Infective endocarditis and meningitis due to Scedosporium prolificans in a renal transplant recipient

Scedosporium prolificans is a ubiquitous filamentous fungi that may cause disseminated diseases in neutropenic patients with hematological malignancies. We report a fatal case of renal transplant recipient who developed both infective endocarditis and meningitis due to S. prolificans during treatment with micafungin and itraconazole for chronic necrotizing aspergillosis. Breakthrough Scedosporium infection should be considered among differential diagnosis of invasive fungal diseases in patients with renal transplant recipients receiving antifungal agents.     

Pharmacokinetic and Pharmacodynamic Evaluation of AZD5847 in a Mouse Model of Tuberculosis

AZD5847, a novel oxazolidinone with an MIC of 1 μg/ml, exhibits exposure-dependent killing kinetics against extracellular and intracellular Mycobacterium tuberculosis. Oral administration of AZD5847 to mice infected with M. tuberculosis H37Rv in a chronic-infection model resulted in a 1.0-log₁₀ reduction in the lung CFU count after 4 weeks of treatment at a daily area under the concentration-time curve (AUC) of 105 to 158 μg · h/ml. The pharmacokinetic-pharmacodynamic parameter that best predicted success in an acute-infection model was an AUC for the free, unbound fraction of the drug/MIC ratio of ≥20. The percentage of time above the MIC in all of the efficacious regimens was 25% or greater.     

Fatal disseminated Scedosporium prolificans infection initiated by ophthalmic involvement in a patient with acute myeloblastic leukemia

Scedosporium prolificans is an opportunistic saprophytic fungus that rapidly disseminates and is intrinsically resistant to currently available antifungal drugs. We report a fatal case of disseminated S. prolificans infection that started with orbital and ocular involvement in a patient with secondary acute myeloblastic leukemia.     

Efficacy and Safety of Danoprevir-Ritonavir plus Peginterferon Alfa-2a–Ribavirin in Hepatitis C Virus Genotype 1 Prior Null Responders

Danoprevir (DNV) is a hepatitis C virus (HCV) protease inhibitor that achieves high sustained virologic response (SVR) rates in combination with peginterferon alfa-2a–ribavirin in treatment-naive HCV genotype 1 (G1)-infected patients. This study explored the efficacy and safety of ritonavir-boosted DNV (DNVr) plus peginterferon alfa-2a–ribavirin in G1-infected prior peginterferon-ribavirin null responders. Null responders (<2-log₁₀ reduction in HCV RNA level at week 12) were given an open-label combination of 100 mg of ritonavir and 100 mg of DNV (100/100 mg DNVr) every 12 h (q12h) plus peginterferon alfa-2a–ribavirin for 12 weeks. All patients achieving an early virologic response (EVR; ≥2-log₁₀ decrease in HCV RNA by week 12) continued treatment with peginterferon alfa-2a–ribavirin; those without an EVR discontinued all study drugs. Twenty-four prior null responders were enrolled; 16 patients (67%) were infected with HCV G1b, and 8 (33%) were infected with G1a. Ninety-six percent of patients had an IL28B non-CC genotype. A sustained virologic response at 24 weeks posttreatment (SVR24) was achieved in 67% of patients, with a higher rate in G1b-infected (88%) than G1a-infected (25%) patients. Resistance-related breakthrough occurred in 4/8 G1a and 1/16 G1b patients through the DNV resistance-associated variant (RAV) NS3 R155K. NS3 R155K was also detected in 2/2 G1a patients who relapsed. Treatment was well tolerated. Two patients withdrew prematurely from study medications due to adverse events. Two serious adverse events were reported; both occurred after completion of DNVr therapy and were considered unrelated to treatment. No grade 3 or 4 alanine aminotransferase (ALT) elevations were observed. DNVr plus peginterferon alfa-2a–ribavirin demonstrated high SVR24 rates in HCV G1b-infected prior null responders and was well tolerated. (This study has been registered at ClinicalTrials.gov under registration no. {"type":"clinical-trial","attrs":{"text":"NCT01185860","term_id":"NCT01185860"}}NCT01185860.)     

