.05). After 24 h of incubation, a significant stimulation of initial colonization was noted for the following combinations: C. albicans/C. glabrata with Klebsiella LPS, C. glabrata/C. tropicalis/C. krusei with Salmonella LPS. In contrast, a significant inhibition of biofilm formation was observed in C. glabrata/C. dubliniensis/C. krusei with Pseudomonas LPS, C. krusei with Serratia LPS, C. dubliniensis with Klebsiella LPS and C. parapsilosis/C. dubliniensis /C. krusei with Salmonella LPS (P<0.05). On further incubation for 48 h, a significant enhancement of biofilm maturation was noted for the following combinations: C. glabrata/C. tropicalis with Serratia LPS, C. dubliniensis with Klebsiella LPS and C. glabrata with Salmonella LPS, and a significant retardation was noted for C. parapsilosis/C. dubliniensis/C. krusei with Pseudomonas LPS, C. tropicalis with Serratia LPS, C. glabrata/C. parapsilosis/C. dubliniensis with Klebsiella LPS and C. dubliniensis with Salmonella LPS (P<0.05). These findings were confirmed by SEM and CLSM analyses. In general, the inhibition of the biofilm development of LPS-treated Candida spp. was accompanied by a scanty architecture with a reduced numbers of cells compared with the profuse and densely colonized control biofilms. These data are indicative that bacterial LPSs modulate in vitro Candida biofilm formation in a species-specific and time-dependent manner. The clinical and the biological relevance of these findings have yet to be explored.

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Endotracheal tubes coated with a broad-spectrum antibacterial ceragenin reduce bacterial biofilm in an in vitro bench top model

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkab019 ◽

2021 ◽

Author(s):

María Consuelo Latorre ◽

María Jesús Pérez-Granda ◽

Paul B Savage ◽

Beatriz Alonso ◽

Pablo Martín-Rabadán ◽

...

Keyword(s):

Biofilm Formation ◽

Laser Scanning ◽

In Vitro Study ◽

Bacterial Biofilm ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Endotracheal Tubes ◽

Clinical Strains ◽

Number Of Cells

Abstract Background Ventilator-associated pneumonia is one of the most common nosocomial infections, caused mainly by bacterial/fungal biofilm. Therefore, it is necessary to develop preventive strategies to avoid biofilm formation based on new compounds. Objectives We performed an in vitro study to compare the efficacy of endotracheal tubes (ETTs) coated with the ceragenin CSA-131 and that of uncoated ETTs against the biofilm of clinical strains of Pseudomonas aeruginosa (PA), Escherichia coli (EC) and Staphylococcus aureus (SA). Methods We applied an in vitro bench top model using coated and uncoated ETTs that were treated with three different clinical strains of PA, EC and SA for 5 days. After exposure to biofilm, ETTs were analysed for cfu count by culture of sonicate and total number of cells by confocal laser scanning microscopy. Results The median (IQR) cfu/mL counts of PA, EC and SA in coated and uncoated ETTs were, respectively, as follows: 1.00 × 101 (0.0–3.3 × 102) versus 3.32 × 109 (6.6 × 108–3.8 × 109), P < 0.001; 0.0 (0.0–5.4 × 103) versus 1.32 × 106 (2.3 × 103–5.0 × 107), P < 0.001; and 8.1 × 105 (8.5 × 101–1.4 × 109) versus 2.7 × 108 (8.6 × 106–1.6 × 1011), P = 0.058. The median (IQR) total number of cells of PA, EC and SA in coated and non-coated ETTs were, respectively, as follows: 11.0 [5.5–not applicable (NA)] versus 87.9 (60.5–NA), P = 0.05; 9.1 (6.7–NA) versus 62.6 (42.0–NA), P = 0.05; and 97.7 (94.6–NA) versus 187.3 (43.9–NA), P = 0.827. Conclusions We demonstrated significantly reduced biofilm formation in coated ETTs. However, the difference for SA was not statistically significant. Future clinical studies are needed to support our findings.

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Characterization of Biofilm Formation by Clinically Relevant Serotypes of Group A Streptococci

Applied and Environmental Microbiology ◽

10.1128/aem.72.4.2864-2875.2006 ◽

2006 ◽

Vol 72 (4) ◽

pp. 2864-2875 ◽

Cited By ~ 92

Author(s):

Cordula Lembke ◽

Andreas Podbielski ◽

Carlos Hidalgo-Grass ◽

Ludwig Jonas ◽

Emanuel Hanski ◽

...

