Fractional Inhibitory Concentration Index Research Articles

Synergistic Effect Antibacterial Activity of The Combination of Andaliman (Zanthoxylum acanthopodium DC) Fruit Essential Oil and Erythromycin against Streptococcus mutans and Streptococcus pyogenes

Background: The concept of synergism is one of the approaches taken to combat the problems related to antibiotic resistance. Objectives: The goal of this study was to determine the synergistic effect of antibacterial activity of a combination of essential oil of Zanthoxylum acanthopodium DC fruit and erythromycin against Streptococcus mutans and Streptococcus pyogenes. Methods: The broth microdilution assay was used to determine the Minimum Inhibitory Concentration (MIC) of Z. acanthpodium DC fruit essential oil and erythromycin. The synergistic effects were assessed using the checkerboard method. Results: MIC value of Z. acanthopodium DC fruit essential oil against both bacteria was 2500 mg/mL. The combination of Z. acanthopodium DC fruit essential oil and erythromycin had a synergistic effect against S. mutans and S. pyogenes with fractional inhibitory concentration index (FICI) values of 0.375 and 0.0872, respectively. Conclusions: These results suggest that a combination of herbal plants and conventional antibiotics could be used as an alternative therapy for bacterial infections.

In vitro bio-activity of Rosa rubiginosa L. (sweet briar) rosehip fixed oil combined with essential oils for acne vulgaris

Cutibacterium acnes, Staphylococcus epidermidis, and Staphylococcus aureus proliferate within accumulated sebum and produce localised inflammation thereby inducing acne vulgaris. Essential oils are one of the leading natural products used for acne and are diluted in fixed oils to reduce irritation and toxicity. This study investigated the in vitro antimicrobial, anti-inflammatory, cytotoxicity, and skin retention properties of Rosa rubiginosa rosehip fixed oil in combination with essential oils having activity against acne vulgaris. The broth microdilution assay was used to determine the minimum inhibitory concentration (MIC), and the sum of the fractional inhibitory concentration index (ΣFIC) was calculated for the interactions. The lipopolysaccharide (LPS) induced inflammatory pathway in RAW 264.7 macrophages was used to assess anti-inflammatory activity. A dual-staining method in A549 epithelial cells was used to assess cytotoxicity. Qualitative Fourier Transform Infrared spectroscopy analysis was used for initial skin retention determination. Rosa rubiginosa oil combined with Cinnamomum zeylanicum essential oil displayed antimicrobial synergy (MIC = 0.42 mg/ mL; ΣFIC = 0.45) against three acne-inducing strains. Rosa rubiginosa fixed oil combined with Styrax benzoin essential oil suppressed LPS-induced nitrite production by 33.80%. Rosa rubiginosa oil combined with Melaleuca quinquenervia essential oil exhibited the lowest cytotoxicity (84.32% cell viability). Rosa rubiginosa oil combined with either C. zeylanicum, Eugenia caryophyllata, Rosa damascena or S. benzoin essential oil was retained within the porcine skin. Rosa rubiginosa fixed oil serves as an ideal carrier oil that can potentiate selected essential oils for the treatment of acne vulgaris.

Synergistic combinations of novel polymyxins and rifampicin with improved eradication of colistin-resistant Pseudomonas aeruginosa biofilms

