Therapeutic efficacy of buforin II and rifampin in a rat model of Acinetobacter baumannii sepsis.

OBJECTIVE: To investigate the efficacy of buforin II and rifampin in an experimental rat model of Acinetobacter baumannii sepsis. DESIGN: Prospective, randomized, controlled animal study. SETTING: Research laboratory in a university hospital. SUBJECTS: Adult male Wistar rats. INTERVENTIONS: The animals received intraperitoneally 1 mL saline containing 2 x 10 colony forming units of A. baumannii ATCC 19606 (model i) or the multiresistant strain (model ii). Immediately after bacterial challenge, animals received intravenously a single dose of isotonic sodium chloride solution (control groups C1 and C2), 1 mg/kg of buforin II, 10 mg/kg of rifampin, and 1 mg/kg of buforin II plus 10 mg/kg of rifampin, respectively. MEASUREMENTS AND MAIN RESULTS: Lethality, bacterial growth in blood and tissue burden, endotoxin, interleukin-6, and tumor necrosis factor-alpha concentrations in plasma. Buforin II showed good antimicrobial activity and achieved a significant reduction of plasma endotoxin and cytokines concentration when compared with control and rifampin-treated groups. Combination among buforin II proved to be the most effective treatment in reducing all variables measured. CONCLUSION: In an experimental model, buforin II and rifampin might have a potential role in the treatment of severe infections due to A. baumannii.

Discovery of a quorum-sensing inhibitor of drug-resistant staphylococcal infections by structure-based virtual screening.

Staphylococci are a major health threat because of increasing resistance to antibiotics. An alternative to antibiotic treatment is preventing virulence by inhibition of bacterial cell-to-cell communication using the quorum-sensing inhibitor RNAIII-inhibiting peptide (RIP). In this work, we identified 2',5-di-O-galloyl-d-hamamelose (hamamelitannin) as a nonpeptide analog of RIP by virtual screening of a RIP-based pharmacophore against a database of commercially available small-molecule compounds. Hamamelitannin is a natural product found in the bark of Hamamelis virginiana (witch hazel), and it has no effect on staphylococcal growth in vitro; but like RIP, it does inhibit the quorum-sensing regulator RNAIII. In a rat graft model, hamamelitannin prevented device-associated infections in vivo, including infections caused by methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis strains. These findings suggest that hamamelitannin may be used as a suppressor to staphylococcal infections.

RNAIII-inhibiting peptide enhances healing of wounds infected with methicillin-resistant Staphylococcus aureus.

Quorum sensing is a mechanism through which a bacterial population receives input from neighboring cells and elicits an appropriate response to enable survival within the host. Inhibiting quorum sensing by RNAIII-inhibiting peptide (RIP) has been demonstrated as a very effective mode of prevention and therapy for device-associated staphylococcal infections and was tested here for healing of wounds that are otherwise resistant to conventional antibiotics. Wounds, established through the panniculus carnosus of BALB/c mice, were inoculated with 5 x 10(7) CFU of methicillin-resistant Staphylococcus aureus. Mice were treated with Allevyn, RIP-soaked Allevyn (containing 20 microg RIP), daily intraperitoneal teicoplanin (7 mg/kg of body weight), Allevyn and teicoplanin, and RIP-soaked Allevyn and daily intraperitoneal teicoplanin. The main outcome measures were quantitative bacterial culture and histological examination with assessment of microvessel density and of vascular endothelial growth factor (VEGF) expression in tissue sections. Treatment with RIP-soaked Allevyn together with teicoplanin injection greatly reduced the bacterial load to 13 CFU/g (control untreated animals had 10(8) CFU/g bacteria). All other treatments were also significantly effective but only reduced the bacterial load to about 10(3) CFU/ml. Histological examination indicated that only treatment with RIP-soaked Allevyn with teicoplanin injection restored epithelial, granulation, and collagen scores, as well as microvessel density and VEGF expression, to the levels found with uninfected mice. In conclusion, we observed that RIP may be useful for the management of infected wounds and that it could represent an exciting and future alternative to the conventional antibiotics, at present considered the gold-standard treatments for methicillin-resistant S. aureus infections.

