In-vitrosusceptibility testing by agar dilution method to determine the minimum inhibitory concentrations of amphotericin B, fluconazole and ketoconazole against ocular fungal isolates

Abstract

Purpose: To standardize in-vitro antifungal susceptibility testing by agar dilution method to find out the minimum inhibitory concentration (MIC) of amphotericin B, fluconazole and ketoconazole on ocular fungal isolates. Methods: A total of 180 ocular fungal isolates (130 filamentous fungi and 50 yeasts) were included. The antifungal drugs such as amphotericin B (0.0625-8 µg/mL), fluconazole (0.2-819.6 µg/mL) and ketoconazole (0.025-6.4 µg/mL) were incorporated in doubling dilutions in the yeast nitrogen base medium. The MIC was determined as the lowest concentration of the antifungal drug preventing growth of macroscopically visible colonies on drug containing plates when there was visible growth on the drug -free control plates. Results: All 50 ocular isolates of yeast were susceptible to amphotericin B, while two (4%) and five (10%) strains were resistant to fluconazole and ketoconazole respectively. Of the 130 filamentous fungi tested, six (4.6%) were resistant to amphotericin B, 49 (37.7%) and 10 (7.6%) were resistant to fluconazole and ketoconazole respectively. Percentile 50 (MIC 50) and Percentile 90 (MIC 90) for all the three antifungal agents were calculated. Aspergillus niger, Aspergillus terreus and Candida krusei were found to be resistant to fluconazole and ketoconazole. Conclusion:This technique was found to be reliable, cost effective and easy to perform with consistent results.

Urinary tract candidiasis in HIV+ patients and sensitivity patterns of recovered<i> Candida </i>species to antifungal drugs in Dschang District Hospital (Cameroon)

“…The minimum inhibitory concentration (MIC) of the antifungal were determined by liquid medium microdilution technique according to the protocol described by the National Committee and Clinical Laboratory Standard (NCCLS, 2002 (Thérèse et al, 2006) …”

“…Spectrum of disease is varying from asymptomatic candiduria to clinical sepsis. Several reports showed that the frequency of urinary tract infection due to yeasts has increased during the last decade (Yashavanth et al, 2013). Changes in the clinical severity of candidiasis and the Candida species prevalence profile may be a reflection of immunological changes in HIV positive patients.…”

Species distribution and antifungal susceptibility profile of <i>Candida spp</i> isolated from urine of hospitalized patients in Dschang District Hospital, Cameroon

“…Since discrepancies in CFU (colony forming unit) criteria to diagnose candiduria have not yet been adequately addressed, the following CFU cut-offs were considered in this study: a quantitative culture with a colony count of ≥10,000 CFU/mL of urine was associated with infection while a colony count of <10,000 CFU/mL of urine was associated with colonization (Wise et al, 2000;Kauffman, 2014). Interpretive breakpoints established by the EUCAST (2008) and Thérèse et al (2006) were used. They were as follows: ketoconazole: Sensitive (S) ≤ 0.125 μg/ml, Intermediate (I), 0.25-0.5 μg/ml, Resistant (R), ≥ 1 μg/ml; fluconazole (S) ≤ 8μg/ml, (I), 16-32 μg/ml, (R) ≥ 64 μg/ml; amphotericin B and nystatin (S) ≤ 1μg/ml, (I), 2-4 μg/ml, (R) ≥ 1 μg/ml.…”

Synthesis and antimicrobial activity of novel oxime derivatives of phenothiazine

“…The synthesized compounds were screened for the antibacterial and antifungal activity by using the agar-cup technique in nutrients agar and potato dextrose agar media, respectively [39][40][41][42][43][44][45][46][47][48][49][50]. Ciprofloxacin and gresiofluvin were used as standard drug for the antibacterial and antifungal activity respectively and zone of inhibition of all newly synthesized compounds (IIIa-j) and (IVa-j) was measured against these standard drugs (Table 1 and 2).…”