BackgroundIncreased prevalence of antimicrobial resistance coupled with a lack of new antibiotics against Gram-negative bacteria emphasize the imperative for novel therapeutic strategies. Colistin-resistant Pseudomonas aeruginosa constitutes a challenge, where conventional treatment options lack efficacy, in particular for biofilm-associated infections. Previously, synergy of colistin with other antibiotics was explored as an avenue for the treatment of colistin-resistant infections, and recently we reported our efforts towards colistin analogs capable of combating planktonic colistin-resistant strains. AimsThe aim of the present study was to investigate whether analogs of polymyxin B with improved potency in wild-type and moderate resistant Gram-negative pathogens would retain similarly increased activity in highly colistin-resistant clinical P. aeruginosa isolates (in planktonic and biofilm growth) when applied alone and in combination with rifampicin. Materials and methodsIn this in vitro study, we tested three analogs of polymyxin B prepared by solid-phase peptide synthesis. Antimicrobial susceptibility testing was performed by measurement of minimum inhibitory concentrations via the broth microdilution method. Interactions between two antimicrobials was quantified in a checkerboard broth microdilution assay by calculating the fractional inhibitory concentration index for each combination. For testing of antibiofilm activity a previously described model with alginate beads encapsulating a biofilm culture was applied. The minimum biofilm eradication concentrations (MBECs) were evaluated, and the fractional biofilm eradication concentration indices were calculated. Three recently identified colistin analogs (CEP932, CEP936 and CEP938) were tested against three isogenic pairs of colistin-susceptible and colistin-resistant P. aeruginosa clinical isolates as well as the reference strain PAO1. ResultsFor bacteria in planktonic growth CEP938 retained almost full potency in all three resistant isolates, while exhibiting similar activity as colistin in susceptible isolates. Against biofilms CEP938 was slightly more potent against PAO1 as compared to colistin, while also retaining activity against a biofilm of the colistin-resistant strain 41,782/98. Next, synergy between CEP938 and the antibiotic rifampicin was explored. Interestingly, CEP938 did not exhibit synergy with rifampicin in planktonic cultures. Importantly, for colistin-resistant biofilms the CEP938-rifampicin combination demonstrated activity superior to that found for the colistin-rifampicin combination. ConclusionsThe present study showed in vitro efficacy of CEP938 against both colistin-susceptible and colistin-resistant P. aeruginosa biofilms as well as an ability of CEP938 to synergize with rifampicin in biofilm eradication.

Unveiling the therapeutic significance of shikimate pathway-derived phenolic acids against penicillin-binding protein 3 of Pseudomonas aeruginosa

ABSTRACT This study investigated the modulatory potential of Shikimate pathway-derived phenolic acids against penicillin-binding protein 3 (PBP3) of Pseudomonas aeruginosa using computational and in vitro methods. The binding and inhibitory capabilities of 22 phenolic acids against the catalytic site of PBP3 were evaluated and revealed ellagic and chlorogenic acids as the top inhibitors, showing superior docking scores of −8.4 kcal/mol each compared to the standard, cefotaxime (−7.5 kcal/mol). Dynamics simulation of their PBP3 complexes indicated chlorogenic acid’s efficacy in inhibiting PBP3 (−33.65 kcal/mol) relative to cefotaxime (−30.10 kcal/mol), while interacting with key catalytically relevant residues. The quantum features analysis using DFT/B3LYP suggested chlorogenic acid’s superior reactivity and compatibility with the PBP3 active site. In vitro evaluation revealed an MIC of 200 mg/ml for chlorogenic acid and 0.8 mg/ml for cefotaxime against Pseudomonas aeruginosa ATCC 27,853, while their combination showed a synergistic action mechanism (FIC index of 0.5). These observations were validated in time-kill kinetics (gradual decrease in viable cells over 24 h). The study concludes chlorogenic acid as promising PBP3 inhibitor. Nonetheless, further studies could focus on the structural modification of chlorogenic acid to improve its pharmacokinetic properties and potential as an antibacterial drug candidate in vivo.

Combination of Intracanal Medicines with Zinc Oxide Nanoparticles for Effective Eradication of Enterococcus faecalis

Background: Intracanal-resistant infections are the most important reason for root canal treatment failure. Therefore, cleaning the root canals is crucial. The efficiency of nanomedicines in eliminating intracanal contaminations and preventing bacterial attachment to surfaces are new strategies in this field. This study aimed to evaluate the effect of intracanal medicines, including calcium hydroxide (CH), zinc oxide nanoparticles (nZnO), pantoprazole (PP), and chlorhexidine (CHX) on Enterococcus faecalis (E. faecalis) in the individual and combinatorial form in an in vitro design in order to introduce an effective medicine for the eradication of E. faecalis. Sterilized water and sodium hypochlorite (NaOCl) 5.25% were used as the negative and positive control of antimicrobial activity, respectively. Methods: E. faecalis (ATCC 29212) was used for bacterial assays. The powder and the gel forms of the tested compounds were used in the analysis. The antibacterial and antibiofilm activities of the medicines were evaluated by the Minimum Inhibitory Concentration (MIC) determination using the broth microdilution method. The anti-biofilm effect of the tested compounds was assessed by Minimum Biofilm Inhibitory Concentration (MBIC). The antibacterial and antibiofilm effects of antimicrobial agent combinations were detected using the checkerboard assay and determination of the Fractional Inhibitory Concentration Index (FICI). Time-kill kinetics were conducted at zero, 2, 4, 6, 8, 10, 12, and 24 h. Results: Except for the MIC of the NaOCl, which was significantly lower than CH, there was no statistically significant difference between groups in MIC and MBIC. Only the mixture of CHX and nZnO and the mixture of PP and nZnO had a synergic effect against the planktonic and biofilm form of E. faecalis. Except for CHX and ZnO nanoparticles in gel form, other medicines did not show significant anti-biofilm effects against E. faecalis. Furthermore, the gel for CHX and nZnO showed stronger anti-biofilm effects. Conclusion: Combination therapy of common intracanal medicines with zinc oxide nanoparticles would lead to higher antibacterial and anti-biofilm effects against E. faecalis compared to conventional intracanal medicaments.

