Potential Synergy Activity of the Novel Ceragenin, CSA-13, against Carbapenem-Resistant Acinetobacter baumannii Strains Isolated from Bacteremia Patients

Carbapenem-resistant Acinetobacter baumannii is an important cause of nosocomial infections, particularly in patients in the intensive care units. As chronic infections are difficult to treat, attempts have been made to discover new antimicrobials. Ceragenins, designed to mimic the activities of antimicrobial peptides, are a new class of antimicrobial agents. In this study, the in vitro activities of CSA-13 either alone or in combination with colistin (sulphate), tobramycin, and ciprofloxacin were investigated using 60 carbapenem-resistant A. baumannii strains isolated from bacteremia patients blood specimens. MICs and MBCs were determined by microbroth dilution technique. Combinations were assessed by using checkerboard technique. The MIC 50 values (mg/L) of CSA-13, colistin, tobramycin, and ciprofloxacin were 2, 1, 1.25, and 80, respectively. The MIC 90 (mg/L) of CSA-13 and colistin were 8 and 4. The MBCs were equal to or twice greater than those of the MICs. Synergistic interactions were mostly seen with CSA-13-colistin (55%), whereas the least synergistic interactions were observed in the CSA-13-tobramycin (35%) combination. No antagonism was observed. CSA-13 appears to be a good candidate for further investigations in the treatment of A. baumannii infections. However, future studies should be performed to correlate the safety, efficacy, and pharmacokinetic parameters of this molecule

Synthesis and Evaluation of a Conjugate Vaccine Composed of Staphylococcus aureus Poly-N-Acetyl-Glucosamine and Clumping Factor A

The increasing frequency, severity and antimicrobial resistance of Staphylococcus aureus infections has made the development of immunotherapies against this pathogen more urgent than ever. Previous immunization attempts using monovalent antigens resulted in at best partial levels of protection against S. aureus infection. We therefore reasoned that synthesizing a bivalent conjugate vaccine composed of two widely expressed antigens of S. aureus would result in additive/synergetic activities by antibodies to each vaccine component and/or in increased strain coverage. For this we used reductive amination, to covalently link the S. aureus antigens clumping factor A (ClfA) and deacetylated poly-N-β-(1–6)-acetyl-glucosamine (dPNAG). Mice immunized with 1, 5 or 10 µg of the dPNAG-ClfA conjugate responded in a dose-dependent manner with IgG to dPNAG and ClfA, whereas mice immunized with a mixture of ClfA and dPNAG developed significantly lower antibody titers to ClfA and no antibodies to PNAG. The dPNAG-ClfA vaccine was also highly immunogenic in rabbits, rhesus monkeys and a goat. Moreover, affinity-purified, antibodies to ClfA from dPNAG-ClfA immune serum blocked the binding of three S. aureus strains to immobilized fibrinogen. In an opsonophagocytic assay (OPKA) goat antibodies to dPNAG-ClfA vaccine, in the presence of complement and polymorphonuclear cells, killed S. aureus Newman and, to a lower extent, S. aureus Newman ΔclfA. A PNAG-negative isogenic mutant was not killed. Moreover, PNAG antigen fully inhibited the killing of S. aureus Newman by antisera to dPNAG-ClfA vaccine. Finally, mice passively vaccinated with goat antisera to dPNAG-ClfA or dPNAG-diphtheria toxoid conjugate had comparable levels of reductions of bacteria in the blood 2 h after infection with three different S. aureus strains as compared to mice given normal goat serum. In conclusion, ClfA is an immunogenic carrier protein that elicited anti-adhesive antibodies that fail to augment the OPK and protective activities of antibodies to the PNAG cell surface polysaccharide

Cytotoxic activities of some Turkish medicinal plants against HeLa cells in vitro

