temporin and Disease-Models--Animal

Sepsis remains a major cause of morbidity and mortality in hospitalized patients, despite intense efforts to improve survival. The primary lead for septic shock results from activation of host effector cells by endotoxin, the lipopolysaccharide (LPS) associated with cell membranes of gram-negative bacteria. For these reasons, the quest for compounds with antiendotoxin properties is actively pursued. We investigated the efficacy of the amphibian skin antimicrobial peptide temporin L in binding Escherichia coli LPS in vitro and counteracting its effects in vivo. Temporin L strongly bound to purified E. coli LPS and lipid A in vitro, as proven by fluorescent displacement assay, and readily penetrated into E. coli LPS monolayers. Furthermore, the killing activity of temporin L against E. coli was progressively inhibited by increasing concentrations of LPS added to the medium, further confirming the peptide's affinity for endotoxin. Antimicrobial assays showed that temporin L interacted synergistically with the clinically used beta-lactam antibiotics piperacillin and imipenem. Therefore, we characterized the activity of temporin L when combined with imipenem and piperacillin in the prevention of lethality in two rat models of septic shock, measuring bacterial growth in blood and intra-abdominal fluid, endotoxin and tumor necrosis factor alpha (TNF-alpha) concentrations in plasma, and lethality. With respect to controls and single-drug treatments, the simultaneous administration of temporin L and beta-lactams produced the highest antimicrobial activities and the strongest reduction in plasma endotoxin and TNF-alpha levels, resulting in the highest survival rates.

Topics: Animals; Anti-Infective Agents; Antimicrobial Cationic Peptides; beta-Lactams; Disease Models, Animal; Drug Therapy, Combination; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Humans; Imipenem; Lipopolysaccharides; Male; Microbial Sensitivity Tests; Peritonitis; Piperacillin; Proteins; Rats; Rats, Wistar; Shock, Septic

Morbidity and mortality from staphylococcal toxic shock remain high, despite the availability of antibiotics to which the microorganism is sensitive.. In in vitro experiments, the ability of temporin A to inhibit lipoteichoic acid-induced production of tumor necrosis factor (TNF)- alpha and nitric oxide (NO) was determined. Also, mouse models of staphylococcal sepsis were used to evaluate the efficacy of temporin A alone and in combination with imipenem. BALB/c mice were injected intravenously with live Staphylococcus aureus or heat-killed cells and then received either isotonic sodium chloride solution, 2 mg/kg temporin A, 7 mg/kg imipenem, or 2 mg/kg temporin A in combination with 7 mg/kg imipenem immediately and 6 h after challenge. The main outcome measures were lethality rates, plasma bacterial counts, and plasma TNF- alpha and interleukin (IL)-6 levels.. The in vitro experiments showed that temporin A did not cause TNF- alpha or NO release. In the in vivo experiments with live bacteria, both compounds reduced lethality rates and bacterial growth. Imipenem exhibited the highest efficacy. The combination-treated group had significantly lower bacterial counts than did the singly-treated groups and the lowest lethality rates. In the experiments with heat-killed cells, only temporin A demonstrated significant efficacy with respect to lethality and reduction of plasma TNF- alpha and IL-6 levels.. This study shows that temporin A can reduce the stimulatory effects of bacterial cell components and suggests that it may be beneficial in the treatment of severe staphylococcal sepsis.

Topics: Animals; Anti-Bacterial Agents; Antimicrobial Cationic Peptides; Disease Models, Animal; Drug Evaluation, Preclinical; Drug Therapy, Combination; Imipenem; Male; Mice; Mice, Inbred BALB C; Proteins; Sepsis; Staphylococcal Infections; Staphylococcus aureus; Treatment Outcome

Bacteria that adhere to implanted medical devices play an important role in industry and in modern medicine. Staphylococci are among the most common pathogens that cause biomaterial infections. Vascular prosthetic graft infection is one of the most feared complications that the vascular surgeon treats, frequently resulting in prolonged hospitalization, organ failure, amputation, and death. A rat model was used to investigate the topical efficacies of temporin A and the quorum-sensing inhibitor RNAIII-inhibiting protein (RIP) as prophylactic agents of vascular prosthetic graft infections caused by Staphylococcus aureus and Staphylococcus epidermidis with intermediate resistance to glycopeptides.. Graft infections were established in the back subcutaneous tissue of adult male Wistar rats by implantation of Dacron prostheses 1 cm2 followed by topical inoculation with 2x10(7) colony-forming units of bacterial strains. The study included, for each staphylococcal strain, a control group (no graft contamination), a contaminated group that did not receive antibiotic prophylaxis, and 6 contaminated groups that received grafts soaked with temporin A, RIP, rifampin, temporin A plus RIP, RIP plus rifampin, or temporin A plus RIP. The infection was evaluated by quantitative agar culture. When tested alone, temporin A and RIP showed comparable efficacies, and their efficacies were significantly higher than that of rifampin against both strains. All combinations showed efficacies significantly higher than that of each single compound. The combinations of temporin A and RIP exerted the strongest antistaphylococcal efficacies, eliminating infection by 100%.. The results of the present study make these molecules potentially useful for antimicrobial chemoprophylaxis in vascular surgery.

Topics: Administration, Topical; Animals; Anti-Bacterial Agents; Antimicrobial Cationic Peptides; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Resistance, Microbial; Drug Therapy, Combination; Glycopeptides; Implants, Experimental; Male; Microbial Sensitivity Tests; Oligopeptides; Polyethylene Terephthalates; Proteins; Rats; Rats, Wistar; Rifampin; Staphylococcal Skin Infections; Staphylococcus aureus; Staphylococcus epidermidis; Subcutaneous Tissue; Treatment Outcome; Vancomycin; Vancomycin Resistance