scholarly journals Quantitation of Candida albicans Ergosterol Content Improves the Correlation between In Vitro Antifungal Susceptibility Test Results and In Vivo Outcome after Fluconazole Treatment in a Murine Model of Invasive Candidiasis

2000 ◽  
Vol 44 (8) ◽  
pp. 2081-2085 ◽  
Author(s):  
Beth A. Arthington-Skaggs ◽  
David W. Warnock ◽  
Christine J. Morrison
Keyword(s):  
Murine Model ◽  
Invasive Candidiasis ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Resistant Isolate ◽  
National Committee ◽  
Ergosterol Content ◽  
In Vitro Antifungal Susceptibility

ABSTRACT MIC end point determination for the most commonly prescribed azole antifungal drug, fluconazole, can be complicated by “trailing” growth of the organism during susceptibility testing by the National Committee for Clinical Laboratory Standards approved M27-A broth macrodilution method and its modified broth microdilution format. To address this problem, we previously developed the sterol quantitation method (SQM) for in vitro determination of fluconazole susceptibility, which measures cellular ergosterol content rather than growth inhibition after exposure to fluconazole. To determine if SQM MICs of fluconazole correlated better with in vivo outcome than M27-A MICs, we used a murine model of invasive candidiasis and analyzed the capacity of fluconazole to treat infections caused by C. albicansisolates which were trailers (M27-A MICs at 24 and 48 h, ≤1.0 and ≥64 μg/ml, respectively; SQM MIC, ≤1.0 μg/ml), as well as those which were fluconazole sensitive (M27-A and SQM MIC, ≤1.0 μg/ml) and fluconazole resistant (M27-A MIC, ≥64 μg/ml; SQM MIC, 54 μg/ml). Compared with the untreated controls, fluconazole therapy increased the survival of mice infected with a sensitive isolate and both trailing isolates but did not increase the survival of mice infected with a resistant isolate. These results indicate that the SQM is more predictive of in vivo outcome than the M27-A method for isolates that give unclear MIC end points due to trailing growth in fluconazole.

scholarly journals Optimizing the Correlation between Results of Testing In Vitro and Therapeutic Outcome In Vivo for Fluconazole by Testing Critical Isolates in a Murine Model of Invasive Candidiasis

1998 ◽  
Vol 42 (1) ◽  
pp. 129-134 ◽  
Author(s):  
John H. Rex ◽  
Page W. Nelson ◽  
Victor L. Paetznick ◽  
Mario Lozano-Chiu ◽  
A. Espinel-Ingroff ◽  
...  
Keyword(s):  
Murine Model ◽  
Invasive Candidiasis ◽  
Response Pattern ◽  
Clinical Laboratory ◽  
Rank Order ◽  
National Committee ◽  
Growth Phenomenon ◽  
Improvement In Survival

ABSTRACT The trailing growth phenomenon seen when determining the susceptibilities of Candida isolates to the azole antifungal agents makes consistent endpoint determination difficult, and the M27-A method of the National Committee for Clinical Laboratory Standards addresses this problem by requiring an 80% reduction in growth after 48 h of incubation. For some isolates, however, minor variations of this endpoint criterion can produce up to 128-fold variations in the resulting MIC. To investigate the significance of this effect, isolates of Candida that exhibited various forms of trailing growth when tested against fluconazole were identified. The isolates were examined in a murine model of invasive candidiasis and were ranked by their relative response to fluconazole by using both improvement in survival and reduction in fungal burden in the kidney. The resulting rank order of in vivo response did not match the MICs obtained by using the M27-A criterion, and these MICs significantly overestimated the resistance of three of the six isolates tested. However, if the MIC was determined after 24 h of incubation and the endpoint required a less restrictive 50% reduction in growth, MICs which better matched the in vivo response pattern could be obtained. Minor variations in the M27-A endpoint criterion are thus required to optimize the in vitro-in vivo correlation for isolates that demonstrate significant trailing growth when tested against fluconazole.

scholarly journals Interpretive Breakpoints for Fluconazole and Candida Revisited: a Blueprint for the Future of Antifungal Susceptibility Testing

2006 ◽  
Vol 19 (2) ◽  
pp. 435-447 ◽  
Author(s):  
M. A. Pfaller ◽  
D. J. Diekema ◽  
D. J. Sheehan
Keyword(s):  
Clinical Studies ◽  
Randomized Clinical Trials ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Strong Relationship ◽  
National Committee ◽  
Disk Diffusion Testing ◽  
Invasive Infections

