Revisiting the Checkerboard to Inform Development of ß-Lactam/ß-Lactamase Inhibitor Combinations.

A two-dimensional "checkerboard" array employing systematic titration (e.g., serial two-fold dilutions) is a well-established in vitro method for exploring the antibacterial effects of novel drug combinations. Minimum inhibitory concentrations (MICs) on the checkerboard are isoeffective points at which the antibiotic potency is the same. Representations of checkerboard MIC curves for a ß-lactam and ß-lactamase inhibitor combination are used in hypothetical "thought experiments" and reveal the ways in which current practices can be improved. Because different types of response (i.e., independence vs. additivity vs. one effective agent; interaction vs. noninteraction) produce different MIC curves, data from different strains/isolates should not be pooled indiscriminately, as the composition of a pooled dataset will influence any derived pharmacokinetic/pharmacodynamic (PK/PD) index. Because the ß-lactamase inhibitor threshold concentration (CT) parameter is a function of the ß-lactam partner dosing regimen, it is not possible to derive a universal PK/PD index target based on CT. Alternative susceptibility testing methods represent different planes through the checkerboard; a fixed ratio method is less prone to bias for all ß-lactam and ß-lactamase inhibitor combinations. Susceptibility test MICs will often not reflect the sensitivity of the strain/isolate to the ß-lactamase inhibitor, so the use of these MICs to normalize PK/PD indices is inappropriate.

Synergistic activity of crocin and crocin loaded in niosomes alone and in combination with fluconazole against Candida albicans isolates: In vitro and in silico study.

INTRODUCTION: Since the drug resistance in Candida species is becoming a serious clinical challenge, novel alternative therapeutic options, particularly herbal medicine, have attracted increasing interest. This study aimed to pinpoint the potential antifungal activity of crocin (Cro), the efficacy of the niosomal formulation of Cro (NCro), and the synergistic activity of both formulations in combination with fluconazole (FLC) against susceptible and resistant C. albicans isolates. MATERIAL AND METHODS: NCro was formulated using the heating method. The in vitro antimycotic activity of Cro, NCro, and FLC was evaluated. Checkerboard and isobologram assays evaluated the interaction between both formulations of Cro and FLC. Necrotic and apoptotic effects of different agents were analyzed using the flow cytometry method. In silico study was performed to examine the interactions between Lanosterol 14 alpha-demethylase and Cro as a part of our screening compounds with antifungal properties. RESULTS: NCro exhibited high entrapment efficiency up to 99.73 ± 0.54, and the mean size at 5.224 ± 0.618 µm (mean ± SD, n = 3). Both formulations of Cro were shown to display good anticandidal activity against isolates. The synergistic effect of the NCro in combination with FLC is comparable to Cro (P-value =0.03). Apoptotic indicators confirmed that tested compounds caused cell death in isolates. The docking study indicated that Cro has interactivity with the protein residue of 14α-demethylase. CONCLUSION: The results showed a remarkable antifungal effect by NCro combined with FLC. Natural compounds, particularly nano-sized carrier systems, can act as an effective therapeutic option for further optimizing fungal infection treatment.

Transparent and Ultra-Thin Flexible Checkerboard Metasurface for Radar-Infrared Bi-Stealth.

This paper proposed a single-layer checkerboard metasurface with simultaneous wideband radar cross-section (RCS) reduction characteristics and low infrared (IR) emissivity. The metasurface consists of an indium tin oxide (ITO)-patterned film, a polyethylene terephthalate (PET) substrate and an ITO backplane from the top downwards, with a total ultra-thin thickness of 1.6 mm. This design also allows the metasurface to have good optical transparency and flexibility. Based on phase cancellation and absorption, the metasurface can achieve a wideband RCS reduction of 10 dB from 10.6 to 19.4 GHz under normal incidence. When the metasurface is slightly cylindrically curved, an RCS reduction of approximately 10 dB can still be achieved from 11 to 19 GHz. The polarization and angular stability of the metasurface have also been verified. The filling rate of the top ITO-patterned film is 0.81, which makes the metasurface have a low theoretical IR emissivity of 0.24. Both simulation and experimental results have verified the excellent characteristics of the proposed checkerboard metasurface, demonstrating its great potential application in radar-IR bi-stealth.

Extrinsic Calibration for a Modular 3D Scanning Quality Validation Platform with a 3D Checkerboard.

