Laboratory control of antimicrobial therapy

Potential role of non-antibiotics (helper compounds) in the treatment of multidrug-resistant Gram-negative infections: mechanisms for their direct and indirect activities.

Hepatitis C virus (HCV) infection affects an estimated 185 million people worldwide, with chronic infection often leading to liver cirrhosis and hepatocellular carcinoma. Although HCV is curable, there is an unmet need for the development of effective and affordable treatment options. Through a cell-based high-throughput screen, we identified chlorcyclizine HCl (CCZ), an over-the-counter drug for allergy symptoms, as a potent inhibitor of HCV infection. CCZ inhibited HCV infection in human hepatoma cells and primary human hepatocytes. The mode of action of CCZ is mediated by inhibiting an early stage of HCV infection, probably targeting viral entry into host cells. The in vitro antiviral effect of CCZ was synergistic with other anti-HCV drugs, including ribavirin, interferon-α, telaprevir, boceprevir, sofosbuvir, daclatasvir, and cyclosporin A, without significant cytotoxicity, suggesting its potential in combination therapy of hepatitis C. In the mouse pharmacokinetic model, CCZ showed preferential liver distribution. In chimeric mice engrafted with primary human hepatocytes, CCZ significantly inhibited infection of HCV genotypes 1b and 2a, without evidence of emergence of drug resistance, during 4 and 6 weeks of treatment, respectively. With its established clinical safety profile as an allergy medication, affordability, and a simple chemical structure for optimization, CCZ represents a promising candidate for drug repurposing and further development as an effective and accessible agent for treatment of HCV infection.

https://stm.sciencemag.org/content/scitransmed/7/282/282ra49.full.pdf

Repurposing of the antihistamine chlorcyclizine and related compounds for treatment of hepatitis C virus infection

Serotonin reuptake inhibitors were recently reported to possess antimicrobial potentials, potentiate activity of several antibiotics, reverse multidrug resistant phenotypes of bacteria and make them susceptible to previously resistant drugs. We investigated antimicrobial potentials of sertraline (SR) against ATCC strains, clinical isolates of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa alone and in-combination with seven antibiotics. Antifungal activity was investigated against four fungal strains including Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus, and Fusarium solani. Intrinsic antibacterial action and Minimum Inhibitory Concentrations (MICs) were determined using well assay, nutrient broth and agar dilution techniques. Disk diffusion and nutrient broth methods were used to study bacterial susceptibility to SR. Minimum Fungicidal Concentrations (MFCs) of SR were determined using Sabouraud dextrose Agar (SDA). Sertraline possesses strong intrinsic antibacterial, antifungal activities and has augmented the antibacterial activities of antibiotics. For S. aureus ATCC 6538, E. coli ATCC 8739 and P. aeruginosa ATCC 9027, the MICs of SR were 20, 40 and 60 μg ml−1, respectively, whereas 55.5% clinical isolates of S. aureus and 50% of E. coli strains were inhibited at 20 and 60 μg ml−1 of SR, respectively. Among the tested fungi, 60% of A. niger and A. fumigatus were inhibited at 40 and 80 μg ml−1, respectively. MFCs were 60 and 80 μg ml−1 for A. flavus and F. solani, respectively. Antibacterial activities of all antibiotics were significantly increased (p < 0.001) with the addition of SR 100 μg ml−1 against all tested bacteria. Combination study revealed that SR had significantly increased the activity of antibiotics, and some previously resistant strains were made susceptible. Thus antidepressants are potential sources of resistance modifying agents when used in combination.

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Sertraline enhances the activity of antimicrobial agents against pathogens of clinical relevance

Potential management of resistant microbial infections with a novel non-antibiotic: the anti-inflammatory drug diclofenac sodium

Methods: The minimum inhibitory concentration (MIC) of dicyclomine against the bacteria was determined by agar and broth dilution methods in vitro. The antibacterial activity of dicyclomine was confirmed by animal experiments. Toxicity and protective efficacy of the drug were tested in vivo. Results: Dicyclomine inhibited most of the bacterial isolates tested at 25-100 µg/ml concentration, and a few were sensitive even at a lower concentration (10 µg/ml). Dicyclomine was found to be bacteriostatic in nature against Shigella dysenteriae 7, and bactericidal against S. aureus NCTC 6571, 8530, and 8531. When administered to Swiss white mice at doses of 30 and 60 µg/mouse, dicyclomine protected the animals challenged with 50 MLD of Salmonella typhimurium NCTC 74. Interpretation & conclusion: Dicyclomine showed inhibitory action against several pathogenic bacteria. It also offered significant protection to mice against the bacterial challange. As dicyclomine is in routine therapeutic use, it may be developed as a potent antimicrobial agent in many infections.

Antibacterial potential of an antispasmodic drug dicyclomine hydrochloride.

Screening for anti-HIV drugs that can combine virucidal and virustatic activities synergistically.