Efficacy of the combination of tachyplesin III and clarithromycin in rat models of Escherichia coli sepsis.

We investigated the efficacy of tachyplesin III and clarithromycin in two experimental rat models of severe gram-negative bacterial infections. Adult male Wistar rats were given either (i) an intraperitoneal injection of 1 mg/kg Escherichia coli 0111:B4 lipopolysaccharide or (ii) 2 x 10(10) CFU of E. coli ATCC 25922. For each model, the animals received isotonic sodium chloride solution, 1 mg/kg tachyplesin III, 50 mg/kg clarithromycin, or 1 mg/kg tachyplesin III combined with 50 mg/kg clarithromycin intraperitoneally. Lethality, bacterial growth in the blood and peritoneum, and the concentrations of endotoxin and tumor necrosis factor alpha (TNF-alpha) in plasma were evaluated. All the compounds reduced the lethality of the infections compared to that for the controls. Tachyplesin III exerted a strong antimicrobial activity and achieved a significant reduction of endotoxin and TNF-alpha concentrations in plasma compared to those of the control and clarithromycin-treated groups. Clarithromycin exhibited no antimicrobial activity but had a good impact on endotoxin and TNF-alpha plasma concentrations. A combination of tachyplesin III and clarithromycin resulted in significant reductions in bacterial counts and proved to be the most-effective treatment in reducing all variables measured.

Efficacy of the amphibian peptide distinctin in a neutropenic mouse model of staphylococcal sepsis.

OBJECTIVE: To investigate the efficacy of distinctin in a neutropenic mouse model of staphylococcal sepsis. DESIGN: Prospective, randomized, and controlled animal study. SETTING: Research laboratory in a University Hospital. SUBJECTS: BALB/c male mice. INTERVENTIONS: Mice were rendered neutropenic by injecting cyclophosphamide (200 mg/kg of body weight/day) on days -4 and -2 preinfection. Infection was induced at time 0 by intraperitoneal injection of 1 x 10(9) colony forming units of the staphylococcal strain. For each model, all animals were randomized to receive intravenous isotonic sodium chloride solution, 1 mg/kg distinctin, and 10 mg/kg imipenem, 10 mg/kg vancomycin, 10 mg/kg teicoplanin or 10 mg/kg linezolid alone, or combined with 1 mg/kg distinctin. MEASUREMENTS AND MAIN RESULTS: Lethality, bacterial growth in blood and peritoneum, spleen, liver, and mesenteric lymph nodes. RESULTS: All combined regimen showed lower lethality rates than singly treated-groups. Distinctin plus vancomycin or teicoplanin exerted the lowest lethality rate. All regimens were significantly superior to controls at reducing blood, spleen, peritoneum, liver and mesenteric lymph node complex bacterial burdens, whereas all combined treated groups were higher effective than singly treated groups. CONCLUSION: Our data indicate that distinctin alone or combined with other antibiotics may be useful in treating severe staphylococcal infections.

Efficacy of the bovine antimicrobial peptide indolicidin combined with piperacillin/tazobactam in experimental rat models of polymicrobial peritonitis.

OBJECTIVE: To investigate the efficacy of piperacillin/tazobactam combined with indolicidin in the prevention of lethality in two rat models of polymicrobial peritonitis. DESIGN: Prospective, randomized, controlled animal study. SETTING: Research laboratory in a university hospital. SUBJECTS: Adult male Wistar rats. INTERVENTIONS: Adult male Wistar rats were given an intraperitoneal injection of 1 mg of Escherichia coli 0111:B4 lipopolysaccharide or had intraabdominal sepsis induced by cecal ligation and puncture. For each model, all animals were randomized to receive isotonic sodium chloride solution intraperitoneally, 1 mg/kg indolicidin, 120 mg/kg piperacillin/tazobactam, and 1 mg/kg indolicidin combined with 120 mg/kg piperacillin/tazobactam. Each group included 20 animals. MEASUREMENTS AND MAIN RESULTS: Main outcome measures were: bacterial growth in blood, peritoneum, spleen, liver, and mesenteric lymph nodes; endotoxin, interleukin-6, and tumor necrosis factor-alpha concentrations in plasma; and lethality. All compounds reduced significantly bacterial growth and lethality compared with saline treatment. Treatment with indolicidin resulted in significant decrease in plasma endotoxin and cytokine levels, whereas piperacillin/tazobactam exerted the opposite effect. The combination between indolicidin and piperacillin/tazobactam proved to be the most effective treatment in reducing all variables measured. CONCLUSION: Indolicidin may have potential therapeutic usefulness alone and when associated with piperacillin/tazobactam in polymicrobial peritonitis.

