In Vitro Pharmacodynamic Characteristics of Amphotericin B, Caspofungin, Fluconazole, and Voriconazole against Bloodstream Isolates of Infrequent Candida Species from Patients with Hematologic Malignancies

ABSTRACT Time-kill and postantifungal effect (PAFE) of amphotericin B, caspofungin, fluconazole, and voriconazole were determined against clinical isolates of Candida guilliermondii, Candida kefyr, and Candida lusitaniae. Azoles displayed fungistatic activity and no measurable PAFE, regardless of the concentration tested. Amphotericin B and caspofungin demonstrated concentration-dependent fungicidal activity, although amphotericin B only produced a significant dose-dependent PAFE against all isolates tested.

Download Full-text

Dynamic Interaction between Fluconazole and Amphotericin B against Cryptococcus gattii

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.06098-11 ◽

2012 ◽

Vol 56 (5) ◽

pp. 2553-2558 ◽

Cited By ~ 29

Author(s):

Julliana Ribeiro Alves Santos ◽

Ludmila Ferreira Gouveia ◽

Erika Linzi Silva Taylor ◽

Maria Aparecida Resende-Stoianoff ◽

Gerson Antônio Pianetti ◽

...

Keyword(s):

Amphotericin B ◽

Cryptococcus Gattii ◽

Content Type ◽

Antagonistic Interaction ◽

Ergosterol Content ◽

Kill Curve ◽

Time Kill ◽

Postantifungal Effect

ABSTRACTCryptococcus gattiiis the main pathogen of cryptococcosis in healthy patients and is treated mainly with fluconazole and amphotericin B. The combination of these drugs has been questioned because the mechanisms of action could lead to a theoretical antagonistic interaction. We evaluated distinct parameters involved in thein vitrocombination of fluconazole and amphotericin B againstCryptococcus gattii. Fourteen strains ofC. gattiiwere used for the determination of MIC, fractional inhibitory concentration, time-kill curve, and postantifungal effect (PAFE). Ergosterol quantification was performed to evaluate the influence of ergosterol content on the interaction between these antifungals. Interaction between the drugs varied from synergistic to antagonistic depending on the strain and concentration tested. Increasing fluconazole levels were correlated with an antagonistic interaction. A total of 48 h was necessary for reducing the fungal viability in the presence of fluconazole, while 12 h were required for amphotericin B. When these antifungals were tested in combination, fluconazole impaired the amphotericin B activity. The ergosterol content decreased with the increase of fluconazole levels and it was correlated with the lower activity of amphotericin B. The PAFE found varied from 1 to 4 h for fluconazole and from 1 to 3 h for amphotericin B. The interaction of fluconazole and amphotericin B was concentration-dependent and special attention should be directed when these drugs are used in combination againstC. gattii.

Download Full-text

In Vitro Interaction and Killing-Kinetics of Amphotericin B Combined with Anidulafungin or Caspofungin against Candida auris

Pharmaceutics ◽

10.3390/pharmaceutics13091333 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1333

Author(s):

Unai Caballero ◽

Elena Eraso ◽

Guillermo Quindós ◽

Nerea Jauregizar

Keyword(s):

Amphotericin B ◽

Antifungal Drugs ◽

Candida Auris ◽

Dose Requirement ◽

Fungistatic Activity ◽

Invasive Infections ◽

Kill Curve ◽

Time Kill ◽

In Vitro Interaction

Treatment of invasive infections caused by Candida auris is challenging due to the limited therapeutic options. The combination of antifungal drugs may be an interesting and feasible approach to be investigated. The aim of this study was to examine the in vitro activity of amphotericin B in combination with anidulafungin or caspofungin against C. auris. In vitro static time–kill curve experiments were conducted for 48 h with different combinations of amphotericin B with anidulafungin or caspofungin against six blood isolates of C. auris. The antifungal activity of 0.5 mg/L of amphotericin B was limited against the six isolates of C. auris. Similarly, echinocandins alone had a negligible effect, even at the highest tested concentrations. By contrast, 1 mg/L of amphotericin B showed fungistatic activity. Synergy was rapidly achieved (8 h) with 0.5 mg/L of amphotericin B plus 2 mg/L of anidulafungin or caspofungin. These combinations lead to a sustained fungistatic effect, and the fungicidal endpoint was reached against some C. auris isolates. Additionally, ≥0.5 mg/L of either of the two echinocandins with 1 mg/L of amphotericin B resulted in fungicidal effect against all C. auris isolates. In conclusion, combinations of amphotericin B with anidulafungin or caspofungin provided greater killing with a lower dose requirement for amphotericin B compared to monotherapy, with synergistic and/or fungicidal outcomes.

