In-vitro pharmacokinetic/pharmacodynamic model data suggest a potential role of new formulations of posaconazole against Candida krusei but not Candida glabrata infections.

Posaconazole exhibits in-vitro activity against Candida glabrata and Candida krusei. Epidemiological cut-off values set by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the Clinical and Laboratory Standards Institute (CLSI) are 1/1 and 0.5/0.5 mg/L, respectively, but clinical breakpoints have not been established to date. This study explored the pharmacodynamics (PD) of posaconazole in a validated one-compartment in-vitro pharmacokinetic (PK)/PD model, and determined the probability of PK/PD target attainment (PTA) for the available formulations. Five C. glabrata and three C. krusei isolates with posaconazole minimum inhibitory concentrations (MICs) of 0.06-2 and 0.03-0.25 mg/L, respectively, were tested in the PK/PD model simulating different time-concentration profiles of posaconazole. The exposure-effect relationship fAUC0-24/MIC was described for EUCAST/CLSI methods, and PTA was calculated in order to determine PK/PD susceptibility breakpoints for oral solution (400 mg q12h), and intravenous (i.v.)/tablet formulations (300 mg q24h). Fungicidal activity (~2log kill) was found against the most susceptible C. glabrata isolate alone, and against all three C. krusei isolates. The corresponding EUCAST/CLSI PK/PD targets (fAUC0-24/MIC) were 102/79 for C. glabrata and 12/8 for C. krusei. Mean PTA was high (>95%) for C. glabrata isolates with EUCAST/CLSI MICs ≤0.03/≤0.03 mg/L for oral solution and ≤0.125/≤0.125 mg/L for i.v. and tablet formulations for the wild-type population. For C. krusei isolates, mean PTA was high (>95%) for EUCAST/CLSI MICs ≤0.25/≤0.5 mg/L for oral solution and ≤1/≤2 mg/L for i.v. and tablet formulations for the wild-type population. The use of posaconazole to treat C. glabrata infections is questionable. Intravenous and tablet formulations may be therapeutic options for the treatment of C. krusei infections, and oral exposure can be optimized with therapeutic drug monitoring (trough levels >0.6-0.9 mg/L).

Voriconazole efficacy against Candida glabrata and Candida krusei: preclinical data using a validated in vitro pharmacokinetic/pharmacodynamic model.

BACKGROUND: Voriconazole exhibits in vitro activity against Candida glabrata and Candida krusei (EUCAST/CLSI epidemiological cut-off values 1/0.25 and 1/0.5 mg/L, respectively). Yet, EUCAST found insufficient evidence to set breakpoints for these species. We explored voriconazole pharmacodynamics (PD) in an in vitro dynamic model simulating human pharmacokinetics (PK). METHODS: Four C. glabrata and three C. krusei isolates (voriconazole EUCAST and CLSI MICs of 0.03-2 mg/L) were tested in the PK/PD model simulating voriconazole exposures (t½ ∼6 h q12h dosing for 3 days). PK/PD breakpoints were determined calculating the PTA for exposure indices fAUC0-24/MIC associated with half-maximal activity (EI50) using Monte Carlo simulation analysis. RESULTS: Fungal load increased from 3.60±0.35 to 8.41±0.24 log10 cfu/mL in the drug-free control, with a maximum effect of ∼1 log10 kill of C. glabrata and C. krusei isolates with MICs of 0.06 and 0.25 mg/L, respectively, at high drug exposures. The 72 h log10 cfu/mL change versus fAUC0-24/MIC relationship followed a sigmoid curve for C. glabrata (R2=0.85-0.87) and C. krusei (R2=0.56-0.76) with EI50 of 49 (32-76) and 52 (33-78) fAUC/MIC for EUCAST and 55 (31-96) and 80 (42-152) fAUC/MIC for CLSI, respectively. The PTAs for C. glabrata and C. krusei isolates with EUCAST/CLSI MICs ≤0.125/≤0.06 mg/L were >95%. Isolates with EUCAST/CLSI MICs of 0.25-1/0.125-0.5 would require trough levels 1-4 mg/L; isolates with higher MICs would not attain the corresponding PK/PD targets without reaching toxicity. CONCLUSIONS: The in vitro PK/PD breakpoints for C. glabrata and C. krusei for EUCAST (0.125 mg/L) and CLSI (0.06 mg/L) bisected the WT populations. Trough levels of >4 mg/L, which are not clinically feasible, are necessary for efficacy against WT isolates.

Epidemiological Trends of Fungemia in Greece with a Focus on Candidemia during the Recent Financial Crisis: a 10-Year Survey in a Tertiary Care Academic Hospital and Review of Literature.