Protective effects of the combination of alpha-helical antimicrobial peptides and rifampicin in three rat models of Pseudomonas aeruginosa infection.

INTRODUCTION: An experimental study has been performed to compare the in vitro activity and the in vivo efficacy of magainin II and cecropin A with or without rifampicin against control and multidrug-resistant Pseudomonas aeruginosa strains. METHODS: In vitro experiments included MIC determinations and synergy studies. For in vivo studies, animals were given an intraperitoneal injection of P. aeruginosa lipopolysaccharide, P. aeruginosa ATCC 27853 and one clinical multiresistant P. aeruginosa strain. Groups of animals received intravenously isotonic sodium chloride solution, 10 mg/kg rifampicin, 1 mg/kg magainin II or 1 mg/kg cecropin A. Two groups of animals received a combined treatment with magainin II + rifampicin or cecropin A + rifampicin at the same dosages as the singly treated groups. In addition, a further group was treated with tazobactam/piperacillin (120 mg/kg). Lethality, bacterial growth in blood and peritoneum, and endotoxin and TNF-alpha concentrations in plasma were evaluated. RESULTS: Combinations of alpha-helical antimicrobial peptides showed in vitro synergistic interaction. Magainin II and cecropin A exerted strong antimicrobial activity and achieved a significant reduction in plasma endotoxin and TNF-alpha concentrations when compared with control and rifampicin-treated groups. Rifampicin exhibited no anti-P. aeruginosa activity and good substantial impact on endotoxin and TNF-alpha plasma concentrations. Combined treatment groups had significant reductions in bacterial count, positive blood cultures and mortality rates when compared with singly treated and control groups. CONCLUSIONS: Our results highlight the potential usefulness of these combinations that provide future therapeutic alternatives in P. aeruginosa infections.

A novel Zip2 Gln/Arg/Leu codon 2 polymorphism is associated with carotid artery disease in aging.

Zinc deficiency represents a risk factor for carotid stenosis (CS) development. In mammals, members of the ZIP family regulate zinc uptake, and hZip2 is a human zinc importer upregulated by zinc depletion. The purpose of this study was to investigate the association of a novel Zip2 Gln/Arg/Leu codon 2 polymorphism with CS, analyzing 250 CS patients and 259 elderly controls. CS patients showed an increased GG genotype frequency (60% vs. 47.5%), and a reduced TT frequency (6% vs. 10%) (p < 0.05 by chi(2) test). In conclusion, Zip2 Gln/Arg/Leu polymorphism plays a role in the susceptibility to carotid artery disease.

BMAP-28 improves the efficacy of vancomycin in rat models of gram-positive cocci ureteral stent infection.

An experimental study was performed to evaluate the efficacy of BMAP-28 alone and in combination with vancomycin in animal models ureteral stent infection due to Enterococcus faecalis and Staphylococcus aureus. Study included a control group without bacterial challenge to evaluate the sterility of surgical procedure, a challenged control group that did not receive any antibiotic prophylaxis and for each bacterial strain three challenged groups that received (a) 10 mg/kg vancomycin intraperitoneally, immediately after stent implantation, (b) BMAP-28-coated ureteral stents where 0.2-cm(2) sterile ureteral stents were incubated in 1mg/l BMAP-28 solution for 30 min immediately before implantation and (c) intraperitoneal vancomycin plus BMAP-28-coated ureteral stent at the above concentrations. Experiments were performed in duplicate. Ureteral stents were explanted at day 5 following implantation and biofilm bacteria enumerated. Our data showed that rats that received intraperitoneal vancomycin showed the lowest bacterial numbers. BMAP-28 combined with vancomycin showed efficacies higher than that of each single compound. These results highlight the potential usefulness of this combination in preventing ureteral stent-associated in gram-positive infections.

