Mechanism of Action for an All-in-One Monoclonal Antibody Against Staphylococcus aureus Infection.

Staphylococcus aureus is a major human pathogen associated with high mortality rates. The extensive use of antibiotics is associated with the rise of drug resistance, and exotoxins are not targeted by antibiotics. Therefore, monoclonal antibody (mAb) therapy has emerged as a promising solution to solve the clinical problems caused by refractory S aureus. Recent research suggests that the synergistic effects of several cytotoxins, including bicomponent toxins, are critical to the pathogenesis of S aureus. By comparing the amino acid sequences, researchers found that α-toxin and bicomponent toxins have high homology. Therefore, we aimed to screen an antibody, designated an all-in-one mAb, that could neutralize α-toxin and bicomponent toxins through hybridoma fusion. We found that this mAb has a significant pharmacodynamic effect within in vivo mouse models and in vitro experiments.

Mnn10 Maintains Pathogenicity in Candida albicans by Extending α-1,6-Mannose Backbone to Evade Host Dectin-1 Mediated Antifungal Immunity.

The cell wall is a dynamic structure that is important for the pathogenicity of Candida albicans. Mannan, which is located in the outermost layer of the cell wall, has been shown to contribute to the pathogenesis of C. albicans, however, the molecular mechanism by which this occurs remains unclear. Here we identified a novel α-1,6-mannosyltransferase encoded by MNN10 in C. albicans. We found that Mnn10 is required for cell wall α-1,6-mannose backbone biosynthesis and polysaccharides organization. Deletion of MNN10 resulted in significant attenuation of the pathogenesis of C. albicans in a murine systemic candidiasis model. Inhibition of α-1,6-mannose backbone extension did not, however, impact the invasive ability of C. albicans in vitro. Notably, mnn10 mutant restored the invasive capacity in athymic nude mice, which further supports the notion of an enhanced host antifungal defense related to this backbone change. Mnn10 mutant induced enhanced Th1 and Th17 cell mediated antifungal immunity, and resulted in enhanced recruitment of neutrophils and monocytes for pathogen clearance in vivo. We also demonstrated that MNN10 could unmask the surface ß-(1,3)-glucan, a crucial pathogen-associated molecular pattern (PAMP) of C. albicans recognized by host Dectin-1. Our results demonstrate that mnn10 mutant could stimulate an enhanced Dectin-1 dependent immune response of macrophages in vitro, including the activation of nuclear factor-κB, mitogen-activated protein kinase pathways, and secretion of specific cytokines such as TNF-α, IL-6, IL-1ß and IL-12p40. In summary, our study indicated that α-1,6-mannose backbone is critical for the pathogenesis of C. albicans via shielding ß-glucan from recognition by host Dectin-1 mediated immune recognition. Moreover, our work suggests that inhibition of α-1,6-mannose extension by Mnn10 may represent a novel modality to reduce the pathogenicity of C. albicans.

Chemical constituents from the rhizome of Polygonum paleaceum and their antifungal activity.

A new compounds neopaleaceolactoside (1), along with nine known compounds phyllocoumarin (2), quercetin (3), quercitrin (4), quercetin-3-methyl ether (5), vincetoxicoside B (6), isoquercitrin (7), kaempferol (8), (-)-epicatechin (9), and chlorogenic acid (10), was isolated from Polygonum paleaceum Wall. Their chemical structures were established based on one-dimensional and two-dimensional nuclear magnetic resonance techniques, mass spectrometry and by comparison with spectroscopic data reported. Some selected compounds were screened for their antifungal activity. Quercetin (3), vincetoxicoside B (6), kaempferol (8), and (-)-epicatechin (9) showed synergistic antifungal activities with the FICI values <0.5. A preliminary structure-activity relationship could be observed that free 3-OH in the structure of flavonoids was important for synergistic antifungal activity.

Single dose intra-articular morphine for pain control after knee arthroscopy.