Characterization and applications of iron oxide nanoparticles synthesized from Phyllanthus emblica fruit extract

Nanotechnology is a treasure trove of diversified themes which are endowed with broad applications. Herein, iron oxide (Fe2O3) nanoparticles were synthesized using Phyllanthus emblica aqueous fruit extract. The UV-Visible spectrum exhibited a surface plasmon resonance peak at 295nm. Fourier Transform Infrared Spectroscopy provided insight into the functional groups responsible for capping. X-ray diffraction analysis authenticated the crystalline nature of nanoparticles, while energy dispersive X-ray spectroscopy divulged that iron and oxygen comprised 54% of the nanoparticles’ weight. Scanning electron microscopy established irregular morphology and agglomeration of nanoparticles. The Fe2O3 nanoparticles validated potent antimicrobial activity against 11 bacterial and 1 fungal isolates. The biggest zone of inhibition (23mm) was measured against S. enterica, whereas the smallest zone of inhibition (12mm) was documented against C. albicans and E. coli. The values for minimum inhibitory concentration ranged between 10 and 15μg/ml for all microbes. Nevertheless, no synergy was exhibited by the nanoparticles with any of the selected antibiotics (Fractional Inhibitory Concentration Index > 1). The photocatalytic dye degradation capability of Fe2O3 nanoparticles was assessed and the observations implied a significant increase in degradation of methyl red although, not of methylene blue. Furthermore, the nanoparticles were in possession of substantial antioxidant (34–38%) and anti-inflammatory (31–38%) capacities. Consequent upon the robust activities of P. emblica-mediated nanoparticles, these can be scrutinized for biomedical and environmental implementations in future.

Polymyxin combined with Ocimum gratissimum essential oil: one alternative strategy for combating polymyxin-resistant Klebsiella pneumoniae.

Introduction. Multidrug-resistant infections present a critical public health due to scarce treatment options and high mortality. Ocimum gratissimum L. essential oil (O.geo) is a natural resource rich in eugenol known for its antimicrobial activity.Hypothesis/Gap Statement. O.geo may exert effective antimicrobial activity against polymyxin-resistant Klebsiella pneumoniae and, when combined with Polymyxin B (PMB), may exhibit a synergistic effect, enhancing treatment efficacy and reducing antimicrobial resistance.Aim. This study aims to investigate the antimicrobial activity of O.geo against polymyxin-resistant K. pneumoniae using in vitro tests and an in vivo Caenorhabditis elegans model.Methodology. The O.geo was obtained by hydrodistillation followed by gas chromatography. The MIC and antibiofilm activity were determined using broth microdilution. Checkerboard and time-kill assays evaluated the combination of O.geo and polymyxin B (PMB), whereas a protein leakage assay verified its action.Results. Eugenol (39.67%) was a major constituent identified. The MIC of the O.geo alone ranged from 128 to 512 µg ml-1. The fractional inhibitory concentration index (0.28) and time-kill assay showed a synergism. In addition, O.geo and PMB inhibited biofilm formation and increased protein leakage in the plasma membrane. The treatment was tested in vivo using a Caenorhabditis elegans model, and significantly increased survival without toxicity was observed.Conclusion. O.geo could be used as a potential therapeutic alternative to combat infections caused by multidrug-resistant bacteria, especially in combination with PMB.