Updated information on the epidemiology of candidemia, particularly during severe socioeconomic events, is important for proper management of these infections. A systematic literature review on candidemia in Greece and a retrospective surveillance study were conducted in a tertiary university hospital during the years of the recent financial crisis (2009 to 2018) in order to assess changes in incidence rates, patient characteristics, species distribution, antifungal susceptibilities, and drug consumption. The average annual incidence of 429 candidemic episodes was 2.03/10,000 bed days, with 9.88 in adult intensive care units (ICUs), 1.74 in surgical wards, and 1.81 in internal medicine wards, where a significant increase was observed (1.15, 1.85, and 2.23/10,000 bed days in 2009 to 2011, 2012 to 2014, and 2015 to 2018, respectively; P = 0.004). Candida albicans was the most common species (41%), followed by Candida parapsilosis species complex [SC] (37%), Candida glabrata SC (11%), Candida tropicalis (7%), Candida krusei (1%), and other rare Candida spp. (3%). Mixed infections were found in 20/429 (4.7%) cases, while 33 (7%) cases were due to non-Candida spp. Overall, 44/311 (14%) isolates were resistant/non-wild type (WT) to the nine antifungals tested, with 23/113 (20%) C. parapsilosis SC and 2/34 (6%) C. glabrata SC isolates being resistant to fluconazole (1 panechinocandin and 2 panazole resistant). All isolates were susceptible/WT to amphotericin B and flucytosine. While the overall consumption of antifungals diminished (P = 0.02), with a mean of 17.93 defined daily doses (DDD)/100 bed days, increased micafungin use was correlated with the rise in C. parapsilosis SC (P = 0.04). A significant increase of candidemia in internal medicine wards and of C. parapsilosis SC infections was found during the years of financial crisis. Although resistance rates remain low (<14%), fluconazole-resistant C. parapsilosis SC and multidrug-resistant C. glabrata SC isolates are of major concern.

Potential of the microbial assay for risk assessment (MARA) for assessing ecotoxicological effects of herbicides to non-target organisms.

Many microbiotests that have been proposed for use in the risk assessment of environmental pollutants have the drawback of lacking relevant published data on various aspects of their test application possibilities and therefore do not receive the regulatory recognition which they may deserve. The MARA bioassay lacks published data for many relevant environmental pollutants, particularly pesticides and this may limit its use in regulatory framework. The present study has assessed the sensitivity of the MARA bioassay relative to other established bioassays (Daphnia magna and Oreochromis niloticus) to two widely used herbicide formulations: Roundup (having glyphosate as active ingredient) and Herbextra (with the active ingredient being 2,4-dichlorophenoxyacetic acid-2,4-D). Roundup was found to be more toxic than Herbextra in all three bioassays. The D. magna EC50 s obtained for Roundup and Herbextra were respectively 5.55 and 356.61 mg/l while the LC50 s for O. niloticus were 11.30 and 222,28 mg/l respectively. In the case of the MARA bioassay microbial toxic concentrations (MTCs) for individual species ranged from 6.85 to 468 mg/l with an overall mean MTC of 101.82 mg/l for glyphosate and from 74.67 to 13,333 mg/l for 2,4-D giving an overall mean MTC of 2855.88 mg/l. Although the overall MTCs from the MARA bioassay were much higher than the LC50 s and EC50 s from the fish and daphnia bioassays respectively, the most sensitive MARA organism for each of the herbicides had MTCs that were comparable to or lower than the corresponding endpoints from the other bioassays implying that the MARA assay is a potentially useful bioassay for risk assessment of pesticides.

Antimicrobial activity of Chinese bayberry extract for the preservation of surimi.

BACKGROUND: Chemical preservatives such as sodium nitrite and potassium sorbate have been widely used to keep surimi products fresh. However, the potential harmfulness to human health cannot be ignored. This study was conducted to develop natural preservatives for the storage of Collichthys surimi. RESULTS: Among the eight Chinese traditional herbs and fruits, Chinese bayberry extract showed the greatest inhibitory effect against surimi spoilage bacteria Serratia marcescens and Pseudomonas aeruginosa. Moreover, N-butanol phase extract of bayberry (NB) showed the greatest activity among the different phases of bayberry extract. When Chinese bayberry extract was combined with tea polyphenol, an additive inhibitory effect was observed on growth of Hansenula anomala, Micrococcus luteus, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. Our results further indicated that the shelf life of surimi products stored at room temperature can be extended when supplemented with Chinese bayberry extract. CONCLUSION: Our results suggest that Chinese bayberry extract can be used as a natural preservative for the storage of Collichthys surimi.

An economical method for (15)N/(13)C isotopic labeling of proteins expressed in Pichia pastoris.

We report a new and cost-effective approach to prepare (15)N/(13)C labeled proteins for NMR using the Pichia pastoris expression system. Four protocols (P1 to P4) were defined and compared using recombinant Ovine interferon-tau (rOvIFN-tau). Our results demonstrate that in order to get full incorporation of (15)N and (13)C, the isotopes are not totally required during the initial growth phase of P. pastoris culture. The addition of small amounts of (15)N and (13)C compounds 6 h prior to the methanol induction phase is sufficient to obtain 99% incorporation of heavy isotopes into the protein. Our optimized protocol P4 is two-thirds less costly than the classical method using (15)N and (13)C isotopes during the entire growth phase.