Optical 3D scanning applications are increasingly used in various medical fields. Setups involving multiple adjustable systems require repeated extrinsic calibration between patients. Existing calibration solutions are either not applicable to the medical field or require a time-consuming process with multiple captures and target poses. Here, we present an application with a 3D checkerboard (3Dcb) for extrinsic calibration with a single capture. The 3Dcb application can register captures with a reference to validate measurement quality. Furthermore, it can register captures from camera pairs for point-cloud stitching of static and dynamic scenes. Registering static captures from TIDA-00254 to its reference from a Photoneo MotionCam-3D resulted in an error (root mean square error ± standard deviation) of 0.02 mm ± 2.9 mm. Registering a pair of Photoneo MotionCam-3D cameras for dynamic captures resulted in an error of 2.2 mm ± 1.4 mm. These results show that our 3Dcb implementation provides registration for static and dynamic captures that is sufficiently accurate for clinical use. The implementation is also robust and can be used with cameras with comparatively low accuracy. In addition, we provide an extended overview of extrinsic calibration approaches and the application's code for completeness and service to fellow researchers.

Antilisterial Effectiveness of Origanum vulgare var. hirtum and Coridothymus capitatus Essential Oils and Hydrolates Alone and in Combination.

The antimicrobial activity of Origanum vulgare var. hirtum (O) and Coridothymus capitatus (C) essential oils (EOs) and hydrolates (HYs) of the same botanical species was evaluated on sixteen L. monocytogenes strains from food and clinical origins. The antimicrobial activity was assessed by Minimum Inhibitory Concentration (MIC) determination, viable cell enumeration over time up to 60 min, and evaluation of the cellular damage through Confocal Laser Scanning Microscope (CLSM) analysis. EOs exhibited antimicrobial activity with MIC values ranging from 0.3125 to 10 µL/mL. In contrast, HYs demonstrated antimicrobial effectiveness at higher concentrations (125-500 µL/mL). The effect of HYs was rapid after the contact with the cells, and the cell count reduction over 60 min of HY treatment was about 1.2-1.7 Log CFU/mL. L. monocytogenes cells were stressed by HY treatment, and red cell aggregates were revealed through CLSM observation. Moreover, the combinations of EOs and HYs had an additive antilisterial effect in most cases and allowed the concentration of use to be reduced, while maintaining or improving the antimicrobial effectiveness. The combined use of EOs and HYs can offer novel opportunities for applications, thereby enhancing the antimicrobial effectiveness and diminishing the concentration of use. This provides the added benefit of reducing toxicity and mitigating any undesirable sensory effects.

A synergistic anti-bacterial and anti-adhesion activity of tea tree (Melaleuca alternifolia) and lemon eucalyptus tree (Eucalyptus citriodora Hook) essential oils on Legionella pneumophila.

Legionella pneumophila is a Gram-negative bacterial pathogen that colonizes natural and artificial water systems and has the ability to form a biofilm. The biofilm protects L. pneumophila from various environmental factors and makes it more resistant to chlorine-based disinfectants. This study investigated the anti-bacterial properties of tea tree (Melaleuca alternifolia (Maiden and Betche) Cheel) oil and lemon eucalyptus tree (Eucalyptus citriodora Hook) essential oils (EOs) and their synergistic, additive inhibitory and anti-adhesive effects against L. pneumophila biofilm formation on polystyrene. The minimum effective concentration (MEC) for tea tree is 12.8 mg ml-1 and for lemon eucalyptus tree EO 6.4 mg ml-1. In the checkerboard assay, different combinations of these two EO show synergistic and additive anti-microbial activity. The minimum anti-adhesive concentration (MAC) for tea tree is 12.8 mg ml-1 and for lemon eucalyptus tree EO 6.4 mg ml-1. A combination of 3.2 mg ml-1 tea tree EO and 0.8 mg ml-1 lemon eucalyptus tree EO showed the strongest anti-adhesive effect against L. pneumophila on polystyrene. The tested oils and their combination showed intriguing potential to inhibit L. pneumophila biofilm formation.

In vitro determination of the combination of ciclopirox and terbinafine in the treatment of dermatophytosis.

