Activities of amphotericin B, fluconazole and voriconazole against Candida bloodstream isolates determined by broth microdilution and disk diffusion methods

Abstract

Objective: Invasive fungal infections caused by Candida species have increased significantly. Candidemia is not only associated with a mortality, but also extends the duration of hospital stay and increases the cost for medical care. Although, the clinical presentations of the patients with candidemia caused by Candida albicans and non-albicans Candida species are indistinguishable, the susceptibilities to antifungal agents of these species are different. This study presents data on antifungal susceptibility profiles of Candida bloodstream isolates. Method: We tested a total of 90 strains, including 35 strains of Candida albicans, 25 strains of Candida tropicalis, 15 strains of Candida parapsilosis, 8 strains of Candida glabrata, 4 strains of Candida krusei and 3 strains of Candida kefyr. Susceptibility to amphotericin B, fluconazole and voriconazole was determined by Clinical Laboratory Standards Institute broth microdilution method (CLSI M27-A3) using RPMI 1640 as test medium supplemented with 2% glucose and disk diffusion methods were performed according to CLSI M44-A2 using methylene blue (0.5 μg/mL) and glucose (2%) enriched Mueller-Hinton agar. Results: In this study, 87.7%, 82.2% of Candida isolates were susceptible to fluconazole with the broth OZET Amac: Candida turlerinin neden oldugu invaziv fungal enfeksiyonlar onemli olcude artmistir. Kandidemiler sadece mortalite ile iliskili olmayip, ayni zamanda hastanede kalis suresinin uzamasina ve tibbi bakim maliyetinin artmasina da sebep olmaktadir. Candida albicans ve non-albicans Candida turlerinin neden oldugu kandidemilerde, hastalarin klinik bulgularinin ayni olmasina ragmen bu turlerin antifungal ilaclara duyarliliklari da farklidir. Bu calismada; Candida kan izolatlarinin antifungal duyarlilik verilerini sunmaktadir. Yontem: 35 Candida albicans, 25 Candida tropicalis, 15 Candida parapsilosis, 8 Candida glabrata, 4 Candida krusei ve 3 Candida kefyr olmak uzere toplam 90 Candida izolati incelendi. Bu turlerin amfoterisin B, flukonazol ve vorikonazole karsi antifungal duyarliliklari %2 glukozla zenginlestirilmis RPMI 1640 agar besiyeri kullanilarak mikrodilusyon yontemi (CLSI M27-A3) ve 0,5 μg/mL metilen mavisi ve %2 glukozla zenginlestirilmis MuellerHinton agar besiyeri kullanilarak disk diffuzyon (CLSI M44-A2) yontemi ile belirlendi. Bulgular: Candida izolatlari mikrodilusyon yontemi ile %87,7 oraninda, disk diffuzyon yontemi ile %82,2 oraninda flukonazole duyarli bulundu. 1 Ataturk Universitesi, Saglik Hizmetleri Meslek Yuksekokulu, ERZURUM 2 Ataturk Universitesi, Tip Fakultesi, Mikrobiyoloji Ve Klinik Mikrobiyoloji Ana Bilim Dali, ERZURUM Gelis Tarihi / Received : Kabul Tarihi / Accepted : Iletisim / Corresponding Author : Nimet YIĞIT Ataturk Universitesi, Saglik Hizmetleri Meslek Yuksekokulu, ERZURUM Tel : +90 442 231 58 53 5865 E-posta / E-mail : nimyigit@hotmail.com 14.02.2014 22.04.2014 DOI ID : 10.5505/TurkHijyen.2014.05658 Turk Hijyen ve Deneysel Biyoloji Dergisi Yigit N, Aktas E. Activities of amphotericin B, fluconazole and voriconazole against Candida bloodstream isolates determined by broth microdilution and disk diffusion methods. Turk Hij Den Biyol Derg, 2014; 71(3): 131-40. Cilt 71  Sayi 3  2014 Turk Hij Den Biyol Derg 132 INTRODUCTION SUSCEPTIBILITY OF CANDIDA BLOODSTREAM ISOLATES A progressive increase in the frequency of candidemia has been observed, particularly among patients receiving antibiotics, immunosuppressive therapy, or parenteral nutrition, as well as among patients exposed to invasive medical procedures such as intravascular catheter, hemodialysis and abdominal surgery (1-3). Candidemia have been associated with significant mortality, especially among critically ill patients. The attributable mortality of candidemia has been estimated at 25-38%. In addition, an increase of 30 days in the length of hospital stay among patients surviving these infections has been demonstrated. The economic impact of these infections is also important (3-6). Although Candida albicans is still considered the most frequently isolated species of candidemic patients, the emergence of non-albicans Candida species is clearly a concern. The resistance of nonalbicans Candida isolates to currently available antifungal drugs represents a major challenge for future empirical therapeutic and prophylactic strategies. Therefore, species directed therapy should be administered for fungemia according to the species identified and its antifungal susceptibility pattern (1, 3). Candida species have various degrees of susceptibility to frequently used antifungal drugs. For instance, Candida lusitaniae is relatively resistant to amphotericin B, C. krusei is intrinsically resistant to fluconazole, C. glabrata is less susceptible or has a higher MICs to it than other Candida species. This phenomenon illustrates the importance of identification and surveillance of Candida species in the clinical settings (7). Large-scale surveillance for bacteremia and fungemia has been conducted world-wide by various organizations, including the Centers for Disease Mikrodilusyon yontemi ile bu izolatlarin %6,6’si (%8,5 C. albicans, %4,0 C. tropicalis ve % 25,0 C. glabrata) flukonazole karsi doza bagli duyarli, %5,5 ise direncli olarak belirlendi. Direncli suslarin dordu C. krusei (%100), biri ise C. albicans (%2,8) idi. Disk diffuzyon yontemi ile Candida suslarinin %12,2’si doza bagli duyarli (%17,1 C. albicans, %12,0 C. tropicalis and %25,0 C. glabrata) olarak, %5,5’i [bir izolat C. albicans (%2,8), dort izolat C. krusei (%100)] ise flukonazole direncli olarak belirlendi. Butun suslar amfoterisin B ve vorikonazole duyarli olarak bulundu. Sonuc: Amfoterisin B ve vorikonazollun Candida izolatlarina karsi in-vitro aktivitesinin yuksek oldugu belirlendi. Antifungal ilaclara direnc artmaktadir ki bundan dolayi fungal patojenlerin duyarlilik profillerini degerlendirmek giderek onem kazanmaktadir. Anahtar Kelimeler: Antifungal duyarlilik, flukonazol, kan izolatlari microdilution method and the disk diffusion method respectively, based on CLSI breakpoints. A further 6.6% were classified as susceptible-dose-dependent (8.5% C. albicans, 4.0% C. tropicalis and 25.0% C. glabrata) and fluconazole resistance was detected in 5.5% of all isolates by microdilution method. Four isolates of these strains were C. krusei (100%) and one strain was C. albicans (2.8%). 12.2% of Candida spp. were classified as susceptible-dose-dependent (17.1% C. albicans, 12.0% C. tropicalis, and 25.0% C. glabrata) and fluconazole resistance was detected in 5.5% of all isolates. Four isolates of these strains were C. krusei (100%) and one strain was C. albicans (2.8%) by disk diffusion method. All isolates were susceptible to amphotericin B and voriconazole using by two methods. Conclusion: Voriconazole and amphotericin B were active in-vitro against yeasts. As antifungal drug resistance may become more frequent, it is increasingly important to evaluate current antifungal susceptibility profiles of fungal pathogens.