Acacia auriculiformis belonging to the family Fabaceae (Leguminosae), is a plant of medicinal importance having antibacterial, anthelmintic, antifilarial and microbicidal activities. Earlier studies have revealed the spermicidal activity of the seeds of the plant. Phytochemical analyses of the methanolic and ethanolic extracts of A.auriculiformis were performed with the help of TLC, HPLC and HPTLC. Several different phytoconstituents were found to be present in both the extracts. These included alkaloids, flavonoids, tannin and phenolic compounds, steroid, triterpenoids, saponins, fats and oils. The flavonoid was characterized further and was found to be quercetin. Quercetin being known for providing antimicrobial activity, the extracts was both tested to determine such an activity in an in vitro system with the help of agar dilution technique following International Guidelines. A total of 13 strains belonging to both Gram positive and Gram negative types were included in this study. The extracts were incorporated into gradually increasing amounts in standard nutrient agar media. The test organisms were grown in nutrient broth for 18hr, standardized to contain 10 5 colony forming units and spot inoculated on agar media. Results were noted after 24hr. Most of the Gram positive and Gram negative bacteria were sensitive to the seed pod extracts of A.auriculiformis. However, 4 organisms were found to be resistant; these included Listeria monocytogenes MTCC 659, Klebsiella pneumoniae 1, Pseudomonas aeruginosa ATCC 27853 and Acinetobacter boumanii 530. It may be pointed out here that all these 4 bacteria were simultaneously resistant to a large number of known commonly used antibiotics. Ethanolic extract was found to be more active than the methanolic extract against both Gram positive and Gram negative bacteria.

Detection of various phytochemical compounds from seeds of a. auriculiformis for possibilities of obtaining potent antimicrobial agents

Despite widespread availability of antibiotics, it is currently advised that clinical administration of antibiotics against pathogenic bacteria should be prohibited due to the emergence of multi-drug resistant bacterial strains. Therefore newer and more effective antimicrobials are in demand to treat such cases. The aldehyde form of pyruvic acid called methylglyoxal has been reported to induce lanthanum-sensitive Ca 2+ transients for growth inhibition in Escheriachia coli. Based on this observation several Gram positive and Gram negative bacteria were tested to determine antibacterial potentiality of methylglyoxal alone and in combination with honey, since methylglyoxal is known to be present in the honey of manuka flowers. Methylglyoxal alone was found to be distinctly active against Staphylococcus aureus and also against E. coli, salmonellae and vibrios, while Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter boumanii were less sensitive to this agent. Supplementation of honey augmented antimicrobial property of methylglyoxal to a great extent. Methylglyoxal was found to be highly bactericidal in nature since there was a sharp fall in the number of viable bacteria after addition of methylglyoxal at the logarithmic growth phase and all the cells were killed within one hour. Rod-shaped cells of E.coli became round and adhered to each other after treatment with methylglyoxal in one hour.

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Evaluation of Bactericidal Action of Methylglyoxal and its Further Potentiation in the Presence of Honey

The flavonoid isolated from ethyl acetate fraction of methanolic extract of leaves of Colebrookea oppositifolia, exhibited distinct antimicrobial activity when tested against 185 bacteria belonging to both Gram positive and Gram negative types. Minimum Inhibitory Concentration (MIC) of fraction Cop1 was determined following CLSI guidelines. This herbal component significantly inhibited many bacterial strains at low levels; out of 55 Staphylococcus aureus 19 were inhibited between 50 and 100 µg/ml while 20 were inhibited at 200µg/ml. All strains of Bacillus spp were inhibited at 100 µg/ml level. Ten of 27 Escherichia coli failed to grow between 50 and 200 µg/ml of Cop1 and 10 others were inhibited at 400 µg/ml concentration. Among 32 strains of Shigella and Salmonella many had MIC value between 100 and 200 µg/ml. Out of 50 vibrios 6 failed to grow at 50 µg/ml of Cop1; while 31 vibrios were inhibited between 100 and 200 µg/ml of extract. Strains o f Proteus and Pseudomonas were less sensitive, while klebsiellae were resistant to Cop1. In vivo studies with this component showed that it could offer statistically significant protection (p<0.001) to Swiss Albino mice challenged with 50X Minimum Lethal Dose (MLD) of a virulent bacterium, Salmonella enterica serovar Typhimurium NCTC 74.

Musfiqua Mookerjee

Papers

Antibacterial potential of an antispasmodic drug dicyclomine hydrochloride.

Screening for anti-HIV drugs that can combine virucidal and virustatic activities synergistically.

Detection of various phytochemical compounds from seeds of a. auriculiformis for possibilities of obtaining potent antimicrobial agents

Evaluation of Bactericidal Action of Methylglyoxal and its Further Potentiation in the Presence of Honey

Evaluation of antimicrobial potentiality of a flavonoid, isolated from the leaf of the plant colebrookea oppositifolia