Journal of Antimicrobial Chemotherapy (1999) 44, 697-700
© 1999 The British Society for Antimicrobial Chemotherapy
Brief report |
In-vitro activity of voriconazole (UK-109,496), LY303366 and other antifungal agents against oral Candida spp. isolates from HIV-infected patients
a Servicio de Microbiología Clínica, Hospital Universitario de Valme, E-41014 Sevilla; b Departamento de Inmunología, Microbiología y Parasitología, Facultad de Medicina y Odontología, Universidad del País Vasco, E-48080 Bilbao, Spain
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Abstract |
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In this report we compare the activity of two new antifungal agents, voriconazole (UK-109,496) and LY303366 with the activities of other antifungals including fluconazole, itraconazole, 5-fluorocytosine (5FC) and amphotericin B against 219 oral Candida spp. isolates from HIV-infected patients. We used the broth microdilution method following the guidelines of the NCCLS. The in-vitro activity of voriconazole (UK-109,496) (MIC90 0.12 mg/L) and LY303366 (CMI90 0.25 mg/L) against clinical isolates of Candida spp. was excellent and comparable with that of amphotericin B (MIC90 0.5 mg/L), and better than those of fluconazole (MIC90
64 mg/L), itraconazole
(MIC90 4 mg/L) and 5FC (MIC90 1 mg/L). |
Introduction |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
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Oropharyngeal and oesophageal candidosis are common fungal infections in HIV-infected patients. Fluconazole has been shown to be effective in the treatment of these mycoses, but its widespread use has been accompanied by the emergence of resistant isolates, mainly in HIV-infected patients. Therefore, newer antifungals such as voriconazole (UK-109,496) and LY303366 may be promising against fungal pathogens. Voriconazole (UK-109,496) is a derivative of fluconazole with excellent pharmacokinetic (it has high oral bioavaibility and is well tolerated) and selective activity against the fungal ergosterol biosynthetic pathway.1,2 LY303366 is a new semisynthetic fungicidal derivative of a natural product class of antifungal agents called echinocandins that inhibit the 1,3 ß-D-glucan synthase, an essential enzyme to the structural integrity of the fungal cell wall.3 Both antifungals have potent in-vitro and in-vivo activity against clinical isolates of different mould and yeast species, e.g. Aspergillus spp. and Candida spp.1,2 ,3 ,4 ,5,6
In the present study, we used the broth microdilution method of the National Comittee of Clinical Laboratory Standards (NCCLS)7 to compare the in-vitro activity of voriconazole and LY303366 with the activities of four other antifungal agents, including fluconazole, itraconazole, 5-fluorocytosine (5FC) and amphotericin B against 219 Candida spp. strains isolated from the oral cavities of HIV-infected patients.
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Materials and methods |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
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Two hundred and nineteen clinical yeast isolates were studied including 183 Candida albicans, 12 Candida glabrata, 11 Candida krusei, 10 Candida tropicalisand three Candida parapsilosis. These isolates were recovered from the oral cavities of HIV-infected patients during the last 3 years. Each strain represented a unique isolate from a patient attending the Valme University Hospital in Seville (Spain) or the Basque Country Medical College in Bilbao (Spain). Identification of Candida spp. isolates was done by using common mycological methods and they were stored at –70°C. In order to evaluate isolates with different susceptibility patterns, the set included strains with fluconazole MIC
64 mg/L and strains from AIDS or HIV-infected
patients with recurrent oral candidosis. Two quality control isolates, C. parapsilosis
(ATCC 22019) and C. krusei ( ATCC 6258) and four type culture collection strains, C.
