The anti-staphylococcal fusidic acid as an efflux pump inhibitor combined with fluconazole against vaginal candidiasis in mouse model.

BACKGROUND: Candida albicans is the most common fungus that causes vaginal candidiasis in immunocompetent women and catastrophic infections in immunocompromised patients. The treatment of such infections is hindered due to the increasing emergence of resistance to azoles in C. albicans. New treatment approaches are needed to combat candidiasis especially in the dwindled supply of new effective and safe antifungals. The resistance to azoles is mainly attributed to export of azoles outside the cells by means of the efflux pump that confers cross resistance to all azoles including fluconazole (FLC). OBJECTIVES: This study aimed to investigate the possible efflux pump inhibiting activity of fusidic acid (FA) in C. albicans resistant isolates and the potential use of Fusidic acid in combination with fluconazole to potentiate the antifungal activity of fluconazole to restore its activity in the resistant C. albicans isolates. METHODS: The resistance of C. albicans isolates was assessed by determination of minimum inhibitory concentration. The effect of Fusidic acid at sub-inhibitory concentration on efflux activity was assayed by rhodamine 6G efflux assay and intracellular accumulation. Mice model studies were conducted to evaluate the anti-efflux activity of Fusidic acid and its synergistic effects in combination with fluconazole. Impact of Fusidic acid on ergosterol biosynthesis was quantified. The synergy of fluconazole when combined with Fusidic acid was investigated by determination of minimum inhibitory concentration. The cytotoxicity of Fusidic acid was tested against erythrocytes. The effect of Fusidic acid on efflux pumps was tested at the molecular level by real-time PCR and in silico study. In vivo vulvovaginitis mice model was used to confirm the activity of the combination in treating vulvovaginal candidiasis. RESULTS: Fusidic acid showed efflux inhibiting activity as it increased the accumulation of rhodamine 6G, a substrate for ABC-efflux transporter, and decreased its efflux in C. albicans cells. The antifungal activity of fluconazole was synergized when combined with Fusidic acid. Fusidic acid exerted only minimal cytotoxicity on human erythrocytes indicating its safety. The FA efflux inhibitory activity could be owed to its ability to interfere with efflux protein transporters as revealed by docking studies and downregulation of the efflux-encoding genes of both ABC transporters and MFS superfamily. Moreover, in vivo mice model showed that using fluconazole-fusidic acid combination by vaginal route enhanced fluconazole antifungal activity as shown by lowered fungal burden and a negligible histopathological change in vaginal tissue. CONCLUSION: The current findings highlight FA's potential as a potential adjuvant to FLC in the treatment of vulvovaginal candidiasis.

Deciphering Campylobacter jejuni DsbA1 protein dynamics in the presence of anti-virulent compounds: a multi-pronged computer-aided approach.

The current study aims to evaluate Asinex library compounds against Campylobacter jejuni DsbA1 protein, a thiol disulfide oxidoreductase enzyme that plays a major role in the oxidative folding of bacterial virulence proteins, making it a promising anti-viral drug target. By employing several techniques of computer-aided drug design, BDC25697459, BDD33601083, and BDC30129064 were identified with binding energy scores of -8.8 kcal/mol, -8.8 kcal/mol, and -8.3 kcal/mol, respectively. However, the control molecule, tetraethylene glycol, exhibited a binding energy score of -7.0 kcal/mol. The control, BDD33601083, and BDC30129064 were unveiled to bind the same co-crystallized binding site (pocket 1), while BDC25697459 interacted with a new binding pocket (pocket 2) adjacent to the control binding region. The molecular dynamics simulation showed that complexes exhibit stable dynamics without significant global or residue-level fluctuations. The average RMSD values were in the range of 2.07 Å-2.45 Å. Similarly, mean RMSF was recorded between 1.30 and 1.42 Å. The C. jejuni DsbA1 was also observed as compact in the presence of the compounds, showing a mean RoG value in the range of 16.42 Å-16.55 Å. In terms of MM/PBSA binding energy, the BDC30129064 complex was ranked top with -44.88 ± 4.14 kcal/mol, whereas the positive control molecule exhibited -22.22 ± 3.33 kcal/mol. From a pharmacokinetic perspective, the compounds are suitable candidates for clinical trial investigation. Preliminary computational analysis of these virtual hits indicates that these compounds have a low potential for ADME and toxicity-associated liabilities. In summary, the compounds displayed a high affinity for the C. jejuni DsbA1 protein, indicating potential efficacy that requires further investigation.Communicated by Ramaswamy H. Sarma.