In Vivo Activity of Cefquinome against Escherichia coli in the Thighs of Neutropenic Mice

Cefquinome is a cephalosporin with broad-spectrum antibacterial activity, including activity against enteric Gram-negative bacilli such as Escherichia coli. We utilized a neutropenic mouse model of colibacillosis to examine the pharmacodynamic (PD) characteristics of cefquinome, as measured by organism number in homogenized thigh cultures after 24 h of therapy. Serum drug levels following 4-fold-escalating single doses of cefquinome were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The pharmacokinetic (PK) properties of cefquinome were linear over a dose range of 10 to 640 mg/kg of body weight. Serum half-lives ranged from 0.29 to 0.32 h. Dose fractionation studies over a 24-h dose range of 2.5 to 320 mg/kg were conducted every 3, 6, 12, or 24 h. Nonlinear regression analysis was used to determine which pharmacodynamic parameter best correlated with efficacy. The free percentage of the dosing interval that the serum levels exceed the MIC (fT_>MIC) was the PK-PD index that best correlated with efficacy (R² = 73% for E. coli, compared with 13% for the maximum concentration of the free drug in serum [fC_max]/MIC and 45% for the free-drug area under the concentration-time curve from 0 to 24 h [fAUC_0-24]/MIC). Subsequently, we employed a similar dosing strategy by using 4-fold-increasing total cefquinome doses administered every 4 h to treat animals infected with four additional E. coli isolates. A sigmoid maximum-effect (E_max) model was used to estimate the magnitudes of the %fT_>MIC associated with net bacterial stasis, a 1-log₁₀ CFU reduction from baseline, and a 2-log₁₀ CFU reduction from baseline; the corresponding values were 28.01% ± 2.27%, 37.23% ± 4.05%, and 51.69% ± 9.72%. The potent bactericidal activity makes cefquinome an attractive option for the treatment of infections caused by E. coli.     

Bactericidal Activity,Absence of Serum Effect,and Time-Kill Kinetics of Ceftazidime-Avibactam against β-Lactamase-Producing Enterobacteriaceae and Pseudomonas aeruginosa

Avibactam, a non-β-lactam β-lactamase inhibitor with activity against extended-spectrum β-lactamases (ESBLs), KPC, AmpC, and some OXA enzymes, extends the antibacterial activity of ceftazidime against most ceftazidime-resistant organisms producing these enzymes. In this study, the bactericidal activity of ceftazidime-avibactam against 18 Pseudomonas aeruginosa isolates and 15 Enterobacteriaceae isolates, including wild-type isolates and ESBL, KPC, and/or AmpC producers, was evaluated. Ceftazidime-avibactam MICs (0.016 to 32 μg/ml) were lower than those for ceftazidime alone (0.06 to ≥256 μg/ml) against all isolates except for 2 P. aeruginosa isolates (1 bla_VIM-positive isolate and 1 bla_OXA-23-positive isolate). The minimum bactericidal concentration/MIC ratios of ceftazidime-avibactam were ≤4 for all isolates, indicating bactericidal activity. Human serum and human serum albumin had a minimal effect on ceftazidime-avibactam MICs. Ceftazidime-avibactam time-kill kinetics were evaluated at low MIC multiples and showed time-dependent reductions in the number of CFU/ml from 0 to 6 h for all strains tested. A ≥3-log₁₀ decrease in the number of CFU/ml was observed at 6 h for all Enterobacteriaceae, and a 2-log₁₀ reduction in the number of CFU/ml was observed at 6 h for 3 of the 6 P. aeruginosa isolates. Regrowth was noted at 24 h for some of the isolates tested in time-kill assays. These data demonstrate the potent bactericidal activity of ceftazidime-avibactam and support the continued clinical development of ceftazidime-avibactam as a new treatment option for infections caused by Enterobacteriaceae and P. aeruginosa, including isolates resistant to ceftazidime by mechanisms dependent on avibactam-sensitive β-lactamases.     

