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We investigated the efficacy of colistin combined with pexiganan in experimental mouse models of Acinetobacter baumannii infection.Adult male BALB/c mice received intraperitoneally 1 mL saline containing 2 × 10 CFU of susceptible and multiresistant A. baumannii. Two hours after bacterial challenge, animals received 1 mg/kg of colistin, 1 mg/kg of pexiganan, or 1 mg/kg of colistin plus 1 mg/kg of pexiganan.Blood culture positivity, the quantities of bacteria in the intra-abdominal fluid, the rate of lethality and immunological studies, such as immunophenotyping and NK cytotoxicity, were evaluated.In the in vitro study, A. baumannii showed susceptibility to colistin and pexiganan and a strong synergy was observed by testing colistin combined with pexiganan with fractionary inhibitory concentration index of 0.312 for both strains.In the in vivo study colistin or pexiganan alone showed a good antimicrobial efficacy. When colistin was combined with pexiganan, the positive interaction produced low bacterial counts that were statistically significant versus singly treated groups. For both strains the highest rate of survival was observed in combined-treated groups (90%).Pexiganan increased NK cytotoxic activity over the levels of infected and colistin-treated animals.In conclusion, pexiganan combined with colistin was found to be efficacious against A. baumannii infection.

There is limited information on the variations of HIV-1 DNA mutation profile in reverse transcriptase (RT) and protease (PR) genes during suppressive antiretroviral treatment (plasma HIV-1 RNA continuously 2.5 copies/ml). Integrated HIV-1 DNA did not show fluctuations during the study period. Sequencing of the PR and RT regions from HIV-1 DNA revealed changes in the resistance mutation profile in five patients. Total HIV-1 DNA declined after the introduction of RAL-based therapy, with a rebound after 2 years. No changes were observed in levels of integrated DNA, suggesting limited effect on archived HIV. The RT and PR sequence changes in archived HIV-1 DNA suggest that variation of the mutation profile can occur even in the absence of detectable HIV-1 RNA. J. Med. Virol. 88:2115-2124, 2016. © 2016 Wiley Periodicals, Inc.

As bacteria are becoming more resistant to commonly used antibiotics, alternative therapies are being sought. whISOBAX (WH) is a witch hazel extract that is highly stable (tested up to 2 months in 37 &deg, C) and contains a high phenolic content, where 75% of it is hamamelitannin and traces of gallic acid. Phenolic compounds like gallic acid are known to inhibit bacterial growth, while hamamelitannin is known to inhibit staphylococcal pathogenesis (biofilm formation and toxin production). WH was tested in vitro for its antibacterial activity against clinically relevant Gram-positive and Gram-negative bacteria, and its synergy with antibiotics determined using checkerboard assays followed by isobologram analysis. WH was also tested for its ability to suppress staphylococcal pathogenesis, which is the cause of a myriad of resistant infections. Here we show that WH inhibits the growth of all bacteria tested, with variable efficacy levels. The most WH-sensitive bacteria tested were Staphylococcus epidermidis, Staphylococcus aureus, Enterococcus faecium and Enterococcus faecalis, followed by Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Streptococcus agalactiae and Streptococcus pneumoniae. Furthermore, WH was shown on S. aureus to be synergistic to linezolid and chloramphenicol and cumulative to vancomycin and amikacin. The effect of WH was tested on staphylococcal pathogenesis and shown here to inhibit biofilm formation (tested on S. epidermidis) and toxin production (tested on S. aureus Enterotoxin A (SEA)). Toxin inhibition was also evident in the presence of subinhibitory concentrations of ciprofloxacin that induces pathogenesis. Put together, our study indicates that WH is very effective in inhibiting the growth of multiple types of bacteria, is synergistic to antibiotics, and is also effective against staphylococcal pathogenesis, often the cause of persistent infections. Our study thus suggests the benefits of using WH to combat various types of bacterial infections, especially those that involve resistant persistent bacterial pathogens.

In this paper, we report the development and viscoelastic properties of hyaluronic acid formulations (HA5, HA30, and HA60, containing 0.5, 3, and 6% HA, respectively) loaded with carvacrol prodrugs (WSCPS) with antibacterial properties. Notably, antimicrobial studies revealed that WSCP1-2 in both HA5 and HA30 formulations showed the best minimum inhibitory concentration (MIC) values against Enterococcus faecium (128 mg/L) and Enterococcus faecalis (256 mg/L) compared to those of carvacrol alone or in formulations with HA. Moreover, rheological analyses showed that HA30 composites exhibited a semi-solid consistency, while HA5 formulations possessed a fluid consistency. Considering these data, HA30 is a useful formulation which guarantees a good percentage of prodrug release (e.g., 30 and 60% for WSCP1 and 2, respectively) as well as a texture suitable for topical administration to treat wounds and/or skin infections.

Background: Pseudomonas aeruginosa is a gram-negative pathogen, associated with a severe mortality rate. It is also difficult to treat due to numerous resistance mechanisms to a wide range of antibiotics. Objective: Evaluate the activity of pexiganan, an antimicrobial peptide, in combination with two clinical antibiotics (azithromycin and tigecycline) that are not active against P. aeruginosa. Methods: Ten clinical P. aeruginosa were isolated from urinary tract infections, blood culture, skin infections and respiratory tract infections. Minimum inhibitory concentrations (MICs) and synergies were evaluated by broth microdilution, checkerboard assays and time-kill studies. In vitro synergy was confirmed with an in vivo experiment using a murine model of sepsis. Results: Pexiganan MICs were included between 2 and 16 mg/L. Tigecycline and azithromycin MICs were high as expected (4-64 mg/L and 32-256 mg/L, respectively). Pexiganan and azithromycin combination resulted to be additive or indifferent while tigecycline and pexiganan combination was synergic against seven out of ten P. aeruginosa and additive against the other strains. In vivo experiment confirmed the in vitro synergy, denoting a significative reduction of bacteria in mice treated with pexiganan and tigecycline combination. Conclusion: Antimicrobial peptides are molecules that could be useful in the fight against infections and pexiganan seems to be one of the most promising. Our results demonstrated that, in association with tigecycline, pexiganan administration could overcome antibiotic resistance and increase the effectiveness of treatment against P. aeruginosa sepsis.

