222 research outputs found
Pharmacodynamic Effects of Simulated Standard Doses of Antifungal Drugs against Aspergillus Species in a New In Vitro Pharmacokinetic/Pharmacodynamic Model
No full textIn conventional MIC tests, fungi are exposed to constant drug concentrations, whereas in vivo, fungi are exposed to changing
drug concentrations. Therefore, we developed a new in vitro pharmacokinetic/pharmacodynamic model where human plasma
pharmacokinetics of standard doses of 1 mg/kg amphotericin B, 4 mg/kg voriconazole, and 1 mg/kg caspofungin were simulated
and their pharmacodynamic characteristics were determined against three clinical isolates of Aspergillus fumigatus, Aspergillus
flavus, and Aspergillus terreus with identical MICs (1 mg/liter for amphotericin B, 0.5 mg/liter for voriconazole) and minimum
effective concentrations (0.5 mg/liter for caspofungin). This new model consists of an internal compartment (a 10-ml dialysis
tube made out of a semipermeable cellulose membrane allowing the free diffusion of antifungals but not galactomannan) inoculated
with Aspergillus conidia and placed inside an external compartment (a 700-ml glass beaker) whose content is diluted after
the addition of antifungal drugs by a peristaltic pump at the same rate as the clearance of the antifungal drugs in human plasma.
Fungal growth was assessed by galactomannan production. Despite demonstrating the same MICs, amphotericin B completely
inhibited (100%) A. fumigatus but not A. flavus and A. terreus, whose growth was delayed for 7.53 and 22.8 h, respectively. Voriconazole
partially inhibited A. fumigatus (49.5%) and A. flavus (27.9%) but not A. terreus; it delayed their growth by 3.99 h (A.
fumigatus) and 5.37 h (A. terreus). Caspofungin did not alter galactomannan production in all of the species but A. terreus. The
new model simulated human pharmacokinetics of antifungal drugs and revealed important pharmacodynamic differences in
their activity
Antifungal susceptibility testing and drug interaction modeling in moulds
No full textContains fulltext :
19230_antisutea.pdf (Publisher’s version ) (Open Access)In this thesis two parameters of in vitro antifungal susceptibility testing of filamentous fungi, the medium and the quantification of fungal growth, were investigated and different drug interaction models were used for analyzing the in vitro combination of various antifungal drugs. A microbroth kinetic system was developed in order to analyze the growth curves of three species of filamentous fungi in five different nutrient media. Two colorimetric methods based on the reduction of the tetrazolium salts, MTT and XTT, was evaluated for the MIC determination of different antifungal drugs against different species of filamentous fungi. High levels of agreement were found between the colorimetric medthods and the NCCLS method for all drugs and species tested. The in vitro combination of terbinafine with three azoles, namely itraconazole, voriconazole and miconazole was tested against clinical S. prolificans isolates using the spectrophotometric method, the colorimetric MTT method and a modified MTT method. In addition, the results were analyzed with parametric and non-parametric approaches of the Loewe additivity and Bliss independence zero interaction theories. Strong synergy was found between terbinafine and the three azoles with miconazole and voriconazole showing the strongest synergy based on Loewe additivity and Bliss independece theory, respectively. Less variable results were obtained with the modified MTT method. Despite its simplicity, results of the FIC index model depended on the choice of MIC endpoints and interpretation endpoints. Furthermore it lacked of good summary. Although the model described by Prichard et al. resulted in a concentration dependent mosaic of interactions, replicates were required for statistical evaluation of the results, good summary was absent and the results were dependent on the concentration range used. The fully parametric model described by Greco et al., although it did not describe precisely the response surface of antifungal combinations, was able to distinguish synergistic and antagonistic interactions and summarized the interaction with a non-unit concentration independent interaction parameter including statistically significance levels without requiring replicates130 p
In Vitro Pharmacokinetic/Pharmacodynamic Modeling of Voriconazole Activity against Aspergillus Species in a New In Vitro Dynamic Model
No full textThe pharmacodynamics (PD) of voriconazole activity against Aspergillus spp. were studied using a new in vitro dynamic model
simulating voriconazole human pharmacokinetics (PK), and the PK-PD data were bridged with human drug exposure to assess
the percent target (near-maximum activity) attainment of different voriconazole dosages. Three Aspergillus clinical isolates (1 A.