Keyword(s):

Biofilm Formation ◽

Laser Scanning ◽

Group A Streptococcus ◽

Three Dimensional ◽

Positive Control ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Subsequent Formation ◽

Group A

ABSTRACT Streptococcus pyogenes (group A streptococcus [GAS]) is a frequent cause of purulent infections in humans. As potentially important aspects of its pathogenicity, GAS was recently shown to aggregate, form intratissue microcolonies, and potentially participate in multispecies biofilms. In this study, we show that GAS in fact forms monospecies biofilms in vitro, and we analyze the basic parameters of S. pyogenes in vitro biofilm formation, using Streptococcus epidermidis as a biofilm-positive control. Of nine clinically important serotype strains, M2, M6, M14, and M18 were found to significantly adhere to coated and uncoated polystyrene surfaces. Fibronectin and collagen types I and IV best supported primary adherence of serotype M2 and M18 strains, respectively, whereas serotype M6 and M14 strains strongly bound to uncoated polystyrene surfaces. Absorption measurements of safranin staining, as well as electron scanning and confocal laser scanning microscopy, documented that primary adherence led to subsequent formation of three-dimensional biofilm structures consisting of up to 46 bacterial layers. Of note, GAS isolates belonging to the same serotype were found to be very heterogeneous in their biofilm-forming behavior. Biofilm formation was equally efficient under static and continuous flow conditions and consisted of the classical three steps, including partial disintegration after long-term incubation. Activity of the SilC signaling peptide as a component of a putative quorum-sensing system was found to influence the biofilm structure and density of serotype M14 and M18 strains. Based on the presented methods and results, standardized analyses of GAS biofilms and their impact on GAS pathogenicity are now feasible.

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High In Vitro Antibacterial Activity of Pac-525 againstPorphyromonas gingivalisBiofilms Cultured on Titanium

BioMed Research International ◽

10.1155/2015/909870 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 6

Author(s):

Ji-yin Li ◽

Xue-jin Wang ◽

Li-na Wang ◽

Xiao-xia Ying ◽

Xiang Ren ◽

...

Keyword(s):

Laser Scanning ◽

Pathogenic Bacteria ◽

Fusobacterium Nucleatum ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Average Cell ◽

Biofilm Thickness ◽

Live Bacteria ◽

In Vitro Antibacterial Activity

In order to investigate the potential of short antimicrobial peptides (AMPs) as alternative antibacterial agents during the treatment of peri-implantitis, the cytotoxic activity of three short AMPs, that is, Pac-525, KSL-W, and KSL, was determined using the MTT assay. The antimicrobial activity of these AMPs, ranging in concentration from 0.0039 mg/mL to 0.5 mg/mL, against the predominant planktonic pathogens, includingStreptococcus sanguis, Fusobacterium nucleatum, andPorphyromonas gingivalis, involved in peri-implantitis was investigated. Furthermore, 2-day-oldP. gingivalisbiofilms cultured on titanium surfaces were treated with Pac-525 and subsequently observed and analysed using confocal laser scanning microscopy (CLSM). The average cell proliferation curve indicated that there was no cytotoxicity due to the three short AMPs. The minimum inhibitory concentration and minimum bactericidal concentration values of Pac-525 were 0.0625 mg/mL and 0.125 mg/mL, respectively, forP. gingivalisand 0.0078 mg/mL and 0.0156 mg/mL, respectively, forF. nucleatum. Using CLSM, we confirmed that compared to 0.1% chlorhexidine, 0.5 mg/mL of Pac-525 caused a significant decrease in biofilm thickness and a decline in the percentage of live bacteria. These data indicate that Pac-525 has unique properties that might make it suitable for the inhibition the growth of pathogenic bacteria around dental implants.

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Antibody response to the 45 kDa Candida albicans antigen in an animal model and potential role of the antigen in adherence

Journal of Medical Microbiology ◽

10.1099/jmm.0.2008/001479-0 ◽

2008 ◽

Vol 57 (12) ◽

pp. 1466-1472 ◽

Cited By ~ 14

Author(s):

Helena Bujdáková ◽

Ema Paulovičová ◽

Silvia Borecká-Melkusová ◽

Juraj Gašperík ◽

Soňa Kucharíková ◽

...