Ceftobiprole is a fifth-generation cephalosporin with activity against methicillin-resistant Staphylococcus aureus (MRSA). One-year surveillance at the Regional Hospital of Ancona (Italy) disclosed a 12% ceftobiprole resistance rate (12/102 isolates; MIC, ≥4 mg/liter). Epidemiological characterization demonstrated that the resistant isolates all belonged to different clones. Penicillin-binding protein (PBP) analysis showed substitutions in all PBPs and a novel insertion in PBP2a. The mecB and mecC genes were not detected. Ceftobiprole susceptibility screening is essential to avoid therapeutic failure and the spread of ceftobiprole-resistant strains.

Complicated skin and soft tissue infections constitute a heterogeneous group of severe disorders, with surgical site infections being the most common hospital-acquired ones. The aim of our study was to investigate the synergistic and bactericidal activities of antimicrobial combinations of fosfomycin with rifampicin and tigecycline against Enterococcus faecalis, Enterococcus faecium and methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates, and also to evaluate their in vivo effects in a mouse wound infection model. In in vitro studies, the combinations of fosfomycin with rifampicin and tigecycline were both synergistic. These synergies were confirmed in in vivo studies: the drug combinations showed the highest antimicrobial effects compared to monotherapy. In conclusion, the efficacy of fosfomycin combinations, also confirmed in our in vivo model, may suggest new directions in the treatment of infected skin and a possible alternative way to control bacterial skin infection.

Prolonged hospitalization and antibiotic therapy are risk factors for the development of methicillin-resistant Staphylococcus aureus (MRSA) infections in thermal burn patients. We used a rat model to study the in vivo efficacy of daptomycin in the treatment of burn wound infections by S. aureus , and we evaluated the wound healing process through morphological and immunohistochemical analysis. A copper bar heated in boiling water was applied on a paraspinal site of each rat, resulting in two full-thickness burns. A small gauze was placed over each burn and inoculated with 5 × 10 7 CFU of S. aureus ATCC 43300. The study included two uninfected control groups with and without daptomycin treatment, an infected control group that did not receive any treatment, and two infected groups treated, respectively, with intraperitoneal daptomycin and teicoplanin. The main outcome measures were quantitative culture, histological evaluation of tissue repair, and immunohistochemical expression of wound healing markers: epidermal growth factor receptor (EGFR) and fibroblast growth factor 2 (FGF-2). The highest inhibition of infection was achieved in the group that received daptomycin, which reduced the bacterial load from 10 7 CFU/ml to about 10 3 CFU/g ( P < 0.01). The groups treated with daptomycin showed better overall healing with epithelialization and significantly higher collagen scores than the other groups, and these findings were also confirmed by immunohistochemical data. In conclusion, our results support the hypothesis that daptomycin is an important modulator of wound repair by possibly reducing hypertrophic burn scar formation.

Background Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of skin and soft-tissue infection worldwide. An adequate immune response acts as a first line of defence against infections and therefore plays an essential role in the maintenance of health. Tocotrienols (T3s), the lesser known isomers of vitamin E, possess many biological properties and have been recognized as immunomodulators. Purpose The aim of this study was to investigate whether the in vivo supplementation with a mixture of 87.1% δ- and 12.9% γ-T3s extract from seeds of Bixa orellana, (T3s) could be effective in increasing the effect of daptomycin (DAP) in a mouse model of wound infection due to MRSA. Study design/methods Bacteria were inoculated onto full-thickness wound on the dorsal side of BALB/c mice at 5 × 106 CFU per mouse. Mice were randomized into five groups: an uninfected group, an infected-untreated group, a T3s-pretreated group with no antibiotics given after challenge, a T3s-pretreated group plus DAP given after challenge, a group only given DAP after challenge. Main outcome measures were: bacterial load on the wounds, analysis of Natural Killer (NK) cytotoxicity, immunological phenotype and markers of tissue repair. Results Our results showed that bacterial load in wounds from mice receiving T3s or DAP alone was 1- or 3-log10 lower, respectively, compared with the infected-untreated group. T3s plus daptomycin showed the highest efficacy, achieving a 4-log10 decrease in bacterial load. This higher antimicrobial effect was associated with increased levels of NK cytotoxicity and markers of wound repair. Conclusion These data suggest that treatment with T3s may be useful for the management of infected wounds as immune adjuvants in combination with DAP.

Health-related quality of life (HRQoL) has been recognized as a central measure of the overall health status in HIV patients. With the availability of different highly effective drug combinations, maximizing quality-adjusted survival has become a major target of HIV treatment. Although the association of HIV RNA and CD4 cell count with clinical HIV progression has been well established, the relation between these markers and HRQoL measures is still unclear.This cross-sectional study investigated the relationship linking HIV RNA and CD4 to HRQoL measures in 181 triple-class-experienced patients with advanced HIV disease. The instrument used was the ISSQoL, a self-administered and HIV-specific HRQoL questionnaire.Data showed no correlation between HRQoL measures and CD4 counts. Higher HIV RNA levels were, however, associated with poor HRQoL scores in 3 out of 9 scales of social functioning, depression and anxiety, and satisfaction with quality of life. In multivariable analyses, only the satisfaction with quality of life mean score remained significantly lower for the HIV RNA ≯100,000 copies/mL group compared to the HIV RNA 50 to 10,000 copies/mL group.Although other determinants of HRQoL in people with HIV should also be considered, this finding suggests a negative impact of high viral load on perceived HRQoL that adds to other described determinants of lower quality of life in people with HIV, such as lower social support and self-reported symptoms.