fumigatus, 1 A. flavus, and 1 A. terreus isolate) with CLSI MICs of 0.5 mg/liter were tested in an in vitro model simulating voriconazole
PK in human plasma with Cmax values of 7, 3.5, and 1.75 mg/liter and a t1/2 of 6 h. The area under the galactomannan
index-time curve (AUCGI) was used as the PD parameter. In vitro PK-PD data were bridged with population human PK of voriconazole
exposure, and the percent target attainment was calculated. The in vitro PK-PD relationship of fAUC0-24-AUCGI followed
a sigmoid pattern (global R20.97), with near-maximum activities (10% fungal growth) observed at an fAUC0-24 (95%
confidence interval [CI]) of 18.9 (14.4 to 23.1) mg · h/liter against A. fumigatus, 26.6 (21.1 to 32.9) mg · h/liter against A. flavus,
and 36.2 (27.8 to 45.7) mg · h/liter against A. terreus (F test;
Corrigendum: Azole-resistance in aspergillus terreusand related species: An emerging problem or a rare phenomenon? (Frontiers in Microbiology (2018) 9 (516) DOI: 10.3389/fmicb.2018.00516)
No full textRaquel Sabino was not included as an author in the published article. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated. © 2019 Zoran, Sartori, Sappl, Aigner, Sánchez-Reus, Rezusta, Chowdhary, Taj-Aldeen, Arendrup, Oliveri, Kontoyiannis, Alastruey-Izquierdo, Lagrou, Lo Cascio, Meis, Buzina, Farina, Drogari-Apiranthitou, Grancini, Tortorano, Willinger, Hamprecht, Johnson, Klingspor, Arsic-Arsenijevic, Cornely, Meletiadis, Prammer, Tullio, Vehreschild, Trovato, Lewis, Segal, Rath, Hamal, Rodriguez-Iglesias, Roilides, Arikan-Akdagli, Chakrabarti, Colombo, Fernández, Martin-Gomez, Badali, Petrikkos, Klimko, Heimann, Uzun, Roudbary, de la Fuente, Houbraken, Risslegger, Sabino, Lass-Flörl and Lackner
Corrigendum: Azole-resistance in aspergillus terreusand related species: An emerging problem or a rare phenomenon? (Frontiers in Microbiology (2018) 9 (516) DOI: 10.3389/fmicb.2018.00516)
No full textRaquel Sabino was not included as an author in the published article. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated. © 2019 Zoran, Sartori, Sappl, Aigner, Sánchez-Reus, Rezusta, Chowdhary, Taj-Aldeen, Arendrup, Oliveri, Kontoyiannis, Alastruey-Izquierdo, Lagrou, Lo Cascio, Meis, Buzina, Farina, Drogari-Apiranthitou, Grancini, Tortorano, Willinger, Hamprecht, Johnson, Klingspor, Arsic-Arsenijevic, Cornely, Meletiadis, Prammer, Tullio, Vehreschild, Trovato, Lewis, Segal, Rath, Hamal, Rodriguez-Iglesias, Roilides, Arikan-Akdagli, Chakrabarti, Colombo, Fernández, Martin-Gomez, Badali, Petrikkos, Klimko, Heimann, Uzun, Roudbary, de la Fuente, Houbraken, Risslegger, Sabino, Lass-Flörl and Lackner
Comparative Evaluation of Sensititre YeastOne and CLSI M38-A2 Reference Method for Antifungal Susceptibility Testing of Aspergillus spp. against Echinocandins
No full textABSTRACT
Sensititre YeastOne (YO) panels were assessed for
in vitro
susceptibility testing of echinocandins against 39 isolates of
Aspergillus fumigatus
,
A. flavus
, and
A. terreus
, including two echinocandin-resistant
A. fumigatus
strains, using different inocula (10
3
, 10
4
, and 10
5
CFU/ml), incubation times (16 to 48 h), and endpoints (first blue or purple well) and compared to CLSI M38-A2. The best agreement was found with an inoculum of 10
4
CFU/ml, incubation times of 20 h for
A. flavus
and of 30 h for
A. fumigatus
and
A. terreus
, and reading the first purple well. The reproducibility within ±1 2-fold dilutions was 100% for all three echinocandins. YO color endpoints were 2 to 3 2-fold dilutions lower than CLSI minimum effective concentrations (MECs) of caspofungin and 1 to 2 2-fold dilutions higher than CLSI MECs of micafungin. For anidulafungin, off-scale YO color endpoints were observed. Nevertheless,
A. fumigatus
echinocandin-resistant isolates were detected after 24 h of incubation.