SUMMARY Developing interpretive breakpoints for any given organism-drug combination requires integration of the MIC distribution, pharmacokinetic and pharmacodynamic parameters, and the relationship between in vitro activity and outcome from both in vivo and clinical studies. Previously, the Subcommittee for Antifungal Testing of the Clinical and Laboratory Standards Institute (CLSI [formerly National Committee for Clinical Laboratory Standards]) proposed MIC interpretive breakpoints for fluconazole and Candida spp. These breakpoints were considered to be somewhat weak, because the clinical data supporting them came largely from mucosal infections and there were very few infections involving strains with elevated fluconazole MICs. We readdress the issue of fluconazole breakpoints for Candida by using published clinical and microbiologic data to provide further validation of the breakpoints proposed by the CLSI in 1997. We also address interpretive breakpoints for agar disk diffusion testing of fluconazole. The MIC distribution for fluconazole was determined with a collection of 13,338 clinical isolates. The overall MIC at which 90% of the isolates were inhibited was 8 μg/ml: 91% were susceptible (S) at a MIC of ≤8 μg/ml and 3% were resistant (R) (MIC ≥ 64 μg/ml). Similar results were obtained for 2,190 isolates from randomized clinical trials. Analysis of available data for 1,295 patient-episode-isolate events (692 represented mucosal infections and 603 represented invasive infections) from 12 published clinical studies demonstrated an overall success rate of 77%, including 85% for those episodes in which the fluconazole MIC was ≤8 μg/ml, 67% for those episodes in which the MIC was 16 to 32 μg/ml, and 42% for those episodes with resistant (MIC ≥ 64 μg/ml) isolates. Pharmacodynamic analysis demonstrated a strong relationship between MIC, fluconazole dose, and outcome. A dose/MIC ratio of ∼25 was supportive of the following susceptibility breakpoints for fluconazole and Candida spp.: S, MIC ≤ 8 μg/ml; susceptible-dose dependent (SDD), MIC = 16 to 32 μg/ml; R, MIC ≥ 64 μg/ml. The corresponding disk test breakpoints are as follows: S, ≥19 mm; SDD, 15 to 18 mm; R, ≤14 mm.

scholarly journals Correlation between Antifungal Susceptibilities ofCoccidioides immitis In Vitro and Antifungal Treatment with Caspofungin in a Mouse Model

2001 ◽  
Vol 45 (6) ◽  
pp. 1854-1859 ◽  
Author(s):  
Gloria M. González ◽  
Rolando Tijerina ◽  
Laura K. Najvar ◽  
Rosie Bocanegra ◽  
Michael Luther ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
National Committee ◽  
In Vitro Susceptibility ◽  
Minimum Effective Concentration ◽  
Study Results ◽  
Significant Difference

ABSTRACT Caspofungin (Merck Pharmaceuticals) was tested in vitro against 25 clinical isolates of Coccidoides immitis. In vitro susceptibility testing was performed in accordance with the National Committee for Clinical Laboratory Standards document M38-P guidelines. Two C. immitis isolates for which the caspofungin MICs were different were selected for determination of the minimum effective concentration (MEC), and these same strains were used for animal studies. Survival and tissue burdens of the spleens, livers, and lungs were used as antifungal response markers. Mice infected with strain 98-449 (48-h MIC, 8 μg/ml; 48-h MEC, 0.125 μg/ml) showed 100% survival to day 50 when treated with caspofungin at ≥1 mg/kg. Mice infected with strain 98-571 (48-h MIC, 64 μg/ml; 48-h MEC, 0.125 μg/ml) displayed ≥80% survival when the treatment was caspofungin at ≥5 mg/kg. Treatment with caspofungin at 0.5, 1, 5, or 10 mg/kg was effective in reducing the tissue fungal burdens of mice infected with either isolate. When tissue fungal burden study results were compared between strains, caspofungin showed no statistically significant difference in efficacy in the organs of the mice treated with both strains. A better in vitro-in vivo correlation was noted when we used the MEC instead of the MIC as the endpoint for antifungal susceptibility testing. Caspofungin may have a role in the treatment of coccidioidomycosis.

