Reducing the incidence of denture stomatitis: are denture cleansers sufficient?

PURPOSE: Candida albicans is the predominant oral yeast associated with denture stomatitis. With an increasing population of denture wearers, the incidence of denture stomatitis is increasing. Effective management of these patients will alleviate the morbidity associated with this disease. The aim of this study was to examine the capacity of four denture cleansers to efficiently decontaminate and sterilize surfaces covered by C. albicans biofilms. MATERIALS AND METHODS: Sixteen C. albicans strains isolated from denture stomatitis patients and strain ATCC 90028 were grown as mature confluent biofilms on a 96-well format and immersed in Dentural, Medical Interporous, Steradent Active Plus, and Boots Smile denture cleansers according to the manufacturers' instructions or overnight. The metabolic activity and biomass of the biofilms were then quantified, and scanning electron microscopy (SEM) used to examine treated biofilms. RESULTS: Dentural was the most effective denture cleanser, reducing the biomass by greater than 90% after 20 minutes. Steradent Active plus was significantly more effective following 10-minute immersion than overnight (p < 0.001). All cleansers reduced the metabolic activity by greater than 80% following overnight immersion; however, Boots Smile exhibited significantly reduced metabolic activity following only a 15-minute immersion (p < 0.001). SEM revealed residual C. albicans material following Dentural treatment. CONCLUSIONS: This study showed that denture cleansers exhibit effective anti-C. albicans biofilm activity, both in terms of removal and disinfection; however, residual biofilm retention that could lead to regrowth and denture colonization was observed. Therefore, alternative mechanical disruptive methods are required to enhance biofilm removal.

Sequential or combination antifungal therapy with voriconazole and liposomal amphotericin B in a Guinea pig model of invasive aspergillosis.

We evaluated combinations of voriconazole (VRC) and liposomal amphotericin B (L-AMB) in a guinea pig invasive aspergillosis model. Simultaneous VRC and L-AMB was most effective, although VRC monotherapy was also effective. These regimens as well as sequential L-AMB followed by VRC were more effective than L-AMB alone or VRC followed by L-AMB.

Candida glabrata is an emerging cause of oropharyngeal candidiasis in patients receiving radiation for head and neck cancer.

Oropharyngeal candidiasis (OPC) is relatively common in patients receiving radiation for head and neck cancer occurring in approximately 25% of patients. Candida albicans has been described as the primary infecting organism. Recently, other organisms, particularly Candida glabrata, have emerged as causative agents of OPC among immunocompromised patients. This study describes the characteristics of 6 patients with head and neck cancer treated with radiotherapy at our institution, who were found to have Candida glabrata-associated OPC and their responses to oral fluconazole. All 6 patients were successfully treated with oral fluconazole. However, most did not respond to the usual dose of 100 mg/day necessitating doses ranging from 200 to 800 mg/day to achieve clinical cure. All 3 patients receiving radiation only were successfully treated with up to 200 mg/day; 2 of 3 patients receiving concomitant chemoradiation required doses ranging from 400 to 800 mg/day. As with systemic infection, previous fluconazole use appears to be a risk factor for this infection, but not with all patients.

Oropharyngeal candidiasis caused by non-albicans yeast in patients receiving external beam radiotherapy for head-and-neck cancer.

PURPOSE: To characterize non-albicans Candida oral infections in patients with head-and-neck cancer receiving external beam radiotherapy (EBRT) with or without concurrent chemotherapy. METHODS AND MATERIALS: Thirty-seven patients with head-and-neck cancer received EBRT in 2.0-Gy daily fractions to a median dose of 60.4 Gy (range 38-82.8, mean 64.6). They were followed for oropharyngeal candidiasis (OPC) confirmed by positive examination, positive KOH smear, and/or positive swab or swish culture. Samples were identified and plated on chromogenic media to identify non-albicans yeasts. Colonies were plated on Sabouraud dextrose slants for microdilution antifungal susceptibility testing to fluconazole. DNA typing, including karyotyping, restriction fragment length polymorphism analysis, and Southern blot hybridization with the moderately repetitive Ca3 probe, was performed on selected isolates to confirm individual species. RESULTS: Of the 37 patients, 10 (27%) developed OPC, and 26 (70.3%) displayed Candida carriage state. The median EBRT dose at time of positive culture was 22.5 Gy and at time of OPC was 28.6 Gy. Of the 6 patients receiving chemotherapy and EBRT, 4 (66%) developed OPC at median dose of 27.6 Gy. Three (8%) of 37 patients were infected with non-albicans Candida, and 3 (30%) of all 10 infections were caused by these organisms. CONCLUSION: Non-albicans Candida is emerging as a relatively common cause of OPC in head-and-neck cancer patients. Chromogenic media are helpful to screen these infections. Our data also suggest a greater likelihood of developing OPC in patients receiving concomitant chemotherapy and EBRT.