The aim of our study was to evaluate the in vitro activity of IB-367 and its bactericidal effect for Pseudomonas aeruginosa and Escherichia coli, associated to a synergic study to test the antibiotic combinations between the peptide and colistin or imipenem. Minimum inhibitory concentrations (MICs), the minimum bactericidal concentrations (MBCs), the synergy test and killing study were carried out to evaluate the IB-367 activity. In the in vivo model, a wound was incised through the panniculus carnosus of BALB/c mice, and then inoculated with 5 × 107 colony-forming units of P. aeruginosa and E. coli. For each strain, the study included an infected or not infected group that did not receive any treatment, and five contaminated groups treated with local IB- 367, intraperitoneal imipenem, intraperitoneal colistin, topical IB-367 local plus intraperitoneal imipenem or intraperitoneal colistin. All isolates were inhibited by IB-367 at concentrations of 4-64 mg/l. Killing by IB-367 was shown to be very rapid: its activity on all Gram-negative bacteria was completed within a 40 min exposure period at a concentration of 2 × MIC/l. Synergy was demonstrated when IB-367 was combined with colistin or imipenem. In in vivo studies, the groups treated with topical IB-367 and intraperitoneal colistin showed the best results in terms of bacterial load inhibition either for Pseudomonas or for E. coli. The good in vitro activity and in vivo efficacy, as well as, the synergic interactions with antibiotics suggest that IB-367 is a promising candidate for potential application in the treatment of wound Gram-negative infections.

BACKGROUND:: There is no consensus on darunavir (DRV) target levels in plasma for clinical use, and information about variability in plasma concentrations is limited. AIM:: To investigate the variability in DRV plasma trough concentrations in the clinical setting, evaluating interindividual and intraindividual variabilities of plasma drug levels among HIV-infected patients receiving ritonavir (RTV)-boosted DRV (DRV/r) within salvage regimens, and evaluate the potential correlation between variability and virological response. METHODS:: Sixty-two patients taking DRV/r (600/100 mg twice a day) were evaluated for trough plasma concentrations and immunovirological parameters after 6 months from the start of the regimen. A subgroup of patients (n = 21) was also evaluated for intraindividual variability (expressed as coefficient of variation) on 2 samples taken at different time points. Drug concentrations were assayed by high-performance liquid chromatography with ultraviolet detection, and the values were expressed as medians with interquartile range (IQR). Genotypic sensitivity score and genotypic inhibitory quotient were calculated. RESULTS:: DRV/r was used with a median of 3 other antiretroviral drugs (raltegravir use 88.7%). Median plasma concentrations were 3.22 mcg/mL (IQR, 2.04-5.69) for DRV and 0.44 mcg/mL (IQR, 0.21-0.70) for RTV. Both drugs showed a high interindividual variability in plasma concentrations (61% and 99.3%, respectively). Only 3 patients (4.8%) had undetectable DRV plasma levels. DRV plasma concentrations showed a significant positive correlation with age (r = 0.298, P = 0.019), but no significant correlation between DRV genotypic inhibitory quotient and HIV-RNA plasma levels (P = 0.614) was found. Intraindividual coefficients of variation were 58.4% for DRV and 47.1% for RTV. Patients with undetectable HIV-RNA showed a trend for lower intraindividual coefficients of variation compared with patients with detectable HIV-RNA (55.9% versus 83.8%, P = 0.156). No major interaction effects with other antiretroviral drugs were found. CONCLUSIONS:: In a context of salvage therapy, both DRV and RTV plasma levels showed high interindividual and intraindividual variabilities. Lower intraindividual variability could be beneficial in maintaining viral suppression. Copyright © 2013 by Lippincott Williams & Wilkins.

The aim of the study was to investigate the efficacy of the quorum sensing inhibitor FS3 and daptomycin in preventing prosthesis biofilm in a rat model of staphylococcal vascular graft infection. Graft infections were established in the back subcutaneous tissue of adult male Wistar rats by implantation of Dacron prostheses followed by topical inoculation with 2×10(7) colony-forming units of Staphylococcus aureus, strain Smith diffuse. The study included a control group, a contaminated group that did not receive any antibiotic prophylaxis and three contaminated groups that received: (i) intraperitoneal daptomycin, (ii) FS3-soacked graft, and (iii) daptomycin plus FS3-soaked graft, respectively. Each group included 15 animals. The infection burden was evaluated by using sonication and quantitative agar culture. Moreover, an in vitro binding-study was performed to quantify the how much FS3 was coated to the surface of the prosthesis. The in vitro studies showed, that minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for daptomycin were lower in presence of FS3. In in vivo studies, when tested alone, daptomycin and FS3 showed good efficacies. Their combination showed efficacies significantly higher than that of each single compound. Daptomycin is an important candidate for prevention of staphylococcal biofilm related infection and FS3 could serve as an interesting anti-staphylococcal antibiotic enhancer.

In staphylococci, quorum sensing regulates both biofilm formation and toxin production, moreover it has been demonstrated to be inhibited by RNAIII inhibiting peptide (RIP). Aim our study was to evaluate the in vitro activity and its in vivo efficacy of the combined administration of FS10, a novel RIP derivative, and tigecycline in an animal model of methicillin-resistant (MR) and methicillin-sensitive (MS) Staphylococcus aureus wound infection. Using a 1.x2 cm template, one full thickness wound was established through the panniculus carnosus on the back subcutaneous tissue of each animal. Infection was determined by inoculation of 5x107 CFU/ml of bacteria, that produced an abscess within 24 h, after this, treatment was initiated. The study included, for each strain, a control group without infection, a control infected group that did not receive any treatment and a control infected group with drug-free foam dressing, and three infected groups treated, respectively, with: FS10-soaked foam dressing (containing 20 μg FS10), daily intraperitoneal tigecycline (7 mg/Kg), FS10-soaked foam dressing (containing 20 μg FS10) and daily intraperitoneal injections of tigecycline (7 mg/Kg). The main outcome measures were quantitative culture and histological examination of tissue repair. The highest inhibition of infection was achieved in the group that received FS10-soaked and parenteral tigecycline reducing the bacterial load from 107 CFU/ml to about 103 CFU/g for MSSA and to about 104 CFU/g for MRSA. The group treated with FS10-soaked foam dressing associated with parenteral tigecycline showed, histologically, better overall healing with epithelialization and collagen scores significantly higher than those of the other groups in both strains. In conclusion, the combined use of topical FS10 with i.p. tigecycline induced positive interaction in vivo, resulting in an enhanced therapeutic benefit versus staphylococcal infections in murine wound models.