BACKGROUND: Knee arthroscopy is a common procedure and is associated with postoperative pain. Intra-articular (IA) injection of morphine for pain control has been widely studied, but its analgesic effect after knee arthroscopy is uncertain. OBJECTIVES: To evaluate the relative effects on pain relief and adverse events of IA morphine given for pain control after knee arthroscopy compared with placebo, other analgesics (local anaesthetics, non-steroidal anti-inflammatory drugs (NSAIDs), other opioids) and other routes of morphine administration. SEARCH METHODS: We searched CENTRAL (The Cochrane Library Issue 4, 2015), MEDLINE via Ovid (January 1966 to May 2015), EMBASE via Ovid (January 1988 to May 2015), and the reference lists of included articles. We also searched the metaRegister of controlled trials, clinicaltrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform for ongoing trials. SELECTION CRITERIA: We identified all the randomised, double-blind controlled trials that compared single dose IA morphine with other interventions for the treatment of postoperative pain after knee arthroscopy. We excluded studies with fewer than 10 participants in each group, using spinal or epidural anaesthesia, or assessing the analgesic effect of IA morphine on chronic pain. DATA COLLECTION AND ANALYSIS: Two authors independently assessed the quality of each trial and extracted information on pain intensity, supplementary analgesics consumption and adverse events. We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created 'Summary of findings' tables. MAIN RESULTS: We included 28 small, low quality studies (29 reports) involving 2564 participants. Of 20 studies (21 reports) comparing morphine with placebo, nine studies with adequate data were included in the meta-analysis. Overall, the risk of bias was unclear. Overall, the quality of the evidence assessed using GRADE was low to very low, downgraded primarily due to risk of bias, small study size, and imprecision.No statistical difference was found between 1 mg IA morphine and placebo in pain intensity (visual analogue scale (VAS)) at early phase (zero to two hours) (mean difference (MD) -0.50, 95% CI -1.15 to 0.14; participants = 297; studies = 7; low quality evidence), medium phase (two to six hours) (MD -0.47, 95% CI -1.09 to 0.14; participants = 297; studies = 7; low quality evidence) and late phase (six to 30 hours) (MD -0.88, 95% CI -1.81 to 0.04; participants = 297; studies = 7; low quality evidence). No significant difference was found between 1 mg and 2 mg morphine for pain intensity at early phase (MD -0.56, 95% CI -1.93 to 0.81; participants = 105; studies = 2; low quality evidence), while 4 mg/5 mg morphine provided better analgesia than 1 mg morphine at late phase (MD 0.67, 95% CI 0.08 to 1.25; participants = 97; studies = 3; low quality evidence). IA morphine was not better than local anaesthetic agents at early phase (MD 1.43, 95% CI 0.49 to 2.37; participants = 248; studies = 5; low quality evidence), NSAIDs at early phase (MD 0.95, 95% CI -0.95 to 2.85; participants = 80; studies = 2; very low quality evidence), sufentanil, fentanyl or pethidine for pain intensity. IA morphine was similar to intramuscular (IM) morphine for pain intensity at early phase (MD 0.21, 95% CI -0.48 to 0.90; participants = 72; studies = 2; very low quality evidence).Meta-analysis indicated that there was no difference between IA morphine and placebo or bupivacaine in time to first analgesic request. Eleven out of 20 studies comparing morphine with placebo reported adverse events and no statistical difference was obtained regarding the incidence of adverse events (risk ratio (RR) 1.09, 95% CI 0.51 to 2.36; participants = 314; studies = 8; low quality evidence). Seven of 28 studies reported participants' withdrawal. There were not enough data for withdrawals to be able to perform meta-analysis. AUTHORS' CONCLUSIONS: We have not found high quality evidence that 1 mg IA morphine is better than placebo at reducing pain intensity at early, medium or late phases. No statistical difference was reported between IA morphine and placebo regarding the incidence of adverse events. The relative effects of 1 mg morphine when compared with IA bupivacaine, NSAIDs, sufentanil, fentanyl and pethidine are uncertain. The quality of the evidence is limited by high risk of bias and small size of the included studies, which might bias the results. More high quality studies are needed to get more conclusive results.

Abolishing Cell Wall Glycosylphosphatidylinositol-Anchored Proteins in Candida albicans Enhances Recognition by Host Dectin-1.