Keyword(s):

Animal Model ◽

Candida Albicans ◽

Biofilm Formation ◽

Laser Scanning ◽

Vaccine Development ◽

Laser Scanning Microscopy ◽

Model Systems ◽

Confocal Laser

The Candida antigen CR3-RP (complement receptor 3-related protein) is supposed to be a ‘mimicry’ protein because of its ability to bind antibody directed against the α subunit of the mammalian CR3 (CD11b/CD18). This study aimed to (i) investigate the specific humoral isotypic response to immunization with CR3-RP in vivo in a rabbit animal model, and (ii) determine the role of CR3-RP in the adherence of Candida albicans in vitro using the model systems of buccal epithelial cells (BECs) and biofilm formation. The synthetic C. albicans peptide DINGGGATLPQ corresponding to 11 amino-acids of the CR3-RP sequence DINGGGATLPQALXQITGVIT, determined by N-terminal sequencing, was used for immunization of rabbits to obtain polyclonal anti-CR3-PR serum and for subsequent characterization of the humoral isotypic response of rabbits. A significant increase of IgG, IgA and IgM anti-CR3-RP specific antibodies was observed after the third (P<0.01) and the fourth (P<0.001) immunization doses. The elevation of IgA levels suggested peptide immunomodulation of the IgA1 subclass, presumably in coincidence with Candida epithelial adherence. Blocking CR3-RP with polyclonal anti-CR3-RP serum reduced the ability of Candida to adhere to BECs, in comparison with the control, by up to 35 % (P<0.001), and reduced biofilm formation by 28 % (P<0.001), including changes in biofilm thickness and integrity detected by confocal laser scanning microscopy. These properties of CR3-RP suggest that it has potential for future vaccine development.

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Daya Antibakteri Ekstrak Daun Api-Api (Avicennia alba) terhadap Vibrio harveyi Penyebab Vibriosis secara Invitro [In Vitro Antibacteria Activity of Api-Api (Avicennia alba) Leave Extract Against Vibrio harveyi Causes Vibriosis]

Jurnal Ilmiah Perikanan dan Kelautan ◽

10.20473/jipk.v10i2.10527 ◽

2018 ◽

Vol 10 (2) ◽

pp. 131

Author(s):

Zurica Melati Fitri ◽

Kismiyati Kismiyati ◽

Ahmad Shofy Mubarak

Keyword(s):

Minimum Inhibitory Concentration ◽

Experimental Method ◽

Pathogenic Bacteria ◽

Inhibitory Concentration ◽

Vibrio Harveyi ◽

Colony Growth ◽

Minimum Concentration ◽

Extract Concentration ◽

Avicennia Alba

AbstrakBudidaya udang dihadapkan pada berbagai kendala penyakit yang timbul dan dapat menyebabkan kematian masal pada larva udang windu, salah satunya vibriosis yang disebabkan oleh bakteri Vibrio harveyi. Zat antibakteri yaitu : flavonoid, saponin dan tanin terbukti dapat membunuh beberapa bakteri patogen. Daun api – api Avicennia alba mengandung zat anti bakteri sehingga berpotensi digunakan untuk membunuh bakteri Vibrio harveyi. Penelitian ini bertujuan untuk mengetahui konsentrasi optimum ekstrak daun api-api (Avicennia alba) dalam menghambat dan membunuh pertumbuhan bakteri Vibrio harveyi. Penelitian ini mengunakan metode eksperimental dengan perlakuan konsentrasi ekstrak daun api-api (Avicennia alba) sebesar 100%, 90% 80%, 70%, 60%, 50%, 40%. 30%, 20%, 10%, 0%. Parameter yang diamati dalam penelitian ini adalah Minimum Inhibitory Concentration (MIC) dan pertumbuhan koloni pada uji Minimum Bacteria Concentration (MBC). Hasil penelitian menunjukan bahwa pada konsentrasi 60% ekstrak daun Avicennia alba dapat menghambat pertumbuhan V.harveyi. Sedangkan pada konsentrasi 90% ekstrak daun Avicennia alba menyebabkan bakteri V.harveyi terbunuh. AbstractShrimp culture has various obstacles such as the emergence of diseases that can cause deaths in tiger shrimp larvae such as vibriosis caused by Vibrio harveyi. Some antibacterial substances such as flavonoid, saponin, and tannin inhibit and kill several pathogenic bacteria. Avicennia alba leaves contain anti-bacterial substances that have the potential to be used to kill Vibrio harveyi bacteria. This study aimed to determine the minimum concentration of Avicennia alba leaves extract for inhibiting and kill the growth of Vibrio harveyi. This study used an experimental method, using Avicennia alba leaves extract concentration treatment of 100%, 90% 80%, 70%, 60%, 50%, 40%. 30%, 20%, 10%, 0%. The parameters observed in this study were the Minimum Inhibitory Concentration (MIC) and bacteria colony growth in Minimum Bacteria Concentration (MBC) test. The results showed that at a concentration of 60% Avicennia alba leaves extract could inhibit the growth of V.harveyi. While at a concentration of 90% Avicennia alba leaves extract, Vibrio harveyi bacteria was killed.