Background Sepsis-induced microcirculatory alterations contribute to tissue hypoxia and organ dysfunction. In addition to its plasma volume expanding activity, human serum albumin (HSA) has anti-oxidant and anti-inflammatory properties and may have a protective role in the microcirculation during sepsis. The concentration of HSA infused may influence these effects. We compared the microcirculatory effects of the infusion of 4% and 20% HSA in an experimental model of sepsis. Methods Adult male Wistar rats were equipped with arterial and venous catheters and received an intravenous infusion of lipopolysaccharide (LPS, serotype O127:B8, 10 mg/kg over 30 minutes) or vehicle (SHAM, n = 6). Two hours later, endotoxemic animals were randomized to receive 10 mL/kg of either 4% HSA (LPS+4%HSA, n = 6), 20% HSA (LPS+20%HSA, n = 6) or 0.9% NaCl (LPS+0.9%NaCl, n = 6). No fluids were given to an additional 6 animals (LPS). Vessel density and perfusion were assessed in the skeletal muscle microcirculation with sidestream dark field videomicroscopy at baseline (t0), 2 hours after LPS injection (t1), after HSA infusion (t2) and 1 hour later (t3). The mean arterial pressure (MAP) and heart rate were recorded. Serum endothelin-1 was measured at t2. Results MAP was stable over time in all groups. The microcirculatory parameters were significantly altered in endotoxemic animals at t1. The infusion of both 4% and 20% HSA similarly increased the perfused vessel density and blood flow velocity and decreased the flow heterogeneity to control values. Microvascular perfusion was preserved in the LPS+20%HSA group at t3, whereas alterations reappeared in the LPS+4%HSA group. Conclusions In a rat model of normotensive endotoxemia, the infusion of 4% or 20% HSA produced a similar acute improvement in the microvascular perfusion in otherwise unresuscitated animals.

There is limited information on the variations of HIV-1 DNA mutation profile in reverse transcriptase (RT) and protease (PR) genes during suppressive antiretroviral treatment (plasma HIV-1 RNA continuously50 copies/ml) with raltegravir (RAL)-based regimens in patients with baseline RT/PR resistant HIV. Twelve multidrug resistant (RT: 12/12, PR: 8/12) HIV-infected patients were followed during effectively suppressive RAL-based therapy. Total and integrated HIV-1 DNA were assessed by real time PCR at baseline and every 6 months. Ultrasensitive (threshold: 2.5 copies/ml) plasma HIV-1 RNA and genotypic analysis of RT and PR in proviral DNA were performed at baseline and at 24 months. Half of the patients had full viral suppression (plasma HIV-RNA 2.5 copies/ml) at month 12. Total HIV-1 DNA declined significantly after 12 months of therapy (from 249.2 to 145.7 copies/10

Background We investigated the efficacy of tigecycline and rifampin alone or combined in preventing ureteral stent infection due to Enterococcus faecalis . Materials and Methods The activities of the two antibiotics were previously studied in vitro in absence or in presence of biofilm. For in vivo research, the 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: (1) 2 mg/kg intraperitoneal tigecycline, immediately after stent implantation; (2) rifampin-coated ureteral stents where 0.2 cm 2 sterile ureteral stents were incubated in 10 mg/L rifampin solution for 30 min immediately before implantation; and (3) intraperitoneal tigecycline plus rifampin-coated ureteral stent at the above concentrations. Ureteral stents were explanted at d 5 following implantation and biofilm bacteria enumerated. Results The in vitro studies showed that the biofilm was strongly affected by the presence of rifampin and, in its presence, tigecycline had MICs and MBCs lower than those obtained in the absence of rifampin. Intraperitoneal tigecycline exerted stronger effect than rifampin on bacterial numbers. The combination rifampin plus tigecycline showed efficacies higher than that of each single compound. Conclusion These results highlight the potential usefulness of tigecycline in preventing enterococcal ureteral stent infections and the role of rifampin as an interesting antibiotic enhancer.

The treatment of HIV disease has led to a new division of management costs by shifting most of the necessary resources from inpatient treatment to outpatient management. Among the initiatives aimed at rationalising the resources available, we compared efficacy, tolerability and pharmacoeconomic impact of different regimes of antiretroviral therapy (ART). The survey covered the first 50 patients, clinically stable and with good viro-immunological response, who switched in June 2012 from an ART based on the triple combination of tenofovir (TDF), emtricitabine (FTC) and a protease inhibitor boosted with ritonavir (PI/r) or a non-nucleoside reverse transcriptase inhibitor (NNRTI), to a treatment based on abacavir (ABC), lamivudine (3TC) and a PI/r or NNRTI. Of the 50 patients who operated the switch, 39 replaced a PI with nevirapine (NVP), for which the largest group of patients was treated with ABC + 3TC + NVP. On 31 May 2015, all patients completed the observation period of 96 weeks, with a mean observation period of 132 weeks and clinical-laboratory checks every four months. Laboratory analysis revealed an optimal maintenance of viral suppression and absolute and relative number of CD4 + lymphocytes and improving trend of creatinine, proteinuria, serum phosphate and bone alkaline phosphatase. There was a variable effect on lipids, with a drop in triglycerides associated with a modest increase in total cholesterol. Much of the HIV-positive population reporting to our hospitals (50%) comprises individuals who have for years been in stable viraemic suppression, making a satisfactory immune recovery while in good overall clinical condition. This type of patient was the target of the present survey. At the end of 96 weeks of observation the new regimes were well tolerated and did not lead to viro-immunological or clinical deterioration. Pharmacoeconomic analysis showed better containment of the overall costs. No patient needed to be hospitalised during the observation period.

The aim of this work was to determine the in vitro activity of tigecycline and its bactericidal effect for a large number of Gram-positive cocci, as well as to investigate its in vitro interaction with six clinically used antibiotics. In vivo, a wound model was established through the panniculus carnosus of BALB/c mice, and then inoculated with 5 × 10(7) colony-forming units (CFU) of Staphylococcus aureus or Enterococcus faecalis. For each bacterial strain, the study included an infected or non-infected group that did not receive any treatment, three groups singly treated with tigecycline, rifampin, and daptomycin, and two groups that received tigecycline treatment plus rifampin or daptomycin. In the in vitro studies, tigecycline, daptomycin, and teicoplanin were active against all of the 48 Gram-positive isolates. The combination of tigecycline with rifampicin and daptomycin was synergistic against S. aureus and Enterococcus spp. In the in vivo studies, all groups treated with single drugs showed statistically significant results compared to the control group. The two groups treated with a combination of drugs showed the highest antimicrobial efficacy. In conclusion, our results suggested a strong activity of tigecycline alone and in combination with other antimicrobial agents against multi-resistant Gram-positive organisms isolated from wound infections.

