DOI: http://dx.doi.org/10.18203/2320-6012.ijrms20183268

In vitro susceptibility testing of four antifungal drugs against fungal isolates in onychomycosis

Smita S. Kulkarni, Jayshree B. Bhakre, Ajit S. Damle

Abstract


Background: Onychomycosis is chronic fungal infection of fingernails and toenails. Variety of fungi cause onychomycosis. Due to importance of high prevalence rate of onychomycosis this study was conducted.

Methods: In this study 100 patients suspected of onychomycosis were examined. Diagnosis of onychomycosis was based on the patient’s history, physical examination, microscopy and culture of nail specimens.

Results: Direct microscopy of the nail clippings in 20% KOH solution was positive in 61% and culture was positive in 54% cases. The common etiological agent was dermatophytes (79.6% cases) followed by non dermatophyte moulds (11.1% cases) and yeasts (9.2% cases). Amongst dermatophytes, T. rubrum was found to be commonest etiological agent (57.6%) followed by T. mentagrophytes. We had performed the in vitro antifungal susceptibility testing of isolated fungal species against Amphotericin B, Fluconazole, Itraconazole and Terbinafine according to standard guidelines recommended by the CLSI. Antifungal susceptibility testing of dermatophytes and non-dermatophyte moulds was performed by broth macrodilution method. For Candida species we used broth macrodilution method as well as disk diffusion method. All three Candida albicans isolates were sensitive to amphotericin B, fluconazole and itraconazole. Two strains of Candida krusei were sensitive to amphotericin B and resistant to fluconazole and itraconazole. Two isolates of T. rubrum had MIC >64µg/ml and one T. Mentagrophytes isolate had MIC 32µg/ml for fluconazole. Among non dermatophyte moulds, Aspergillus niger and one isolate of Fusarium oxysporum showed high MICs against fluconazole.

Conclusions: Terbinafine exhibited the lowest MICs among all the tested antifungal drugs.


Keywords


Dermatophytes, Nails, Non dermatophyte moulds antifungal susceptibility testing, Onychomycosis

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References


Matnani G, Roy I, Gandham N, Mandal A, Ujagare M, Jadhav SV. Identification and antifungal susceptibility testing of fungal infections in clinical samples of suspected superficial fungal infections. International Journal of Medical and Clinical Research. 2012 Jan 1;3(7):215.

National Committee for Clinical Laboratory Standards Reference method for broth dilution antifungal susceptibility testing of yeasts; Approved standard NCCLS document M27-A (ISBN 1-56238-469-4). National Committee for Clinical Laboratory Standards, Pennsylvania, USA; 2002.

Clinical and Laboratory Standards Institute (CLSI). Reference method for broth dilution antifungal susceptibility testing of filamentous fungi; Approved standard- Second edition. CLSI document M38-A2. (ISBN 1-56238-668-9). Clinical and Laboratory Standards Institute, Pennsylvania, USA; 2008.

Fernández-Torres B, Cabanes FJ, Carrillo-Munoz AJ, Esteban A, Inza I, Abarca L, et al. Collaborative evaluation of optimal antifungal susceptibility testing conditions for dermatophytes. Journal of clinical microbiology. 2002 Nov 1;40(11):3999-4003.

Jessup CJ, Warner J, Isham N, Hasan I, Ghannoum MA. Antifungal susceptibility testing of dermatophytes: establishing a medium for inducing conidial growth and evaluation of susceptibility of clinical isolates. J Clin Microbiol. 2000 Jan 1;38(1):341-4.

CLSI. Method for Antifungal Disk Diffusion Susceptibility Testing of Yeasts; Approved guidelines- second edition. CLSI Document M44-A2 (ISBN 1-56238-488-0). CLSI, Pennsylvania, USA; 2003.

Fernández-Torres B, Carrillo AJ, Martın E, Del Palacio A, Moore MK, Valverde A, et al. In vitro activities of 10 antifungal drugs against 508 dermatophyte strains. Antimicrobial agents and chemotherapy. 2001 Sep 1;45(9):2524-8.

Espinel-Ingroff A, Bartlett M, Bowden R, Chin NX, Cooper C, Fothergill A, et al. Multicenter evaluation of proposed standardized procedure for antifungal susceptibility testing of filamentous fungi. J Clin Microbiol. 1997 Jan 1;35(1):139-43.

Espinel-Ingroff A, Bartlett M, Chaturvedi V, Ghannoum M, Hazen KC, Pfaller MA, et al. Optimal susceptibility testing conditions for detection of azole resistance in Aspergillus spp.: NCCLS collaborative evaluation. Antimicrobial agents and chemotherapy. 2001 Jun 1;45(6):1828-35.

Pfaller MA, Vu Q, Lancaster M, Espinel-Ingroff A, Fothergill A, Grant C, et al. Multisite reproducibility of colorimetric broth microdilution method for antifungal susceptibility testing of yeast isolates. J Clin Microbiol. 1994 Jul 1;32(7):1625-8.

Hill P, Rogers K, McKinney W. Antifungal susceptibilities of Candida sp. in New Zealand. N Z Med J. 2001;114:528-9.

Ghannoum MA, Chaturvedi V, Espinel-Ingroff A, Pfaller MA, Rinaldi MG, Lee-Yang W, et al. Intra-and interlaboratory study of a method for testing the antifungal susceptibilities of dermatophytes. J Clin Microbiol. 2004 Jul 1;42(7):2977-9.

Korting HC, Ollert M, Abeck D. Results of German multicenter study of antimicrobial susceptibilities of Trichophyton rubrum and Trichophyton mentagrophytes strains causing tinea unguium. German Collaborative dermatophyte drug susceptibility study group. Antimicrob Agents Chemother. 1995; 39:1206-8.

Norris HA, Elewski BE, Ghannoum MA. Optimal growth conditions for the determination of the antifungal susceptibility of three species of dermatophytes with the use of a microdilution method. J Am Acad Dermatol. 2000;40:S9-S13.

Fernández-Torres B, Cabanes FJ, Carrillo-Munoz AJ, Esteban A, Inza I, Abarca L, et al. Collaborative evaluation of optimal antifungal susceptibility testing conditions for dermatophytes. J Clin Microbiol. 2002 Nov 1;40(11):3999-4003.

Santos DA, Hamdan JS. In vitro activities of four antifungal drugs against Trichophyton rubrum isolates exhibiting resistance to fluconazole. Mycoses. 2007;50:286-9.

Gehrt A, Peter J, Pizzo PA, Walsh TJ. Effect of increasing inoculum sizes of pathogenic filamentous fungi on MICs of antifungal agents by broth microdilution method J Clin Microbiol. 1995;33:1302-7.

Perea S, Fothergill AW, Sutton DA, Rinaldi MG. Comparison of in vitro activities of voriconazole and five established antifungal agents against different species of dermatophytes using a broth macrodilution method. J Clin Microbiol. 2001;39(1):385-8.

Fernandez-Torres, B, Yazquez-Yeiga H, Liovo X, Pereiro M, Guarro, J. In vitro susceptbility to itraconazole, clotrmazole, ketoconazole and terbiafine of 100 isolates of Trichiphyton rubrum. Chemotherapy. 2000;46:390-4.

Ryder NS, Favre B. Antifungal activity and mechanism of action of terbinafine. Rev Contemp Pharmacother. 1997;8:275-87.