Nystatin vs. Miconazole Nitrate: In Vitro Testing of Candida Albicans Killing Over Time

The opportunistic pathogen, Candida albicans (C. albicans), is the leading cause of cutaneous candidiasis, including common superficial skin infections like intertrigo and diaper dermatitis (diaper rash).

Comorbidities, including obesity and diabetes, treatment with antibiotics, chemotherapy or steroids, and immunosuppression contribute to elevated risk of skin candidiasis. To relieve common discomforts associated with superficial fungal infections, including itching, cracking, redness, burning, irritation, and chafing, topical antifungal ointments can be applied to the skin surface. Some treatments require a prescription, such as those with the active ingredient nystatin, while others are available over the counter, such as ointments containing 2% miconazole nitrate.

Following standard guidelines (ASTM E2315-16, ASTM E1054-08), time kill procedures were performed for quantitative assessment of antifungal activity of white petrolatum-based ointments containing no active ingredient&, nystatin (100,000 units/g)*, or miconazole nitrate (2%)$ against C. albicans (ATCC 10231). Equal amounts of ointments were aseptically measured and then inoculated with C. albicans in simulated wound fluid. Samples were immediately neutralized (time zero) or incubated in a humidified 35–39°C incubator until neutralization at time points 6, 12, and 24 hours, followed by enumeration. Samples were tested in triplicate and the mean log reduction between inactive control& and test samples*,$ was calculated for each time point.

The nystatin-containing ointment resulted in mean log reductions of 0.05, 1.08, and 2.50 at 6, 12, and 24 hours, respectively. The miconazole nitrate-containing ointment was slightly more effective, resulting in mean log reductions of 0.08, 1.31, and 2.8 at 6, 12, and 24 hours, respectively. These results demonstrate that both ointments effectively kill greater than 99% of C. albicans by 24 hours, an important finding since over-the-counter treatments are often cheaper and more readily available to patients with cutaneous candidiasis infections.