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Spatial Arrangements and Associative Behavior of Species in an In Vitro Oral Biofilm Model

Applied and Environmental Microbiology ◽

10.1128/aem.67.3.1343-1350.2001 ◽

2001 ◽

Vol 67 (3) ◽

pp. 1343-1350 ◽

Cited By ~ 56

Author(s):

M. Guggenheim ◽

S. Shapiro ◽

R. Gmür ◽

B. Guggenheim

Keyword(s):

Biofilm Formation ◽

Laser Scanning ◽

Fusobacterium Nucleatum ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Streptococcus Sobrinus ◽

Growth Phenomenon ◽

Associative Behavior ◽

Species Specific

ABSTRACT The spatial arrangements and associative behavior ofActinomyces naeslundii, Veillonella dispar, Fusobacterium nucleatum, Streptococcus sobrinus, and Streptococcus oralis strains in an in vitro model of supragingival plaque were determined. Using species-specific fluorescence-labeled antibodies in conjunction with confocal laser scanning microscopy, the volumes and distribution of the five strains were assessed during biofilm formation. The volume-derived cell numbers of each strain correlated well with respective culture data. Between 15 min and 64 h, populations of each strain increased in a manner reminiscent of batch growth. The microcolony morphologies of all members of the consortium and their distributions within the biofilm were characterized, as were interspecies associations. Biofilms formed 15 min after inoculation consisted principally of single nonaggregated cells. All five strains adhered strongly to the saliva-conditioned substratum, and therefore, coadhesion played no role during the initial phase of biofilm formation. This observation does not reflect the results of in vitro coaggregation of the five strains, which depended upon the nature of the suspension medium. While the possibility cannot be excluded that some interspecies associations observed at later stages of biofilm formation were initiated by coadhesion, increase in bacterial numbers appeared to be largely a growth phenomenon regulated by the prevailing cultivation conditions.

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Sanguinarine Inhibits Mono- and Dual-Species Biofilm Formation by Candida albicans and Staphylococcus aureus and Induces Mature Hypha Transition of C. albicans

Pharmaceuticals ◽

10.3390/ph13010013 ◽

2020 ◽

Vol 13 (1) ◽

pp. 13 ◽

Cited By ~ 1

Author(s):

Weidong Qian ◽

Wenjing Wang ◽

Jianing Zhang ◽

Miao Liu ◽

Yuting Fu ◽

...

Keyword(s):

Biofilm Formation ◽

Laser Scanning ◽

Inhibitory Concentration ◽

Fluorescent Dyes ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Matrix Component ◽

New Agents ◽

Diffusion Assay ◽

And Staphylococcus Aureus

Previous studies have reported that sanguinarine possesses inhibitory activities against several microorganisms, but its effects on mono- and dual-species biofilms of C. albicans and S. aureus have not been fully elucidated. In this study, we aimed to evaluate the efficacy of sanguinarine for mono- and dual-species biofilms and explore its ability to induce the hypha-to-yeast transition of C. albicans. The results showed that the minimum inhibitory concentration (MIC) and minimum biofilm inhibitory concentration (MBIC90) of sanguinarine against C. albicans and S. aureus mono-species biofilms was 4, and 2 μg/mL, respectively, while the MIC and MBIC90 of sanguinarine against dual-species biofilms was 8, and 4 μg/mL, respectively. The decrease in the levels of matrix component and tolerance to antibiotics of sanguinarine-treated mono- and dual-species biofilms was revealed by confocal laser scanning microscopy combined with fluorescent dyes, and the gatifloxacin diffusion assay, respectively. Meanwhile, sanguinarine at 128 and 256 μg/mL could efficiently eradicate the preformed 24-h biofilms by mono- and dual-species, respectively. Moreover, sanguinarine at 8 μg/mL could result in the transition of C. albicans from the mature hypha form to the unicellular yeast form. Hence, this study provides useful information for the development of new agents to combat mono- and dual-species biofilm-associated infections, caused by C. albicans and S. aureus.