Download Full-text

In vitro susceptibility testing of Candida species isolated from blood stream infections to five conventional antifungal drugs

10.36811/ijbm.2019.110016 ◽

2019 ◽

pp. 124-129

Author(s):

Mahdis Hosein Khezri ◽

Farideh Zaini ◽

Parivash Kordbache ◽

Mohammad Ghahri ◽

Pegah Ardi ◽

...

Keyword(s):

Candida Albicans ◽

Amphotericin B ◽

Candida Species ◽

Bloodstream Infections ◽

Blood Stream ◽

Candida Guilliermondii ◽

Antifungal Drugs ◽

In Vitro Susceptibility ◽

Dose Dependent

Candida is an opportunistic fungal pathogen which can cause fatal bloodstream infections (BSIs) in immunocompromised and immunodeficient persons. In this study, the susceptibility of 196 Candida species isolated from bloodstream infections (BSI) to 5 antifungal drugs were conducted from October 2014 through October 2017. The antifungal drugs used in this study were including fluconazole, itraconazole, voriconazole, Amphotericin B and Caspofungin. From 196 studied isolates, Candida albicans comprised 63.3% of the isolates, followed by C.parapsilosis (18.9 %), C. glabrata (8.7%), C. tropicalis (6.1%), C.krusei (2%) and C.gillermundii (1%). In this study, all isolates of Candida albicans and Candida non-albicans species were completely resistant to voriconazole and itraconazole. Of the 196 Candida isolates, 80 isolates with MIC of 32-16 μg/ml had a dose dependent susceptibility to fluconazole and 111 isolates showed resistance (MIC=64 μg / ml) and only 5 isolates were sensitive (MIC=8 μg / ml) to fluconazole. In this study, out of 196 isolates, 37 isolates were sensitive to amphotericin (MIC=1 μg/ml) and 159 isolates were resistant to amphotericin B (MIC>1 μg/ml). Caspofungin was effective on 104 isolates (MIC<2 μg/ml) and 92 isolates were non-susceptible (MIC>2 μg / ml) to this drug. Out of 124 isolates of Candida albicans, 3 were susceptible, 61 susceptible dose dependent and 60 were resistant to fluconazole. Only 24 isolates were susceptible to amphotericin B and 100 isolates showed resistance to this antifungal drug. Eighty-eight isolates were sensitive to caspofungin and 36 isolates were insensitive. With respect to susceptibility to fluconazole, among 37 isolates of Candida parapsilosis, one was identified as susceptible, 13 isolates were susceptible dose dependent and 13 were resistant. Of these isolates, five were susceptible and 32 isolates were resistant to amphotericin B and caspofungin. Of 12 isolates of Candida tropicalis, 11 showed resistance and 1 was susceptible dose dependent to fluconazole. Of these isolates, 11 were resistant to amphotericin B and 1 isolate was sensitive. Ultimately, only 2 isolates showed susceptibility to caspofungin. Out of 17 isolates of Candida glabrata, 13 isolates were resistant, and 4 isolates had a dose-dependent sensitivity to fluconazole. Eight isolates were susceptible and 9 isolates were resistant to caspofungin. Seven isolates were susceptible and 10 isolates were resistant to amphotericin B. All four Candida krusei isolates showed resistance to the five drugs used in the study. Of the two Candida guilliermondii isolates, both were resistant to amphotericin B, but 1 was sensitive to fluconazole and 1 was identified to be dose-dependent susceptible. One isolate was resistant to and the other one was susceptible to caspofungin. Our findings shows the prevalence of resistant candida species to conventional treatments and indicate that candidemia caused by Candida resistant species is incrasing. Keywords: Candidiasis; Antifungal drugs; Candidemia; Iran