albicans (ATCC 64550, ATCC 90028 and ATCC 64548) and C. tropicalis
(ATCC 750) were included in the tests. The NCCLS M27-A broth microdilution method7 was used. Yeasts were obtained from 24 h cultures on Sabouraud dextrose agar (SDA, Difco, MI, USA) at 35°C. The turbidities of the yeast suspensions were adjusted by a spectrophotometric method, and the suspensions were diluted 1:1000 in RPMI medium supplemented with 2% glucose, resulting in twice the test inoculum (1 x 103 to 5 x 103 cfu/mL) as demonstrated by quantitative colony counts on SDA. Voriconazole (Pfizer, Sandwich, UK), LY303366 (Eli-Lilly, Indianapolis, IN, USA), fluconazole (Pfizer), itraconazole (Janssen, Beerse, Belgium) and amphotericin B (Squibb, Barcelona, Spain) stock solutions were prepared in 100% dimethyl sulphoxide (DMSO; Sigma, USA). Additive two-fold dilutions of these agents were prepared in DMSO at final concentration, followed by further dilutions (1:50) in RPMI 1640 medium (Sigma) buffered to pH 7.0 with 0.165 M morpholine propane sulphonic acid (MOPS) buffer (Sigma). 5FC (Roche Laboratories, Basel, Switzerland) was prepared in sterile water and diluted in RPMI medium instead of DMSO. Final drug concentrations were 0.03–16 mg/L for voriconazole, LY303366 and amphotericin B, 0.06–32 mg/L for itraconazole and 5FC and 0.12–64 mg/L for fluconazole. Microdilution trays were incubated at 35°C and examined at 24 h or 48 h or until growth was evident (heavy growth) for MIC determination. For voriconazole, fluconazole, itraconazole and 5FC the MIC was defined as the lowest concentration showing prominent growth inhibition (approximately 50%), for amphotericin B and LY303366, the MIC was defined as the lowest concentration showing 100% growth inhibition.
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Results |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
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Table I summarizes the in-vitro susceptibilities of the 219 yeast isolates to voriconazole, LY303366, fluconazole, itraconazole, 5FC and amphotericin B. A broad range of MICs was observed with each antifungal agent for the various species tested. The in-vitro activity of voriconazole (MIC90 0.12 mg/L) and LY303366 (MIC90 0.25 mg/L) against the Candida spp.clinical isolates studied was excellent and was comparable with that of amphotericin B (MIC90 0.5 mg/L), and better than those of fluconazole (MIC90
64 mg/L), itraconazole (MIC90 4 mg/L) and
5FC (MIC90 1 mg/L).
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Voriconazole showed good activity against C. albicans (MIC90 0.12 mg/L); however, three isolates from this species had MICs of
16 mg/L. These strains were
recovered from the oral cavities of HIV-infected patients who had received previous treatments
with fluconazole. These high MICs were not observed in isolates from the other Candida spp.
Five Candida spp. strains (four C. albicans and one C. glabrata) had
LY303366 MICs 2 mg/L, and only one of these strains had elevated MICs for the
rest of the antifungal agents tested.
The MICs of fluconazole for 43 Candida spp. isolates were 64 mg/L (Table II).
The MIC90 of voriconazole and LY303366 for all these strains was 0.25 mg/L. C.
tropicalis showed a voriconazole MIC90 of 
0.03 mg/L and an LY303366
MIC90 of 1 mg/L.
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Discussion |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
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The mode of action of voriconazole and LY303366 means that they possess a more extended spectrum of activity than fluconazole. Voriconazole shows good activity against Candida and Cryptococcus spp. and most moulds. Preliminary clinical and experimental studies have also shown that voriconazole is effective in the treatment of invasive pulmonary aspergillosis, pulmonary and meningeal cryptococcosis, and oropharyngeal and disseminated candidosis.2 On the other hand LY303366 shows good activity against Candida spp., Aspergillus fumigatus and Pneumocystis carinii, but not against Cryptococcus neoformans (this pathogen has little or no 1,3 ß-D-glucan synthase).3
The results of the present study support the findings reported previously by other investigators.1,4,6,8,9,10 In-vitro studies have demonstrated that voriconazole and LY303366 are as active as amphotericin B and more active than fluconazole, itraconazole and 5FC against most Candida spp.
We observed that both voriconazole and LY303366 had a very potent activity (MIC90 0.25 mg/L and 0.12 mg/L, respectively) against isolates of C. krusei and C. glabrata, species usually considered resistant to azoles such as fluconazole. This excellent in-vitro activity against fluconazole-resistant Candida spp. is remarkable and it may have important implications for the management of Candida spp. infections, as voriconazole and LY303366 are available in both oral and parenteral form.3
We found that LY303366 possessed good activity (MICs 0.25 mg/L) against C.
albicans and C. tropicalis, including strains for which the fluconazole MICs were
64 mg/L. The difference in potency between LY303366 and the triazoles is emphasized by
the extremely low MICs of LY303366 (0.25 mg/L) observed with isolates of Candida
spp. for which there are elevated fluconazole and itraconazole MICs.10 Echinocandin and pneumocandin MICs have been demostrated to correlate
well with in-vivo activity.9 Results for C. parapsilosis
are inconclusive due to the small number of isolates studied.
