The diagnosis of oral candidiasis is best confirmed by which of the following?

The diagnosis of oral candidiasis is best confirmed through microscopic examination of smears. This method allows for direct visualization of the Candida organisms in the oral mucosa, typically on a prepared slide from a scraping of the affected area. The presence of yeast cells, pseudohyphae, or hyphae under the microscope provides strong evidence for the diagnosis of candidiasis.

This approach is rapid and effective, as it enables clinicians to make a definitive diagnosis based on direct evidence, allowing for prompt management of the condition. Other diagnostic methods, such as biopsy, can provide additional information but are more invasive and not the first-line approach for confirming oral candidiasis. Blood counts and serological exams are not specific for candidiasis and do not provide direct confirmation of oral lesions.