Antifungal Susceptibility Methods and Their Potential Clinical Relevance

Evaluation of antifungal activity of standardized extract of Salvia rhytidea Benth. (Lamiaceae) against various Candida isolates

OBJECTIVES

Salvia species have long been described in traditional medicine for various indications. Owing to the widespread use of this genus by ethnic populations, especially for various infections ranging from skin disease to gastrointestinal disorders, we were encouraged to determine whether Salvia rhytidea could be effective against fungal infections. Given the increased incidence of candidiasis in the past decade, limits on the use of antifungal drugs, emergence of azole-resistant Candida species and increased incidence of treatment failures, it is necessary to identify a novel agent with antifungal properties. Aim of the study was to evaluate the antifungal properties of S. rhytidea against various Candida isolates.

MATERIALS AND METHODS

In this study, at first rosmarinic acid content of plant extract was determined. A total of 96 Candida isolates were tested, including the following species: Candida albicans (n=42), Candida glabrata (n=16), Candida tropicalis (n=11), Candida krusei (n=9), Candida parapsilosis (n=9), Candida lusitaniae (n=7) and Candida guilliermondii (n=2). The in vitro antifungal activity of methanolic extracts of S. rhytidea Benth. was evaluated against Candida isolates and compared with that of the standard antifungal drug nystatin by using a broth microdilution method, according to CLSI.

RESULTS

Phytochemical screening results showed that the methanolic extract of S. rhytidea Benth. was rich in flavonoids and tannins. The minimal inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values of S. rhytidea Benth. ranged from 3.125 to>100μg/ml and 6.25 to>100μg/ml respectively. The growth inhibition value displayed that C. tropicalis, C. krusei and C. albicans isolates were most susceptible to S. rhytidea.

CONCLUSIONS

Findings show that S. rhytidea possesses an antifungal effect against Candida isolates.

Anidulafungin

Anidulafungin is a novel antifungal agent which, like other echinocandins, inhibits beta-(1,3)-D-glucan synthase and disrupts fungal cell-wall synthesis. It has marked antifungal activity against a broad spectrum of Candida spp. and Aspergillus spp., including amphotericin B- and triazole-resistant strains. In clinical trials, anidulafungin has primarily been evaluated in patients with oesophageal and invasive candidiasis. Preliminary data are emerging for other indications such as invasive aspergillosis. In a large, multicentre, double-blind, double-dummy, randomised trial in patients with oesophageal candidiasis, intravenous anidulafungin 50 mg/day was as effective as oral fluconazole 100 mg/day regarding end-of-treatment rates of endoscopic cure and clinical and microbiological success. Duration of treatment was approximately 2-3 weeks, and patients in both groups received a loading dose of study drug (twice the daily maintenance dose) on day 1. Anidulafungin is generally well tolerated. Across the dosage range 50-100 mg/day, adverse events appear not to be dose- or infusion-related. In the largest clinical trial to date, the most common treatment-related adverse events were phlebitis/thrombophlebitis, headache, nausea, vomiting and pyrexia.