Multiple patterns of resistance to fluconazole in Candida glabrata isolates from a patient with oropharyngeal candidiasis receiving head and neck radiation.

Candida glabrata has emerged in recent years as a significant cause of systemic fungal infection. We have previously reported on the first three patients receiving radiation for head and neck cancer to develop oropharyngeal candidiasis due to C. glabrata. The goal of this study was to track the development of increased fluconazole resistance in C. glabrata isolates and to evaluate previously described genetic mechanisms associated with this resistance from one of these three patients. The patient was a 52-year-old man with squamous cell carcinoma treated with radiation. At week 7 of his radiation, he developed oropharyngeal candidiasis, which was treated with 200 mg of fluconazole daily for 2 weeks. Serial cultures from this and three subsequent time points yielded C. glabrata. Isolates from these cultures were subjected to antifungal susceptibility testing, DNA karyotyping, and evaluation of the expression of genes previously associated with C. glabrata resistance to fluconazole, CgCDR1, CgCDR2, and CgERG11. Two strains (A and B) of C. glabrata were identified and found to display different patterns of resistance development and gene expression. Strain A developed resistance over a 2-week period and showed no overexpression of these genes. In contrast, strain B first showed resistance 6 weeks after fluconazole therapy was discontinued but showed overexpression of all three genes. In conclusion, development of resistance to fluconazole by C. glabrata is a highly varied process involving multiple molecular mechanisms.

Replacement of Candida albicans with C. dubliniensis in human immunodeficiency virus-infected patients with oropharyngeal candidiasis treated with fluconazole.

Candida dubliniensis is an opportunistic yeast that has been increasingly implicated in oropharyngeal candidiasis (OPC) in human immunodeficiency virus (HIV)-infected patients but may be underreported due to its similarity with Candida albicans. Although most C. dubliniensis isolates are susceptible to fluconazole, the inducibility of azole resistance in vitro has been reported. Thus, the use of fluconazole prophylaxis in the treatment of these patients may have contributed to the increasing rates of isolation of C. dubliniensis. In this study, yeast strains were collected from the oral cavities of HIV-infected patients enrolled in a longitudinal study of OPC. Patients received fluconazole for the suppression or treatment of OPC, and isolates collected at both study entry and end of study were chosen for analysis. Samples were plated on CHROMagar Candida medium for initial isolation and further identified by Southern blot analysis with the species-specific probes Ca3 (for C. albicans) and Cd25 (for C. dubliniensis). Fluconazole MICs were determined by using NCCLS methods. At study entry, susceptible C. albicans isolates were recovered from oral samples in 42 patients who were followed longitudinally (1 to 36 months). C. albicans strains from 12 of these patients developed fluconazole resistance (fluconazole MIC, >/=64 micro g/ml). C. dubliniensis was not detected at end of study in any of these patients. Of the remaining 30 patients, eight (27%) demonstrated a replacement of C. albicans by C. dubliniensis when a comparison of isolates obtained at baseline and those from the last culture was done. For the 22 of these 30 patients in whom no switch in species was detected, the fluconazole MICs for initial and end-of-study C. albicans isolates ranged from 0.125 to 2.0 micro g/ml. For the eight patients in whom a switch to C. dubliniensis was detected, the fluconazole MICs for C. dubliniensis isolates at end of study ranged from 0.25 to 64 micro g/ml: the fluconazole MICs for isolates from six patients were 0.25 to 2.0 micro g/ml and those for the other two were 32 and 64 micro g/ml, respectively. In conclusion, a considerable number of patients initially infected with C. albicans strains that failed to develop fluconazole resistance demonstrated a switch to C. dubliniensis. C. dubliniensis in this setting may be underestimated due to lack of identification and may occur due to the impact of fluconazole on the ecology of oral yeast species.

Efficacy of caspofungin alone and in combination with voriconazole in a Guinea pig model of invasive aspergillosis.