Relocating Glyceryl Trinitrate as an Anti-Virulence Agent against Pseudomonas aeruginosa and Serratia marcescens: Insights from Molecular and In Vivo Investigations.

The problem of antibiotic resistance is a global critical public health concern. In light of the threat of returning to the pre-antibiotic era, new alternative approaches are required such as quorum-sensing (QS) disruption and virulence inhibition, both of which apply no discernible selective pressure on bacteria, therefore mitigating the potential for the development of resistant strains. Bearing in mind the significant role of QS in orchestrating bacterial virulence, disrupting QS becomes essential for effectively diminishing bacterial virulence. This study aimed to assess the potential use of sub-inhibitory concentration (0.25 mg/mL) of glyceryl trinitrate (GTN) to inhibit virulence in Serratia marcescens and Pseudomonas aeruginosa. GTN could decrease the expression of virulence genes in both tested bacteria in a significant manner. Histopathological study revealed the ability of GTN to alleviate the congestion in hepatic and renal tissues of infected mice and to reduce bacterial and leukocyte infiltration. This study recommends the use of topical GTN to treat topical infection caused by P. aeruginosa and S. marcescens in combination with antibiotics.

Antibiotics resistance as a major public health concern: A pharmaco-epidemiological study to evaluate prevalence and antibiotics susceptibility-resistance pattern of bacterial isolates from multiple teaching hospitals.

BACKGROUND: Multi Drugs Resistance (MDR) is among the most worrisome healthcare issues resulting from inappropriate and indiscriminate utilization of antimicrobial agents which has compromised the efficacy and reliability of antimicrobial agents (AMAs). This has not only put a huge burden on the health care system but also is a major cause of morbidity and mortality. This project was designed to evaluate the prevalence of various microbial strains among patients admitted to various teaching hospitals and to assess their susceptibility and resistance towards clinically approved antibiotics. METHODS: The study was conducted during August 2021-February 2022 to determine the prevalence of common resistant strains of bacteria and to analyze their susceptibility pattern to the commonly prescribed antibiotics using standard procedures. One hundred and thirty biological samples including urine, blood, cerebrospinal fluid (CSF), wound swabs, pus and sputum were collected from the site of infection from the patients admitted at different wards of North West General Hospital (NWGH), Peshawar, Pakistan, Khyber Teaching Hospital (KTH), Peshawar Pakistan, and Hayat Abad Medical Complex (HMC) Peshawar Pakistan. Samples were collected and cultured following standard hospital procedures. The cultured samples were subjected to identification procedures including Gram staining, morphological characterization of bacterial colonies and biochemical assessments. The identified bacteria were tested for their susceptibility using Kirby-Bauer disc diffusion method. The diameter of Inhibitory Zones (DIZ) was analyzed following Clinical and Laboratory Standards Institute (CLSI) criteria. Minimum Inhibitory Concentrations (MICs) were evaluated using agar dilution method. Antimicrobials sensitivity were presented as antibiogram following CLSI M39 standard. RESULTS: A total of one hundred and thirty biological samples were collected, out of which one hundred and nine samples were positive for bacterial growth and were further processed for detailed analysis. The frequency and type of bacteria isolated from various cultures indicated that Gram negative bacteria (n = 92/109) were more dominant than Gram-positive (n = 17/109) pathogens. The most prevalent bacteria isolated was Escherichia coli (29.35 %), followed by Staphylococcus aureus (15.59 %), and Klebsiella spp, (12.84 %). In addition, other pathogens including, Enterobacter spp, Citrobacter spp, and Acinetobacter spp. showed a prevalence of 9.175 %, 8.25 %, and 5.50 % respectively. As indicated in the antbiogram, several organisms exhibited considerble decline in the sensitivies towards various antibiotics. A high percentage of resistance was observed against some antibiotics including trimethoprim, co-trimoxazole, amoxicillin/clavulanate, ciprofloxacin, piperacillin/tazobactam, cefotaxime and ceftazidime. CONCLUSION: The prevalence of resistant strains of pathogens is increasing day by day, while the antibiotics commonly prescribed against them are losing their efficacy, which is pushing the world to the era of pre-antibiotics. Unfortunately, the discovery of novel antibiotics is limited and researchers speculate that the is pushing towards pre-antibiotics era. Subsequently, efforts must be directed towards ensuring rational antibiotics use to prevent emergence of MDR pathogens. Our findings indicated that Gram negative bacteria including Escherichia coli was most prevalent. Other bacterial strains including S. aureus, Klebsiella spp, Enterobacter spp, Citrobacter spp, and Acinetobacter spp. were found among the causative agents. Unfortunately, considerable decline in the sensitivities of various bacterial isolated were observed towards the tested antibiotics. Previous studies reported the high prevalence of E. coli and S. aureus in clinical samples of Pakistani hospitals including hospitals in Peshawar and thus our findings are in agreement with the previous reports. Pharmacists being experts can play their role by promoting the optimal use of antimicrobial agents and educating healthcare professionals, patients and the public.