scholarly journals In Vitro Antifungal Susceptibility Of Griseofulvin, Fluconazole, Itraconazole And Terbinafine Against Clinical Isolates Of Trichophyton Rubrum And Trichophyton Mentagrophytes

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
K R Reddy ◽  
S Ram Reddy
Keyword(s):  
Trichophyton Rubrum ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Trichophyton Mentagrophytes ◽  
Drug Susceptibility ◽  
Antifungal Drugs ◽  
Clinical Isolates ◽  
National Committee ◽  
In Vitro Antifungal Susceptibility

Investigations on antifungal drug susceptibility were carried out on 90 clinical isolates of Trichophyton rubrum, and Trichophyton mentagrophytes with four antifungal drugs, namely griseofulvin, fluconazole, itraconazole and terbinafine as suggested by National Committee for Clinical Laboratory Standards (NCCLS) M27–A (1997) document by broth macrodilution method to standardize in vitro antifungal susceptibility testing and to find out the Minimum Inhibitory Concentration (MIC) of the drugs. In this study, terbinafine was found to be the most efficient drug for all isolates. Terbinafine had the lowest MIC range of 0.001 g/ml to 0.09 g/ml and MIC50 was low at 0.005 g/ml and MIC90 was also low at 0.04 g/ml against T.rubrum; and MIC range of 0.001μg/ml to 0.19μg/ml with a MIC50 of 0.01μg/ml and MIC90 at 0.09μg/ml against T.mentagrophytes. Itraconazole showed antifungal activity superior to that of fluconazole, with a MIC range of 0.04g/ml to 1.56g/ml, with MIC50 at 0.19μg/ml and MIC90 at 1.56g/ml against T.rubrum; and MIC range of 0.04μg/ml to 1.56μg/ml, with MIC50 at 0.19μg/ml and MIC90 at 0.78μg/ml against T.mentagrophytes. Griseofulvin appears to be still a potent drug for management of dermatophytoses. Griseofulvin had a MIC range of 0.15g/ml to 5.07 g/ml with MIC50 at1.26 g/ml and MIC90 at 2.53 g/ml against T.rubrum; and MIC range of 0.31μg/ml to 5.07μg/ml with MIC50 at 1.26μg/ml and MIC90 at 2.53μg/ml against T.mentagrophytes. Fluconazole showed a high MIC range of 0.19 g/ml to 50 g/ml and MIC50 was high at 1.56g/ml and MIC90 was also high at 12.5 g/ml against T.rubrum; and a high MIC range of 0.09μg/ml to 25.0μg/ml, with MIC50 at 1.56μg/ml and MIC90 at 12.5μg/ml towards T.mentagrophytes. The technique was found to be easy to perform and reliable with consistent results.

In vitro antifungal susceptibility of griseofulvin, fluconazole, itraconazole and terbinafine against clinical isolates of Trichophyton rubrum and Trichophyton mentagrophytes

2014 ◽  
Vol 1 (4) ◽  
pp. 26-28
Author(s):  
KR Reddy ◽  
SR Reddy
Keyword(s):  
Trichophyton Rubrum ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Trichophyton Mentagrophytes ◽  
Drug Susceptibility ◽  
Antifungal Drugs ◽  
Clinical Isolates ◽  
National Committee ◽  
In Vitro Antifungal Susceptibility