Background Gram-negative sepsis ranks as the leading cause of death in intensive care units, and its incidence is increasing steadily and mortality rates has not changed much over recent decades. Materials and Methods We investigated the efficacy of the amphibian peptide, citropin 1.1 alone and in combination with tazobactam-piperacillin (TZP) in two experimental mice models of gram-negative sepsis. Animals were given an intraperitoneal injection of (1) 1 mg Escherichia coli 0111:B4 LPS, and (2) 2 × 10 10 CFU of E. coli ATCC 25922. For each model, all animals were randomized to receive intraperitoneally isotonic sodium chloride solution, 1 mg/Kg citropin 1.1 and 120 mg/Kg of TZP, and finally 1 mg/Kg citropin 1.1 plus 60 mg/Kg of TZP. Lethality, bacterial growth in blood and peritoneum, and oxidative stress indices in plasma were evaluated. Results All compounds reduced the lethality compared with controls. Treatment with citropin 1.1 resulted in significant decrease in plasma endotoxin and cytokine levels, while TZP exerted opposed effect. The combination between citropin 1.1 and TZP proved to be the most effective treatment in reducing all variables measured. Conclusion Due to its multifunctional properties, citropin 1.1 may become an important future consideration to treat conditions in which oxidative organ failure may be present.

Summary Background Chronic leg ulceration is a common health problem. It is well known that a clinically relevant bacterial load in chronic cutaneous wounds interferes significantly with the normal process of healing. Staphylococcus aureus is the most important representative of the staphylococcal group which causes clinically relevant infections within immunocompetent patients. Objectives To investigate the efficacy of a single treatment of antimicrobial photodynamic therapy (APDT) with RLP068/Cl in a mouse model of a surgical wound infection induced with a methicillin-resistant strain of S. aureus (MRSA). Methods Wounds, established through the panniculus carnosus of BALB/c and CD1 mice, were inoculated with 5 × 107 c.f.u. of MRSA. Mice were randomized into four groups respectively receiving no treatment, APDT with placebo, APDT with a new phthalocyanine derivative (RLP068/Cl) and intraperitoneal teicoplanin. Results On day 2 from infection, a strong reduction of bacterial counts (≈ 3 logs) was observed in mice treated with RLP068/Cl in comparison with infected untreated mice. On day 9 from infection, a comparable and significant (≈ 2 logs) reduction of bacterial counts was found in mice treated with RLP068/Cl or with teicoplanin. At this time, histological examinations revealed that wounds treated with RLP068/Cl showed a complete re-epithelialization with a continuous epithelial lining. Conclusions The results of the in vivo study demonstrated that APDT with RLP068/Cl may be useful in the management of chronic infected wounds, accelerating the repair process through a significant bacterial inhibition.

An experimental study was performed to evaluate the interaction between s-thanatin and colistin both in vitro and in vivo, using two Pseudomonas aeruginosa strains with different patterns of susceptibilities. We evaluated whether selecting for colistin-resistant P. aeruginosa could be prevented in vitro by combining colistin with s-thanatin. The strains were serially exposed in broth to twofold stepwise increasing concentrations of colistin alone or in combination with a fixed concentration [0.25× minimum inhibitory concentration (MIC)] of s-thanatin. We also performed an in vitro synergy study. For in vivo studies, a mouse model of Pseudomonas sepsis has been used. Main outcome measures were lethality and quantitative blood cultures. Exposure to colistin alone gradually selected for Pseudomonas strains with an increased MIC. In vitro studies, s-thanatin showed a positive interaction with colistin, and was able to prevent its resistance. In vivo studies, s-thanatin combined with colistin exhibited the highest efficacy on all main outcome measurements. These results highlight the potential usefulness of this combination and provide a future therapeutic alternative in severe Pseudomonas infections.

We investigated the efficacy of the peptide s-thanatin alone and in combination with tigecycline in an animal model of sepsis induced by cecal ligation and puncture. Adult male Wistar rats were randomized to receive intravenously isotonic sodium chloride solution, 5 mg/kg s-thanatin, 2 mg/kg tigecycline, 5 mg/kg s-thanatin combined with 2 mg/kg tigecycline. The experiment was also performed with administration of the drugs 360 min after the surgical procedure to better investigate the clinical situation where there is an interval between the onset of sepsis and the initiation of therapy. Lethality, bacterial growth in blood, peritoneum, spleen and liver, and NO indices were evaluated. All compounds reduced the lethality when compared to control. In all experiments, the compounds reduced significantly bacterial growth and lethality compared with saline treatment. Treatment with s-thanatin resulted in significant decrease in plasma NO levels compared to tigecycline and control group. The combination between s-thanatin and tigecycline proved to be the most effective treatment in reducing all variables measured. S-thanatin may have potential therapeutic usefulness alone and when associated to tigecycline in polymicrobial peritonitis.

RIP is a novel antibiotic against staphylococci. It acts at least in part by competing with RNAIII activating protein (RAP) by downregulating TRAP histidine phosphorylation, and by downregulating the expression of the Acessory Gene Regulator (agr). While much is known about the function of the agr as a quorum sensing system that regulates virulence, not much is known about TRAP. TRAP is a 167-kDa protein that is highly conserved among staphylococci and is involved in DNA protection from stress. TRAP is membrane-associated but does not have a transmembrane domain, and thus it may be bound to the membrane through other proteins. To search for these proteins, protein-protein interaction studies were carried out using a bacterial two-hybrid system, and OpuCA was discovered as a TRAP-binding protein. OpuCA is an ATP binding-cytoplasmic (ABC) domain of an OpuC ABC transporter. S. aureus OpuC– mutant strain was constructed and shown to be less tolerant to salt stress, and was defective in choline uptake. OpuC– cells were less pathogenic and showed reduced TRAP phosphorylation and agr activity, did not respond to RAP, and were defective in biofilm formation in vitro and in vivo. These results suggest that OpuC acts as a transporter and also plays a role in S. aureus pathogenesis.