The aim of this study was to characterize the biological activities of traditionally used medicinal plants generally collected from Kirklareli, Turkey against cancer. We evaluated the cytotoxic activities of different extracts prepared from Urtica dioica L. 1, Achillea millefolium L. ssp. pannonica 2, Malva sylvestris L. 3, Stachys cretica L. ssp. mersinaea (Boiss.) Rechf.f. (endemic) 4, Melissa officinalis L. 5, Cotinus coggyria Scop. 6, Sorbus aucuparia L. 7, and Plantago major L. ssp. major 8 species. Ethanol (a), petroleum ether (b), dichloromethane (c) and ethyl acetate (d) fractions of each plant material were obtained. Cytotoxicity in HeLa cells was evaluated using the MTT assay. Among the extracts, 7c, 2b, 6d, 7d, 7a, 2c, and 3b showed potent cytotoxic activity with IC50 values of less than 50 mu g/mL, in descending order. Dichloromethane extract of S. aucuparia is considered highly active, with IC50 of 15 03 (mean +/- SD) mu g/mL. The extracts 8a and 8b also showed good cytotoxic activity. According to the results, dichloromethane extracts of S. aucuparia had the most potent anticancer activity in HeLa cells and should be considered as a potential clinical agent. The results support the ethnomedical claims for these species and suggest further in vitro and/or in vivo studies of the active extracts

Cytotoxic activities of some Turkish medicinal plants against HeLa cells <em>in vitro</em>

43-49The aim of this study was to characterize the biological activities of traditionally used medicinal plants generally collected from Kırklareli, Turkey against cancer. We evaluated the cytotoxic activities of different extracts prepared from Urtica dioica L. 1, Achillea millefolium L. ssp. pannonica 2, Malva sylvestris L. 3, Stachys cretica L. ssp . mersinaea (Boiss.) Rechf.f. (endemic) 4, Melissa officinalis L. 5, Cotinus coggyria Scop. 6, Sorbus aucuparia L. 7 , and Plantago major L. ssp. major 8 species. Ethanol (a), petroleum ether (b), dichloromethane (c) and ethyl acetate (d) fractions of each plant material were obtained. Cytotoxicity in HeLa cells was evaluated using the MTT assay. Among the extracts, 7c, 2b, 6d, 7d, 7a, 2c, and 3b showed potent cytotoxic activity with IC50 values of less than 50 μg/mL, in descending order. Dichloromethane extract of S. aucuparia is considered highly active, with IC50 of 15±03 (mean ± SD) μg/mL. The extracts 8a and 8b also showed good cytotoxic activity. According to the results, dichloromethane extracts of S. aucuparia had the most potent anticancer activity in HeLa cells and should be considered as a potential clinical agent. The results support the ethnomedical claims for these species and suggest further in vitro and/or in vivo studies of the active extracts

Effects of Ceragenins and Antimicrobial Peptides on the A549 Cell Line and an In Vitro Co-Culture Model of A549 Cells and <i>Pseudomonas aeruginosa</i>

Pseudomonas aeruginosa is an important pathogen that can adhere to host tissues and epithelial surfaces, especially during chronic infections such as cystic fibrosis (CF) lung infections. The effect of ceragenins and antimicrobial peptides (AMP) on this colonization was investigated in a co-culture infection model. After determining the antimicrobial effects of the substances on P. aeruginosa planktonic cells, their cytotoxicity on the A549 cell line was also determined. After the A549 cell line was infected with P. aeruginosa, the effect of antimicrobials on intracellular bacteria as well as the effects in inhibiting the adhesion of P. aeruginosa were investigated. In addition, LDH release from cells was determined by performing an LDH experiment to understand the cytotoxicity of bacterial infection and antimicrobial treatment on cells. CSA-131 was determined as the antimicrobial agent with the highest antimicrobial activity, while the antimicrobial effects of AMPs were found to be much lower than those of ceragenins. The antimicrobial with the lowest IC50 value was determined as the combination of CSA-131 with Pluronic F127. CSA-13 has been determined to be the most effective antimicrobial with its effectiveness to both intracellular bacteria and bacterial adhesion. Nevertheless, further safety, efficacy, toxicity, and pharmacological studies of ceragenins are needed to evaluate clinical utility

In Vitro Activities of the Cationic Steroid Antibiotics CSA-13, CSA-131, CSA-138, CSA-142, and CSA-192 Against Carbapenem-resistant Pseudomonas aeruginosa

Objectives: Pseudomonas aeruginosa is an important opportunistic pathogen that is difficult to treat because of the antibiotic resistance that has developed in recent years. Increasing carbapenem resistance has led to a rise in hospital infections caused by this bacterium. As a result, researchers have begun to search for new molecules. Ceragenins are the general name for membrane-acting cationic steroid antimicrobial molecules that have activity similar to that of antimicrobial peptides. In this study, we investigated the in vitro activities of the cationic steroid antibiotics (CSAs) CSA-13. CSA-131, CSA-138, CSA-142, CSA-192, and colistin on carbapenem-resistant Pseudomonos aeruginosa (CRPA)

