Anti-Infective Agents - Volume 18, Issue 3, 2020

In the current world, development and spread of antimicrobial resistance among bacteria have been raised and antimicrobial-resistant bacteria are one of the most important health challenges. The antimicrobial resistance genes can easily move and transfer among diverse bacterial species and strains. The human gut microbiota consists of a dense microbial population including trillions of microorganisms. Recently, studies have shown that the bacteria which make the major part of gut microbiota, harbor a variety of antimicrobial resistance genes which are called gut resistome. The transfer of resistance genes from commensal bacteria to gut-resident opportunistic bacteria may involve in the emergence of multi-drug resistant (MDR) bacteria. Thus, the main aim of the current mini-review was to study the mechanisms of exchange of antimicrobial resistance genes by commensal and opportunistic pathogenic bacteria in the human gut.

Background: Due to newly emerging microbial infections and the development of resistance against cutting-edge therapeutics, innovative and robust medicinal agents are required. Small ring heterocycles, such as pyrazole and its derivatives have been acknowledged to possess myriad biological properties and the presence of pyrazole in clinics like celecoxib, phenylbutazone (anti-inflammatory), CDPPB (antipsychotic), rimonabant (anti-obesity), antipyrine, difenamizole (analgesic), fipronil (broad-spectrum insecticidal), betazole (H2-receptor agonist) and fezolamide (antidepressant) drugs has proven the pharmacological perspective of pyrazole nucleus. Objectives: The current review paper aimed at a recent update made on novel methodologies adopted in the synthesis of pyrazole derivatives with the emphasis on antibacterial (DNA gyrase inhibition) and antifungal activities. Methods: Pyrazole is one of the major tools to be investigated in drug design and discovery. Many studies have been reported by researchers that have claimed the significant biological potential of these derivatives. However, numerous studies on pyrazoles compounds shown to exhibit potential antifungal and antibacterial activities, the focus has also been made on DNA gyrase inhibition. Additionally, some important patents granted to this heterocyclic nucleus related to antimicrobial potential are also addressed appropriately. Results: DNA gyrase is a promising biotarget yet to be explored against a number of medicinal agents. The present work provides valuable insight into synthetic methods and antibacterials/antifungal significance of pyrazoles in general as well as new inhibitors of DNA gyrase in particular. Conclusion: The manuscript constitutes a valuable reference which advocates candidature of pyrazoles as a potential therapeutic alternative as antibacterial and antifungal agent.

Introduction: In this research, we have reported the chemical composition and bioactivity of the essential oil from flowers of Matricaria chamomilla var. Chamomilla (MCCO) for the first time. The essential oil was extracted using a Clevenger-type apparatus. The chemical composition of the essential oil was identified by chromatography methods. DPPH Radical Scavenging Activity (RSA), β-carotene bleaching (BCB), and Ferrous Ion Chelating ability (FIC) were chosen to evaluate the MCCO antioxidant activity. Disc diffusion assay and Mínimum Inhibitory Concentration method (MIC) were selected to investigate antibacterial activity of MCCO. Hemolytic activity of MCCO on Red Blood Cells (RBCs) was measured through optical density. Methods: MTT method was used to determine the cytotoxicity effects of MCCO on human cáncer cells. MCCO was dominated byoxygenated sesquiterpenes (59.01%). α-Bisabolone oxide A (35.74%), α- bisabolol oxide A (19.07%), (Z)-β-farnesene (6.63%), and chamazulene (6.46%)wasfound as themajorcomponents oftheessentialoil. The oil represented an acceptable antioxidant activity. For antibacterial activity, MCCO prevented the growth of all selected microorganisms. The oil can be considered as a strong antibacterial agent as well as anantioxidant. Results: MCCO showed a low hemolytic rate (below 1.5%) on RBCs. The safety of MCCO as a food additive or other uses was suggested by the hemolysis result. Conclusion: MCCO was identified as a weak agent in the cytotoxicity assay.

Introduction: Currently animal venoms are considered a potential source of numerous bioactive peptides of biochemical and pharmacological interest, such as peptides with antithrombotic, anticoagulant and antimicrobial activity. Methods: Such is the case of the venom from the genus Scolopendromorpha, where numerous PAMs ranging from 2.5 to 4.4 kDa have been purified, they are broad spectrum isolates only of S. subspinipes mutilans. Results: In this study, an antimicrobial peptide (SPC13) of 13 kDa, present in the venom of Scolopendra polymorpha was purified by electroelution and presented antimicrobial activity against S. aureus and P. aeruginosa with MIC of 45 and 192.5 μg/ml respectively, as well as bacteriostatic activity against E. coli at a concentration of 155μg/ml. Conclusion: Additionally, this peptide has a 20.5% hemolytic activity. A partial sequence of SPC13 showed 98% identity with the histone H3 reported in S. viridis (GenkBank: DQ222181.1).