<i>Iv vitro</i> synergistic antimicrobial interactions between the extract of <i>Azadirachta indica</i> and antibiotics against <i>Bacillus subtilis</i>

This study aims to investigate the in vitro antimicrobial interactions between crude aqueous extract of Azadirachta indica and standard antibiotics, including ciprofloxacin, and norfloxacin. Using checkerboard techniques with Bacillus subtilis as the test microorganism, the synergistic effect of Azadirachta indica and antibiotics (ciprofloxacin and norfloxacin), was determined. The checkerboard assay presented FIC indices indicative of synergy, particularly notable with the combination of A. indica extract and the antibiotics. Specifically, with the 4:6, 8:2, and 9:1 ratios of ciprofloxacin and 1.9 to 9:1 of norfloxacin. These results suggest a potentiation of antibacterial effects when the plant extract is used in conjunction with conventional antibiotics. The synergistic interaction could potentially reduce the required doses of antibiotics, thereby minimizing side effects and the risk of antibiotic resistance.

Evaluation of antifungal and apoptotic effects of linalool, citral, and carvacrol separately and in combination with nystatin against clinical isolates of Pichia kudriavzevii

Pichia kudriavzevii (formerly Candida krusei) poses a significant threat to immunocompromised patients due to its inherent resistance to various antifungal drugs. This study explored the anticandidal potential of citral, linalool, and carvacrol in combination with nystatin against P. kudriavzevii strains.Using the microdilution method following CLSI guidelines, Minimum Inhibitory Concentrations (MICs) and fungicidal concentrations (MFCs) were determined. Citral exhibited MIC values ranging from 50 to 100 µg/ml, averaging 70.24 ± 16.99 µg/ml, while carvacrol had MIC values of 50 to 100 µg/ml, averaging 86.90 ± 16.99 µg/ml. Linalool demonstrated weaker antifungal activity, with MIC values between 100 and 200 µg/ml, averaging 150 ± 38.73 µg/ml. The study assessed the synergistic effectsof these phenols with nystatin through fractional inhibitory concentration indices (FICIS). In addition, flow cytometry was employed to assess apoptosis induction in P. kudriavzevii cells.Carvacrol displayed a remarkable synergistic effect in combination with nystatin against all 21 isolates tested. Conversely, linalool showed synergy in 17 isolates, while citral exhibited synergy in only 2 isolates. These findings highlight distinct patterns of synergy between the different compounds and nystatin against P. kudriavzevii. Also, Carvacrol emerged as the most potent inducer of apoptosis across all P. kudriavzevii strains, followed by citral and linalool. This suggests that carvacrol not only possesses a stronger antifungal effect but also has a more pronounced ability to trigger programmed cell death in P. kudriavzevii. In conclusion, the study supports the potential of carvacrol, citral and linalool, as anticandidal agents, suggesting their supplementation with nystatin for treating P. kudriavzevii infections.

Synergistic antimicrobial combination of third-generation cephalosporins and polymyxin B against carbapenem-polymyxin-resistant Klebsiella pneumoniae: an in vitro and in vivo analysis.

Antibiotic combination therapy is a promising approach to address the urgent need for novel treatment options for infections caused by carbapenem-polymyxin-resistant Klebsiella pneumoniae (CPR-Kp). The present study aimed to investigate the synergistic potential of four cephalosporins in combination with polymyxin B (PMB). A checkerboard assay was performed to evaluate the synergistic effects of cephalexin (CLX), cefixime, cefotaxime (CTX), and cefmenoxime (CMX) in combination with PMB. Subsequently, experiments evaluating the use of CTX or CMX in combination with PMB (CTX-PMB or CMX-PMB, respectively), including growth curve and SynergyFinder analysis, antibiofilm activity assays, cell membrane integrity assays, and scanning electron microscopy, were performed. Safety assessments were also conducted, including hemolysis and toxicity evaluations, using Caenorhabditis elegans. Furthermore, an in vivo model in C. elegans was adopted to assess the treatment efficacy against CPR-Kp infections. CTX-PMB and CMX-PMB exhibited low fractional inhibitory concentration indexes ranging from 0.19 to 0.50 and from 0.25 to 1.5, respectively, and zero interaction potency scores of 37.484 and 15.076, respectively. The two combinations significantly reduced growth and biofilm formation in CPR-Kp. Neither CTX-PMB nor CMX-PMB compromised bacterial cell integrity. Safety assessments revealed a low hemolysis percentage and high survival rates in the C. elegans toxicity evaluations. The in vivo model revealed that the CTX-PMB and CMX-PMB treatments improved the survival rates of C. elegans. The synergistic effects of the CTX-PMB and CMX-PMB combinations, both in vitro and in vivo, indicate that these antibiotic pairings could represent effective therapeutic options for infections caused by CPR-Kp.

A synergistic interaction between Citrus hystrix peel essential oil and tetracycline and evaluation of their antibacterial mechanism of action in vitro and in silico against Escherichia coli.