Temporin A is effective in MRSA-infected wounds through bactericidal activity and acceleration of wound repair in a murine model.

We investigated the effect of topical temporin A in the management of methicillin-resistant strain of Staphylococcus aureus (MRSA)-infected experimental surgical wounds in mice. The wound, cut through the panniculus carnosus of BALB/c mice, was inoculated with 5x10(7) colony-forming units of MRSA. Mice were treated with Allevyn, temporin A-soaked Allevyn, Allevyn and daily intraperitoneal teicoplanin (7mg/kg), temporin A-soaked Allevyn and daily intraperitoneal teicoplanin. Main outcome measurements were: quantitative bacterial culture, histological examination with assessment of micro-vessel density and of vascular endothelial growth factor (VEGF) expression in tissue sections, and VEGF plasma levels alike. Treatment with temporin-A associated with teicoplanin injection significantly reduced bacterial load to 0.85 x 10(1)+/-0.1 x 10(1)CFU/ml. Histological examination showed that infected mice receiving temporin A-soaked Allevyn (with or without teicoplanin) had a higher degree of granulation tissue formation and collagen deposition compared to the other treated groups. A significant increase in serum VEGF expression was observed in mice receiving temporin A topically and temporin A topically associated with intraperitoneal teicoplanin. In conclusion our results demonstrated that temporin A is effective in the management of infected wounds, by a significant bacterial growth inhibition and acceleration of wound repair process.

Tachyplesin III and granulocyte-colony stimulating factor enhance the efficacy of tazobactam/piperacillin in a neutropenic mouse model of polymicrobial peritonitis.

We investigated the efficacy of tazobactam/piperacillin (TZP), tachyplesin III and granulocyte-colony stimulating factor (G-CSF) in an experimental murine neutropenic intraabdominal infection. BALB/c male mice were rendered neutropenic by intraperitoneal administration of cyclophosphamide on days -4 and -2 pre-infection. Septic shock was induced by cecal ligation and puncture. Animals received intravenously isotonic sodium chloride solution (control group C1), 1mg/kg of tachyplesin III, 120 mg/kg of TZP, 0.1mg/kg of G-CSF, tachyplesin III plus TZP, G-CSF plus TZP and finally tachyplesin III plus G-CSF plus TZP, respectively. Lethality, bacterial growth in blood, peritoneum, spleen, liver, and mesenteric lymph nodes, endotoxin, IL-6 and TNF-alpha concentrations in plasma were evaluated. All compounds reduced the lethality when compared to controls. Endotoxin and cytokine plasma levels were significantly higher in TZP-treated animals compared to tachyplesin III-treated animals. Finally, all drug combinations showed to be the most effective treatment in reducing all variables measured. Interestingly, the strongest results concerning the bacterial growth inhibition, lethality and endotoxemia were obtained when the three compounds were contemporaneously administered. The presence of their positive interaction makes tachyplesin III and G-CSF potentially valuable as an adjuvant for antimicrobial chemotherapy of sepsis.

The antimicrobial peptide tachyplesin III coated alone and in combination with intraperitoneal piperacillin-tazobactam prevents ureteral stent Pseudomonas infection in a rat subcutaneous pouch model.

We investigated the efficacy of Tachyplesin III alone or combined with piperacillin-tazobactam (TZP) to prevent biofilm formation in vitro and in a rat model of Pseudomonas aeruginosa ureteral stent infection. We have observed that in vitro TZP, in presence of Tachyplesin III, showed minimal inhibitory concentrations (MIC)s twofold and minimal bactericidal concentrations (MBC)s eightfold lower. The in vivo study showed that rats that received intraperitoneal TZP showed the lowest bacterial numbers. Tachyplesin III combined with TZP showed efficacies higher than that of each single compound. Coating ureteral stents with Tachyplesin III is able to inhibit bacterial growth up to 1,000 times.

