The Oral Thrush


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Photo of white lumpy patches in the mouth.
Overgrowth of Candida in the mouth is called thrush. It often appears as white patches. (credit: modification of work by Centers for Disease Control and Prevention)

OpenStax Microbiology

The yeast Candida is part of the normal human microbiota, but overgrowths, especially of Candida albicans, can lead to infections in several parts of the body. When Candida  infection develops in the oral cavity, it is called oral thrush. Oral thrush is most common in infants because they do not yet have well developed immune systems and have not acquired the robust normal microbiota that keeps Candida in check in adults. Oral thrush is also common in immunodeficient patients and is a common infection in patients with AIDS.

Oral thrush is characterized by the appearance of white patches and pseudomembranes in the mouth and can be associated with bleeding. The infection may be treated topically with nystatin or clotrimazole oral suspensions, although systemic treatment is sometimes needed. In serious cases, systemic azoles such as fluconazole or itraconazole (for strains resistant to fluconazole), may be used. Amphotericin B can also be used if the infection is severe or if the Candida species is azole-resistant.


Parker, N., Schneegurt, M., Thi Tu, A.-H., Forster, B. M., & Lister, P. (n.d.). Microbiology. Houston, Texas: OpenStax. Access for free at:


Antifungal Activity of Capric Acid, Nystatin, and Fluconazole and Their In Vitro Interactions Against Candida Isolates from Neonatal Oral Thrush

Due to the increasing resistance of various Candida species to azole drugs, particularly fluconazole, it would be of significant importance to look for alternative therapies. The aim of this study was to investigate the antifungal activity of capric acid and its in vitro interactions with nystatin and fluconazole against Candida isolates. A total of 40 Candida isolates (C. albicans, 36; C. kefyr, 2; C. tropicalis, 1; C. glabrata, 1) collected from the oral cavity of neonates with oropharyngeal candidiasis and a reference strain of C. albicans (ATCC 10231) were used in this study. Antifungal activity of capric acid and two comparator antifungal drugs, namely fluconazole and nystatin, was tested according to CLSI M27-A3/M60 method. The in vitro interaction between capric acid with fluconazole and nystatin was determined following a checkerboard method and results were interpreted using fractional inhibitory concentration index. Nystatin had the lowest minimum inhibitory concentrations (range, 0.125-8 μg/mL; geometric mean [GM], 0.6229 μg/mL) followed by fluconazole (range, 0.5-16 μg/mL; GM, 1.9011 μg/mL) and capric acid (range, 128-2,048 μg/mL; GM, 835.9756 μg/mL). When tested in combination, capric acid with fluconazole demonstrated synergistic, indifferent, and antagonistic interactions in 3 (7.317%), 24 (58.536%), and 14 (34.146%) cases, respectively. For combination of capric acid with nystatin, synergistic, indifferent, and antagonistic interactions were observed in 1 (2.439%), 19 (46.341%), and 21 (51.219%) cases, respectively. All cases of synergistic interactions were against resistant or susceptible dose-dependent isolates. Fluconazole, nystatin, and capric acid seem to be more effective when they are used alone compared with their combination. However, their combination might be effective on resistant isolates.

Keywords: Candida; Saccharomyces boulardii; antifungal agents; capric acid; complementary therapies; probiotics.

Preparation, Optimization, and Evaluation of Hyaluronic Acid-Based Hydrogel Loaded with Miconazole Self-Nanoemulsion for the Treatment of Oral Thrush