Citrus hystrix essential oil (CHEO) have shown various pharmacological properties including antibacterial activity. This EO also possessed antibacterial effect against foodborne pathogens. There is less information available about the synergy interaction between CHEO and tetracycline, as well as their mechanism of action. Therefore, this study was conducted to evaluate the synergistic effect of CHEO and tetracycline against clinical isolate of Escherichia coli. Antibiofilm, bacteriolytic, and efflux pump inhibitor activities were also performed. The chemical composition of CHEO was analysed using GC-MS. Three major compounds, D-limonene (25.02%), β-pinene (23.37%), and β-sabinene (22.20%) were identified. CHEO exhibited moderate antibacterial activity with MIC value of 250 μg/mL. The combination of CHEO (7.8 μg/mL) and tetracycline (62.5 μg/mL) produced a synergistic effect on E. coli with fractional inhibitory concentration index of 0.5. This mixture inhibited biofilm formation in E. coli. The combination of 7.8 μg/mL CHEO and 62.5 μg/mL tetracycline demonstrated bacteriolytic activity. In addition, the CHEO at 250 μg/mL showed a significant effect in inhibiting efflux pump. D-limonene has a binding free energy value of -20.13 kcal/mol with ompA transmembrane domain of E. coli. This finding indicates that CHEO has a potency to be developed as natural antibacterial against E. coli.

In vitro antimicrobial activity of chlorhexidine in combination with essential oils of Mentha x piperita L. & Thymus serpyllum L. & Pelargonium graveolens L’hér

ABSTRACT In this study, the antimicrobial potential of Mentha piperita & Thymus serpyllum &Pelargonium graveolens essential oil combinations was evaluated with Chlorhexidine. These species used ethnobotanically against throat infections. The commercial oils were analysed by GC-MS to confirm phytochemistry. Antimicrobial evaluation of the essential oils against Staphylococcus aureus and Streptococcus mutans were performed using in vitro microdilution assay. Binary combinations of Chlorhexidine-essential oils were evaluated using the checkerboard method. M. piperita essential oil contained 47% menthol as the major component, whereas the main component of T. serpyllum essential oil was 19% geraniol, and the main component of P. graveolens was 25% citronellol, respectively. The calculated fractional inhibition concentration index (FICI) of chlorhexidine-T. serpyllum combinations against S. mutans resulted as antagonistic (FICI 3.3643), while the FICI of chlorhexidine-P. graveolens essential oil combination resulted in synergistic (FICI 0.4326). Also, the FICI value = 0.252 of chlorhexidine-P. graveolens essential oil combinations against S. aureus were synergistic. To the best of our knowledge, combinations of these oils with Chlorhexidine were observed for the first time in this study with the potential application as mouthwash formulation.

Vibriocidal efficacy of Bifidobacterium bifidum and Lactobacillus acidophilus cell-free supernatants encapsulated in chitosan nanoparticles against multi-drug resistant Vibrio cholerae O1 El Tor