The lipopeptides Pal-Lys-Lys-NH(2) and Pal-Lys-Lys soaking alone and in combination with intraperitoneal vancomycin prevent vascular graft biofilm in a subcutaneous rat pouch model of staphylococcal infection.

Staphylococcal infections are often associated with the use of implantable medical devices. Such infections are difficult to treat because of biofilm resistance to antibiotics and are common causes of morbidity and mortality. Graft infections were established in the back subcutaneous tissue of adult male Wistar rats by implantation of Dacron prostheses followed by topical inoculation with 2x10(7) colony-forming units of bacterial strains. The study included a control group, a contaminated group that did not receive any antibiotic prophylaxis and five contaminated groups that received intraperitoneal vancomycin, Pal-Lys-Lys-NH(2) and Pal-Lys-Lys-soacked graft, and vancomycin plus Pal-Lys-Lys-NH(2) or Pal-Lys-Lys-soacked graft, respectively. The infection was evaluated by using sonication and quantitative agar culture. Moreover, an in vitro antibiotic susceptibility assay for Staphylococcus aureus biofilms was performed to elucidate the same activity. When tested alone, vancomycin and lipopeptides showed comparable efficacies. All combinations showed efficacies significantly higher than that of each single compound. Vancomycin combined to Pal-Lys-Lys-NH(2) exerted the strongest anti-staphylococcal efficacies. The in vitro studies showed, that MIC and MBC values for vancomycin were lower in presence of lipopeptides. They reduce the bacterial load and to enhance the effect of vancomycin in the prevention of vascular graft staphylococcal infections.

Distinctin improves the efficacies of glycopeptides and betalactams against staphylococcal biofilm in an experimental model of central venous catheter infection.

The ability of microorganisms to adhere to medical implants is a problem of high visibility and has been focused in numerous investigations. To assess the efficacy of distinctin and conventional antibiotics in the treatment of central venous catheter in vitro and in vivo studies were performed. The in vitro susceptibility assay was performed against S. aureus biofilms developed on 96-well polystyrene tissue culture plates. Efficacy studies were performed in a rat model of CVC infection. Twenty-four hours after implantation, the catheters were filled with distinctin. Thirty minutes later, rats were challenged via the CVC with S. aureus. Administration of antibiotics into the CVC at a concentration equal to the MBC for adherent cells, or at 1024 microg/mL began 24 h later. The killing activities of all antibiotics against adherent bacteria were at least four- to eightfold lower than against freely growing cells. When antibiotics were used in distinctin pretreated wells, they showed a significant increase of activity. The in vivo studies showed that when CVCs were pretreated with distinctin biofilm bacterial load was further decreased to 10(1) CFU/mL and bacteremia was not detected. Distinctin displays potential as an adjunctive agent to antibiotics in the treatment of CVC-related infections.

Pretreatment with the protegrin IB-367 affects Gram-positive biofilm and enhances the therapeutic efficacy of linezolid in animal models of central venous catheter infection.

BACKGROUND: Biofilms play an important role in the pathogenesis of several chronic infections and nosocomial infections related to indwelling medical devices. METHODS: To assess the efficacy of IB-367 and linezolid (LZD) in the treatment of central venous catheter (CVC) infections using the antibiotic-lock technique, in vitro and in vivo studies were performed. The in vitro antibiotic susceptibility assay for Staphylococcus aureus and Enterococcus faecalis biofilms developed on 96-well polystyrene tissue culture plates was performed to determine the activity of the compounds. Efficacy studies were performed in rat models of Gram-positive CVC infection. Silastic catheters were implanted into the superior cava of adult male Wistar rats. Twenty-four hours after implantation, the catheters were pretreated by filling with IB-367. Thirty minutes later, rats were challenged via the CVC with 1.0 x 10(6) CFU (colony forming units) of S aureus strain diffuse Smith and clinical isolate of slime-producing E faecalis. Administration of LZD into the CVC at a concentration equal to the minimum bacteriocidal concentration observed using adherent cells or at a much higher concentration (1024 microg/mL) began 24 hours later. RESULTS: Both for S aureus and E faecalis, the killing activities of LZD against adherent bacteria were at least 4-fold to 8-fold lower than that against freely growing cells. For both strains, in IB-367-pretreated wells, LZD strongly increases its activity. The in vivo studies showed that when CVCs were pretreated with IB-367, Gram-positive biofilm bacterial load was further decreased to 10(1) CFU/mL and bacteremia was not detected. CONCLUSIONS: IB-367 has potential as an adjunctive agent to LZD in the treatment of Gram-positive biofilm infections such as CVC infections.

