Lugol's solution eradicates Staphylococcus aureus biofilm in vitro

Efficient and Selective, In Vitro and In Vivo, Antimicrobial Photodynamic Therapy with a Dicationic Chlorin in Combination with KI

Various cationic photosensitizers employed in antimicrobial photodynamic therapy (aPDT) have the ability to photoinactivate planktonic bacteria under conditions of low phototoxicity to mammalian cells and without generating antimicrobial resistance (AMR). However, the photoinactivation of biofilms requires orders-of-magnitude higher photosensitizer concentrations, which become toxic to host cells. Remarkably, the bactericidal effect of a dicationic di-imidazolyl chlorin toward planktonic S. aureus and E. coli was observed in this work for concentrations below 400 nM under illumination at 660 nm and below 50 μM for the corresponding biofilms. At the latter concentrations, the chlorin is phototoxic toward human keratinocyte cells. However, in the presence of 50 mM KI, bactericidal concentrations are reduced to less than 50 nM for planktonic bacteria and to less than 1 μM for biofilms. It is shown that the potentiation with KI involves the triiodide anion. This potentiation elicits a bactericidal effect without appreciable cytotoxicity to keratinocytes. It becomes possible to selectively inactivate biofilms with aPDT. An exploratory study treating mice with wounds infected with E. coli expressing GFP with 20 μM chlorin and 120 J cm-2 at 652 nm confirmed the potential of this chlorin to control localized infections.

Bacterial vaginosis: a review of approaches to treatment and prevention

Bacterial vaginosis (BV) is a common cause of vaginitis worldwide and is associated with serious reproductive health outcomes, including increased risk of preterm birth, sexually transmitted infections, and pelvic inflammatory disease. The current and only FDA-approved treatment regimens for BV are antibiotics, such as metronidazole and clindamycin. Antibiotics provide a short-term cure for bacterial vaginosis; however, fail to provide a consistent long-term cure for many women. Fifty to eighty percent of women experience a BV recurrence within a year of completing antibiotic treatment. This may be because after antibiotic treatment, beneficial strains of Lactobacillus, such as L. crispatus, do not recolonize the vagina. In the absence of an effective long-term cure, patients, providers, and researchers are exploring different approaches to treatment and prevention, resulting in a rapid evolution of perspectives on BV pathogenesis and approaches to management. Current areas of investigation for BV management include probiotics, vaginal microbiome transplantation, pH modulation, and biofilm disruption. Behavioral modifications that may help include smoking cessation, condom use and hormonal contraception. Additional strategies considered by many people include dietary modification, non-medical vaginally applied products, choice of lubricant, and treatments from medical practices outside of allopathic medicine. This review aims to provide a comprehensive and up to date outline of the landscape of ongoing and potential treatment and prevention strategies for BV.

Lugol's solution and Gentian violet eradicate methicillin-resistant Staphylococcus aureus biofilm in skin wound infections

The study aimed to evaluate the antibacterial efficacy of Lugol's solution 5% and Gentian violet 1% against methicillin-resistant Staphylococcus aureus (MRSA) biofilm in vivo. The bactericidal efficacy for treatment of MRSA-biofilm skin wound infection was tested in a murine model. Luciferase-tagged S. aureus Xen31, a MRSA-strain derived from S. aureus ATCC-3359130, was used for infection. Wounds were made in the skin of mice and infected with MRSA. The mice were treated with Lugol's solution and Gentian violet. Application of the antimicrobial agents started 24 hours post infection and was repeated daily for five-days. The antimicrobial effect on the biofilm bacteria was evaluated by measuring bioluminescence from MRSA daily for seven-days. Lugol's solution and Gentian violet showed a significant reduction in luminescent signals from the first assessment day to all subsequent days (P < .001). Lugol's solution and Gentian violet effectively eradicated MRSA in biofilm in vivo and could be alternatives or in addition to topical antibiotics when MRSA-biofilm wound infection is suspected.