Fungi can shield surface pathogen-associated molecular patterns (PAMPs) for evading host immune attack. The most common and opportunistic human pathogen, Candida albicans, can shield ß-(1 3)-glucan on the cell wall, one of the major PAMPs, to avoid host phagocyte Dectin-1 recognition. The way to interfere in the shielding process for more effective antifungal defense is not well established. In this study, we found that deletion of the C. albicans GPI7 gene, which was responsible for adding ethanolaminephosphate to the second mannose in glycosylphosphatidylinositol (GPI) biosynthesis, could block the attachment of most GPI-anchored cell wall proteins (GPI-CWPs) to the cell wall and subsequently unmask the concealed ß-(1,3)-glucan. Neutrophils could kill the uncloaked gpi7 mutant more efficiently with an augmented respiratory burst. The gpi7 mutant also stimulated Dectin-1-dependent immune responses of macrophages, including activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathways and secretion of specific cytokines, such as tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and IL-12p40. Furthermore, the gpi7 null mutant could induce an enhanced inflammatory response through promoting significant recruitment of neutrophils and monocytes and could stimulate stronger Th1 and Th17 cell responses to fungal infections in vivo. These in vivo phenotypes also were Dectin-1 dependent. Thus, we assume that GPI-CWPs are involved in the immune mechanism of C. albicans escaping from host recognition by Dectin-1. Our studies also indicate that the blockage of GPI anchor synthesis is a strategy to inhibit C. albicans evading host recognition.

Vaccination with Recombinant Non-transmembrane Domain of Protein Mannosyltransferase 4 Improves Survival during Murine Disseminated Candidiasis.

Candida albicans is the most common cause of invasive fungal infections in humans. The C. albicans cell wall proteins play an important role in crucial host-fungus interactions and might be ideal vaccine targets to induce protective immune response in host. Meanwhile, protein that is specific to C. albicans is also an ideal target of vaccine. In this study, 11 proteins involving cell wall biosynthesis, yeast-to-hypha formation, or specific to C. albicans were chosen and were successfully cloned, purified and verified. The immune protection of vaccination with each recombinant protein respectively in preventing systemic candidiasis in BALB/c mice was assessed. The injection of rPmt4p vaccination significantly increased survival rate, decreased fungal burdens in the heart, liver, brain, and kidneys, and increased serum levels of both immunoglobulin G (IgG) and IgM against rPmt4p in the immunized mice. Histopathological assessment demonstrated that rPmt4p vaccination protected the tissue structure, and decreased the infiltration of inflammatory cells. Passive transfer of the rPmt4p immunized serum increased survival rate against murine systemic candidiasis and significantly reduced organ fungal burden. The immune serum enhanced mouse neutrophil killing activity by directly neutralizing rPmt4p effects in vitro. Levels of interleukin (IL)-4, IL-10, IL-12p70, IL-17A and tumor necrosis factor (TNF)-α in serum were higher in the immunized mice compared to those in the adjuvant control group. In conclusion, our results suggested that rPmt4p vaccination may be considered as a potential vaccine candidate against systemic candidiasis.

Ssa1-targeted antibody prevents host invasion by Candida albicans.

Introduction: Candida albicans is a commensal fungus that colonizes most healthy individuals' skin and mucosal surfaces but can also cause life-threatening invasive infections, particularly in immunocompromised patients. Despite antifungal treatment availability, drug resistance is increasing, and mortality rates remain unacceptably high. Heat shock protein Ssa1, a conserved member of the Hsp70 family in yeast, is a novel invasin that binds to host cell cadherins, induces host cell endocytosis, and enables C. albicans to cause maximal damage to host cells and induces disseminated and oropharyngeal disease. Result: Here we discovered a mouse monoclonal antibody (mAb 13F4) that targeting C. albicans Ssa1 with high affinity (EC50 = 39.78 ng/mL). mAb 13F4 prevented C. albicans from adhering to and invading human epithelial cells, displayed antifungal activity, and synergized with fluconazole in proof of concept in vivo studies. mAb 13F4 significantly prolonged the survival rate of the hematogenous disseminated candidiasis mice to 75%. We constructed a mAb 13F4 three-dimensional structure using homology modeling methods and found that the antigen-binding fragment (Fab) interacts with the Ssa1 N-terminus. Discussion: These results suggest that blocking Ssa1 cell surface function may effectively control invasive C. albicans infections and provide a potential new treatment strategy for invasive fungal infections.