Comparative in vitro antimicrobial activities of CSA-142 and CSA-192, second-generation ceragenins, with CSA-13 against various microorganisms

Ceragenins, a novel family of antibiotics, are cationic derivatives of cholic acid and display broad-spectrum antimicrobial activities. Multiple ceragenins have been synthesized and studied, and most published data are with ceragenin CSA-13. This study aimed to investigate the in vitro antimicrobial properties of second-generation ceragenins, CSA-142 and CSA-192, and compare them to CSA-13. The antimicrobial activities of CSA-13, CSA-142 and CSA-192 were studied against 20 strains of Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans. Time-kill curve methods were performed to determine the bactericidal and fungicidal activities of the ceragenins against three strains of each microorganism. Overall, CSA-13 showed the lowest MIC values, but also CSA-142 and CSA-192 had good activities against tested microorganisms. The killing curves showed that ceragenins generally had bactericidal and fungicidal effects. The bactericidal and fungicidal behaviours of CSA-142 and CSA-192 may make them good alternative agents to CSA-13

Investigation of the in vitro antifungal and antibiofilm activities of ceragenins CSA-8, CSA-13, CSA-44, CSA-131, and CSA-138 against Candida species

Cationic steroid antimicrobials (CSA-ceragenin) are a new class of antimicrobial agent. In vitro activities of CSA-8, CSA-13, CSA-44, CSA-131, and CSA-138 and amphotericin B (AMP-B) were assessed against 50 nonrepeat Candida spp. isolates MICs, MFCs and combination studies were determined. Antibiofilm activities of CSAs, AMP-B, 2 azoles, and 2 echinocandins against Candida albicans were performed. Also, effects of coating the wells of plate with selected CSAs and antifungals were measured. The MIC50 (mu g/mL) values of CSA-8, CSA-13, CSA-44, CSA-131, CSA-138, and AMP-B were 16, 1, 2, 1, 1, and 1, respectively. The MFCs were equal to or 2-fold greater than those of the MICs. Synergistic interactions were mostly seen with CSA-13+ AMP-B combination, whereas the least synergistic interactions were observed with the CSA-131+ AMP-B combination. CSAs inhibited the attachment of Candida biofilms. The studied CSAs and antifungals inhibited C. albicans biofilm formation. In conclusion, CSA-13, CSA-131, and CSA-138 appear to be good candidates (alone or in combination) in the treatment of Candida infections as well as biofilm-related ones. (C) 2018 Elsevier Inc. All rights reserved

In vitro Activities of the Novel Ceragenin CSA-13, Alone or in Combination with Colistin, Tobramycin, and Ciprofloxacin, against Pseudomonas aeruginosa Strains Isolated from Cystic Fibrosis Patients

Background: The rise in the rates of antibiotic resistance among Pseudomonas aeruginosa strains from cystic fibrosis (CF) patients is concerning and underscores the need for the development of novel compounds. Among them CSA-13, a cationic steroid molecule, mimics the activity of naturally occurring antimicrobial peptides. Methods: MICs and MBCs were determined using the microbroth dilution technique. Combinations were assessed using the checkerboard technique. The bactericidal activity of CSA-13 in combination with colistin was measured using the time-kill curve method for two strains. Results: The MIC 90 values of CSA-13, colistin, tobramycin, and ciprofloxacin were 2, 1, 1, and 2 mg/l, respectively. The MBCs were equal to or two-fold greater than those of the MICs. With a fractional inhibitory concentration index of <= 0.5 as borderline, synergistic interactions were mostly seen with the CSA-13-colistin combination (54%). No antagonism was observed. The results of the time-kill curve analysis demonstrated rapid bactericidal activity of CSA-13 and synergism with colistin; in one strain early synergy was achieved. Conclusion: CSA-13 appears to be a good candidate in the treatment of P. aeruginosa strains in CF patients. Future studies should be performed to correlate the safety, efficacy, and pharmacokinetic parameters of this molecule. Copyright (C) 2012 S. Karger AG, Base