Summary Background An increasing number of antimycotics have become available for the treatment of dermatophytoses; however, there are reports suggesting recalcitrance to therapy or resistance of a dermatophyte against conventional treatment. Lipopeptides represent novel therapeutic drugs with a new mode of action. Objectives The aim of this study was to investigate the in vitro effects of the lipopeptide Pal-Lys-Lys-NH2 (PAL) alone and in combination with standard antifungal agents, such as fluconazole (FLU), itraconazole (ITRA) and terbinafine (TER) against 24 clinical isolates of dermatophytes belonging to four species. Methods A broth microdilution method following the Clinical and Laboratory Standards Institute recommendations (M38-A) was used for testing drugs alone and in combination. Results PAL minimum inhibitory concentrations (MICs) ranged from ≤ 0·25 to > 16 μg mL−1 and they were similar to those of FLU and higher than those of either ITRA or TER. Synergy, defined as a fractional inhibitory concentration (FIC) index of ≤ 0·50, was observed in 67%, 52% and 15% of PAL/ITRA, PAL/TER and PAL/FLU interactions, respectively. None of these combinations yielded antagonistic interactions (FIC index > 4). When synergy was not achieved, there was still a decrease in the MIC of one or both drugs used in the combination. Conclusions Our study demonstrates that PAL has potential activity against dermatophytes. In addition, the in vitro activity of PAL can be enhanced upon combination with standard drugs. This lipopeptide applied in the form of lacquer, spray or ointment, could represent an interesting new therapy, particularly when combined with conventional treatment in recalcitrant or resistant dermatophyte infections.

To investigate the efficacy of distinctin in a neutropenic mouse model of staphylococcal sepsis.Prospective, randomized, and controlled animal study.Research laboratory in a University Hospital.BALB/c male mice.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.Lethality, bacterial growth in blood and peritoneum, spleen, liver, and mesenteric lymph nodes.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.Our data indicate that distinctin alone or combined with other antibiotics may be useful in treating severe staphylococcal infections.

Staphylococcal spp. are notorious for causing biofilm-related device-associated infections, leading to tens of thousands of deaths per year. In this paper, we review quorum sensing inhibitors as potential therapeutics for even the most persistent infections. The animal models reviewed are subcutaneous graft, central venous catheter (CVC), ureteral stent and wound models, and a wound case study. The therapeutic approaches reviewed are the use of RNAIII inhibiting peptide (RIP) and its non-peptide analog. These have been shown to prevent or treat infections caused by any staphylococcal strain tested, including antibiotic-resistant strains like CA-MRSA USA300. (Int J Artif Organs 2008; 31: 761–70)

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 1 mg/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.

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.

Introduction Surgical site infections are the second most common cause of nosocomial infections and, typically, gram-positive pathogens are involved. Materials and methods A mouse model was used to investigate the efficacy of different methods for the treatment of wound infections. A full thickness wound was established on the back subcutaneous tissue of adult male BALB/c mice. A small gauze was placed over each wound and then inoculated with 5 × 10 7 colony-forming units of Staphylococcus aureus . The study included a control group that did not receive any treatment and four contaminated groups treated, respectively, with: (1) drug-free Allevyn (Smith and Nephew Healthcare, Yorkshire, United Kingdom), (2) teicoplanin-soaked Allevyn, (3) drug-free Allevyn and daily intraperitoneal teicoplanin (7 mg/kg) and, finally, (4) teicoplanin-soaked Allevyn and daily intraperitoneal teicoplanin (7 mg/kg). Main outcome measures were quantitative bacterial culture, assessment of vascular endothelial growth factor (VEGF) plasma levels, histological examination with assessment of microvessel density, and of VEGF expression in tissue sections. Results Data analysis showed that strong inhibition of bacterial growth was achieved in any group treated with intraperitoneal teicoplanin. However, the highest inhibition of bacterial growth was obtained in the group that received teicoplanin-soaked Allevyn and intraperitoneal teicoplanin. Histological examination showed that each treatment modality was able to reduce the delay in wound repair. The most effective treatment appeared to be the local application of teicoplanin-soaked hydro gel foam. The tissue effects were associated with an increase in neovascularization and VEGF expression by endothelial cells and fibroblasts in the granulation tissue. Bacterial colonies also were reduced, especially when teicoplanin was given parenterally. Conclusions Soaking a hydro cellular foam with an antistaphylococcal agents, such as teicoplanin, may be useful for the management of infected wounds.

Biofilms play an important role in the pathogenesis of several chronic infections and nosocomial infections related to indwelling medical devices.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.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.IB-367 has potential as an adjunctive agent to LZD in the treatment of Gram-positive biofilm infections such as CVC infections.

The in vitro activity of the lipopeptide PAL-Lys-Lys-NH(2) (PAL), alone or combined with either fluconazole (FLU) or amphotericin B (AMB), was investigated against 14 Cryptococcus neoformans isolates. PAL MICs ranged from 1.0 to 4.0 microg/ml. Fungicidal activity was observed. Synergy, defined as a fractional inhibitory concentration (FIC) index ofor =0.5, was observed in 21.4% of PAL/AMB interactions. Antagonism (FIC index4) was never observed. The broad antifungal activity and the positive interactions with AMB suggest that PAL can represent a promising candidate in infections due to C. neoformans.

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 2 × 10 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.

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 μg/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 101 CFU/mL and bacteremia was not detected. Distinctin displays potential as an adjunctive agent to antibiotics in the treatment of CVC-related infections. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2007

The in vitro activities of tachyplesin III were investigated against 20 multidrug-resistant Pseudomonas aeruginosa clinical isolates. Methods included minimal inhibitory concentrations, minimal bactericidal concentrations, time-kill studies, checkerboard titration method, endotoxin-binding activity and cytotoxicity assay. Overall the organisms were susceptible to the peptide at concentrations of 0.50-4 mg/l. Tachyplesin III completely inhibits the endotoxin procoagulant activity at 22.36 mg/l concentration. Fractional inhibitory concentration indexes demonstrated synergy between the peptide and betalactams or colistin. In conclusion, the intrinsic antibacterial and antiendotoxin activities and the synergistic interactions demonstrated with clinically used antibiotics make tachyplesin III valuable as potential candidate for new therapeutic strategies aimed to treat P. aeruginosa infection.