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Effect of Cinnamon Oil on icaA Expression and Biofilm Formation by Staphylococcus epidermidis

Applied and Environmental Microbiology ◽

10.1128/aem.00875-09 ◽

2009 ◽

Vol 75 (21) ◽

pp. 6850-6855 ◽

Cited By ~ 93

Author(s):

Titik Nuryastuti ◽

Henny C. van der Mei ◽

Henk J. Busscher ◽

Susi Iravati ◽

Abu T. Aman ◽

...

Keyword(s):

Staphylococcus Epidermidis ◽

Biofilm Formation ◽

Laser Scanning ◽

Antimicrobial Agents ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Pcr Analysis ◽

Minimal Bactericidal Concentration ◽

Cinnamon Oil ◽

Broth Microdilution Method

ABSTRACT Staphylococcus epidermidis is notorious for its biofilm formation on medical devices, and novel approaches to prevent and kill S. epidermidis biofilms are desired. In this study, the effect of cinnamon oil on planktonic and biofilm cultures of clinical S. epidermidis isolates was evaluated. Initially, susceptibility to cinnamon oil in planktonic cultures was compared to the commonly used antimicrobial agents chlorhexidine, triclosan, and gentamicin. The MIC of cinnamon oil, defined as the lowest concentration able to inhibit visible microbial growth, and the minimal bactericidal concentration, the lowest concentration required to kill 99.9% of the bacteria, were determined using the broth microdilution method and plating on agar. A checkerboard assay was used to evaluate the possible synergy between cinnamon oil and the other antimicrobial agents. The effect of cinnamon oil on biofilm growth was studied in 96-well plates and with confocal laser-scanning microscopy (CLSM). Biofilm susceptibility was determined using a metabolic 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Real-time PCR analysis was performed to determine the effect of sub-MIC concentrations of cinnamon oil on expression of the biofilm-related gene, icaA. Cinnamon oil showed antimicrobial activity against both planktonic and biofilm cultures of clinical S. epidermidis strains. There was only a small difference between planktonic and biofilm MICs, ranging from 0.5 to 1% and 1 to 2%, respectively. CLSM images indicated that cinnamon oil is able to detach and kill existing biofilms. Thus, cinnamon oil is an effective antimicrobial agent to combat S. epidermidis biofilms.

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Formulation of a Semisolid Emulsion Containing Leptospermum scoparium Essential Oil and Evaluation of In Vitro Antimicrobial and Antibiofilm Efficacy

Planta Medica ◽

10.1055/a-1330-8765 ◽

2021 ◽

Author(s):

Gemma C. Porter ◽

Syarida H. Safii ◽

Natalie J. Medlicott ◽

Warwick J. Duncan ◽

Geoffrey R. Tompkins ◽

...

Keyword(s):

Essential Oil ◽

Laser Scanning ◽

Oral Bacteria ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Minimal Bactericidal Concentration ◽

Apoptotic Pathway ◽

Oil Emulsion ◽

Leptospermum Scoparium

AbstractManuka oil, an essential oil derived from the Leptospermum scoparium, has been traditionally used for wound care and as a topical antibacterial, antifungal, and anti-inflammatory. However, the essential oil is not well retained at mucosal sites, such as the oral cavity, where the benefits of the aforementioned properties could be utilized toward the treatment of persistent biofilms. Within this study, L. scoparium essential oil was incorporated into a semisolid emulsion for improved delivery. The safety profile of L. scoparium essential oil on human gingival fibroblasts was determined via cell viability, cytotoxicity, and caspase activation. The minimal bactericidal concentration of L. scoparium essential oil was determined, and the emulsionʼs antibiofilm effects visualized using confocal laser scanning microscopy. L. scoparium essential oil demonstrated a lower IC50 (0.02% at 48 h) when compared to the clinical control chlorhexidine (0.002% at 48 h) and displayed lower cumulative cytotoxicity. Higher concentrations of L. scoparium essential oil (≥ 0.1%) at 6 h resulted in higher caspase 3/7 activation, suggesting an apoptotic pathway of cell death. A minimal bactericidal concentration of 0.1% w/w was observed for 6 oral bacteria and 0.01% w/v for Porphyromonas gingivalis. Textural and rheometric analysis indicated increased stability of emulsion with a 1 : 3 ratio of L. scoparium essential oil: Oryza sativa carrier oil. The optimized 5% w/w L. scoparium essential oil emulsion showed increased bactericidal penetrative effects on Streptococci gordonii biofilms compared to oil alone and to chlorhexidine controls. This study has demonstrated the safety, formulation, and antimicrobial activity of L. scoparium essential oil emulsion for potential antibacterial applications at mucosal sites.

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