Download Full-text

In Vitro Synergistic Interactions of Isavuconazole and Echinocandins against Candida auris

Antibiotics ◽

10.3390/antibiotics10040355 ◽

2021 ◽

Vol 10 (4) ◽

pp. 355

Author(s):

Unai Caballero ◽

Sarah Kim ◽

Elena Eraso ◽

Guillermo Quindós ◽

Valvanera Vozmediano ◽

...

Keyword(s):

Interaction Model ◽

Antifungal Drugs ◽

Health Concern ◽

Candida Auris ◽

Fungistatic Activity ◽

Drug Concentrations ◽

Low Concentrations ◽

Wide Range ◽

Time Kill

Candida auris is an emergent fungal pathogen that causes severe infectious outbreaks globally. The public health concern when dealing with this pathogen is mainly due to reduced susceptibility to current antifungal drugs. A valuable alternative to overcome this problem is to investigate the efficacy of combination therapy. The aim of this study was to determine the in vitro interactions of isavuconazole with echinocandins against C. auris. Interactions were determined using a checkerboard method, and absorbance data were analyzed with different approaches: the fractional inhibitory concentration index (FICI), Greco universal response surface approach, and Bliss interaction model. All models were in accordance and showed that combinations of isavuconazole with echinocandins resulted in an overall synergistic interaction. A wide range of concentrations within the therapeutic range were selected to perform time-kill curves. These confirmed that isavuconazole–echinocandin combinations were more effective than monotherapy regimens. Synergism and fungistatic activity were achieved with combinations that included isavuconazole in low concentrations (≥0.125 mg/L) and ≥1 mg/L of echinocandin. Time-kill curves revealed that once synergy was achieved, combinations of higher drug concentrations did not improve the antifungal activity. This work launches promising results regarding the combination of isavuconazole with echinocandins for the treatment of C. auris infections.

Download Full-text

Molecular Identification and Antifungal Susceptibility of Yeast Isolates Causing Fungemia Collected in a Population-Based Study in Spain in 2010 and 2011

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02155-13 ◽

2013 ◽

Vol 58 (3) ◽

pp. 1529-1537 ◽

Cited By ~ 82

Author(s):

Jesús Guinea ◽

Óscar Zaragoza ◽

Pilar Escribano ◽

Estrella Martín-Mazuelos ◽

Javier Pemán ◽

...

Keyword(s):

Hot Spot ◽

Antifungal Susceptibility ◽

Point Mutations ◽

Population Based ◽

Candida Guilliermondii ◽

Population Based Study ◽

Content Type ◽

Candida Lusitaniae ◽

Species Specific

ABSTRACTWe report the molecular identifications and antifungal susceptibilities of the isolates causing fungemia collected in the CANDIPOP population-based study conducted in 29 Spanish hospitals. A total of 781 isolates (from 767 patients, 14 of them having mixed fungemia) were collected. The species found most frequently wereCandida albicans(44.6%),Candida parapsilosis(24.5%),Candida glabrata(13.2%),Candida tropicalis(7.6%),Candida krusei(1.9%),Candida guilliermondii(1.7%), andCandida lusitaniae(1.3%). OtherCandidaand non-Candidaspecies accounted for approximately 5% of the isolates. The presence of cryptic species was low. Compared to findings of previous studies conducted in Spain, the frequency ofC. glabratahas increased. Antifungal susceptibility testing was performed by using EUCAST and CLSI M27-A3 reference procedures; the two methods were comparable. The rate of fluconazole-susceptible isolates was 80%, which appears to be a decrease compared to findings of previous studies, explained mainly by the higher frequency ofC. glabrata. Using the species-specific breakpoints and epidemiological cutoff values, the rate of voriconazole and posaconazolein vitroresistance was low (<2%). In the case ofC. tropicalis, using the EUCAST procedure, the rate of azole resistance was around 20%. There was a correlation between the previous use of azoles and the presence of fluconazole-resistant isolates. Resistance to echinocandins was very rare (2%), and resistance to amphotericin B also was very uncommon. The sequencing of the hot spot (HS) regions fromFKS1orFKS2genes in echinocandin-resistant isolates revealed previously described point mutations. The decrease in the susceptibility to fluconazole in Spanish isolates should be closely monitored in future studies.