The Short-Day Cycle Induces Intestinal Epithelial Purine Metabolism Imbalance and Hepatic Disfunctions in Antibiotic-Mediated Gut Microbiota Perturbation Mice

Intestinal microbiota dysbiosis is related to many metabolic diseases in human health. Meanwhile, as an irregular environmental light–dark (LD) cycle, short day (SD) may induce host circadian rhythm disturbances and worsen the risks of gut dysbiosis. Herein, we investigated how LD cycles regulate intestinal metabolism upon the destruction of gut microbes with antibiotic treatments. The growth indices, serum parameters, concentrations of short-chain fatty acids (SCFAs), and relative abundance of intestinal microbes were measured after euthanasia; intestinal contents, epithelial metabolomics, and hepatic transcriptome sequencing were also assessed. Compared with a normal LD cycle (NLD), SD increased the body weight, spleen weight, and serum concentration of aspartate aminotransferase, while it decreased high-density lipoprotein. Meanwhile, SD increased the relative abundance of the Bacteroidetes phylum while it decreased the Firmicutes phylum in the gut of ABX mice, thus leading to a disorder of SCFA metabolism. Metabolomics data revealed that SD exposure altered gut microbial metabolism in ABX mice, which also displayed more serious alterations in the gut epithelium. In addition, most differentially expressed metabolites were decreased, especially the purine metabolism pathway in epithelial tissue. This response was mainly due to the down-regulation of adenine, inosine, deoxyguanosine, adenylsuccinic acid, hypoxanthine, GDP, IMP, GMP, and AMP. Finally, the transcriptome data also indicated that SD has some negative effects on hepatic metabolism and endocrine, digestive, and disease processes. Overall, SD induced an epithelial and hepatic purine metabolism pathway imbalance in ABX mice, as well as the gut microbes and their metabolites, all of which could contribute to host metabolism and digestion, endocrine system disorders, and may even cause diseases in the host.

Topical Therapy Failure in Chronic Suppurative Otitis Media is Due to Persister Cells in Biofilms

OBJECTIVE

Chronic suppurative otitis media (CSOM) is characterized by a chronically draining middle ear. CSOM is typically treated with multiple courses of antibiotics or antiseptics which are successful in achieving quiescence; however, the disease is prone to relapse. Understanding why these treatment failures occur is essential.

STUDY DESIGN

The minimum inhibitory concentration (MIC), minimal biofilm eradication concentration, and the inhibitory zone were determined for ototopicals and ofloxacin for the laboratory strains and CSOM-derived isolates. The percentage of persister cells and bacterial biofilm formation were measured. Disease eradication was tested in a validated in-vivo model of CSOM after treatment with ofloxacin.

SETTING

Microbiology Laboratory.

METHODS

Basic science experiments were performed to measure the effectiveness of a number of compounds against CSOM bacteria in a number of distinct settings.

RESULTS

The minimal biofilm eradication concentration is higher than is physiologically achievable with commercial preparations, except for povo-iodine. Clincial isolates of CSOM have equivalent biofilm-forming ability but increased proportions of persister cells. Ofloxacin can convert to inactive disease temporarily but fails to eradicate disease in an in-vivo model.

CONCLUSIONS

Higher percentages of persister cells in clinical CSOM isolates are associated with resistance to ototopicals. Current ototopicals, except povo-iodine, have limited clinical effectiveness; however, it is unknown what the maximum achievable concentration is and there are ototoxicity concerns. Fluoroquinolones, while successful in producing inactive disease in the short term, have the potential to encourage antimicrobial resistance and disease recalcitrance and do not achieve a permanent remission. Given these limitations, clinicians should consider surgery earlier or use of clinically safe concentrations of povo-iodine earlier into the treatment algorithm.

A bacteriocin-based treatment option for Staphylococcus haemolyticus biofilms

Bacteriocins are ribosomally-synthesized antimicrobial peptides, showing great potential as novel treatment options for multidrug-resistant pathogens. In this study, we designed a novel hybrid bacteriocin, Hybrid 1 (H1), by combing the N-terminal part and the C-terminal part of the related bacteriocins enterocin K1 (K1) and enterocin EJ97 (EJ97), respectively. Like the parental bacteriocins, H1 used the membrane-bound protease RseP as receptor, however, it differed from the others in the inhibition spectrum. Most notably, H1 showed a superior antimicrobial effect towards Staphylococcus haemolyticus—an important nosocomial pathogen. To avoid strain-dependency, we further evaluated H1 against 27 clinical and commensal S. haemolyticus strains, with H1 indeed showing high activity towards all strains. To curtail the rise of resistant mutants and further explore the potential of H1 as a therapeutic agent, we designed a bacteriocin-based formulation where H1 was used in combination with the broad-spectrum bacteriocins micrococcin P1 and garvicin KS. Unlike the individual bacteriocins, the three-component combination was highly effective against planktonic cells and completely eradicated biofilm-associated S. haemolyticus cells in vitro. Most importantly, the formulation efficiently prevented development of resistant mutants as well. These findings indicate the potential of a bacteriocins-based formulation as a treatment option for S. haemolyticus.