INTRODUCTION: The cases of dermatophytosis are increasing and they are associated with a higher number of therapeutic failures leading the doctor to prescribe combinations of antifungals as therapy. The objective was to evaluate the interaction of terbinafine and ciclopirox, the most commonly antifungals used in the clinic, in dermatophyte isolates. METHODOLOGY: The minimum inhibitory concentrations (MIC) of ciclopirox and terbinafine were determined by the broth microdilution method according CLSI and the checkerboard assay was used to evaluate the interaction between the antifungal agents. RESULTS: For terbinafine the mic50 was 0.125 ug/mL and mic90 was 0.250 ug/mL. For ciclopirox the values were 2.0 ug/mL for mic50 and 4.0 ug/mL for mic90. No synergistic interaction was observed for the dermatophyte isolates tested. CONCLUSION: These results suggest that the use of terbinafine in combination with ciclopirox, which is widely used in the clinic, may not be a good choice for the treatment of onychomycosis.

Phenotypic, molecular, and in silico characterization of coumarin as carbapenemase inhibitor to fight carbapenem-resistant Klebsiella pneumoniae.

BACKGROUND: Carbapenems represent the first line treatment of serious infections caused by drug-resistant Klebsiella pneumoniae. Carbapenem-resistant K. pneumoniae (CRKP) is one of the urgent threats to human health worldwide. The current study aims to evaluate the carbapenemase inhibitory potential of coumarin and to test its ability to restore meropenem activity against CRKP. Disk diffusion method was used to test the antimicrobial susceptibility of K. pneumoniae clinical isolates to various antibiotics. Carbapenemase genes (NDM-1, VIM-2, and OXA-9) were detected using PCR. The effect of sub-MIC of coumarin on CRKP isolates was performed using combined disk assay, enzyme inhibition assay, and checkerboard assay. In addition, qRT-PCR was used to estimate the coumarin effect on expression of carbapenemase genes. Molecular docking was used to confirm the interaction between coumarin and binding sites within three carbapenemases. RESULTS: K. pneumoniae clinical isolates were found to be multi-drug resistant and showed high resistance to meropenem. All bacterial isolates harbor at least one carbapenemase-encoding gene. Coumarin significantly inhibited carbapenemases in the crude periplasmic extract of CRKP. The checkerboard assay indicated that coumarin-meropenem combination was synergistic exhibiting a fractional inhibitory concentration index ≤ 0.5. In addition, qRT-PCR results revealed that coumarin significantly decreased carbapenemase-genes expression. Molecular docking revealed that the binding energies of coumarin to NDM1, VIM-2, OXA-48 and OXA-9 showed a free binding energy of -7.8757, -7.1532, -6.2064 and - 7.4331 Kcal/mol, respectively. CONCLUSION: Coumarin rendered CRKP sensitive to meropenem as evidenced by its inhibitory action on hydrolytic activity and expression of carbapenemases. The current findings suggest that coumarin could be a possible solution to overcome carbapenems resistance in CRKP.

Antimicrobial combinations against Helicobacter pylori including benzoxadiazol-based flavodoxin inhibitors: in vitro characterization.

IMPORTANCE: The antimicrobial resistance of Helicobacter pylori (Hp) currently poses a threat to available treatment regimens. Developing antimicrobial drugs targeting new bacterial targets is crucial, and one such class of drugs includes Hp-flavodoxin (Hp-fld) inhibitors that target an essential metabolic pathway in Hp. Our study demonstrated that combining these new drugs with conventional antibiotics used for Hp infection treatment prevented the regrowth observed with drugs used alone. Hp-fld inhibitors show promise as new drugs to be incorporated into the treatment of Hp infection, potentially reducing the development of resistance and shortening the treatment duration.

Antimicrobial Activity of Ceragenins against Vancomycin-Susceptible and -Resistant Enterococcus spp.

Ceragenins (CSAs) are a new class of antimicrobial agents designed to mimic the activities of endogenous antimicrobial peptides. In this study, the antibacterial activities of various ceragenins (CSA-13, CSA-44, CSA-90, CSA-131, CSA-138, CSA-142, and CSA-192), linezolid, and daptomycin were assessed against 50 non-repeated Enterococcus spp. (17 of them vancomycin-resistant Enterococcus-VRE) isolated from various clinical specimens. Among the ceragenins evaluated, the MIC50 and MIC90 values of CSA-44 and CSA-192 were the lowest (2 and 4 µg/mL, respectively), and further studies were continued with these two ceragenins. Potential interactions between CSA-44 or CSA-192 and linezolid were tested and synergistic interactions were seen with the CSA-192-linezolid combination against three Enterococcus spp., one of them VRE. The effects of CSA-44 and CSA-192 on the MIC values of vancomycin were also investigated, and the largest MIC change was seen in the vancomycin-CSA-192 combination. The in vivo effects of CSA-44 and CSA-192 were evaluated in a Caenorhabditis elegans model system. Compared to no treatment, increased survival was observed with C. elegans when treated with ceragenins. In conclusion, CSA-44 and CSA-192 appear to be good candidates (alone or in combination) for the treatment of enterococcal infections, including those from VRE.