Download Full-text

Assessment of Candida auris Response to Antifungal Drugs Using Time–Kill Assays and an Animal Model

Open Forum Infectious Diseases ◽

10.1093/ofid/ofx163.003 ◽

2017 ◽

Vol 4 (suppl_1) ◽

pp. S73-S73 ◽

Cited By ~ 1

Author(s):

Ronen Ben-Ami ◽

Liat Ashkenazi ◽

Judith Berman ◽

Nuphar Korolker ◽

Anna Novikov

Keyword(s):

Amphotericin B ◽

Fungicidal Activity ◽

Antifungal Drugs ◽

Rank Test ◽

Infection Model ◽

Candida Auris ◽

Fungistatic Activity ◽

Kill Curve ◽

Time Kill

Abstract Background Candida auris is an emerging nosocomial pathogen that is resistant to Fluconazole and variably susceptible to other systemic drug classes. Treatment with echinocandins has been recommended based on MICs in the susceptible range, but supporting in vivo data is lacking. Methods We tested the MIC of C. auris strains (n = 12) to fluconazole, voriconazole, posaconazole. anidulafungin, amphotericin B and flucytosine. Representative C. auris strains from Israel and South Africa, and a reference C. albicans strain were analysed using time–kill curve assays. Fungicidal activity was defined as reduction of ≥3 log from baseline CFU/ml. Response to caspofungin treatment was assessed in BALB/c mice immunosuppressed with cyclophosphamide and inoculated with 7 × 107C. auris cells by tail vein injection. Mice were treated from day +1 to day +7 with caspofungin (IP) at doses of 1 or 5 mg/kg and compared with sham-treated controls. Survival was assessed daily. Kaplan-Meier survival analyses were performed and treatment arms were compared using the log-rank test. Results Drug susceptibility results (MIC50 and MIC90) were: fluconazole, 64 and 128 mg/l; voriconazole, 0.5 and 24 mg/l; posaconazole, 0.5 and 27 mg/l; anidulafungin, 0.03 and 0.06 mg/l; amphotericin B, 2 and 8 mg/l; flucytosine, 0.3 and 1 mg/l. Time–kill curve analyses showed log reduction from baseline CFU concentration of −3.0 to −2.8 for fluconazole (MIC ×1), 5.6–6.1 for amphotericin B (MIC ×4) and −0.4 to −0.9 for caspofungin (MIC ×16), consistent with fungicidal activity of amphotericin B and weak fungistatic activity of caspofungin. In the mouse model, survival rate was similar with sham treatment (33%) and treatment with caspofungin 1 mg/kg/day (44%) and 5 mg/kg/day (22%), P = 0.7. Conclusion Despite generally low MIC, caspofungin has only mild fungistatic activity on C. auris and no effect on survival in a mouse infection model. Amphotericin B has fungicidal activity against C. auris. Disclosures All authors: No reported disclosures.

Download Full-text

Posaconazole against Candida glabrata Isolates with Various Susceptibilities to Fluconazole

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00130-08 ◽

2008 ◽

Vol 52 (6) ◽

pp. 1929-1933 ◽

Cited By ~ 10

Author(s):

Elisabetta Spreghini ◽

Carmelo Massimo Maida ◽

Serena Tomassetti ◽

Fiorenza Orlando ◽

Daniele Giannini ◽

...