Miconazole nitrate (MZ) is a BCS class II antifungal poorly water-soluble drug with limited dissolution properties and gastrointestinal side effects. Self-nanoemulsifying delivery system-based gel of MZ can improve both solubility and oral mucosal absorption with enhanced antifungal activity. The study aims to formulate MZ self-nanoemulsion (MZ-NE) and combine it within hyaluronic acid-based gel. MZ solubility in various oils, surfactants, and cosurfactant used in NE formulations were evaluated. Mixture design was implemented to optimize the levels of NE components as a formulation variable to study their effects on the mean globule size and antifungal inhibition zones. Further, the optimized MZ-NE was loaded into a hyaluronic acid gel base. Rheological behavior of the prepared gel was assessed. Ex vivo permeability of optimized formulation across buccal mucous of sheep and inhibition against Candida albicans were examined. Mixture design was used to optimize the composition of MZ-NE formulation as 22, 67, and 10% for clove oil, Labrasol, and propylene glycol, respectively. The optimized formulation indicated globule size of 113 nm with 29 mm inhibition zone. Pseudoplastic flow with thixotropic behavior was observed, which is desirable for oral gels. The optimized formulation exhibited higher ex vivo skin permeability and enhanced antifungal activity by 1.85 and 2.179, respectively, compared to MZ-SNEDDS, and by 1.52 and 1.72 folds, respectively, compared to marketed gel. Optimized MZ-NE hyaluronic acid-based oral gel demonstrated better antifungal activity, indicating its potential in oral thrush pharmacotherapy.

Keywords: antifungal; hyaluronic acid; miconazole; oral thrush; self-nanoemulsion.

Incidence of oral thrush in patients with COPD prescribed inhaled corticosteroids: Effect of drug, dose, and device

Background and aims: Little information is available on real-life occurrence of oral thrush in COPD patients treated with ICS. We investigated oral thrush incidence in COPD patients prescribed FDC ICS/LABA therapies and assessed whether it is modulated by the ICS type, dose, and delivery device.

Methods: We conducted a historical, observational, matched cohort study (one baseline year before and one outcome year after initiation of therapy) using data from the UK Optimum Patient Care Research Database. We assessed oral thrush incidence in patients initiating long-acting bronchodilators or FDC ICS/LABA therapy. We then compared different combination therapies (budesonide/formoterol fumarate dihydrate [BUD/FOR] and fluticasone propionate/salmeterol xinafoate [FP/SAL]) and devices (DPI and pMDI).

Results: Patients prescribed FDC ICS/LABA had significantly greater odds of experiencing oral thrush than those prescribed long-acting bronchodilators alone (adjusted OR 2.18 [95% CI 1.84-2.59]). Significantly fewer patients prescribed BUD/FOR DPI developed oral thrush compared with FP/SAL DPI (OR 0.77 [0.63-0.94]) when allowing for differences in prescribed doses between the drugs. A significantly smaller proportion of patients developed oral thrush in the FP/SAL pMDI arm than in the FP/SAL DPI arm (OR 0.67 [0.55-0.82]). Additionally, in the FP/SAL cohort (both DPI and pMDI), increased risk of oral thrush was significantly associated with high ICS daily dose (OR 1.97 [1.22-3.17] vs low daily dose).

Conclusions: ICS use increases oral thrush incidence in COPD and this effect is dose-dependent for FP/SAL therapies. Of the therapies assessed, FP/SAL pMDI and BUD/FOR DPI may be more protective against oral thrush.

Keywords: Chronic obstructive pulmonary disease; Dry powder inhaler; Inhaled corticosteroid; Oral candidiasis; Pressurised metered-dose inhaler; Spacer.

Single-Dose Fluconazole Therapy for Oral Thrush in Hospice and Palliative Medicine Patients

Background: Oral thrush is a common fungal infection of the mouth experienced by palliative medicine and hospice patients who have advanced cancer. Individuals often experience distressing symptoms that affect their oral intake with most regimens adding to pill burden. This is an open-label prospective observational study to assess the efficacy of a single-dose fluconazole 150 mg for oral thrush.

Methods: Palliative medicine and hospice patients with a clinical diagnosis of oral thrush, a life expectancy of more than 1 week, and were able to swallow were enrolled. Signs and symptoms were evaluated on day 1 prior to administration of 150 mg of fluconazole and between days 3 to 5 after treatment.

Results: Of 57 patients, 55 (96.5%) had more than 50% improvement in signs and symptoms. Both the number and severity of symptoms changed significantly posttreatment ( P < .001). Side effects were few.

Conclusion: Single-dose fluconazole 150 mg is an effective treatment of oral thrush for individuals with advanced cancer.

Keywords: advanced cancer; fluconazole; hospice; oral candidiasis; oral thrush; palliative medicine.