Assessment of a combination of plasma anti-histone autoantibodies and PLA2/PE ratio as potential biomarkers to clinically predict autism spectrum disorders.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficiencies in social interaction and repetitive behaviors. Multiple studies have reported abnormal cell membrane composition and autoimmunity as known mechanisms associated with the etiopathogenesis of ASD. In this study, multiple regression and combined receiver operating characteristic (ROC) curve as statistic tools were done to clarify the relationship between phospholipase A2 and phosphatidylethanolamine (PE) ratio (PLA2/PE) as marker of lipid metabolism and membrane fluidity, and antihistone-autoantibodies as marker of autoimmunity in the etiopathology of ASD. Furthermore, the study intended to define the linear combination that maximizes the partial area under an ROC curve for a panel of markers. Forty five children with ASD and forty age- and sex-matched controls were enrolled in the study. Using ELISA, the levels of antihistone-autoantibodies, and PLA2 were measured in the plasma of both groups. PE was measured using HPLC. Statistical analyses using ROC curves and multiple and logistic regression models were performed. A notable rise in the area under the curve was detected using combined ROC curve models. Additionally, higher specificity and sensitivity of the combined markers were documented. The present study indicates that the measurement of the predictive value of selected biomarkers related to autoimmunity and lipid metabolism in children with ASD using a ROC curve analysis should lead to a better understanding of the pathophysiological mechanism of ASD and its link with metabolism. This information may enable the early diagnosis and intervention.

Bee Pollen and Probiotics May Alter Brain Neuropeptide Levels in a Rodent Model of Autism Spectrum Disorders.

Neuropeptides play a major role in maintaining normal brain development in children. Dysfunction of some specific neuropeptides can lead to autism spectrum disorders (ASD) in terms of social interaction and repetitive behavior, but the exact underlying etiological mechanisms are still not clear. In this study, we used an animal model of autism to investigate the role of bee pollen and probiotic in maintaining neuropeptide levels in the brain. We measured the Alpha-melanocyte-stimulating hormone (α-MSH), Beta-endorphin (ß-End), neurotensin (NT), and substance P (SP) in brain homogenates of six studied groups of rats. Group I served as control, given only PBS for 30 days; Group II as an autistic model treated with 250 mg PPA/kg BW/day for 3 days after being given PBS for 27 days. Groups III-VI were denoted as intervention groups. G-III was treated with bee pollen (BP) 250 mg/kg body weight/day; G-IV with Lactobacillus paracaseii (LB) (109 CFU/mL) suspended in PBS; G-V with 0.2 g/kg body weight/day Protexin®, a mixture of probiotics (MPB); and G-VI was transplanted with stool from normal animals (FT) for 27 days prior to the induction of PPA neurotoxicity on the last 3 days of study (days 28-30). The obtained data were analyzed through the use of principal component analysis (PCA), discriminant analysis (DA), hierarchical clustering, and receiver operating characteristic (ROC) curves as excellent statistical tools in the field of biomarkers. The obtained data revealed that brain levels of the four measured neuropeptides were significantly reduced in PPA-treated animals compared to healthy control animals. Moreover, the findings demonstrate the ameliorative effects of bee pollen as a prebiotic and of the pure or mixed probiotics. This study proves the protective effects of pre and probiotics against the neurotoxic effects of PPA presented as impaired levels of α-MSH, ß-End, NT, and SP.