Isavuconazole (BAL4815) Pharmacodynamic Target Determination in an In Vivo Murine Model of Invasive Pulmonary Aspergillosis against Wild-Type and cyp51 Mutant Isolates of Aspergillus fumigatus

Invasive pulmonary aspergillosis (IPA) continues to rise in concert with increasing numbers of immune suppression techniques to treat other medical conditions and transplantation. Despite these advances, morbidity and mortality rates remain unacceptably high. One strategy used to optimize outcomes is antifungal pharmacodynamic (PD) examination. We explored the pharmacodynamics of a new triazole in development, isavuconazole, in a murine neutropenic IPA model. Ten A. fumigatus isolates were used, including four wild-type isolates and six cyp51 mutants. The MIC range was 0.125 to 8 mg/liter. Following infection, groups of mice were treated orally with the prodrug (BAL8557) at 40 to 640 mg/kg/12 h for 7 days. Efficacy was determined by quantitative PCR of lung homogenates. At the start of therapy, mice had 4.97 log₁₀ conidial equivalents (CE)/ml of lung homogenate, and this increased to 6.82 log₁₀ CE/ml of lung homogenate in untreated animals. The infection model was uniformly lethal in untreated control mice. The PD target endpoints examined included the static-dose AUC/MIC ratio and the 1-log₁₀ killing AUC/MIC ratio. A stasis endpoint was achieved for all isolates with an MIC of ≤1 mg/liter and 1-log₁₀ killing in all isolates with an MIC of ≤0.5 mg/liter, regardless of the presence or absence of the cyp51 mutation. The static-dose range was 65 to 617 mg/kg/12 h. The corresponding median free-drug AUC/MIC ratio was near 5. The 1-log₁₀ killing dose range was 147 to 455 mg/kg/12 h, and the corresponding median free-drug AUC/MIC ratio was 11.1. These values are similar to those previously reported for other triazoles.     

Efficacy of Ceftaroline Fosamil in a Staphylococcal Murine Pneumonia Model

Ceftaroline fosamil is a cephalosporin with activity against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). The objective of this study was to characterize the dose-response relationship of ceftaroline fosamil against S. aureus in an immunocompromised murine pneumonia model, as well as to evaluate the efficacy of the humanized regimen of 600 mg intravenously (i.v.) every 12 h. Seventeen S. aureus (2 methicillin-susceptible Staphylococcus aureus [MSSA], 15 MRSA) isolates with ceftaroline MICs of 0.5 to 4 μg/ml were utilized. The pharmacokinetics of ceftaroline in serum and epithelial lining fluid (ELF) were evaluated to determine bronchopulmonary exposure profiles in infected and uninfected animals, using single and human-simulated doses. Serum fT>MIC (the percentage of time that free drug concentrations remain above the MIC) of 17% to 43% was required to produce a 1-log₁₀ kill in the dose-ranging studies. These targets were readily achieved with the humanized exposure profile, where decreases of 0.64 to 1.95 log₁₀ CFU were observed against 13 MRSA and both MSSA isolates tested. When taken as a composite, the fT>MICs required for stasis and a 1-log₁₀ kill were 16% and 41%, respectively. ELF concentrations were similar to serum concentrations across the dosing interval in infected and uninfected animals. The serum fT>MIC targets required in this lung infection model were similar to those observed with ceftaroline against S. aureus in a murine thigh infection model. Exposures simulating the human dose of 600 mg i.v. every 12 h achieved pharmacodynamic targets against MRSA and MSSA considered susceptible by current U.S. FDA breakpoints.     

Pharmacodynamics of Ceftaroline against Staphylococcus aureus Studied in an In Vitro Pharmacokinetic Model of Infection

An in vitro single-compartment dilutional pharmacokinetic model was used to study the pharmacodynamics of ceftaroline against Staphylococcus aureus (both methicillin-susceptible S. aureus [MSSA] and methicillin-resistant S. aureus [MRSA]). Mean serum free concentrations of ceftaroline (the active metabolite of the prodrug ceftaroline fosamil) dosed in humans at 600 mg every 12 h (q12h) were simulated, and activities against 12 S. aureus strains (3 MSSA strains and 9 MRSA strains, 3 of which had a vancomycin-intermediate phenotype) were determined. Ceftaroline produced 2.5- to 4.0-log₁₀-unit reductions in viable counts by 24 h with all strains and a 0.5- to 4.0-log-unit drop in counts at 96 h. The antibacterial effect could not be related to the strain MIC across the ceftaroline MIC range from 0.12 to 2.0 μg/ml. In dose-ranging studies, the cumulative percentage of a 24-h period that the free drug concentration exceeded the MIC under steady-state pharmacokinetic conditions (fT_MIC) of 24.5% ± 8.9% was associated with a 24-h bacteriostatic effect, one of 27.8% ± 9.5% was associated with a −1-log-unit drop, and one of 32.1% ± 8.1% was associated with a −2-log-unit drop. The MSSA and MRSA strains had similar fT_MIC values. fT_MIC values increased with increasing duration of exposure up to 96 h. Changes in ceftaroline population analysis profiles were related to fT_MIC. fT_MICs of <50% were associated with growth on 4× MIC recovery plates at 96 h of drug exposure. These data support the use of ceftaroline fosamil at doses of 600 mg q12h to treat S. aureus strains with MICs of ≤2 μg/ml. An fT_MIC of 25 to 30% would make a suitable pharmacodynamic index target, but fT_MIC values of ≥50% are needed to suppress the emergence of resistance and require clinical evaluation.     