The cathelicidin-derived tritrpticin enhances the efficacy of ertapenem in experimental rat models of septic shock.

Sepsis remains a serious clinical problem despite intense efforts to improve survival. In this study, the efficacy of ertapenem combined with the cathelicidin tritrpticin was investigated in two rat models of septic shock. Main outcome measures were bacterial growth in blood, peritoneum, spleen, liver, and mesenteric lymph nodes; endotoxin, interleukin 6, and tumor necrosis factor alpha concentrations in plasma; and lethality. Adult male Wistar rats were given (1) an intraperitoneal injection of 1 mg Escherichia coli serotype 0111:B4 LPS or (2) intra-abdominal sepsis induced via cecal ligation and puncture. For each model, all animals were randomized to receive intraperitoneally isotonic sodium chloride solution, 1 mg/kg tritrpticin, 15 mg/kg ertapenem, and 1 mg/kg tritrpticin combined with 15 mg/kg ertapenem. Each group included 20 animals. All compounds significantly reduced bacterial growth and lethality as compared with saline treatment. Treatment with tritrpticin resulted in significant decrease in plasma endotoxin and cytokine levels, whereas ertapenem exerted opposite effect. The combination between tritrpticin and ertapenem proved to be the most effective treatment in reducing all variables measured. In conclusion, tritrpticin enhances ertapenem efficacy in gram-negative septic shock rat models.

RNAIII-inhibiting peptide in combination with the cathelicidin BMAP-28 reduces lethality in mouse models of staphylococcal sepsis.

A mouse model of staphylococcal sepsis was used to evaluate the efficacy of RNAIII-inhibiting peptide (RIP) combined with the cathelicidin BMAP-28. Preliminary in vitro studies showed that both peptides, alone or combined, were able to inhibit the lipoteichoic acid-induced production of tumor necrosis factor alpha and nitric oxide by RAW 264.7 cells. For in vivo experiments, the main outcome measures were lethality, quantitative blood cultures, and detection of tumor necrosis factor alpha and interleukin 6 plasma levels. BALB/c mice were injected i.v. with 2.0 x 10(6) colony-forming units of live Staphylococcus aureus ATCC 25923 or with 5.0 x 10(8) heat-killed cells of the same strain. All animals were randomized to receive i.v. isotonic sodium chloride solution, 10-mg/kg RIP, alone or in combination with 2-mg/kg BMAP-28, 7-mg/kg imipenem, or 7-mg/kg vancomycin, immediately and at 6 hours after bacterial challenge. In in vivo experiments performed with live bacteria, all compounds reduced lethality rates and bacteremia when compared with controls. In general, combined-treated groups had significantly lower bacteremia when compared with single-treated groups. Lowest lethality rates and bacteremia were obtained when RIP was administered in combination with BMAP-28 or vancomycin. In the experiments performed using heat-killed organisms, only BMAP-28 demonstrated significant efficacy on lethality rates and cytokines plasma levels when compared with controls. RIP combined with BMAP-28 exhibited the highest efficacy on all main outcome measurements. These data were observed on both immediate and delayed treatments. These results highlight the capacity of RIP and BMAP-28 to reduce the septic effects of bacterial cell components and exotoxins, and suggest their potential use in the treatment of severe staphylococcus-associated sepsis.

Effects of the antimicrobial peptide BMAP-27 in a mouse model of obstructive jaundice stimulated by lipopolysaccharide.