Site-directed mutagenesis of Serine-72 reveals the location of the fructose 6-phosphate regulatory site of the Agrobacterium tumefaciens ADP-glucose pyrophosphorylase.

The allosteric regulation of ADP-glucose pyrophosphorylase is critical for the biosynthesis of glycogen in bacteria and starch in plants. The enzyme from Agrobacterium tumefaciens is activated by fructose 6-phosphate (Fru6P) and pyruvate (Pyr). The Pyr site has been recently found, but the site where Fru6P binds has remained unknown. We hypothesize that a sulfate ion previously found in the crystal structure reveals a part of the regulatory site mimicking the presence of the phosphoryl moiety of the activator Fru6P. Ser72 interacts with this sulfate ion and, if the hypothesis is correct, Ser72 would affect the interaction with Fru6P and activation of the enzyme. Here, we report structural, binding, and kinetic analysis of Ser72 mutants of the A. tumefaciens ADP-glucose pyrophosphorylase. By X-ray crystallography, we found that when Ser72 was replaced by Asp or Glu side chain carboxylates protruded into the sulfate-binding pocket. They would present a strong steric and electrostatic hindrance to the phosphoryl moiety of Fru6P, while being remote from the Pyr site. In agreement, we found that Fru6P could not activate or bind to S72E or S72D mutants, whereas Pyr was still an effective activator. These mutants also blocked the binding of the inhibitor AMP. This could potentially have biotechnological importance in obtaining enzyme forms insensitive to inhibition. Other mutations in this position (Ala, Cys, and Trp) confirmed the importance of Ser72 in regulation. We propose that the ADP-glucose pyrophosphorylase from A. tumefaciens have two distinct sites for Fru6P and Pyr working in tandem to regulate glycogen biosynthesis.

Design, Microwave-Assisted Synthesis and In Silico Prediction Study of Novel Isoxazole Linked Pyranopyrimidinone Conjugates as New Targets for Searching Potential Anti-SARS-CoV-2 Agents.

A series of novel naphthopyrano[2,3-d]pyrimidin-11(12H)-one containing isoxazole nucleus 4 was synthesized under microwave irradiation and classical conditions in moderate to excellent yields upon 1,3-dipolar cycloaddition reaction using various arylnitrile oxides under copper(I) catalyst. A one-pot, three-component reaction, N-propargylation and Dimroth rearrangement were used as the key steps for the preparation of the dipolarophiles3. The structures of the synthesized compounds were established by 1H NMR, 13C NMR and HRMS-ES means. The present study aims to also predict the theoretical assembly of the COVID-19 protease (SARS-CoV-2 Mpro) and to discover in advance whether this protein can be targeted by the compounds 4a-1 and thus be synthesized. The docking scores of these compounds were compared to those of the co-crystallized native ligand inhibitor (N3) which was used as a reference standard. The results showed that all the synthesized compounds (4a-l) gave interesting binding scores compared to those of N3 inhibitor. It was found that compounds 4a, 4e and 4i achieved greatly similar binding scores and modes of interaction than N3, indicating promising affinity towards SARS-CoV-2 Mpro. On the other hand, the derivatives 4k, 4h and 4j showed binding energy scores (-8.9, -8.5 and -8.4 kcal/mol, respectively) higher than the Mpro N3 inhibitor (-7.0 kcal/mol), revealing, in their turn, a strong interaction with the target protease, although their interactions were not entirely comparable to that of the reference N3.