Clinical and In Vitro Resistance to GS-9669, a Thumb Site II Nonnucleoside Inhibitor of the Hepatitis C Virus NS5B Polymerase

Treatment with GS-9669, a novel nonnucleoside inhibitor (site II) of hepatitis C virus (HCV) nonstructural 5B (NS5B) polymerase, resulted in significant antiviral activity in HCV genotype (GT) 1 patients dosed at 50 and 500 mg once daily (QD) and at 50, 100, and 500 mg twice daily (BID) for 3 days. This report characterizes the virologic resistance to GS-9669 in vitro and in GT1 HCV-infected patients from a phase I clinical study. An in vitro resistance selection study with GS-9669 revealed substitutions at several NS5B residues that conferred resistance. The M423 variants were selected at low drug concentrations (5× the 50% effective concentration [EC₅₀]), and the L419, R422, and I482 variants were selected at higher drug concentrations (20× the EC₅₀). During the phase I clinical study, substitutions at NS5B residues 419, 422, and 486 were the predominant changes associated with GS-9669 monotherapy. Substitutions at position 423 were observed only in GT1a patients in the low-dose groups (50 and 100 mg BID). Interestingly, four HCV patients had substitutions at position 423 at baseline. Consistent with the low resistance level at this position, three patients with M423I or M423V at baseline achieved >2-log₁₀ reductions of HCV RNA when treated with 100 mg BID or with 500 mg QD or BID of GS-9669. The fourth patient, who had the M423V substitution at baseline, had a 4.4-log₁₀ reduction of HCV RNA with 500 mg BID of GS-9669. Phenotypic analyses demonstrated that the viral isolates with multiple GS-9669 resistance-associated variants have reduced susceptibility to GS-9669 and lomibuvir (VX-222) but are not cross-resistant to other classes of HCV inhibitors. (This study has been registered at ClinicalTrials.gov under registration no. {"type":"clinical-trial","attrs":{"text":"NCT01431898","term_id":"NCT01431898"}}NCT01431898.)     

Pharmacodynamics of Cefquinome in a Neutropenic Mouse Thigh Model of Staphylococcus aureus Infection

Cefquinome is a cephalosporin with broad-spectrum antibacterial activity, including activity against Staphylococcus aureus. The objective of our study was to examine the in vivo activity of cefquinome against S. aureus strains by using a neutropenic mouse thigh infection model. Cefquinome kinetics and protein binding in infected neutropenic mice were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In vivo postantibiotic effects (PAEs) were determined after a dose of 100 mg/kg of body weight in mice infected with S. aureus strain ATCC 29213. The animals were treated by subcutaneous injection of cefquinome at doses of 2.5 to 320 mg/kg of body weight per day divided into 1, 2, 3, 6, or 12 doses over 24 h. Cefquinome exhibited time-dependent killing and produced in vivo PAEs at 2.9 h. The percentage of time that serum concentrations were above the MIC (%T_>MIC) was the pharmacokinetic-pharmacodynamic (PK-PD) index that best described the efficacy of cefquinome. Subsequently, we employed a similar dosing strategy by using increasing total cefquinome doses that increased 4-fold and were administered every 4 h to treat animals infected with six additional S. aureus isolates. A sigmoid maximum effect (E_max) model was used to estimate the magnitudes of the ratios of the %T that the free-drug serum concentration exceeded the MIC (%T_>fMIC) associated with net bacterial stasis, a 0.5-log₁₀ CFU reduction from baseline, and a 1-log₁₀ CFU reduction from baseline; the respective values were 30.28 to 36.84%, 34.38 to 46.70%, and 43.50 to 54.01%. The clear PAEs and potent bactericidal activity make cefquinome an attractive option for the treatment of infections caused by S. aureus.     