Residual HIV viremia, defined by low levels of plasma HIV RNA with enhanced-sensitivity assays, may persist even in the presence of successful antiretroviral therapy, but little is known about its determinants. Our objective was to evaluate the rate and determinants of residual viremia in patients who show stable undetectable plasma HIV-1 RNA with conventional assays. Forty-four multidrug-experienced patients with undetectable levels of HIV RNA for at least 2 years under raltegravir-based regimens were evaluated. An ultrasensitive (2.5 copies/ml) real-time PCR method was used to quantify plasma HIV RNA. After 12 months of salvage treatment, 48.3% of the patients had residual viremia between 2.5 and 37 copies/ml. The proportion of patients with plasma HIV RNA below 2.5 copies/ml decreased from 51.7% at 12 months to 30.8% at 24 months. The presence of residual viremia was not associated with levels of viremia before starting raltegravir. Considering CD4 counts, hepatitis B or C virus (HBV or HCV) coinfection, or other demographic characteristics, for the time interval between HIV diagnosis and initiation of antiretroviral therapy, patients with a longer interval (>1 year) were significant less likely to have RNA levels below 2.5 copies/ml at 12 months compared to patients who started therapy within 1 year of HIV diagnosis (28.6% vs. 73.3%, p=0.027). Half of the patients showing undetectable HIV viremia with conventional assays had low-level viremia with ultrasensitive assays, with no predictive role of viroimmunological status at the start of the regimen. The potential influence of the interval between HIV diagnosis and initiation of treatment should be confirmed in subjects with a known date of seroconversion.

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.

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 1.0 × 10 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 μg/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.

OBJECTIVE: To investigate the efficacy of amphibian antimicrobial peptides in preventing bacterial translocation and neutralizing endotoxins in bile duct-ligated rats. DESIGN: Prospective, randomized, controlled animal study. SETTING: Research laboratory in a university hospital. SUBJECTS: Adult male Wistar rats. INTERVENTIONS: Adult male Wistar rats underwent sham operation or bile duct ligation (BDL). Eight groups were studied: sham operation with saline treatment, sham operation with 120 mg/kg tazobactam-piperacillin, sham operation with 2 mg/kg uperin 3.6, sham operation with 2 mg/kg magainin2, BDL with saline treatment, BDL with 120 mg/kg tazobactam-piperacillin, BDL with 2 mg/kg uperin 3.6, and BDL with 2 mg/kg magainin2. MEASUREMENTS AND MAIN RESULTS: Main outcome measures were: endotoxin and tumor necrosis factor-alpha concentrations in plasma and evidence of bacterial translocation in blood, peritoneum, liver, and mesenteric lymph nodes. Endotoxin and tumor necrosis factor-alpha plasma levels were significantly higher in BDL rats compared with sham-operated animals. All amphibian peptides achieved a significant reduction of plasma endotoxin and tumor necrosis factor-alpha concentration when compared with saline- and tazobactam-piperacillin-treated groups. On the other hand, both tazobactam-piperacillin and peptides significantly reduced bacterial growth compared with the control. Tazobactam-piperacillin and magainin2 exerted the maximal inhibition of bacterial growth. CONCLUSION: In conclusion, because of their multifunctional properties, amphibian peptides could be interesting compounds to inhibit bacterial translocation and endotoxin release in obstructive jaundice.

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.

The in vitro activity of the histatin derivative P-113, alone or combined with eight antibiotics, was investigated against multidrug-resistant strains isolated from clinical specimens of immunocompromised patients with pneumonia. The gram-negative isolates were susceptible to P-113. S. aureus showed less susceptibility. Synergy was demonstrated when P-113 was combined with beta-lactams against gram-negative organisms.

To investigate the efficacy of pexiganan, a 22-residue magainin analog, alone and combined with betalactmas antibiotics in three experimental rat models of Gram-negative septic shock. Adult male Wistar rats were given (i) an intraperitoneal injection of 1 mg Escherichia coli 0111:B4 LPS; (ii) 2x10(10)CFU of E. coli ATCC 25922; and (iii) 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 pexiganan, 1 mg/kg polymyxin B, 20 mg/kg imipenem, 60 mg/kg piperacillin alone and combined with 1 mg/kg pexiganan. Each group included 15 animals. Lethality, bacterial growth in blood or intra-abdominal fluid, endotoxin and TNF-alpha concentrations in plasma. All compounds reduced the lethality when compared to controls. Piperacillin and imipenem significantly reduced the lethality and the number of E. coli in abdominal fluid compared with saline treatment. Pexiganan showed a slightly lower antimicrobial activity than betalactams even though it achieved a substantial higher decrease in endotoxin and TNF-alpha plasma concentrations than imipenem and piperacillin. No statistically significant differences were noted for antimicrobial and antiendotoxin activities between pexiganan and polymyxin B. Combination between pexiganan and betalactams showed to be the most effective treatment in reducing all variables measured. The use of a novel antimicrobial compound able to bind to LPS associated to potent antibiotics such as betalactams may become an important future consideration for sepsis treatment.

RNAIII-inhibiting peptide (RIP, YSPWTNF-NH2) is a quorum-sensing peptide inhibitor that prevents Staphylococcus aureus toxin production and biofilm formation. A mouse sepsis model was used to test the efficacy of RIP alone or in combination with conventional antibiotics in suppressing S. aureus-induced sepsis. Mice were injected intravenously with 3.0x10(6)CFU of S. aureus ATCC 25923 or with 3.0x10(6)CFU of S. aureus strain Smith diffuse. All animals were randomized to receive intravenously isotonic sodium chloride solution as a control, or 20 mg/kg RIP alone or combined with 20 mg/kg cefazolin, 10 mg/kg imipenem, or 10 mg/kg vancomycin immediately or 6 h after bacterial challenge. Main outcome measures were bacteremia and lethality. All compounds reduced lethality when compared to controls. Although, in general combined-treated groups had significant lower bacterial counts when associated to singly-treated groups only the combination between RIP and vancomycin with respect to cefazolin gave a statistically significant decrease in the lethality rate. Lowest lethality rates (10%) and bacteremia (10(2)CFU/ml) were obtained when RIP was administered in combination with vancomycin. Because RIP can be synergistic with current antibiotic therapies and help to reduce S. aureus exotoxins production, it can be considered a promising agent to associate with antibiotics for further clinical research into treatment of sepsis.