Potential of Polyethyleneimine as an Adjuvant To Prepare Long-Term and Potent Antifungal Nanovaccine.

Background: Candida albicans infections are particularly prevalent in immunocompromised patients. Even with appropriate treatment with current antifungal drugs, the mortality rate of invasive candidiasis remains high. Many positive results have been achieved in the current vaccine development. There are also issues such as the vaccine's protective effect is not persistent. Considering the functionality and cost of the vaccine, it is important to develop safe and efficient new vaccines with long-term effects. In this paper, an antifungal nanovaccine with Polyethyleneimine (PEI) as adjuvant was constructed, which could elicit more effective and long-term immunity via stimulating B cells to differentiate into long-lived plasma cells. Materials and Methods: Hsp90-CTD is an important target for protective antibodies during disseminated candidiasis. Hsp90-CTD was used as the antigen, then introduced SDS to "charge" the protein and added PEI to form the nanovaccine. Dynamic light scattering and transmission electron microscope were conducted to identify the size distribution, zeta potential, and morphology of nanovaccine. The antibody titers in mice immunized with the nanovaccine were measured by ELISA. The activation and maturation of long-lived plasma cells in bone marrow by nanovaccine were also investigated via flow cytometry. Finally, the kidney of mice infected with Candida albicans was stained with H&E and PAS to evaluate the protective effect of antibody in serum produced by immunized mice. Results: Nanoparticles (NP) formed by Hsp90-CTD and PEI are small, uniform, and stable. NP had an average size of 116.2 nm with a PDI of 0.13. After immunizing mice with the nanovaccine, it was found that the nano-group produced antibodies faster and for a longer time. After 12 months of immunization, mice still had high and low levels of antibodies in their bodies. Results showed that the nanovaccine could promote the differentiation of B cells into long-lived plasma cells and maintain the long-term existence of antibodies in vivo. After immunization, the antibodies in mice could protect the mice infected by C. albicans. Conclusion: As an adjuvant, PEI can promote the differentiation of B cells into long-lived plasma cells to maintain long-term antibodies in vivo. This strategy can be adapted for the future design of vaccines.

Evaluation of the in vitro Activity and in vivo Efficacy of Anidulafungin-Loaded Human Serum Albumin Nanoparticles Against Candida albicans.

Recent decades have seen a significant increase in invasive fungal infections, resulting in unacceptably high mortality rates. Anidulafungin (AN) is the newest echinocandin and appears to have several advantages over existing antifungals. However, its poor water solubility and burdensome route of administration (i.e., repeated, long-term intravenous infusions) have limited its practical use. The objective of this study was to develop anidulafungin-loaded Human Serum Albumin (HSA) nanoparticles (NP) so as to increase both its solubility and antifungal efficacy. HSA was reduced using SDS and DTT, allowing liberation of free thiols to form the intermolecular disulfide network and nanoassembly. Reduced HSA was then added to MES buffer (0.1 M, pH 4.8) and magnetically stirred at 350 rpm and 25°C with AN (m/m 50:1) for 2 h to form nanoparticles (AN NP). We next performed routine antifungal susceptibility testing of Candida strains (n = 31) using Clinical and Laboratory Standards Institute (CLSI) methodologies. Finally, the in vivo efficacy of both AN and AN NP was investigated in a murine model of invasive infection by one of the most common fungal species-C. albicans. The results indicated that our carrier formulations successfully improved the water solubility of AN and encapsulated AN, with the latter having a particle size of 29 ± 1.5 nm with Polymer dispersity index (PDI) equaling 0.173 ± 0.039. In vitro AN NP testing revealed a stronger effect against Candida species (n = 31), with Minimum Inhibitory Concentration (MIC) values 4- to 32-fold lower than AN alone. In mice infected with Candida and having invasive candidiasis, we found that AN NP prolonged survival time (P < 0.005) and reduced fungal burden in kidneys compared to equivalent concentrations of free drug (P < 0.0001). In conclusion, the anidulafungin nanoparticles developed here have the potential to improve drug administration and therapeutic outcomes for individuals suffering from fungal diseases.