Opto-chemical treatment for enhanced high-level disinfection of mature bacterial biofilm in a Teflon-based endoscope model

Medical societies and public health agencies rigorously emphasize the importance of adequate disinfection of flexible endoscopes. The aim of this work was to propose a novel opto-chemical disinfection treatment against Staphylococcus aureus grown in mature biofilm on Teflon-based endoscope channel models. Laser irradiation using near-infrared and blue wavelengths combined with a low concentration of chemical disinfectant induced both irreversible thermal denaturation and intercellular oxidative stress as a combined mechanism for an augmented antimicrobial effect. The opto-chemical method yielded a 6.7–log₁₀ reduction of the mature Staphylococcus aureus biofilms (i.e., approximately 1.0-log₁₀ higher than current requirement of standard treatment). The proposed technique may be a feasible disinfection method for mitigating the risk associated with infection transmission.     

Evaluation of Ceftaroline,Vancomycin, Daptomycin,or Ceftaroline plus Daptomycin against Daptomycin-Nonsusceptible Methicillin-Resistant Staphylococcus aureus in an In Vitro Pharmacokinetic/Pharmacodynamic Model of Simulated Endocardial Vegetations

Infective endocarditis (IE) caused by methicillin-resistant Staphylococcus aureus (MRSA) with reduced susceptibility to vancomycin and daptomycin has few adequate therapeutic options. Ceftaroline (CPT) is bactericidal against daptomycin (DAP)-nonsusceptible (DNS) and vancomycin-intermediate MRSA, but supporting data are limited for IE. This study evaluated the activities of ceftaroline, vancomycin, daptomycin, and the combination of ceftaroline plus daptomycin against DNS MRSA in a pharmacokinetic/pharmacodynamic (PK/PD) model of simulated endocardial vegetations (SEVs). Simulations of ceftaroline-fosamil (600 mg) every 8 h (q8h) (maximum concentration of drug in serum [C_max], 21.3 mg/liter; half-life [t_1/2], 2.66 h), daptomycin (10 mg/kg of body weight/day) (C_max, 129.7 mg/liter; t_1/2, 8 h), vancomycin (1 g) q8h (minimum concentration of drug in serum [C_min], 20 mg/liter; t_1/2, 5 h), and ceftaroline plus daptomycin were evaluated against 3 clinical DNS, vancomycin-intermediate MRSA in a two-compartment, in vitro, PK/PD SEV model over 96 h with a starting inoculum of ∼8 log₁₀ CFU/g. Bactericidal activity was defined as a ≥3-log₁₀ CFU/g reduction from the starting inoculum. Therapeutic enhancement of combinations was defined as ≥2-log₁₀ CFU/g reduction over the most active agent alone. MIC values for daptomycin, vancomycin, and ceftaroline were 4 mg/liter, 4 to 8 mg/liter, and 0.5 to 1 mg/liter, respectively, for all strains. At simulated exposures, vancomycin was bacteriostatic, but daptomycin and ceftaroline were bactericidal. By 96 h, ceftaroline monotherapy offered significantly improved killing compared to other agents against one strain. The combination of DAP plus CPT demonstrated therapeutic enhancement, resulting in significantly improved killing versus either agent alone against 2/3 (67%) strains. CPT demonstrated bactericidal activity against DNS, vancomycin-intermediate MRSA at high bacterial densities. Ceftaroline plus daptomycin may offer more rapid and sustained activity against some MRSA in the setting of high-inoculum infections like IE and should also be considered.     