Investigations on antifungal drug susceptibility were carried out on 90 clinical isolates of Trichophyton rubrum, and Trichophyton mentagrophytes with four antifungal drugs, namely griseofulvin, fluconazole, itraconazole and terbinafine as suggested by National Committee for Clinical Laboratory Standards (NCCLS) M27A (1997) document by broth macrodilution method to standardize in vitro antifungal susceptibility testing and to find out the Minimum Inhibitory Concentration (MIC) of the drugs. In this study, terbinafine was found to be the most efficient drug for all isolates. Terbinafine had the lowest MIC range of 0.001 g/mlto 0.09 g/ml and MIC50 was low at 0.005 g/ml and MIC90 was also low at 0.04 g/ml against T. rubrum; and MIC range of 0.001pg/ml to 0.19pg/ml with a MIC50 of 0.01pg/ml and MIC90 at 0.09 pg/ml against T. mentagrophytes. Itraconazole showed antifungal activity superior to that of fluconazole, with a MIC range of 0.04g/ml to l.56g/ml, with MIC50 at 0.19pg/m land MIC90 at l.56g/ml against T. rubrum; and MIC range of 0.04.g/ml to 1.56pg/ml, with MIC50 at 0.19pg/ml and MIC90 at 0.78pg/ml against T. mentagrophytes. Griseofulvin appears to be still a potent drug for management of dermatophytoses. Griseofulvin had a MIC range of 0.15g/ml to 5.07 g/ml with MIC50 at l.26 g/ml and MIC90 at 2.53 g/ml against T. rubrum; and MIC range of 0.31pg/ml to 5.07pg/ml with MIC50 at 1.26pg/ml and MIC90 at 2.53pg/ml against T. mentagrophytes. Fluconazole showed a high MIC range of 0.19 g/ml to 50 g/ml and MIC50 was high at 1.56g/ml and MIC90 was also high at 12.5 g/ml against T. rubrum; and a high MIC range of 0.09pg/ml to 25.0pg/ml, with MIC50 at 1.56pg/ml and MIC90 at 12.5pg/ml towards T. mentagrophytes. The technique was found to be easy to perform and reliable with consistent results.DOI: http://dx.doi.org/10.3126/jucms.v1i4.9569 Journal of Universal College of Medical Sciences (2013) Vol.1 No.04: 26-28

scholarly journals Interactions of Posaconazole and Flucytosine against Cryptococcus neoformans

2001 ◽  
Vol 45 (5) ◽  
pp. 1355-1359 ◽  
Author(s):  
Francesco Barchiesi ◽  
Anna Maria Schimizzi ◽  
Laura K. Najvar ◽  
Rosie Bocanegra ◽  
Francesca Caselli ◽  
...  
Keyword(s):  
Combination Therapy ◽  
Cryptococcus Neoformans ◽  
Clinical Laboratory ◽  
Combined Therapy ◽  
Antifungal Susceptibility ◽  
National Committee ◽  
Treatment Groups ◽  
Beneficial Effects

ABSTRACT A checkerboard methodology, based on standardized methods proposed by the National Committee for Clinical Laboratory Standards for broth microdilution antifungal susceptibility testing, was applied to study the in vitro interactions of flucytosine (FC) and posaconazole (SCH 56592) (FC-SCH) against 15 isolates of Cryptococcus neoformans. Synergy, defined as a fractional inhibitory concentration (FIC) index of <0.50, was observed for 33% of the isolates tested. When synergy was not achieved, there was still a decrease in the MIC of one or both drugs when they were used in combination. Antagonism, defined as a FIC of >4.0, was not observed. The in vitro efficacy of combined therapy was confirmed by quantitative determination of the CFU of C. neoformans 486, an isolate against which the FC-SCH association yielded a synergistic interaction. To investigate the potential beneficial effects of this combination therapy in vivo, we established two experimental murine models of cryptococcosis by intracranial or intravenous injection of cells ofC. neoformans 486. At 1 day postinfection, the mice were randomized into different treatment groups. One group each received each drug alone, and one group received the drugs in combination. While combination therapy was not found to be significantly more effective than each single drug in terms of survival, tissue burden experiments confirmed the potentiation of antifungal activity with the combination. Our study demonstrates that SCH and FC combined are significantly more active than either drug alone against C. neoformans in vitro as well in vivo. These findings suggest that this therapeutic approach could be useful in the treatment of cryptococcal infections.

scholarly journals Treatment of murine pulmonary blastomycosis with SCH 51048, a broad-spectrum triazole antifungal agent.

1995 ◽  
Vol 39 (4) ◽  
pp. 996-997 ◽  
Author(s):  
A M Sugar ◽  
M Picard
Keyword(s):  
Broad Spectrum ◽  
Murine Model ◽  
Antifungal Agent ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Blastomyces Dermatitidis ◽  
National Committee ◽  
Triazole Derivative

The in vitro and in vivo activities of a new broad-spectrum triazole derivative, SCH 51048, against Blastomyces dermatitidis were evaluated. As determined by using the new National Committee for Clinical Laboratory Standards proposed standard for susceptibility testing of yeasts, SCH 51048 was the most active of the four agents tested in vitro against 13 strains of B. dermatitidis. In a well-described murine model of acute pulmonary blastomycosis, SCH 51048 was comparable to amphotericin B and at least 30 times more active than itraconazole. On the basis of these experiments, clinical evaluation of SCH 51048 for the use in treatment of human blastomycosis should proceed.