Voriconazole possessed good activity against C. albicans and C. tropicalis
at concentrations of 2 mg/L. However, we found, as did Rhunke et al.2 and Marco et al.,5 that
for C. albicansisolates for which fluconazole MICs were high, voriconazole MICs were
proportionally higher than those for fluconazole-susceptible C. albicans isolates (<64
mg/L), which may indicate cross-resistance. Barry & Brown1
also found a small number of C. albicans isolates with MICs higher than 4
mg/L. We observed three C. albicans isolates with MICs of 16 mg/L. Reduced
susceptibility and cross-resistance between azole antifungals are not uncommon and are probably
related to the same mechanisms of action. Whether MICs higher than 4 mg/L might reflect
resistance to this agent needs to be substantiated by clinical studies and its clinical consequences
need to be evaluated. Further assessment of the clinical significance of the relative potency of
voriconazole and LY303366 awaits the generation of human pharmacokinetic data and the
results of comparative clinical trials.The present results suggest that voriconazole and LY303366
may be potent agents in the treatment of fungal infections due to Candida spp. Clinical
trials currently in progress will determine the efficacy and safety in the treatment of human
candidosis.
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Acknowledgments |
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We thank Drs María Íngeles Echebarría, Jose Manuel Aguirre and Laureano Ribacoba for their help with clinical isolates and data. This work was financed in part by grants 97/2052 from the Ministerio de Sanidad y Consumo / Fondo de Investigación Sanitaria—Plan Nacional de Investigación Científica y Desarrollo Tecnológico, modalidad C para 1997 and UPV 093.327-EC233/97 from the Universidad del País Vasco and was also financed in part by a grant from Eli-Lilly and Company, and Pfizer, Inc.
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Notes |
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* Corresponding author. Tel: +349-5-459-6352; Fax:+349-5-459-6395.
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References |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
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1 . Barry, A. L. & Brown, S. D. (1996). In vitro studies of two triazole antifungal agents (Voriconazole [UK-109,496] and Fluconazole) against Candida species . Antimicrobial Agents and Chemotherapy 40, 1948–9.[Abstract]
2 . Schwartz, S., Milatovic, D. & Thiel, E. (1997). Succesful treatment of cerebral aspergillosis with a novel triazole (voriconazole), in a patient with acute leukaemia. British Journal of Haematology 97, 663–5.[Web of Science][Medline]
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Denning, D. W. (1997). Echinocandins and
pneumocandins, a new antifungal class with a novel mode of action. Journal of
Antimicrobial Chemotherapy40, 611–4.
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Marco, F., Pfaller, M. A., Messer, S. & Jones, R. N.
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5 . Murphy, M., Bernard, E. M., Ishimaru, T. & Armstrong, D. (1997). Activity of voriconazole (UK-109,496) against clinical isolates of Aspergillus species and its effectiveness in an experimental model of invasive pulmonary aspergillosis. Antimicrobial Agents and Chemotherapy 41, 696–8.[Abstract]
6 . Ruhnke, M., Schmidt-Westhausen, A. & Trautmann, M. (1997). In vitro activities of voriconazole (UK-109,496) against fluconazole susceptible and resistant Candida albicans isolates from oral cavities of patients with human immunodeficiency virus infection. Antimicrobial Agents and Chemotherapy 42, 575–82.
7 . National Comittee for Clinical Laboratory Standards. (1997). Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts—Approved Standard M27-A. NCCLS, Villanova, PA.
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Espinel-Ingroff, A. (1998). In vitro
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9 . Krishnarao, T. V. & Galgiani, J. N. (1997). Comparison of the in vitro activities of the echinocandine LY303366, the pneumocandin MK-0991, and fluconazole against Candida species and Cryptococcus neoformans. Antimicrobial Agents and Chemotherapy 41,1957 –60.[Abstract]
10 . Uzun, Ö., Kocagöz, S., Çetinkaya, Y., Arikan, S. & Ünal, S. (1997). In vitro activity of a new echinocandin, LY303366, comaprred with those of amphotericin B and fuconazole against clinical yeaste isolates. Antimicrobial Agents and Chemotherapy 41, 1156–7.[Abstract]
Received 14 December 1998; returned 26 March 1999; revised 16 April 1999; accepted 28 April 1999
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