Daily laxative therapy reduces organ dysfunction in mechanically ventilated patients: a phase II randomized controlled trial

IntroductionConstipation is a common problem in intensive care units. We assessed the efficacy and safety of laxative therapy aiming to promote daily defecation in reducing organ dysfunction in mechanically ventilated patients.MethodsWe conducted a prospective, randomized, controlled, nonblinded phase II clinical trial at two general intensive care units. Patients expected to remain ventilated for over 3 days were randomly assigned to daily defecation or control groups. The intervention group received lactulose and enemas to produce 1–2 defecations per day. In the control group, absence of defecation was tolerated up to 5 days. Primary outcome was the change in Sequential Organ Failure Assessment (SOFA) score between the date of enrollment and intensive care unit discharge, death or day 14.ResultsWe included 88 patients. Patients in the treatment group had a higher number of defecations per day (1.3 ± 0.42 versus 0.7 ± 0.56, p < 0.0001) and lower percentage of days without defecation (33.1 ± 15.7 % versus 62.3 ±24.5 %, p < 0.0001). Patients in the intervention group had a greater reduction in SOFA score (–4.0 (–6.0 to 0) versus –1.0 (–4.0 to 1.0), p = 0.036) with no difference in mortality rates or in survival time. Adverse events were more frequent in the treatment group (4.5 (3.0–8.0) versus 3.0 (1.0–5.7), p = 0.016), including more days with diarrhea (2.0 (1.0–4.0) versus 1.0 (0–2.0) days, p < 0.0001). Serious adverse events were rare and did not significantly differ between groups.ConclusionsLaxative therapy improved daily defecation in ventilated patients and was associated with a greater reduction in SOFA score.

Trial registration

Clinical Trials.gov {"type":"clinical-trial","attrs":{"text":"NCT01607060","term_id":"NCT01607060"}}NCT01607060, registered 24 May 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1047-x) contains supplementary material, which is available to authorized users.     

The electricidal effect: reduction of Staphylococcus and pseudomonas biofilms by prolonged exposure to low-intensity electrical current

The activity of electrical current against planktonic bacteria has previously been demonstrated. The short-term exposure of the bacteria in biofilms to electrical current in the absence of antimicrobials has been shown to have no substantial effect; however, longer-term exposure has not been studied. A previously described in vitro model was used to determine the effect of prolonged exposure (i.e., up to 7 days) to low-intensity (i.e., 20-, 200-, and 2,000-microampere) electrical direct currents on Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis biofilms. Dose- and time-dependent killing was observed. A maximum of a 6-log₁₀-CFU/cm² reduction was observed when S. epidermidis biofilms were exposed to 2,000 microamperes for at least 2 days. A 4- to 5-log₁₀-CFU/cm² reduction was observed when S. aureus biofilms were exposed to 2,000 microamperes for at least 2 days. Finally, a 3.5- to 5-log₁₀-CFU/cm² reduction was observed when P. aeruginosa biofilms were exposed to electrical current for 7 days. A higher electrical current intensity correlated with greater decreases in viable bacteria at all time points studied. In conclusion, low-intensity electrical current substantially reduced the numbers of viable bacteria in staphylococcal or Pseudomonas biofilms, a phenomenon we have labeled the “electricidal effect.”     

Microcirculatory effects of the transfusion of leukodepleted or non-leukodepleted red blood cells in patients with sepsis: a pilot study

Introduction

Microvascular alterations impair tissue oxygenation during sepsis. A red blood cell (RBC) transfusion increases oxygen (O₂) delivery but rarely improves tissue O₂ uptake in patients with sepsis. Possible causes include RBC alterations due to prolonged storage or residual leukocyte-derived inflammatory mediators. The aim of this study was to compare the effects of two types of transfused RBCs on microcirculation in patients with sepsis.

Methods

In a prospective randomized trial, 20 patients with sepsis were divided into two separate groups and received either non-leukodepleted (n = 10) or leukodepleted (n = 10) RBC transfusions. Microvascular density and perfusion were assessed with sidestream dark field (SDF) imaging sublingually, before and 1 hour after transfusions. Thenar tissue O₂ saturation (StO₂) and tissue hemoglobin index (THI) were determined with near-infrared spectroscopy, and a vascular occlusion test was performed. The microcirculatory perfused boundary region was assessed in SDF images as an index of glycocalyx damage, and glycocalyx compounds (syndecan-1, hyaluronan, and heparan sulfate) were measured in the serum.