Background: Nasal carriage of Staphylococcus aureus (S. aureus) constitutes an important risk factor for subsequent infections in some types of patient populations. Decolonization of carriers using intranasal mupirocin is widely used as a preventive measure. However, resistance to this agent has been rising and causing failure in the decolonization, highlighting the need for new alternatives. Objective: The objective of our study was to evaluate the antibacterial activity of polyaminosteroid analogues (squalamine and BSQ-1) against S. aureus strains with different levels of mupirocin-resistance. Methods: Using the broth microdilution method, we evaluated the minimum inhibitory concentration (MIC) of these molecules against S. aureus clinical strains including mupirocin-resistant strains. The emergence of resistance was evaluated by long-term and repeated exposure of a susceptible S. aureus strain to subinhibitory concentrations of squalamine, BSQ-1 or mupirocin. Results: We found that squalamine and BSQ-1 are active against mupirocin-susceptible and -resistant clinical isolates with MIC values of 3.125 μg/mL. Additionally, repeated exposure of a S. aureus strain to squalamine and BSQ-1 did not lead to the emergence of resistant bacteria, contrarily to mupirocin. Conclusion: Our study suggests that these molecules constitute promising new alternatives to mupirocin for nasal decolonization and prevention of endogenous infections.

Background: 3,5-Bis(arylidene)-4-piperidinones (BAP) belong to a wide class of cross conjugated dienones. The 1,5-diaryl-3-oxo-1,4-pentadienyl fragment of the BAP moiety is responsible for the molecule's anti-tumor, antioxidant, antimicrobial and anti-inflammatory manifestations. In the present study, we present combinations of phosphonate and 3,5-bis(arylidene)-4- piperidone pharmacophores. The anti-inflammatory, anti-oxidant potential, anti-proliferative, cytotoxic potential and antimicrobial of the title compounds were evaluated in in-vitro bioassay paradigms. Methods: A novel class of phosphonate linked 3,5-Bis(aryl methylene)-4-piperidone derivatives were synthesized from simple, versitalie and efficient synthetic methodology. All of the synthesized compounds were screened for their in vitro anti-inflammatory, in vitro anti-oxidant potential, in vitro anti-proliferative, in vitro cytotoxic potential and in vitro antimicrobial activity. Amongst all the synthesized compounds in series, phosphonate derivatives of 3,5-Bis(arylmethylene)-4- piperidone containing 4-hydroxy-3-methoxyphenyl curcumin like prototype were more active than phenyl substituted compounds. Results: The results of the screening revealed that compounds 5e, 5f, 5g, 5h were more active candidates as compared to 5a, 5b, 5c and 5d, however 5d can be readily endorsed as the most active compound of the series. Structure- activity relationship of the synthesized series suggested that structural resemblance of the synthesized compounds with that of curcumin was enormously accountable for the compounds anti-inflammatory, antioxidant and cytotoxic potential activity. Conclusion: The in-vitro biological spectrum indicated that the substitution of groups at third and fourth position and alkyl phosphonates substitution potentiates the activity as compared to curcumin.

Aims: Drug resistance enzymes like beta-lactamases and Extended-Spectrum Beta- Lactamases (ESBLs) are mostly produced in the response of mutation and a few other factors. These enzymes are plasmid-mediated that can confer resistance against several β-lactam agents including cephalosporin and extended-spectrum cephalosporin. This study is conducted to determine the frequency of ESBL producing Klebsiella strains and to compare the phenotypic detection methods among various clinical samples collected from a commercial centralized Microbiology diagnostic laboratory. Materials and Methods: 125 Klebsiella strains were collected for this study. After identification and susceptibility testing, the phenotypic characterization of ESBL producing K. pneumoniae (n=89) and K. oxytoca (n=36) species was performed by using the double disc synergy test and the combination disc test. Results: In our study, 80 (64%) Klebsiella isolates were found to be ESBL positive due to their ability to produce an extended zone of inhibition with combination disc whereas 45 (36%) isolates were ESBL negative with no extended zone of inhibition. The phenotypic findings obtained by using the combination disc method and double disc synergy method were re-confirmed by molecular methods. By comparing the phenotypic finding with the genotypic results, we identified 80 (64%) Klebsiella isolates as ESBL positive and 45 (36%) isolates as ESBL negative. These genotypic findings of the ESBL producing strains were similar to the results obtained from the combination disc method. It also confirmed that the double disc synergy test was unable to detect 47 ESBL producing klebsiella strains. Conclusion: For implementing strict infection control policy and to stop the spread of resistant strains, it is important to detect ESBL producing isolates more rapidly. A suitable antimicrobial therapy can be started timely with the early detection of resistance enzymes either phenotypically or genotypically. It has been proved that the combination disc test can be used more reliably and preferably as compared to the double disc synergy test for the detection of ESBL enzymes produced by Klebsiella strains.