Antifungal Biofilm Inhibitory Effects of Combinations of Diclofenac and Essential Oils.

Systemic fungal infections have risen in recent decades and most of them are caused by Candida species, which are becoming increasingly resistant to conventional antifungal drugs. Biofilm production has been considered the most common growth form of Candida cells and is associated with a high level of antifungal resistance. At present, international research reports on the antifungal activity of non-traditional antimicrobial drugs and their potential use against life-threatening resistant fungal infections. Indeed, drug repurposing has led to the consideration of well-known compounds as a last-line therapy. The goal of this work is to evaluate the potential synergistic antifungal biofilm activity of new combinations between diclofenac sodium salt (DSS), a widely used non-steroidal anti-inflammatory drug (NSAID), with the essential oils (EOs) of Mentha piperita, Pelargonium graveolens, and Melaleuca alternifolia, whose antifungal activity has been well documented over the years. The in vitro antifungal activity of DSS and EOs was determined on different Candida strains. Susceptibility testing and the synergism of DSS and EOs versus biofilm cells was performed by using the broth microdilution assay and checkerboard methods. Minimum inhibitory concentrations (sMIC50) of DSS alone ranged from 1.25 to 2.05 mg/mL for all the strains considered. These values significantly decreased when the drug was used in combination with the EOs. The fractional inhibitory concentration index (FICI) was lower than 0.5 for almost all the associations, thus indicating a significant synergism, particularly for the DSS-Pelargonium graveolens combination towards the Candida strains examined. These preliminary results show that the combination of the EOs with DSS improves the antifungal activity on all the tested Candida strains, significantly lowering the concentrations of the components used and thus allowing any toxic effects to be overcome.

Activity of Cinnamic Acid Derivatives with 4-Chloro-2-mercaptobenzenesulfonamide Moiety against Clinical HLAR and VRE Enterococcus spp.

The rapid increase in strains that are resistant to antibiotics requires new active compounds to be found whose mechanism of action on bacteria is different to those that are currently known. Of particular interest are compounds that occur in plants as secondary metabolites. The focus of this study concerns the examination of the effects of synthetic cinnamic acid derivatives, with 4-chloro-2-mercaptobenzenesulfonamide moiety on Enterococcus spp. with HLAR (high-level aminoglycoside resistance) and VRE (vancomycin-resistant Enterococcus) mechanisms. The minimum inhibitory concentration (MIC) values of the tested compounds were determined using the serial dilution method for Enterococcus spp. groups, and the most active compounds were as follows: 16d, 17c, 16a, 16c and 16f (2-4 µg/mL). These compounds, at a concentration of 4 × MIC, inhibited the biofilm formation of HLAR strains (70 to 94%). At concentrations of 2 × MIC and 4 × MIC, they also inhibited the growth of VRE strains (42 to 96%). The best effect produced on the formed biofilm was demonstrated by compound 16f (from 62% MIC concentration to 89% 4 × MIC concentration) on the tested HLAR strains. In vitro studies, using the peripheral blood of domestic sheep, demonstrated the stable bacteriostatic activity of the tested compounds against Enterococcus spp. The compounds 16a, 16c, 16d, 16f and 17c showed synergism and additivity with ampicillin, streptomycin, gentamicin and vancomycin against resistant strains of Enterococcus spp. The tested compounds, when combined, reduce the MIC for antibiotics by 800 to 10,000 times for HLAR strains and by 8 to 10,000 times for VRE strains. The MIC of the tested compounds, in combination with antibiotics, is reduced 2-16-fold for HLAR strains and 2-32-fold for VRE strains. These studies demonstrate the potential for the therapeutic use of synthetic, cinnamic acid derivatives, with 4-chloro-2-mercaptobenzenesulfonamide moiety, to work against clinical strains of Enterococcus spp.