Results

No differences were observed in microvascular parameters at baseline and after transfusion between the groups, except for the proportion of perfused vessels (PPV) and blood flow velocity, which were higher after transfusion in the leukodepleted group. Microvascular flow index in small vessels (MFI) and blood flow velocity exhibited different responses to transfusion between the two groups (P = 0.03 and P = 0.04, respectively), with a positive effect of leukodepleted RBCs. When within-group changes were examined, microcirculatory improvement was observed only in patients who received leukodepleted RBC transfusion as suggested by the increase in De Backer score (P = 0.02), perfused vessel density (P = 0.04), PPV (P = 0.01), and MFI (P = 0.04). Blood flow velocity decreased in the non-leukodepleted group (P = 0.03). THI and StO₂ upslope increased in both groups. StO₂ and StO₂ downslope increased in patients who received non-leukodepleted RBC transfusions. Syndecan-1 increased after the transfusion of non-leukodepleted RBCs (P = 0.03).

Conclusions

This study does not show a clear superiority of leukodepleted over non-leukodepleted RBC transfusions on microvascular perfusion in patients with sepsis, although it suggests a more favorable effect of leukodepleted RBCs on microcirculatory convective flow. Further studies are needed to confirm these findings.

Trial registration

ClinicalTrials.gov, {"type":"clinical-trial","attrs":{"text":"NCT01584999","term_id":"NCT01584999"}}NCT01584999     

Specific Activities of Dolastatin 10 and Peptide Derivatives against Cryptococcus neoformans

The biosynthetic peptide dolastatin 10 is currently in phase I and II cancer clinical trials. We evaluated the antifungal spectrum of dolastatin 10 and four structural modifications. In broth macrodilution assays, the peptides were fungicidal for American Type Culture Collection strains and clinical isolates (including fluconazole-resistant strains) of Cryptococcus neoformans but no other yeasts or filamentous fungi examined. Specificity for C. neoformans was also demonstrated in the solid-phase disk diffusion assay, and fungicidal activity was confirmed in time-kill experiments. For a methyl ester modification, the MICs at which 50 and 90% of 19 clinical isolates were inhibited (MIC₅₀ and MIC₉₀, respectively) were 0.195 and 0.39 μg/ml, respectively. The MFC₅₀ (50% minimum fungicidal concentration) for this peptide was 0.39 μg/ml, and the MFC₉₀ was 0.78 μg/ml. MICs and MFCs were identical or lower in the presence of human serum but increased with lowered pH. These peptides should be pursued as potential chemotherapeutics for C. neoformans, a leading cause of infection and mortality in immunocompromised patients.     

In Vitro Inactivation of Chlamydia trachomatis by Fatty Acids and Monoglycerides

The antichlamydial effects of several fatty acids and monoglycerides were studied by incubating Chlamydia trachomatis bacteria with equal volumes of lipid solutions for 10 min and measuring the reduction in infectivity titer compared with that in a control solution without lipid. Caprylic acid (8:0), monocaprylin (8:0), monolaurin (12:0), myristic acid (14:0), palmitoleic acid (16:1), monopalmitolein (16:1), oleic acid (18:1), and monoolein (18:1) at concentrations of 20 mM (final concentration, 10 mM) had negligible effects on C. trachomatis. In contrast, lauric acid (12:0), capric acid (10:0), and monocaprin (10:0) caused a greater than 10,000-fold (>4-log₁₀) reduction in the infectivity titer. When the fatty acids and monoglycerides were further compared at lower concentrations and with shorter exposure times, lauric acid was more active than capric acid and monocaprin was the most active, causing a greater than 100,000-fold (>5-log₁₀) inactivation of C. trachomatis at a concentration of 5 mM for 5 min. The high levels of activity of capric and lauric acids and particularly that of monocaprin are notable and suggest that these lipids have specific antichlamydial effects. The mode of action of monocaprin was further studied by removal of the lipid by centrifugation before inoculation of Chlamydia onto host cells and by electron microscopy. The results indicate that the bacteria are killed by the lipid, possibly by disrupting the membrane(s) of the elementary bodies. A 50% effective concentration of 30 μg/ml was found by incubation of Chlamydia with monocaprin for 2 h. The rapid inactivation of large numbers of C. trachomatis organisms by monocaprin suggests that it may be useful as a microbicidal agent for the prevention of the sexual transmission of C. trachomatis.