Keyword(s):

Experimental Model ◽

Candida Glabrata ◽

Therapeutic Option ◽

Resistant Isolate ◽

Dependent Manner ◽

Fungal Burden ◽

Systemic Infections ◽

Time Kill ◽

Dose Dependent

ABSTRACT We investigated the in vitro activities of posaconazole (POS), fluconazole (FLC), amphotericin B (AMB), and caspofungin (CAS) against four clinical isolates of Candida glabrata with various susceptibilities to FLC (FLC MICs ranging from 1.0 to >64 μg/ml). POS MICs ranged from ≤0.03 to 0.5 μg/ml; AMB MICs ranged from 0.25 to 2.0 μg/ml, while CAS MICs ranged from 0.03 to 0.25 μg/ml. When FLC MICs increased, so did POS MICs, although we did not observe any isolate with a POS MIC greater than 0.5 μg/ml. Time-kill experiments showed that POS, FLC, and CAS were fungistatic against all isolates, while AMB at eight times the MIC was fungicidal against three out of four isolates of C. glabrata tested. Then, we investigated the activity of POS in an experimental model of disseminated candidiasis using three different isolates of C. glabrata: one susceptible to FLC (S; FLC MICs ranging from 1.0 to 4.0 μg/ml; POS MIC of ≤0.03 μg/ml), one susceptible in a dose-dependent manner (SDD; FLC MICs ranging from 32 to 64 μg/ml; POS MICs ranging from 0.125 to 0.25 μg/ml), and another one resistant to FLC (R; FLC MIC of >64 μg/ml; POS MIC of 0.5 μg/ml). FLC significantly reduced the kidney burden of mice infected with the S strain (P = 0.0070) but not of those infected with the S-DD and R strains. POS was significantly effective against all three isolates at reducing the kidney fungal burden with respect to the controls (P ranging from 0.0003 to 0.029). In conclusion, our data suggest that POS may be a useful option in the management of systemic infections caused by C. glabrata. Additionally, the new triazole may be a therapeutic option in those cases where an FLC-resistant isolate is found to retain a relatively low POS MIC.

Download Full-text

Caspofungin at Catheter Lock Concentrations Eradicates Mature Biofilms of Candida lusitaniae and Candida guilliermondii

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03117-14 ◽

2014 ◽

Vol 58 (8) ◽

pp. 4953-4956 ◽

Cited By ~ 10

Author(s):

Maria Simitsopoulou ◽

Daniela Kyrpitzi ◽

Aristea Velegraki ◽

Thomas J. Walsh ◽

Emmanuel Roilides

Keyword(s):

Amphotericin B ◽

Liposomal Amphotericin ◽

Candida Guilliermondii ◽

Liposomal Amphotericin B ◽

Antibiofilm Activity ◽

Test Species ◽

Content Type ◽

Lock Therapy ◽

Catheter Lock ◽

Candida Lusitaniae

ABSTRACTThe antibiofilm activities of caspofungin, anidulafungin, micafungin, and liposomal amphotericin B were studied againstCandida lusitaniae,Candida guilliermondii, and aCandida albicanscontrol strain. While anidulafungin and micafungin (0.007 to 2,048 mg/liter) showed reduced activity against biofilms of both test species, caspofungin displayed concentration-dependent antibiofilm activity, reaching complete and persistent eradication at concentrations achievable during lock therapy (512 to 2,048 mg/liter,P< 0.05). Although liposomal amphotericin B strongly inhibited mature biofilms, it possessed lower antibiofilm activity than caspofungin (P< 0.05).

Download Full-text

In VitroInteraction between Alginate Lyase and Amphotericin B against Aspergillus fumigatus Biofilm Determined by Different Methods

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01875-12 ◽

2012 ◽

Vol 57 (3) ◽

pp. 1275-1282 ◽

Cited By ~ 32

Author(s):

Francesca Bugli ◽

Brunella Posteraro ◽

Massimiliano Papi ◽

Riccardo Torelli ◽

Alessandro Maiorana ◽

...