The addition of tocilizumab to DMARD therapy for rheumatoid arthritis: a meta-analysis of randomized controlled trials.

PURPOSE: Tocilizumab is a humanized monoclonal antibody that binds to the interleukin-6 receptor. The purpose of this study was to evaluate the effect of adding tocilizumab to disease-modifying antirheumatic drug (DMARD) therapy for the treatment of rheumatoid arthritis (RA). METHODS: We performed a meta-analysis of relevant randomized controlled trials (RCTs) identified in PubMed, Cochrane library, and Embase. The primary efficacy outcome was the proportion of patients with a 20% improvement in RA signs and symptoms according to American College of Rheumatology (ACR) criteria (ACR20 response). The primary safety outcomes were the proportion of patients reporting at least one adverse event and the proportion of patients reporting at least one serious adverse event. RESULTS: Four RCTs, involving 2701 patients, were included in our meta-analysis. The addition of tocilizumab to therapeutic regimens with DMARDs was associated both clinically and statistically with an increased number of patients achieving the ACR20 response [8 mg/kg, risk ratio (RR) 2.53, 95% confidence interval (CI) 1.89-3.39; 4 mg/kg, RR 1.96, 95% CI 1.40-2.73], as well as the ACR50 and ACR70 response, and showing remission according to the Disease Activity Score based on 28 joints. However, the benefits were gained at the expense of the tendency of the patient to experience more adverse events (8 mg/kg, RR 1.12, 95% CI 1.03-1.20; 4 mg/kg, RR 1.08, 95% CI 1.00-1.17). The new finding was that the clinical benefit from the increased tocilizumab dose (from 4 to 8 mg/kg) was not correlated with a higher incidence of adverse events. CONCLUSIONS: The superior efficacy of combined tocilizumab + DMARD therapy is associated with the tendency for the patient to have more adverse events. Consequently, the benefits and disadvantages of such combined treatments should be carefully balanced against each other in RA therapy. We suggest that 8 mg/kg every 4 weeks should be the recommended dose of tocilizumab.

Incidence and risk of significantly raised blood pressure in cancer patients treated with bevacizumab: an updated meta-analysis.

PURPOSE: Bevacizumab is a humanized monoclonal antibody targeting vascular endothelial growth factor. The aim of this study was to gain a better understanding of the overall incidence and risk of significantly raised blood pressure in cancer patients who receive bevacizumab therapy. METHODS: We performed a meta-analysis of relevant randomized controlled trials (RCTs) identified in PubMed, Cochrane library, Embase, and American Society of Clinical Oncology conferences. Overall incidence rates, relative risks (RRs), and 95% confidence intervals (CIs) were calculated using a random-effects model. The primary clinical endpoint was significantly raised blood pressure (grade 3 or above). RESULTS: A total of 12,949 cancer patients with a variety of solid tumors from 19 RCTs were included in our meta-analysis. The overall incidence of significantly raised blood pressure was 8% (95% CI 6-10%) among patients receiving bevacizumab. Bevacizumab treatment was associated with a statistically significant increased risk of developing significantly raised blood pressure (RR 5.38, 95% CI 3.63-7.97). The RRs of significantly raised blood pressure in patients receiving bevacizumab at 5 and 2.5 mg/kg per week were 7.17 (95% CI, 3.91-13.13) and 4.11 (95% CI 2.49-6.78), respectively. Among cancer patients, those with renal cell carcinoma (RR 13.77, 95% CI 2.28-83.15) and breast cancer (RR 18.83, 95% CI 1.23-292.29) who received bevacizumab at 5 mg/kg per week had a higher risk of developing significantly raised blood pressure. CONCLUSIONS: Among the patients included in the trials analyzed in this meta-analysis, the addition of bevacizumab to cancer therapy treatments significantly increased the risk of significantly raised blood pressure. The risk may be dose-dependent and vary with tumor type.