BackgroundCholera is a diarrheal disease recognized for being caused by toxin-producing Vibrio (V.) cholerae. This study aims to assess the vibriocidal and immunomodulatory properties of derived cell-free supernatants (CFSs) of Bifidobacterium (B.) bifidum and Lactobacillus (L.) acidophilus encapsulated in chitosan nanoparticles (CFSb-CsNPs and CFSa-CsNPs) against clinical multi-drug resistance (MDR) isolates of V. cholerae O1 El Tor.MethodsWe synthesized CFSb-CsNPs and CFSa-CsNPs using the ionic gelation technique. The newly nanostructures were characterized for size, surface zeta potential, morphology, encapsulation efficacy (EE), stability in different pH values and temperatures, release profile, and in vitro cytotoxicity. The antimicrobial and antibiofilm effects of the obtained nanocomposites on clinical MDR isolates (N = 5) of V. cholerae E1 Tor O1 were investigated by microbroth dilution assay and crystal violet staining, respectively. We conducted quantitative real-time PCR (qRT-PCR) to analyze the relative gene expressions of Bap, Rbmc, CTXAB, and TCP in response to CFSb-CsNPs and CFSa-CsNPs. Additionally, the immunomodulatory effects of formulated structures on the expression of TLR2 and TLR4 genes in human colorectal adenocarcinoma cells (Caco-2) were studied.ResultsNano-characterization analyses indicated that CFSb-CsNPs and CFSa-CsNPs exhibit spherical shapes under scanning electron microscopy (SEM) imaging, with mean diameters of 98.16 ± 0.763 nm and 83.90 ± 0.854 nm, respectively. Both types of nanoparticles possess positive surface charges. The EE% of CFSb-CsNPs was 77 ± 4.28%, whereas that of CFSa-CsNPs was 62.5 ± 7.33%. Chitosan (Cs) encapsulation leads to increased stability of CFSs in simulated pH conditions of the gastrointestinal tract in which the release rates for CFSb-CsNPs and CFSa-CsNPs were reached at 58.00 ± 1.24% and 55.01 ± 1.73%, respectively at pH = 7.4. The synergistic vibriocidal effects observed from the co-administration of both CFSb-CsNPs and CFSa-CsNPs, as evidenced by a fractional inhibitory concentration (FIC) index of 0.57, resulting in a significantly lower MIC of 2.5 ± 0.05 mg/mL (p < 0.0001) compare to individual administration. The combined antibacterial effect of CFSb-CsNPs and CFSa-CsNPs on Bap (0.14 ± 0.05), Rbmc (0.24 ± 0.01), CTXAB (0.30 ± 0.09), and TCP (0.38 ± 0.01) gene expression was significant (p < 0.001). Furthermore, co-administration of CFSb-CsNPs and CFSa-CsNPs also demonstrated the potency of suppressing TLR 2/4 (0.20 ± 0.01 and 0.12 ± 0.02, respectively) gene expression (p = 0.0019) and reduced Caco-2 cells attached bacteria to 526,000 ± 51,46 colony-forming units/mL (11.19%) (p < 0.0001).ConclusionOur study revealed that encapsulating CFSs within CsNPs enhances their vibriocidal activity by improving stability and enabling a controlled release mechanism at the site of interaction between the host and bacteria. Additionally, the simultaneous use of CFSb-CsNPs and CFSa-CsNPs exhibited superior vibriocidal potency against MDR V. cholerae O1 El Tor strains, indicating these combinations as a potential new approach against MDR bacteria.

Therapeutic efficacy of compound organic acids administration on methicillin-resistant Staphylococcus aureus-induced arthritis in broilers

Avian arthritis is a common disease in the poultry industry, and the etiology is complex. Bacterial arthritis is usually caused by Staphylococcus aureus (S. aureus) infection. This study explored the minimum inhibitory concentration (MIC) of different organic acids against S. aureus MRSA85 and found that vanillic acid, suberic acid, itaconic acid, salicylic acid, and other organic acids had significant inhibitory effects on this strain, especially cinnamic acid, which exhibited the best inhibitory effect. The Fractional Inhibitory Concentration Index (FICI) test further revealed the synergistic effect among some compound organic acids, which can significantly enhance the antibacterial efficiency against MRSA85 while reducing the risk of bacterial resistance. Under the low concentrations (1/2 or 1/4 MIC) conditions, the MIC of the compound organic acids against S. aureus remains unchanged, and it can even enhance the sensitivity of antibiotic-resistant S. aureus to Oxacillin. Furthermore, the compound organic acids could effectively promote the recovery of S. aureus-induced arthritis in broiler models, reduce inflammatory responses, and lower down bacterial loads and inflammatory cytokine levels in joints, which indicated that the effects of the Compound 2 is comparable to that of the trimethoprim-sulfamethoxazole group. These results support the potential and application value of organic acids and their compounds, including Compound 1 to 3, as novel antibacterial agents in the treatment of S. aureus infections.

Zidovudine in synergistic combination with nitrofurantoin or omadacycline: in vitro and in murine urinary tract or lung infection evaluation against multidrug-resistant Klebsiella pneumoniae.