Staphylococci are a major cause of infections associated with indwelling medical devices. Biofilm formation on these devices adds to the antibiotic resistance seen among clinical isolates. RNAIII-inhibiting peptide (RIP) is a heptapeptide that inhibits staphylococcal pathogenesis, including biofilm formation, by obstructing quorum sensing mechanisms. Bismuth ethanedithiol (BisEDT) also prevents biofilm formation at subinhibitory concentrations. RIP and BisEDT were combined to prevent infections in a rat graft model, using antibiotic sensitive and resistant strains of Staphylococcus aureus and Staphylococcus epidermidis. BisEDT, RIP, or rifampin, or their combinations reduced the graft associated bacterial load over seven days. BisEDT-RIP was the best combination, reducing bacterial load to undetectable levels. BisEDT-RIP may prove useful for coating medical devices to prevent staphylococcal infections.

Background Morbidity and mortality from Pseudomonas aeruginosa sepsis remain high despite the availability of antibiotics to which the microorganism is sensitive. Methods The in vitro activity of histatin derivative P-113d was investigated against Pseudomonas aeruginosa. In addition, its in vivo efficacy was studied in 3 rat models of infection: intraperitoneal injection of 1 mg of P. aeruginosa 10 lipopolysachharide, intraperitoneal injection of 2 x 10(10) cfu of P. aeruginosa ATCC 27853, and intra-abdominal sepsis induced by cecal ligation and puncture. Rats received isotonic sodium chloride solution parenterally (control groups), 1 mg of P-113d/kg of body weight, 1 mg of polymyxin B/kg of body weight, or 20 mg of imipenem/kg of body weight. Main outcomes measured were abdominal exudate and plasma bacterial growth, plasma concentrations of endotoxin and tumor necrosis factor (TNF)- alpha, and lethality. Results The in vivo studies showed that all compounds reduced lethality, when compared with results for the control group. Overall, P-113d exhibited a slightly lower antimicrobial activity than did imipenem, even though P-113d achieved a substantial decrease in plasma concentrations of endotoxin and TNF- alpha, compared with the imipenem. No statistically significant differences for antimicrobial and antiendotoxin activities were noted between P-113d and polymyxin B. Discussion These results provide evidence for double antiendotoxin and antimicrobial activity for P-113d and point to its potential use for the treatment of severe infections.

The in vitro activity of CA(1-7)M(2-9)NH(2), a 15-residue synthetic hybrid peptide derived from the sequences of cecropin A and melittin, alone and in combination with amoxicillin-clavulanate, imipenem, clarithromycin, ciprofloxacin, rifampin, and vancomycin, was investigated against 40 nosocomial isolates of methicillin-resistant Staphylococcus aureus. Antimicrobial activity of CA(1-7)M(2-9)NH(2) was measured by minimal inhibitory concentration, MBC, and time-kill studies. All isolates were inhibited at concentrations of 1 to 16 microg/mL. Combination studies performed with S. aureusATCC 43300 demonstrated synergy only when CA(1-7)M(2-9)NH(2) was combined with amoxicillin-clavulanate and imipenem. Our findings show that CA(1-7)M(2-9)NH(2) is active against methicillin-resistant S. aureusand that its activity is enhanced when it is combined with several antimicrobial agents.

Objective. To investigate the efficacy of RNAIII-inhibiting peptide (RIP) and nisin as prophylactic agents in a rat model of vascular graft infection.Design. Prospective, randomized, controlled animal study.Materials. Two hundred and twenty adult male Wistar rats. Staphylococcus epidermidis ATCC 12228 and one clinical isolate of methicillin-resistant S. epidermidis. Drugs: RIP, nisin and rifampin.Methods. Graft infections were established in the dorsal subcutaneous tissue by implantation of 1 cm2 sterile Dacron grafts, followed by topical bacterial inoculation: grafts were retrieved at 7 days. The study included a control group (without inoculation) and two series composed of five groups for each staphylococcal strain: one contaminated group that did not receive any antibiotic prophylaxis, three contaminated groups that received grafts soaked with 10 mg/l RIP, 10 mg/l nisin, 10 mg/l rifampin, or RIP+nisin. The main outcome measure was the extent of bacterial at graft harvest.Results. The bacterial counts for methicillin-resistant S. epidermidis on explanted grafts were 6.1±2.8×102, 7.8±3.0×103 and 5.5±2.9×104 for RIP, nisin and rifampin, respectively. RIP and nisin used in combination reduced the bacterial count to

The in vitro activity of three polycationic peptides, cecropin A, melittin, and cecropin A-melittin hybrid peptide CA(1-7)M(2-9)NH2, alone and in combination with various clinically used antimicrobial agents, was investigated against 32 nosocomial isolates of Acinetobacter baumannii. Antimicrobial activities were measured by MIC, MBC and bacterial killing assay. The peptides demonstrated different ranges of inhibitory values: overall, the organisms were more susceptible to CA(1-7)M(2-9)NH2 (MIC range, 0.25-16 mg/l) than to cecropin A (0.50-32 mg/l) and melittin (0.50-32 mg/l). Synergy was observed when CA(1-7)M(2-9)NH2 and melittin were combined with beta-lactam antibiotics.

Background— 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. Methods and Results— Graft infections were established in the back subcutaneous tissue of adult male Wistar rats by implantation of Dacron prostheses 1 cm 2 followed by topical inoculation with 2×10 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%. Conclusions— The results of the present study make these molecules potentially useful for antimicrobial chemoprophylaxis in vascular surgery.

Staphylococcus aureus is a prevalent cause of bacterial infections associated with indwelling medical devices. RNA III inhibiting peptide (RIP) is known to inhibit S. aureus pathogenesis by disrupting quorum-sensing mechanisms. RIP was tested in the present study for its ability to inhibit S. aureus biofilm formation in a rat Dacron graft model. The activity of RIP was synergistic with those of antibiotics for the complete prevention of drug-resistant S. aureus infections.