Iron-Depletion prevents biofilm formation in Pseudomonas Aeruginosa through twitching mobility and quorum sensing.

Influence of iron-depletion on twitching motility and quorum sensing (QS) system in P. aeruginosa was evaluated. The results demonstrated iron-depletion can retard biofilm formation and increase the twitching motility and expression of QS-related genes, suggesting a potential interaction between twitching motility and QS system in P. aeruginosa biofilm formation.

Preventing Candida albicans from subverting host plasminogen for invasive infection treatment.

Candida albicans is a common fungal pathogen in humans that colonizes the skin and mucosal surfaces of the majority healthy individuals. How C. albicans disseminates into the bloodstream and causes life-threatening systemic infections in immunocompromised patients remains unclear. Plasminogen system activation can degrade a variety of structural proteins in vivo and is involved in several homeostatic processes. Here, for the first time, we characterized that C. albicans could capture and "subvert" host plasminogen to invade host epithelial cell surface barriers through cell-wall localized Eno1 protein. We found that the "subverted" plasminogen system plays an important role in development of invasive infection caused by C. albicans in mice. Base on this finding, we discovered a mouse monoclonal antibody (mAb) 12D9 targeting C. albicans Eno1, with high affinity to the 254FYKDGKYDL262 motif in α-helices 6, ß-sheet 6 (H6S6) loop and direct blocking activity for C. albicans capture host plasminogen. mAb 12D9 could prevent C. albicans from invading human epithelial and endothelial cells, and displayed antifungal activity and synergistic effect with anidulafungin or fluconazole in proof-of-concept in vivo studies, suggesting that blocking the function of cell surface Eno1 was effective for controlling invasive infection caused by Candida spp. In summary, our study provides the evidence of C. albicans invading host by "subverting" plasminogen system, suggesting a potential novel treatment strategy for invasive fungal infections.

Turning weakness into strength: Albumin nanoparticle-redirected amphotericin B biodistribution for reducing nephrotoxicity and enhancing antifungal activity.

As the gold standard treatment for invasive fungal infection, amphotericin B (AmB) is limited by its severe nephrotoxicity. It has been shown that AmB complex with albumin in vivo forms a sub-10 nm nanocomplex within kidney excretion size range and eventually induces the nephrotoxicity. This study presents an approach to take advantage of the "weakness" of such unique interaction between AmB and albumin to form AmB nanocomplex beyond the size range of kidney excretion. Herein, a novel strategy was developed by directly assembling molecular BSA into larger-sized nanostructures with the reconstructed intermolecular disulfide bond and hydrophobic interaction. The rich binding sites of AmB within BSA nanostructures enabled the efficient AmB loading and forming nanoparticle (AmB-NP) which exceeds the size range of kidney excretion (~ 60 nm). We found nanoassembly with BSA redirected biodistribution of AmB with a 2.8-fold reduction of drug accumulation in the kidney and significantly improved its renal impairment in mice. Furthermore, we found that nanoassembly with BSA significantly increased the biodistribution of AmB in brain and endowed it 100-folds increase in pharmacological effect against meningoencephalitis caused by common fungal pathogen Cryptococcus neoformans. Together, this study not merely overcomes the nephrotoxicity of AmB using its "weakness" by a nanoassembly method, and provides a new strategy for reducing toxicity of drugs with high albumin binding rate in vivo.

Dectin-1 Facilitates IL-18 Production for the Generation of Protective Antibodies Against Candida albicans.

Invasive candidiasis (IC) is one of the leading causes of death among immunocompromised patients. Because of limited effective therapy treatment options, prevention of IC through vaccine is an appealing strategy. However, how to induce the generation of direct candidacidal antibodies in host remains unclear. Gpi7 mutant C. albicans is an avirulent strain that exposes cell wall ß-(1,3)-glucans. Here, we found that vaccination with the gpi7 mutant strain could protect mice against invasive candidiasis caused by C. albicans and non-albicans Candida spp. The protective effects induced by gpi7 mutant relied on long-lived plasma cells (LLPCs) secreting protective antibodies against C. albicans. Clinically, we verified a similar profile of IgG antibodies in the serum samples from patients recovering from IC to those from gpi7 mutant-vaccinated mice. Mechanistically, we found cell wall ß-(1,3)-glucan of gpi7 mutant facilitated Dectin-1 receptor dependent nuclear translocation of non-canonical NF-κB subunit RelB in macrophages and subsequent IL-18 secretion, which primed protective antibodies generation in vivo. Together, our study demonstrate that Dectin-1 engagement could trigger RelB activation to prime IL-18 expression and established a new paradigm for consideration of the link between Dectin-1 mediated innate immune response and adaptive humoral immunity, suggesting a previously unknown active vaccination strategy against Candida spp. infection.