Limited treatment options and multidrug-resistant (MDR) Klebsiella pneumoniae present a significant therapeutic challenge, underscoring the need for novel approaches. Drug repurposing is a promising tool for augmenting the activity of many antibiotics. This study aimed to identify novel synergistic drug combinations against K. pneumoniae based on drug repurposing. We used the clinically isolated GN 172867 MDR strain of K. pneumoniae to determine the reversal resistance activity of zidovudine (AZT). The combined effects of AZT and various antibiotics, including nitrofurantoin (NIT) and omadacycline (OMC), were examined using the checkerboard method, growth curves, and crystal violet assays to assess biofilms. An in vitro combination activity testing was carried out in 12 isolates of K. pneumoniae. In vivo murine urinary tract and lung infection models were used to evaluate the therapeutic effects of AZT + NIT and AZT + OMC, respectively. The fractional inhibitory concentration index and growth curve demonstrated that AZT synergized with NIT or OMC against K. pneumoniae strains. In addition, AZT + NIT inhibited biofilm formation and cleared mature biofilms. In vivo, compared with untreated GN 172867-infected mice, AZT + NIT and AZT + OMC treatment decreased colony counts in multiple tissues (P < 0.05) and pathological scores in the bladder and kidneys (P < 0.05) and increased the survival rate by 60% (P < 0.05). This study evaluated the combination of AZT and antibiotics to treat drug-resistant K. pneumoniae infections and found novel drug combinations for the treatment of acute urinary tract infections. These findings suggest that AZT may exert significant anti-resistance activity.

GC-MS Analysis and Evaluation of Combination effect of Syzygium cumini L. Skeels Ethanolic Seed Extract and Vancomycin against Clinical Methicillin-Resistant Staphylococcus aureus

Syzygium cumini (L.) has been traditionally used as an antimicrobial agent and is potential to be developed. The ethanol extract of S. cumini seed was obtained through maceration and assessed for its antibacterial activity using a dilution method, with extract concentrations of 1.625; 3.125; 6.25; 12.5, and 25mg/ml. The minimum inhibitory concentration (MIC) and fractional inhibitory concentration index (FICI) of the extract-antibiotic combination against Methicillin-Resistant Staphylococcus aureus were determined. Phytochemical screening was performed using Gas Chromatography-Mass Spectrometry (GC-MS) and the result revealed the presence of 22 compounds in S. cumini ethanolic seed extract, including fatty acids (69.63%), sesquiterpenes (11.29%), monoterpenes (2.94%), steroids (6.06%), and others (8.59%). The MIC of the single extract and vancomycin against the tested bacteria was 0.78mg/ml and 2µg/ml, respectively. The lowest concentration (MIC) of the extract-vancomycin combination inhibiting the growth of MRSA was 0.39mg/ml. The FICI value was 1.5, suggesting indifferent interaction between the extract and antibiotic.

Exploring the Antibiofilm Effect of Sertraline in Synergy with Cinnamomum verum Essential Oil to Counteract Candida Species.

The emergence and spread of drug-resistant pathogens, resulting in antimicrobial resistance, continue to compromise our capability to handle commonly occurring infectious diseases. The rapid global spread of multi-drug-resistant pathogens, particularly systemic fungal infections, presents a significant concern, as existing antimicrobial drugs are becoming ineffective against them. In recent decades, there has been a notable increase in systemic fungal infections, primarily caused by Candida species, which are progressively developing resistance to azoles. Moreover, Candida species biofilms are among the most common in clinical settings. In particular, they adhere to biomedical devices, growing as a resilient biofilm capable of withstanding extraordinarily high antifungal concentrations. In recent years, many research programs have concentrated on the development of novel compounds with possible antimicrobial effects to address this issue, and new sources, such as plant-derived antimicrobial compounds, have been thoroughly investigated. Essential oils (EOs), among their numerous pharmacological properties, exhibit antifungal, antibacterial, and antiviral activities and have been examined at a global scale as the possible origin of novel antimicrobial compounds. A recent work carried out by our research group concerned the synergistic antibacterial activities of commercially available and chemically characterized Cinnamomum verum L. essential oil (C. verum EO) in association with sertraline, a selective serotonin reuptake inhibitor whose repositioning as a non-antibiotic drug has been explored over the years with encouraging results. The aim of this work was to explore the synergistic effects of C. verum EO with sertraline on both planktonic and sessile Candida species cells. Susceptibility testing and testing of the synergism of sertraline and C. verum EO against planktonic and sessile cells were performed using a broth microdilution assay and checkerboard methods. A synergistic effect was evident in both the planktonic cells and mature biofilms, with significant reductions in fungal viability. Indeed, the fractional inhibitory concentration index (FICI) was lower than 0.5 for all the associations, thus indicating significant synergism of the associations with the Candida strains examined. Moreover, the concentrations of sertraline able to inhibit Candida spp. strain growth and biofilm formation significantly decreased when it was used in combination with C. verum EO for all the strains considered, with a reduction percentage in the amount of each associated component ranging from 87.5% to 97%.