Background: Scabies is an enervating parasitic infestation of skin caused by Sarcoptes scabiei, affecting besides 130 million people at any time. Globally, this neglected tropical disease is amenable for 0.07% of the total burden of disease. Amomum subulatum Rox. (Large Cardamom) plant parts are used in traditional medicine for curing dyspepsia, skin disease, anorexia, dysentery, hyperacidity, ulcers, wounds, cardiac debility, fever, cough, liver congestion and gonorrhoea. Objective: The objective of this study was the phytochemical characterization of essential oil of A. subulatum leaves and evaluate its anti-scabies potential against S. scabiei. Methods: Essential oil was collected by hydrodistillation of fresh leaves of A. subulatum using Clevenger apparatus and subjected to Gas Chromatography (GC), gas chromatography-mass spectrometry (GC-MS) for identification and quantification of components of oil. Anti-scabies potential of essential oil of leaves of A. subulatum against S. scabiei was investigated by contact bioassay method. Results: GC and GC-MS analysis results revealed the presence of 39 constituents, of which terpinen-4- ol (29.87%), eucalyptol (18.69%), β-phallendrene (7.97%), γ-terpinene (6.67%), p-cymene (6.20%), were detected as major constituents. Oxygenated monoterpenes predominated in the A. subulatum essential oil, and constituted 59.03% of the total oil composition. The anti-scabies study demonstrated their scabicidal potential as its 10% concentration caused 100% mortality within 60 min. Conclusion: The result indicated anti-scabies potential of essential oil of A. subulatum so can be used as an alternative for the treatment and effective control of S. scabiei.

Background: Anti-phospholipid antibodies have the potential to become an alternative to conventional antibiotics for humans. The Antiphospholipid Syndrome (APS) is an autoimmune disease where the body’s defense system incorrectly reacts against its own phospholipids. APS is distinct through the existence of venous and arterial thromboses, frequently multiple and recurring fetal losses, commonly accompanied by moderate thrombocytopenia. Anti-phospholipid antibodies include lupus anti-coagulant, anti- cardiolipin, anti-beta 2 glycoprotein 1, and anti-prothrombin antibodies. Methods: In this study, the mechanism of action of Anti-phospholipid antibodies against Klebsiella pneumonia and Staphylococcus aureus was investigated in great detail using a unique combination of imaging and biophysical techniques. Antibacterial activity of antiphospholipid antibodies was detected by a diffusion method and the investigation of the complexity of antibody-antigen was done by spectroscopic examination, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) imaging. Results: There was a profound change in the bacteria treated with healthy and patient serum in the optical microscopic study. In all of the studied fields, bacterial treatment with patient serum immediately induced bacterial swelling and cumulative accumulation of the bacteria while no changes were observed in the healthy serum. Anti-bacterial activities of patient serum were detected on the plate. The result of this study showed that after platelet activation by thrombin and incubation with antiphospholipid antibodies, the platelet was aggregated. The transmission electron microscopy (TEM) image showed that the cell wall of Klebsiella pneumonia and Staphylococcus aureus incubated with antiphospholipid had a bizarre shape and antiphospholipid antibodies bound to bacterial membranes. Conclusion: The data indicated that antiphospholipid antibodies with hemolysis activities have an effect on Gram-positive and negative bacteria and these antibodies have the potential to become antibiotic for human.

Background: Infectious diseases contribute to substantial mortality and morbidity worldwide despite advances in therapeutic intervention highlighting the need to identify drugs with antimicrobial properties. Methods: Here, we utilised several compounds from the following classes: porphyrin, naphthalene diimide, aminophenol derivatives, and benzodioxane, and evaluated their antibacterial activities. Bactericidal and bacteriostatic activity of these compounds were determined against methicillinresistant Staphylococcus aureus (MRSA) and Escherichia coli K1 with various concentrations of the drugs. Moreover, the ability of the bacteria to bind/associate to host cells was also ascertained in the absence and presence of aforementioned compounds. Results: The results revealed that porphyrin derivative (AYTHPP) had potent effects against MRSA, abolishing viability and blocking binding to the host cells. Importantly, novel AYTHPP exhibited powerful effects against MRSA even though it was not photoactivated. In contrast, other compounds, including naphthalene diimide, acetamol derivatives and benzodioxane, showed no inhibitory effects. Conclusion: The mechanism of action of porphyrin is likely through the production of reactive oxygen species causing oxidative stress, leading to apoptosis and/or necrosis via perturbations in the plasma membrane. Future studies will determine their in vivo efficacy together will associated molecular mode of action.