Synergistic effects of aminoglycosides and fosfomycin on Pseudomonas aeruginosa in vitro and biofilm infections in a rat model.

OBJECTIVES: To study the in vitro and in vivo efficacy of aminoglycosides against Pseudomonas aeruginosa, either alone or in combination with fosfomycin. METHODS: Using an in vitro study to assess inhibition of the growth of P. aeruginosa, MIC(90) and MIC(50) values of amikacin, gentamicin, netilmicin, tobramycin and isepamicin were determined, either alone or in combination with fosfomycin, and then the fractional inhibitory concentration index was calculated. In the biofilm-infected rat model, the efficacy and effects of treatment with isepamicin and fosfomycin on infection were studied. RESULTS: The combinations of amikacin and fosfomycin or isepamicin and fosfomycin showed the most significant synergistic effects against P. aeruginosa as compared with other treatments. In the biofilm-infected rat model, as a single agent, neither isepamicin nor fosfomycin reduced C-reactive protein level and numbers of white blood cells, or reduced the colony counts of the bacteria from both tissue and silica gel tubes. However, the combination of these two agents resulted in a good therapeutic effect. CONCLUSIONS: Combination of aminoglycosides and fosfomycin not only showed a positive effect in vitro but also improved the therapeutic effect in a biofilm-infected rat model. This offers an effective treatment strategy against some therapy-resistant infections.

Ertapenem versus piperacillin/tazobactam for the treatment of complicated infections: a meta-analysis of randomized controlled trials.

BACKGROUND: Ertapenem, a new carbapenem with a favorable pharmacokinetic profile, has been approved for the treatment of complicated intra-abdominal Infections (cIAIs), acute pelvic infections (APIs) and complicated skin and skin-structure infections (cSSSIs). The aim of this study is to compare the efficacy and safety of ertapenem with piperacillin/tazobactam, which has been reported to possess good efficacy for the treatment of these complicated infections. METHODS: We performed a meta-analysis of randomized controlled trials identified in PubMed, Cochrane library and Embase that compared the efficacy and safety of ertapenem with piperacillin/tazobactam for the treatment of complicated infections including cIAIs, APIs, cSSSIs. The primary efficacy outcome was clinical treatment success assessed at the test-of-cure visit. The primary safety outcome was drug related clinical and laboratory adverse events occurred during the treatment and the post-treatment period. RESULT: Six RCTs, involving 3161 patients, were included in our meta-analysis. Ertapenem was associated similar clinical treatment success with piperacillin/tazobactam for complicated infections treatment (clinically evaluable population, 1937 patients, odds ratios: 1.15, 95% confidence intervals: 0.89-1.49; modified intention to treat population, 2855 patients, odds ratios: 1.03, 95% confidence intervals: 0.87-1.22). All of secondary efficacy outcomes analysis obtained similar findings with clinical treatment success. No difference was found about the incidence of drug related adverse events between ertapenem and piperacillin/tazobactam groups. CONCLUSION: This meta-analysis provides evidence that ertapenem 1 g once a day can be used as effectively and safely as recommended dose of piperacillin/tazobactam, for the treatment of complicated infections, particularly of mild to moderate severity. It is an appealing option for the treatment of these complicated infections.

Effects of iron depletion on antimicrobial activities against planktonic and biofilm Pseudomonas aeruginosa.