Combinatory Use of hLF(1-11), a Synthetic Peptide Derived from Human Lactoferrin, and Fluconazole/Amphotericin B against Malassezia furfur Reveals a Synergistic/Additive Antifungal Effect.

The increasing resistance of Malassezia yeasts against commonly used antifungal drugs dictates the need for novel antifungal compounds. Human lactoferrin-based peptides show a broad spectrum of antimicrobial activities. Various assays were performed to find the optimal growth conditions of the yeasts and to assess cell viability, using media with low lipid content to avoid peptide binding to medium components. In the current study, we tested the antimicrobial susceptibility of 30 strains of M. furfur that cover the known IGS1 genotypic variation. hLF(1-11) inhibited the growth of all species tested, resulting in minimum inhibitory concentrations (MIC) values ranging from 12.5 to 100 μg/mL. In the combinatory tests, the majority of fractional inhibitory concentration indexes (FIC) for the tested strains of M. furfur were up to 1.0, showing that there is a synergistic or additive effect on the efficacy of the antifungal drugs when used in combination with hLF(1-11). Results showed that hLF(1-11) could be combined with fluconazole or amphotericin for the antimicrobial treatment of resistant strains, enhancing the potency of these antifungal drugs, resulting in an improved outcome for the patient.

α-Lactalbumin based scaffolds for infected wound healing and tissue regeneration

Interruption of wound healing by multi-drug resistant-bacterial infection is a harmful issue for the worldwide health care system, and conventional treatment approaches may not resolve this issue due to antimicrobial resistance. So, there is an unmet need to develop scaffolds with intrinsic wound healing properties to combat bacterial-infected wounds. Inspired by the α-lactalbumin’s (Lalb’s) ability to promote collagen synthesis, we herein electrospun Lalb with cephalexin (CPL) and epigallocatechin (EP) to produce nanofibers (CE-Lalb NFs) to solve this issue. The CE-Lalb NFs were prepared using the electrospinning technique and subjected to physicochemical characterizations, in vitro, and in vivo assessments. The CE-Lalb NFs promoted fibroblast migration, proliferation, and collagen synthesis, while CPL/EP annihilated MRSA and E. coli infections. Physicochemical characterizations proved the successful fabrication and doping of CE-Lalb NFs. Antimicrobial assays and fractional inhibitory concentration index (FICI) declared synergistic antibacterial activity of CE-Lalb NFs against MRSA and E. coli. The in vivo and immunohistochemical data evidenced its exceptional potential for wound healing, promoting growth factor, collagen synthesis, and reduced scar formation. The presence of mature collagen, fewer inflammatory cytokines, increased expression of blood vessels, and low expression of IL-6 at the wound site support in vitro and in vivo results. In our view, the tailored scaffold is the next step for personalized wound dressings that could meet patients with infected wounds’ unmet needs by the subscription of noninvasive and easily navigable therapeutic options.

Bioflavonoid Baicalein Modulates Tetracycline Resistance by Inhibiting Efflux Pump in Staphylococcus aureus.

The rise in antibiotic resistance among bacterial pathogens, particularly Staphylococcus aureus, has become a critical global health issue, necessitating the search for novel antimicrobial agents. S. aureus uses various mechanisms to resist antibiotics, including the activation of efflux pumps, biofilm formation, and enzymatic modification of drugs. This study explores the potential of baicalein, a bioflavonoid from Scutellaria baicalensis, in modulating tetracycline resistance in S. aureus by inhibiting efflux pumps. The synergistic action of baicalein and tetracycline was evaluated through various assays. The minimum inhibitory concentration (MIC) of baicalein and tetracycline against S. aureus was 256 and 1.0 μg/mL, respectively. Baicalein at 64 μg/mL reduced the MIC of tetracycline by eightfold, indicating a synergistic effect (fractional inhibitory concentration index: 0.375). Time-kill kinetics demonstrated a 1.0 log CFU/mL reduction in bacterial count after 24 hours with the combination treatment. The ethidium bromide accumulation assay showed that baicalein mediated significant inhibition of efflux pumps, with a dose-dependent increase in fluorescence. In addition, baicalein inhibited DNA synthesis by 73% alone and 92% in combination with tetracycline. It also markedly reduced biofilm formation and the invasiveness of S. aureus into HeLa cells by 52% at 64 μg/mL. These findings suggest that baicalein enhances tetracycline efficacy and could be a promising adjunct therapy to combat multidrug-resistant S. aureus infections.