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Development of an in vitro pharmacokinetic/pharmacodynamic model in the presence of serum for studying micafungin activity against Candida albicans: a need for revision of CLSI susceptibility breakpoints
No full textBackground: The CLSI breakpoint for micafungin and Candida albicans is 0.25 mg/L, higher than the CLSI epidemiological cut-off value (0.03 mg/L) whereas the EUCAST values are identical (0.016 mg/L). We developed a novel in vitro dialysis-diffusion pharmacokinetic/pharmacodynamic (PK/PD) model, confirmed correlation to in vivo outcome and studied micafungin pharmacodynamics against Canida albicans. Methods: Four C. albicans isolates, including a weak (F641L) and a strong (R647G) fks1 mutants, were studied using a 104 cfu/mL inoculum and RPMI medium with and without 10% pooled human serum. The exposure-effect relationship fAUC0–24/MIC was described for CLSI and EUCAST methodology. Monte Carlo simulation analysis included standard (100 mg i.v.) and higher (150–300 mg) doses q24h to determine the corresponding probability of target attainment (PTA). Results: The in vitro PK/PD targets for stasis/1-log kill were 36/57 fAUC0–24/MIC in absence and 2.8/9.2 fAUC0–24/ MIC in the presence of serum, and similar for wild-type and fks mutant isolates. The PTAs for both PK/PD targets were high (>95%) for EUCAST susceptible isolates but not for CLSI susceptible non-wild-type isolates (CLSI MICs 0.06–0.25 mg/L). 300 mg q24h was needed to attain PK/PD targets for non-wild-type isolates with CLSI MICs 0.06–0.125 mg/L and EUCAST MICs 0.03–0.06 mg/L. Conclusion: The in vitro 1-log kill effect corresponded to stasis in animal model and mycological response in patients with invasive candidiasis, thereby validating the model for studying pharmacodynamics of echinocandins in vitro. EUCAST breakpoints were well supported by our findings but our data questions whether the current CLSI breakpoint, which is higher than the epidemiological cut-off values, is appropriate. © The Author(s) 2023. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy. All rights reserved
Assessing Clinical Potential of Old Antibiotics against Severe Infections by Multi-Drug-Resistant Gram-Negative Bacteria Using In Silico Modelling
No full textIn the light of increasing antimicrobial resistance among gram-negative bacteria and the lack of new more potent antimicrobial agents, new strategies have been explored. Old antibiotics, such as colistin, temocillin, fosfomycin, mecillinam, nitrofurantoin, minocycline, and chloramphenicol, have attracted the attention since they often exhibit in vitro activity against multi-drug-resistant (MDR) gram-negative bacteria, such as Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. The current review provides a summary of the in vitro activity, pharmacokinetics and PK/PD characteristics of old antibiotics. In silico modelling was then performed using Monte Carlo simulation in order to combine all preclinical data with human pharmacokinetics and determine the probability of target (1-log kill in thigh/lung infection animal models) attainment (PTA) of different dosing regimens. The potential of clinical efficacy of a drug against severe infections by MDR gram-negative bacteria was considered when PTA was >95% at the epidemiological cutoff values of corresponding species. In vitro potent activity against MDR gram-negative pathogens has been shown for colistin, polymyxin B, temocillin (against E. coli and K. pneumoniae), fosfomycin (against E. coli), mecillinam (against E. coli), minocycline (against E. coli, K. pneumoniae, A. baumannii), and chloramphenicol (against E. coli) with ECOFF or MIC90 ≤ 16 mg/L. When preclinical PK/PD targets were combined with human pharmacokinetics, Monte Carlo analysis showed that among the old antibiotics analyzed, there is clinical potential for polymyxin B against E. coli, K. pneumoniae, and A. baumannii; for temocillin against K. pneumoniae and E. coli; for fosfomycin against E. coli and K. pneumoniae; and for mecillinam against E. coli. Clinical studies are needed to verify the potential of those antibiotics to effectively treat infections by multi-drug resistant gram-negative bacteria
Twenty Years in EUCAST Anti‑Fungal Susceptibility Testing: Progress & Remaining Challenges
No full textSince its inception in 2002, the EUCAST Antifungal Susceptibility Testing Subcommittee
(AFST) has developed and refined susceptibility testing methods for yeast, moulds and dermatophytes, and established epidemiological cut-off values and breakpoints for antifungals. For yeast, three challenges have been addressed. Interpretation of trailing growth in fluconazole susceptibility testing, which has been proven without impact on efficacy if below the 50% endpoint. Variability in rezafungin MIC testing due to laboratory conditions, which has been solved by the addition of Tween 20 to the growth medium in E.Def 7.4. And third, interpretation of MICs for rare yeast with no breakpoints, where recommendations have been established for MIC-based clinical advice. For moulds, refinements include the validation of spectrophotometer reading for A. fumigatus to facilitate objective MIC determination, and for dermatophytes the establishment of a microdilution method with automated reading and a selective medium to minimise the risk of contaminations. Recent initiatives involve development and validation of agar-based screening assays for detection of potential azole and echinocandin resistance in A. fumigatus and Aspergillus species, respectively, and of terbinafine resistance in Trichophyton species. Moreover, the development of a EUCAST guidance document for molecular resistance testing represents an advancement, particularly for identifying target gene alterations associated with resistance. In summary, EUCAST AFST continues to play a pivotal role in standardizing AFST and facilitating accurate interpretation of susceptibility data for clinical decision-making. Adoption of EUCAST breakpoints for commercial test methods, however, requires thorough validation to ensure concordance with EUCAST reference testing species-specific MIC distributions.The authors declare that no funds, grants, or
other support were received during the preparation of this
manuscript
- …