Keyword(s):

Invasive Aspergillosis ◽

Aspergillus Fumigatus ◽

Amphotericin B ◽

Extracellular Polymeric Substances ◽

Alginate Lyase ◽

Antifungal Drugs ◽

Antibiofilm Activity ◽

Content Type ◽

Time Kill

ABSTRACTAspergillus fumigatusbiofilms represent a problematic clinical entity, especially because of their recalcitrance to antifungal drugs, which poses a number of therapeutic implications for invasive aspergillosis, the most difficult-to-treatAspergillus-related disease. While the antibiofilm activities of amphotericin B (AMB) deoxycholate and its lipid formulations (e.g., liposomal AMB [LAMB]) are well documented, the effectiveness of these drugs in combination with nonantifungal agents is poorly understood. In the present study,in vitrointeractions between polyene antifungals (AMB and LAMB) and alginate lyase (AlgL), an enzyme degrading the polysaccharides produced as extracellular polymeric substances (EPSs) within the biofilm matrix, againstA. fumigatusbiofilms were evaluated by using the checkerboard microdilution and the time-kill assays. Furthermore, atomic force microscopy (AFM) was used to image and quantify the effects of AlgL-antifungal combinations on biofilm-growing hyphal cells. On the basis of fractional inhibitory concentration index values, synergy was found between both AMB formulations and AlgL, and this finding was also confirmed by the time-kill test. Finally, AFM analysis showed that whenA. fumigatusbiofilms were treated with AlgL or polyene alone, as well as with their combination, both a reduction of hyphal thicknesses and an increase of adhesive forces were observed compared to the findings for untreated controls, probably owing to the different action by the enzyme or the antifungal compounds. Interestingly, marked physical changes were noticed inA. fumigatusbiofilms exposed to the AlgL-antifungal combinations compared with the physical characteristics detected after exposure to the antifungals alone, indicating that AlgL may enhance the antibiofilm activity of both AMB and LAMB, perhaps by disrupting the hypha-embedding EPSs and thus facilitating the drugs to reach biofilm cells. Taken together, our results suggest that a combination of AlgL and a polyene antifungal may prove to be a new therapeutic strategy for invasive aspergillosis, while reinforcing the EPS as a valuable antibiofilm drug target.

Download Full-text

In VitroAntifungal Activity of Naftifine Hydrochloride against Dermatophytes

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01084-13 ◽

2013 ◽

Vol 57 (9) ◽

pp. 4369-4372 ◽

Cited By ~ 23

Author(s):

M. Ghannoum ◽

N. Isham ◽

A. Verma ◽

S. Plaum ◽

A. Fleischer ◽

...

Keyword(s):

Developed Countries ◽

Microsporum Canis ◽

Test Panel ◽

Resistance Development ◽

Epidermophyton Floccosum ◽

Content Type ◽

Development Of Resistance ◽

Time Kill ◽

Dose Dependent

ABSTRACTThe incidence of superficial dermatophytoses is high in developed countries, and there remains a need for effective topical antifungals. In this study, we evaluated thein vitroantifungal activity of naftifine hydrochloride, the active ingredient in naftifine hydrochloride cream and gel 1% and 2%, against dermatophytes. The MICs and minimum fungicidal concentrations (MFCs) of naftifine hydrochloride against 350 clinical strains, includingTrichophyton rubrum,T. mentagrophytes,T. tonsurans,Epidermophyton floccosum, andMicrosporum canis, were determined using the CLSI methodology. Subsets from this test panel were subsequently tested in a time-kill assay at 0.125×, 0.25×, 0.5×, and 1× the MFC for each isolate. CFU counts were performed over a period of 48 h of incubation. Additionally, in order to determine the potential for resistance development, six strains were subjected to 15 serial passages in concentrations higher than the MIC for each strain. MICs were determined following each passage. The MIC range against the dermatophyte isolates tested was 0.015 to 1.0 μg/ml, with naftifine hydrochloride being fungicidal against 85% of theTrichophytonspecies. The time-kill assay showed dose-dependent activity, with the greatest reduction in the numbers of CFU corresponding to the highest drug concentration. There was no increase in MIC for any strains following repeated exposure to naftifine hydrochloride. Naftifine hydrochloride demonstrated potent activity against all dermatophytes tested, and none of the isolates within this test panel demonstrated the potential for the development of resistance. Thus, future clinical studies of naftifine hydrochloride against dermatophytes may be warranted for the treatment of superficial dermatophytoses.

Download Full-text