Synthesis and antifungal evaluation against Candida spp. of the (E)-3-(furan-2-yl)acrylic acid.

Infections of fungal origin are mainly caused by Candida spp. Some species, such as C. albicans, C. glabrata, C. parapsilosis, and C. tropicalis, stand out as promoters of diseases in humans. This study evaluated the synthesis and antifungal effects of (E)-3-(furan-2-yl)acrylic acid. The synthesis of the compound showed a yield of 88%, considered high. The minimum inhibitory concentration of the synthetic compound, amphotericin B, and fluconazole isolated against four Candida species ranged from 64 to 512 µg/mL, 1 to 2 µg/mL, and 32 to 256 µg/mL, respectively. The synergistic effect of the test compound was observed when associated with amphotericin B against C. albicans and C. tropicalis, with no antagonism between the substances against any of the strains tested. The potential drug promoted morphological changes in C. albicans, decreasing the amount of resistance and virulence, and reproduction structures, such as the formation of pseudohyphae, blastoconidia, and chlamydospores. Furthermore, it was also possible to identify the fungistatic profile of the test substance by studying the growth kinetics of C. albicans. Finally, it was observed that the test compound stimulated ergosterol biosynthesis by the yeast, probably by activating microbial resistance responses.

Influence of spatial frequency in visual stimuli for cVEP-based BCIs: evaluation of performance and user experience.

Code-modulated visual evoked potentials (c-VEPs) are an innovative control signal utilized in brain-computer interfaces (BCIs) with promising performance. Prior studies on steady-state visual evoked potentials (SSVEPs) have indicated that the spatial frequency of checkerboard-like stimuli influences both performance and user experience. Spatial frequency refers to the dimensions of the individual squares comprising the visual stimulus, quantified in cycles (i.e., number of black-white squares pairs) per degree of visual angle. However, the specific effects of this parameter on c-VEP-based BCIs remain unexplored. Therefore, the objective of this study is to investigate the role of spatial frequency of checkerboard-like visual stimuli in a c-VEP-based BCI. Sixteen participants evaluated selection matrices with eight spatial frequencies: C001 (0 c/°, 1×1 squares), C002 (0.15 c/°, 2×2 squares), C004 (0.3 c/°, 4×4 squares), C008 (0.6 c/°, 8×8 squares), C016 (1.2 c/°, 16×16 squares), C032 (2.4 c/°, 32×32 squares), C064 (4.79 c/°, 64×64 squares), and C128 (9.58 c/°, 128×128 squares). These conditions were tested in an online spelling task, which consisted of 18 trials each conducted on a 3×3 command interface. In addition to accuracy and information transfer rate (ITR), subjective measures regarding comfort, ocular irritation, and satisfaction were collected. Significant differences in performance and comfort were observed based on different stimulus spatial frequencies. Although all conditions achieved mean accuracy over 95% after 2.1 s of trial duration, C016 stood out in terms user experience. The proposed condition not only achieved a mean accuracy of 96.53% and 164.54 bits/min with a trial duration of 1.05s, but also was reported to be significantly more comfortable than the traditional C001 stimulus. Since both features are key for BCI development, higher spatial frequencies than the classical black-to-white stimulus might be more adequate for c-VEP systems. Hence, we assert that the spatial frequency should be carefully considered in the development of future applications for c-VEP-based BCIs.

In Vitro antibiotic combinations of Colistin, Meropenem, Amikacin, and Amoxicillin/clavulanate against multidrug-resistant Klebsiella pneumonia isolated from patients with ventilator-associated pneumonia.

BACKGROUND: Hospital infections such as ventilator-associated pneumonia (VAP) due to multidrug-resistant Klebsiella pneumoniae (MDR-KP) strains have increased worldwide. In addition, biofilm production by these resistant isolates has confronted clinicians with higher treatment failure and infection recurrence. Given the paucity of new agents and limited data on combination therapy for MDR-KPs, the present study sought to evaluate the in vitro activity of several antibiotic combinations against planktonic and biofilm MDR-KPs isolated from patients with VAP. RESULTS: All 10 carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates demonstrated multidrug resistance against the tested antibiotics. At planktonic mode, combinations of colistin-meropenem and amoxicillin/clavulanate in combination with meropenem, colistin, or amikacin showed synergism against 60-70% isolates. On the other hand, in the biofilm state, colistin-based combinations exhibited synergism against 50-70% isolates and the most effective combination was colistin-amikacin with 70% synergy. CONCLUSIONS: The results revealed that combinations of amoxicillin/clavulanate with colistin, meropenem, or amikacin in the planktonic mode and colistin with amoxicillin/clavulanate, meropenem, or amikacin in the biofilm mode could effectively inhibit CRKP isolates, and thus could be further explored for the treatment of CRKPs.