Background: The microorganisms such as Penicillium expansum and Botrytis cinerea are wellknown pathogens in apples during postharvest. So, to protect apples from these pathogens, chemical control methods were exercised. Introduction: The main objective of this work was to study the chemical composition and the in-vitro and in-vivo antifungal properties of essential oil and hydrosol extract of Marrubium vulgare. Methods: In this work, the air-dried aerial parts of Marrubium vulgare were hydrodistilled in a Clevengertype apparatus. The essential oil and hydrosol extract isolated were analyzed using Gas Chromatography (GC) and Mass Spectrometry (GC/MS). The in-vitro antifungal activity of the both extracts was investigated against Botrytis cinerea, Penicillium expansum and Alternaria alternata fungi using radial growth technique. The effect of the essential oil and hydrosol extract on disease development of apple caused by Penicillium expansum in the in-vivo conditions was assessed. Results: The essential oil of Marrubium vulgare was characterized principally by E-β-caryophyllene (23.5%), E-β-farnesene (21%), α-humulene (14.8%), β-bisabolene (11.1%), caryophyllene oxide (6.8%) and phytol (3.1%). While, the methyl-eugenol (65.5%), α-Bisabolol (12.5%), linalool (6.5%) and caryophyllene oxide (6.2%) were the major compounds of hydrosol extract. The result of in-vitro antifungal activity of hydrosol extract showed an interesting antifungal inhibition against Botrytis cinerea, Penicillium expansum and Alternaria alternata with percentage inhibition ranging from 77% to 89% at low concentration of 0.15 mL/L. The essential oil was found to inhibit the growth of Penicillium expansum in a dose-dependent manner, with a percentage inhibition of 100% at 30 mL/L. Furthermore, essential oil and hydrosol extract have demonstrated promising in-vivo antifungal activity to control infection of apples by Penicillium expansum up to 25th day of storage, compared with the control. Conclusion: The preventive and protective effects of essential oil and hydrosol extract could be exploited as an ideal alternative to synthetic fungicides for using the protection of stored apples from fungal phytopathogens.

Introduction: Marburg viruses are a group of negative-stranded RNA virus. It was first identified in 1967 during a small outbreak. During that outbreak, the fatality rate increased highly and so many people died by the Marburg virus. Later seven strains of Marburg virus were identified from those infected humans. This virus causes Marburg Virus Disease (MVD) in human referred to as Marburg hemorrhagic fever. Marburg virus is endemic only to Africa; however, there have been outbreaks in Europe and the U.S.A. in recent times. Objective: However, the Marburg virus has a high fatality rate, so a preventive measure should be taken to prevent infection. As there is no effective therapeutic agent available against these viruses, effective vaccine design touching all strains would be a great step for human health. Methods: In our recent study, we used in silico analysis for designing a novel epitope-based vaccine against all strains of Marburg virus. As it consists of several structural proteins and multiple sequence alignment (MSA) of Glycoproteins, RNA-directed RNA polymerases, Nucleoproteins, Vp24 proteins, Vp30, Vp35, and Vp40 proteins showed all strains of Marburg virus were conserved in RNA-directed RNA polymerase proteins. Using that protein’s conserved region, T-cell and B-cell epitopes were determined. Results: Among the predicted epitope, only TIGNRAPYI was found to be highly immunogenic with 100% conservancy among all strain of human Marburg virus. The analysis also showed both types I and II major histocompatibility complex molecules interact with this epitope and found to be nonallergenic too. Conclusion: In vivo study of the proposed peptide is suggested for novel universal vaccine production that might be an effective way to prevent human Marburg virus disease.

Introduction: In continuation of our efforts to find new antimicrobials, herein we report the synthesis of various pyrazole, pyrazoline, and pyridine based novel bioactive heterocycles (3a-t). Methods: Newly synthesized compounds were analysed for their antimicrobial activity. Compounds 3c, 3h, 3i, 3k, 3n, and 3q showed significant antimicrobial activity. Results: Molecular docking study for the most active analogues against DNA gyrase subunit b (PDB ID: 1KZN) corroborated well with the observed antimicrobial potency exhibiting significant binding affinity. Conslusion: Interpretation of the chemical structures reported in this paper was based on IR, 1H NMR, 13C NMR, and mass spectral data.