An experimental study was designed to investigate the efficacy of BMAP-27, a compound of the cathelicidin family, in neutralizing Escherichia coli 0111:B4 lipopolysaccharide (LPS) in bile duct-ligated mice. Main outcome measures were: endotoxin and TNF-alpha concentrations in plasma, evidence of bacterial translocation in blood and peritoneum, and lethality. Adult male BALB/c mice were injected intraperitoneally with 2 mg/kg E. coli 0111:B4 LPS 1 week after sham operation or bile duct ligation (BDL). Six groups were studied: sham with placebo, sham with 120 mg/kg tazobactam-piperacillin (TZP), sham with 1 mg/kg BMAP-27, BDL with placebo, BDL with 120 mg/kg TZP, and BDL with 1mg/kg BMAP-27. After LPS, TNF-alpha plasma levels were significantly higher in BDL mice compared to sham-operated animals. BMAP-27 achieved a significant reduction of plasma endotoxin and TNF-alpha concentration when compared with placebo- and TZP-treated groups. On the other hand, both TZP and BMAP-27 significantly reduced the bacterial growth compared with saline treatment. Finally, LPS induced 60% and 55% lethality in BDL placebo- and TZP-treated treated mice and no lethality in sham-operated mice, while only BMAP-27 significantly reduced the lethality to 10%. In light of its dual antimicrobial and anti-endotoxin properties, BMAP-27 could be an interesting compound to inhibit bacterial translocation and endotoxin release in obstructive jaundice.

Experimental study on the efficacy of combination of alpha-helical antimicrobial peptides and vancomycin against Staphylococcus aureus with intermediate resistance to glycopeptides.

An experimental study has been performed to compare the in vitro activity and the in vivo efficacy of magainin II and cecropin A, two alpha-helical antimicrobial peptides, and vancomycin against Staphylococcus aureus with intermediate resistance to glycopeptides. In vitro experiments included MIC determination, time-kill and synergy studies. For in vivo studies, a mouse model of staphylococcal sepsis has been used. Main outcome measures were: lethality, quantitative blood cultures and detection of TNF-alpha and interleukin-6 (IL-6) plasma levels. Combinations of alpha-helical antimicrobial peptides showed in vitro synergistic interaction. Significant increase in efficacy was also observed in vivo: combined-treated groups had significant lower bacteremia when compared to single-treated groups. Magainin II combined with vancomycin exhibited the highest efficacy on all main outcome measurements. These results highlight the potential usefulness of these combinations and provide future therapeutic alternative in infections due to glycopeptides resistant staphylococci in the coming years.

Pre-treatment of central venous catheters with the cathelicidin BMAP-28 enhances the efficacy of antistaphylococcal agents in the treatment of experimental catheter-related infection.

An in vitro antibiotic susceptibility assay for Staphylococcus aureus biofilms developed on 96-well polystyrene tissue culture plates was performed to elucidate the activity of the 27 residues cathelicidin peptide BMAP-28, quinupristin/dalfopristin (Q/D), linezolid, and vancomycin. Efficacy studies were performed in a rat model of staphylococcal CVC infection. Silastic catheters were implanted into the superior cava. Twenty-four hours after implantation the catheters were filled with BMAP-28. Thirty minutes later rats were challenged via the CVC with 1.0x10(6) CFU of S. aureus strain Smith diffuse. Administration of antibiotics into the CVC at a concentration equal to the MBC observed using adherent cells, or at a much higher concentration (1024 microg/mL) began 24 h later. The inhibition activities of all antibiotics against adherent bacteria were at least two-four-fold lower that against freely growing cells. When antibiotics were used in BMAP-28 pre-treated wells, they showed higher activities. The in vivo studies showed that when CVCs were pre-treated with BMAP-28 or with a high dose of antibiotics, biofilm bacterial load was reduced from 10(7) to 10(3) CFU/mL and bacteremia reduced from 10(3) to 10(1) CFU/mL. When CVCs were treated with both BMAP-28 and antibiotics, biofilm bacterial load was further decreased to 10(1) CFU/mL and bacteremia was not detected. These results suggest that CVC pre-treated with BMAP-28 represents an attractive choice for the treatment of device-related infections caused by staphylococci.