Use of spectrophotometric reading for in vitro antifungal susceptibility testing ofAspergillusspp.

1999 ◽  
Vol 45 (10) ◽  
pp. 871-874 ◽  
Author(s):  
Eric Dannaoui ◽  
Florence Persat ◽  
Marie-France Monier ◽  
Elisabeth Borel ◽  
Marie-Antoinette Piens ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Antifungal Susceptibility Testing ◽  
Aspergillus Species ◽  
National Committee ◽  
Broth Microdilution Method

A comparative study of visual and spectrophotometric MIC endpoint determinations for antifungal susceptibility testing of Aspergillus species was performed. A broth microdilution method adapted from the National Committee for Clinical Laboratory Standards (NCCLS) was used for susceptibility testing of 180 clinical isolates of Aspergillus species against amphotericin B and itraconazole. MICs were determined visually and spectrophotometrically at 490 nm after 24, 48, and 72h of incubation, and MIC pairs were compared. The agreement between the two methods was 99% for amphotericin B and ranged from 95 to 98% for itraconazole. It is concluded that spectrophotometric MIC endpoint determination is a valuable alternative to the visual reference method for susceptibility testing of Aspergillus species.Key words: antifungal, susceptibility testing, Aspergillus, spectrophotometric reading.

scholarly journals Interactions between Triazoles and Amphotericin B against Cryptococcus neoformans

2000 ◽  
Vol 44 (9) ◽  
pp. 2435-2441 ◽  
Author(s):  
Francesco Barchiesi ◽  
Anna M. Schimizzi ◽  
Francesca Caselli ◽  
Andrea Novelli ◽  
Stefania Fallani ◽  
...  
Keyword(s):  
Combination Therapy ◽  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Clinical Laboratory ◽  
Fungal Infections ◽  
National Committee ◽  
Positive Interaction ◽  
Pronounced Increase

ABSTRACT The interaction of amphotericin B (AmB) and azole antifungal agents in the treatment of fungal infections is still a controversial issue. A checkerboard titration broth microdilution-based method that adhered to the recommendations of the National Committee for Clinical Laboratory Standards was applied to study the in vitro interactions of AmB with fluconazole (FLC), itraconazole (ITC), and the new investigational triazole SCH 56592 (SCH) against 15 clinical isolates ofCryptococcus neoformans. Synergy, defined as a fractional inhibitory concentration (FIC) index of ≤0.50, was observed for 7% of the isolates in studies of the interactions of both FLC-AmB and ITC-AmB and for 33% of the isolates in studies of the SCH-AmB interactions; additivism (FICs, >0.50 to 1.0) was observed for 67, 73, and 53% of the isolates in studies of the FLC-AmB, ITC-AmB, and SCH-AmB interactions, respectively; indifference (FICs, >1.0 to ≤2.0) was observed for 26, 20, and 14% of the isolates in studies of the FLC-AmB, ITC-AmB, and SCH-AmB interactions, respectively. Antagonism (FIC >2.0) was not observed. When synergy was not achieved, there was still a decrease, although not as dramatic, in the MIC of one or both drugs when they were used in combination. To investigate the effects of FLC-AmB combination therapy in vivo, we established an experimental model of systemic cryptococcosis in BALB/c mice by intravenous injection of cells of C. neoformans 2337, a clinical isolate belonging to serotype D against which the combination of FLC and AmB yielded an additive interaction in vitro. Both survival and tissue burden studies showed that combination therapy was more effective than FLC alone and that combination therapy was at least as effective as AmB given as a single drug. On the other hand, when cells of C. neoformans 2337 were grown in FLC-containing medium, a pronounced increase in resistance to subsequent exposures to AmB was observed. In particular, killing experiments conducted with nonreplicating cells showed that preexposure to FLC abolished the fungicidal activity of the polyene. However, this apparent antagonism was not observed in vivo. Rather, when the two drugs were used sequentially for the treatment of systemic murine cryptococcosis, a reciprocal potentiation was often observed. Our study shows that (i) the combination of triazoles and AmB is significantly more active than either drug alone against C. neoformans in vitro and (ii) the concomitant or sequential use of FLC and AmB for the treatment of systemic murine cryptococcosis results in a positive interaction.

Sign in / Sign up

Export Citation Format

Share Document