A novel untrained SSVEP-EEG feature enhancement method using canonical correlation analysis and underdamped second-order stochastic resonance.

Objective: Compared with the light-flashing paradigm, the ring-shaped motion checkerboard patterns avoid uncomfortable flicker or brightness modulation, improving the practical interactivity of brain-computer interface (BCI) applications. However, due to fewer harmonic responses and more concentrated frequency energy elicited by the ring-shaped checkerboard patterns, the mainstream untrained algorithms such as canonical correlation analysis (CCA) and filter bank canonical correlation analysis (FBCCA) methods have poor recognition performance and low information transmission rate (ITR). Methods: To address this issue, a novel untrained SSVEP-EEG feature enhancement method using CCA and underdamped second-order stochastic resonance (USSR) is proposed to extract electroencephalogram (EEG) features. Results: In contrast to typical unsupervised dimensionality reduction methods such as common average reference (CAR), principal component analysis (PCA), multidimensional scaling (MDS), and locally linear embedding (LLE), CCA exhibits higher adaptability for SSVEP rhythm components. Conclusion: This study recruits 42 subjects to evaluate the proposed method and experimental results show that the untrained method can achieve higher detection accuracy and robustness. Significance: This untrained method provides the possibility of applying a nonlinear model from one-dimensional signals to multi-dimensional signals.

Efficacy of oritavancin and nisin alone and their combination against vancomycin resistant enterococci strains in hospitalized patients in Turkiye.

PURPOSE: Vancomycin-Resistant Enterococci (VREs) have emerged and become a problem that threatens the health of hospitalized patients. VRE can cause different serious infections of the urinary tract, the bloodstream, wound and other body sites. VREs are resistant to multiple antibiotics and treatment options are very limited. We aimed to investigate the efficacy of oritavancin and nisin alone and their combination against VRE strains. METHODS: VRE isolates from rectal swabs of hospitalized patients were identified by conventional and commercial methods. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of oritavancin and nisin against VRE strains were determined. The synergistic effect of both agent combinations was examined by the Checkerboard test. RESULTS: All VRE strains were identifined as Enterococcus faecium. The MIC value of oritavancin was found in the range of 0.015-0.24 â€‹µg/mL; in which 48 strains were susceptible (≤0.12 â€‹µg/mL) and two strains were resistant (>0.12 â€‹µg/mL). The MBC of oritavancin was determined in the range of 0.06-3.84 â€‹µg/mL. The MIC of nisin was found in the range of 12.5-100 â€‹µg/mL; in which 32 strains were susceptible (≤50 â€‹µg/mL) and 18 strains were resistant (>50 â€‹µg/mL). MBC of nisin was determined in the range of 25-800 â€‹µg/mL. Two oritavancin resistant strains were displayed indifference effect, whereas from 18 nisin resistant strains, 11 showed indifference, and seven displayed synergistic effect. Thirty-eight out of 48 strains which were sensitive to oritavancin showed indifference and 10 revealed synergistic effect, whereas 29 of 32 strains which were sensitive to nisin showed indifference and three had synergistic effect. CONCLUSIONS: A synergistic combination of oritavansin and nisin was detected in 20 strains (40%), Our study is the first study in Turkiye.

Cell free extract-mediated biogenic synthesis of ZnONPs and their application with kanamycin as a bactericidal combination.