OBJECTIVES: Iron plays an important role in the development of Pseudomonas aeruginosa biofilm. Here we evaluated effects of iron depletion on the antimicrobial activity of ceftazidime, tobramycin and ciprofloxacin against planktonic and biofilm Pseudomonas aeruginosa. METHODS: We tested the sensitivities of wild-type PAO1, type-IV pilus mutant PAO-DeltapilHIJK and the quorum-sensing mutant PAO-JP2 P. aeruginosa planktonic cultures and biofilms to antibiotics under iron-depleted conditions. KEY FINDINGS: In planktonic bacteria, the minimum concentration that inhibited visible growth (MIC) of ciprofloxacin was increased slightly in an iron-depleted environment in all three strains, whereas the MIC of tobramycin was similar in iron-depleted and control environments. The MIC of ceftazidime increased in the PAO-JP2 strain when iron was depleted. Tobramycin achieved the best bactericidal effect in biofilms. Viable counts were reduced by one log under iron-depleted conditions in all three strains when tobramycin reached 4 MIC and when ceftazidime and ciprofloxacin reached 8 MIC. CONCLUSIONS: This study suggests that once the biofilm is formed, iron depletion may only slightly promote the bactericidal effect of antibiotics on PAO1, PAO-DeltapilHIJK and PAO-JP2. Although these changes were relatively small, iron as one of the environmental factors should not be ignored when evaluating bactericidal effect of antibiotics. The combination of an iron chelator and antibiotics may have therapeutic value under certain bacterial growth conditions.

The critical role of Dectin-1 in host controlling systemic Candida krusei infection.

There are increasing invasive fungal infections associated with non-albicans, which causes mortal infections in immune deficiency population. Candida krusei is a major non-albicans that exhibits intrinsic resistance to fluconazole and makes clinical treatment difficult. Previous studies revealed that C-type lectin receptors (CLRs) Dectin-1 plays critical roles in host defense against C. albicans infections. C. krusei and C. albicans are phylogenetically different although in the same genus. Whether Dectin-1 contributes to host immune response against C. krusei infection is still unknown. In the present study, we explored the potential roles of the Dectin-1 in host defense against C. krusei. We found that Dectin-1 ligand ß-(1,3)-glucan markedly exposed on the cell surface of C. krusei, while ß-(1,3)-glucan of C. albicans is masked. Dectin-1 is required for host myeloid cells recognition, killing of C. krusei, and development of subsequent Th1 and Th17 cell-mediated adaptive immune response. Furthermore, Dectin-1-deficient mice (Dectin-1-/- ) are more susceptible to C. krusei infection. Together, we confirmed the important roles of Dectin-1 in host defense against C. krusei infection, demonstrating a previously unknown mechanism for C. krusei infection. Our study, therefore, provides a further understanding of host immune response against C. krusei.

Dectin-1 plays an important role in host defense against systemic Candida glabrata infection.

Candida glabrata is the second most common pathogen of severe candidiasis in immunocompromised hosts, following C. albicans. Although C. glabrata and C. albicans belong to the same genus, they are phylogenetically distinct. C-type lectin receptors (CLRs), acting as pattern-recognition receptors (PRRs), play critical roles in host defense against C. albicans infections. However, our understanding of the specific roles of CLRs in host defense against C. glabrata is limited. Here, we explored the potential roles of the C-type lectins Dectin-1 and Dectin-2 in host defense against C. glabrata. We found that both Dectin-1-deficient mice (Dectin-1-/-) and Dectin-2-deficient mice (Dectin-2-/-) are more susceptible to C. glabrata infection. Dectin-1confers host higher sensitivity for sensing C. glabrata infections, while the effect of Dectin-2 in the host defense against C. glabrata is infection dose dependent. Dectin-1 is required for host myeloid cells recognition, killing of C. glabrata, and development of subsequent Th1 and Th17 cell-mediated adaptive immune response. Significantly impaired inflammatory responses such as inflammatory cells recruitment and cytokines release that were induced by C. glabrata were manifested in Dectin-1-deficient mice. Together, our study demonstrates that Dectin-1 plays an important role in host defense against systemic Candida glabrata infections, indicating a previous unknown control mechanism for this particular type of infection in host. Our study, therefore, provides new insights into the host defense against C. glabrata.