The antifungal activity of caspofungin acetate (CAS) alone and in combination with voriconazole (VRC) was evaluated in an immunosuppressed transiently neutropenic guinea pig model of invasive aspergillosis. Guinea pigs were immunosuppressed with triamcinolone at 20 mg/kg of body weight/day subcutaneously beginning 4 days prior to lethal intravenous challenge with Aspergillus fumigatus and were made temporarily neutropenic with cyclophosphamide administered at 150 mg/kg intraperitoneally (i.p.) 1 day prior to challenge. Therapy with i.p. CAS at 1 and 2.5 mg/kg/day (with and without oral VRC at 5 mg/kg/day), oral VRC at 5 mg/kg/day, or i.p. amphotericin B (AMB) at 1.25 mg/kg/day was begun 24 h after challenge and was continued for 5 days. Mortality occurred in 12 of 12 untreated controls, whereas mortality occurred in 4 of 12 and 6 of 12 guinea pigs treated with CAS at 1 and 2.5 mg/kg/day, respectively, and in 3 of 12 guinea pigs treated with AMB. No mortality occurred among animals treated with CAS at 1 mg/kg/day plus VRC at 5 mg/kg/day, CAS at 2.5 mg/kg/day plus VRC at 5 mg/kg/day, or VRC at 5 mg/kg/day alone. Both CAS regimens increased the survival times and reduced the colony counts in tissue compared with those for the controls. Treatment with VRC and AMB significantly reduced the colony counts in the tissues of selected animals compared with those in the tissues of the controls. Treatment with VRC and AMB also resulted in reductions in colony counts in tissues compared with those in the tissues of animals treated with CAS (the difference was not statistically significant) and improved the survival times but did not sterilize tissues. Combination therapies with CAS plus VRC at either dose reduced colony counts in tissues 1,000-fold over those for the controls and were the only regimens that significantly reduced the numbers of positive cultures. The combinations of CAS plus VRC were highly effective in this model and should be further evaluated for use against invasive aspergillosis.

Candida glabrata oropharyngeal candidiasis in patients receiving radiation treatment for head and neck cancer.

Candida glabrata colonization is common in patients receiving radiation treatment for head and neck cancer, but to our knowledge has never been described as the infecting organism with oropharyngeal candidiasis (OPC). This study presents the first three patients described with C. glabrata OPC in this patient population. Patient 1 developed C. glabrata OPC and required fluconazole, 800 mg/day, for clinical resolution. Antifungal susceptibility testing revealed a MIC of fluconazole of >64 microg/ml. Elapsed time from initial culturing to treatment decision was 7 days. Patients 2 and 3 developed C. glabrata OPC. They were patients in a study evaluating OPC infections, and cultures were taken immediately. CHROMagar Candida plates with 0, 8, and 16 microg of fluconazole/ml were employed for these cultures. Lavender colonies, consistent with C. glabrata, grew on the 0- and 8-microg plates but not on the 16-microg plate from patient 2 and grew on all three plates from patient 3. Based on these data, a fluconazole dose of 200 mg/day was chosen for patient 2 and a dose of 400 mg/day was chosen for patient 3, with clinical resolution in both. Elapsed time from initial culturing to treatment decision was 2 days. C. glabrata does cause OPC in head and neck radiation treatment patients, and the use of fluconazole-impregnated chromogenic agar may significantly reduce treatment decision time compared to that with conventional culturing and antifungal susceptibility testing.

Efficacy of ravuconazole (BMS-207147) in a guinea pig model of disseminated aspergillosis.

Ravuconazole (BMS-207147, ER-30346), an oral triazole, was evaluated in an immunosuppressed temporarily neutropenic guinea pig model of invasive aspergillosis. In this model, guinea pigs were immunosuppressed with triamcinolone 20 mg/kg sc od beginning 4 days before challenge and made neutropenic with cyclophosphamide 300 mg/kg ip 1 day before challenge. Treatments of ravuconazole 5, 10 and 25 mg/kg po od were compared with itraconazole 2.5 and 5.0 mg/kg po bd and amphotericin B 1.25 mg/kg ip od. Treatment began 24 h after lethal intravenous challenge with Aspergillus fumigatus and continued for 5 days. Mortality occurred in eight of eight untreated control animals versus none of eight treated with ravuconazole 5 or 10 mg/kg/day or itraconazole 10 mg/kg/day. Mortality occurred in one of eight animals treated with ravuconazole 25 mg/kg/day, one of eight with amphotericin B and two of eight treated with itraconazole 5 mg/kg/day. Compared with controls, each of the antifungals examined significantly reduced the tissue burden in liver and brain, although only the highest doses of the azole drugs and amphotericin B significantly reduced tissue burden in the kidney. All three doses of ravuconazole improved survival and also reduced the tissue burden of ASPERGILLUS: In this model of invasive aspergillosis, ravuconazole showed significant activity and may be a useful compound in human disease.