Antimicrobial resistance (AMR) is a main public health issue and a challenge for the scientific community all over the globe. Hence, there is a burning need to build new bactericides that resist the AMR. The ZnONPs were produced by cell free extract of mint (Mentha piperita L.) leaves. Antibiotics that are ineffective against resistant bacteria like Escherichia coli and Staphylococcus aureus were treated. The antibiotics were first screened, and then antibacterial activity was checked by disk diffusion, and MIC of Mp-ZnONPs individually and using Kanamycin (KAN) were determined against these pathogens by broth microdilution method. The synergism between Mp-ZnONPs and KAN was confirmed by checkerboard assay. The MIC showed robust antibacterial activity against the tested pathogens. The combination of KAN and Mp-ZnONPs reduces the MIC of KAN as it efficiently inhibits E. coli's growth, and KAN significantly enhances the antibacterial activity of Mp-ZnONPs. Taken together, Mp-ZnONPs have strong antimicrobial activity, and KAN significantly improves it against the tested pathogens, which would offer an effective, novel, and benign therapeutic methodology to regulate the incidence. The combination of Mp-ZnONPs and KAN would lead to the development of novel bactericides, that could be used in the formulation of pharmaceutical products.

Investigation of in vitro efficacy of quercetin-meropenem combination in carbapenemase-producing Klebsiella pneumoniae isolates.

INTRODUCTION: In recent years, the rapid spread of carbapenem-resistant K. pneumoniae, their higher mortality rates, and limited treatment alternatives cause difficulties in the treatment of these infections. New treatment alternatives are needed to cope with resistant strains. In recent years, natural products such as Quercetin have started to be preferred in combination studies due to their antimicrobial effects and low side-effect profiles. The aim of this study was to investigate the in vitro efficacy of the combination of Quercetin and Meropenem on carbapenemase-producing (blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP), carbapenem-resistant K.pneumoniae isolates using the checkerboard method. METHODOLOGY: Thirty Carbapenem-resistant K.pneumoniae strains in the culture collection of our laboratory were included in our study. Carbapenemase genes were determined using the Xpert® Carba-R (Cepheid, USA). Synergism with meropenem was assessed by checkerboard analysis, followed by FIC index, and combination index calculation. RESULTS: Twenty (66.6%) strains had OXA-48, 6 (20%) NDM, 1 (3.3%) KPC, 1 (3.3%) OXA-48+NDM genes, and 2 strains (6.6%) gene could not be detected. In the Quercetin and Meropenem combination study, synergy was found in 24 (80%) of the strains; an additive effect was found in 5 (16.6%) and an antagonist effect in 1 (3.3%). In 19 (63.3%) of the strains, meropenem MIC values were below the sensitive limit (MIC ≤ 2 µg/mL). CONCLUSIONS: Although the combination of quercetin and meropenem has a high synergistic effect in carbapenem-resistant K. pneumoniae isolates, it seems that the carbapenemase species affects this situation. however, more work is needed on this subject.

In vivo efficacy of pitavastatin combined with itraconazole against Aspergillus fumigatus in silkworm models.

Azole resistance in Aspergillus fumigatus is a worldwide concern and new antifungal drugs are required to overcome this problem. Statin, a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, has been reported to suppress the growth of A. fumigatus, but little is known about its in vivo antifungal effect against A. fumigatus. In this study, we evaluated the in vivo efficacy of pitavastatin (PIT) combined with itraconazole (ITC) against azole-susceptible and azole-resistant strains with silkworm models. Prolongation of survival was confirmed in the combination-therapy (PIT and ITC) group compared to the no-treatment group in both azole-susceptible and azole-resistant strain models. Furthermore, when the azole-susceptible strain was used, the combination-therapy resulted in a higher survival rate than with ITC alone. Histopathological analysis of the silkworms revealed a reduction of the hyphal amount in both azole-susceptible and azole-resistant strain models. Quantitative evaluation of fungal DNA by qPCR in azole-susceptible strain models clarified the reduction of fungal burden in the combination-therapy group compared with the no-treatment group and ITC-alone group. These results indicate that the efficacy of PIT was enhanced when combined with ITC in vivo. As opposed to most statins, PIT has little drug-drug interaction with azoles in humans and can be used safely with ITC. This combination therapy may be a promising option as an effective treatment in clinical settings in the future. IMPORTANCE Azole resistance among A. fumigatus isolates has recently been increasingly recognized as a cause of treatment failure, and alternative antifungal therapies are required to overcome this problem. Our study shows the in vivo efficacy of PIT combined with ITC against A. fumigatus using silkworm models by several methods including evaluation of survival rates, histopathological analysis, and assessment of fungal burden. Contrary to most statins, PIT can be safely administered with azoles because of less drug-drug interactions, so this study should help us to verify how to make use of the drug in clinical settings in the future.