A bacteriocin-based antimicrobial formulation to effectively disrupt the cell viability of methicillin-resistant Staphylococcus aureus (MRSA) biofilms

Antibiotic-resistant and biofilm-associated infections brought about by methicillin-resistant Staphylococcus aureus (MRSA) strains is a pressing issue both inside as well as outside nosocomial environments worldwide. Here, we show that a combination of two bacteriocins with distinct structural and functional characteristics, garvicin KS, and micrococcin P1, showed a synergetic antibacterial activity against biofilms produced in vitro by S. aureus, including several MRSA strains. In addition, this bacteriocin-based antimicrobial combination showed the ability to restore the sensitivity of the highly resilient MRSA strain ATCC 33591 to the β-lactam antibiotic penicillin G. By using a combination of bacterial cell metabolic assays, confocal and scanning electron microscopy, we show that the combination between garvicin KS, micrococcin P1, and penicillin G potently inhibit cell viability within S. aureus biofilms by causing severe cell damage. Together these data indicate that bacteriocins can be valuable therapeutic tools in the fight against biofilm-associated MRSA infections.

Synergistic effect of fennel essential oil and hydrogen peroxide on bacterial biofilm

Introduction

Staphylococcal biofilm formation significantly challenges wound management. The causes of difficult-to-treat wounds are not only methicillin-resistant staphylococci, but also methicillin-sensitive strains with different patterns of resistance. Bacterial biofilm significantly limits the access and activity of antimicrobials used in dermatological infections.

Aim

To evaluate the synergistic effect of fennel essential oil (FEO) and H₂O₂ on biofilm formation by Staphylococcus aureus (MSSA and MRSA) reference strains.

Material and methods

Minimum inhibitory concentration (MIC) values were determined for FEO and H₂O₂ against S. aureus reference strains by the broth microdilution method. The combined effects of the FEO and H₂O₂ were calculated and expressed in terms of a fractional inhibitory concentration index (FICI) using the checkerboard method. The FEO composition was analyzed by the GC-MS method. The data were analysed by one-way ANOVA.

Results

Decreased MIC values for FEO combined with H₂O₂ were observed in comparison to FEO itself. The combinations of FEO and H₂O₂ determined synergistic effects on all S. aureus reference strains. Subinhibitory concentration of FEO alone and in combination with 0.5 MIC of H₂O₂ significantly decreased the production of biofilm biomass in S. aureus strains and reduced the metabolic activity of attached cells.

Conclusions

Combination of fennel essential oil containing nearly 80% trans-anethole and H₂O₂ represents a potential for further basic and applied research on wound management.

Bioactive glass S53P4 eradicates Staphylococcus aureus in biofilm/planktonic states in vitro

Background: Increasing antimicrobial resistance to antibiotics is a substantial health threat. Bioactive glass S53P4 (BAG) has an antimicrobial effect that can reduce the use of antibiotics. The aim of this study was to evaluate the antimicrobial efficacy of BAG in vitro on staphylococci in biofilm and in planktonic form. Secondary aims were to investigate whether supernatant fluid primed from BAG retains the antibacterial capacity and if ciprofloxacin enhances the effect.Methods: BAG-S53P4 granules, <45 µm, primed in tryptic soy broth (TSB) were investigated with granules present in TSB (100 mg/mL) and after removal of granules (100, 200, and 400 mg/mL). The efficacy of BAG to eradicate Staphylococcus aureus biofilm in vitro was tested using 10 different clinical strains and 1 reference strain in three test systems: the biofilm-oriented antiseptic test based on metabolic activity, the biofilm bactericidal test based on culturing surviving bacteria, and confocal laser scanning microscopy (CLSM) combined with LIVE/DEAD staining.Results: Exposure to 48 h primed BAG granules (100 mg/mL) produced bactericidal effects in 11/11 strains (p = 0.001), and CLSM showed reduction of viable bacteria in biofilm (p = 0.001). Supernatant primed 14 days, 400 mg/mL, reduced metabolic activity (p < 0.001), showed bactericidal effects for 11/11 strains (p = 0.001), and CLSM showed fewer viable bacteria (p = 0.001). The supernatant primed for 48 h, or in concentrations lower than 400 mg/mL at 14 days, did not completely eradicate biofilm.Conclusion: Direct exposure to BAG granules, or primed supernatant fluid, effectively eradicated S. aureus in biofilm. The anti-biofilm effect is time- and concentration-dependent. When BAG had reached its full antimicrobial effect, ciprofloxacin had no additional effect.