Antifungal Susceptibility In Vitro Determined by the Etest(r) for Candida Obtained from the Oral Cavity of Irradiated and Elderly Individuals

What Is Candida Doing in My Food? A Review and Safety Alert on Its Use as Starter Cultures in Fermented Foods

The use of yeasts as starter cultures was boosted with the emergence of large-scale fermentations in the 20th century. Since then, Saccharomyces cerevisiae has been the most common and widely used microorganism in the food industry. However, Candida species have also been used as an adjuvant in cheese production or as starters for coffee, cocoa, vegetable, meat, beer, and wine fermentations. A thorough screening of candidate Candida is sometimes performed to obtain the best performing strains to enhance specific features. Some commonly selected species include C. pulcherrima (teleomorph Metschnikowia pulcherrima) (wine), C. parapsilosis (teleomorph Monilia parapsilosis) (coffee), C. famata (teleomorph Debaryomyces hansenii) (cheese), and C. zeylanoides (teleomorph Kurtzmaniella zeylanoides) and C. norvegensis (teleomorph Pichia norvegensis) (cocoa). These species are associated with the production of key metabolites (food aroma formation) and different enzymes. However, safety-associated selection criteria are often neglected. It is widely known that some Candida species are opportunistic human pathogens, with important clinical relevance. Here, the physiology and metabolism of Candida species are addressed, initially emphasizing their clinical aspects and potential pathogenicity. Then, Candida species used in food fermentations and their functional roles are reported. We recommended that Candida not be used as food cultures if safety assessments are not performed. Some safety features are highlighted to help researchers choose methods and selection criteria.

Prevalence and susceptibility profile of Candida spp. isolated from patients in cancer therapy

OBJECTIVE

This study determined the prevalence of Candida spp. in the saliva of cancer patients. Furthermore, we assessed the antimicrobial activity of mouthwashes against the isolated strains and its susceptibility to amphotericin B and fluconazole.

METHODS

Thirty-four cancer patients undergoing radiotherapy, chemotherapy alone or combined treatment were investigated for oral Candida spp. colonization and compared in regard to mucositis presence. The maximum inhibitory dilution was used to assess the antimicrobial activity of Periogard®, Cepacol® Cool Ice and 0.12 % Chlorhexidine Digluconate mouthwashes against the isolates. In parallel, susceptibility to amphotericin B and fluconazole was determined by agar-based E-test. Data did not adhere to normal distribution as inferred by the Shapiro-Wilk test and statistical analysis was conducted by non-parametric McNemar test (α0.05).

RESULTS

Twenty-seven participants (79.4 %) were male, 19 (55.9 %) had mucositis and 9 (26.5 %) were colonized by Candida spp. 12 different strains of Candida spp. were isolated, being Candida albicans the most prevalent strain. Risk of Candida spp. colonization was increased by almost twofold among the participants with mucositis (odds ratio: 1.84; 95 % confidence interval: 0.37-9.07). Mouthwash Cepacol® Cool Ice presented better antimicrobial activity against Candida spp. while 0.12 % Chlorhexidine exhibited the worst activity. All strains were sensitive to amphotericin B, and 2 non-albicans strains were dose-dependent sensitive to fluconazole.

CONCLUSION

Considering the increased risk of colonization byCandida spp. in patients with mucositis, and the emergence of antifungal drug resistance, the antiseptics use could benefit the maintenance of cancer patient's oral health.

Study of Microbial Interaction Formed by "Candida krusei" and "Candida glabrata": "In Vitro" and "In Vivo" Studies

Abstract Recently, the non-albicans Candida species have become recognized as an important source of infection and oral colonization by association of different species in a large number of immunosuppressed patients. The objective of this study was to evaluate the interactions between C. krusei and C. glabrata in biofilms formed in vitro and their ability to colonize the oral cavity of mouse model. Monospecies and mixed biofilms were developed of each strain, on 96-well microtiter plates for 48 h. These biofilms were analyzed by counting colony-forming units (CFU/mL) and by determining cell viability, using the XTT hydroxide colorimetric assay. For the in vivo study, twenty-four mice received topical applications of monospecie or mixed suspensions of each strain. After 48 h, yeasts were recovered from the mice and quantified by CFU/mL count. In the biofilm assays, the results for the CFU/mL count and the XTT assay showed that the two species studied were capable of forming high levels of in vitro monospecie biofilm. In mixed biofilm, the CFU of C. krusei increased (p=0.0001) and C. glabrata decreased (p=0.0001). The metabolic activity observed in XTT assay of mixed biofilm was significantly reduced compared with a single C. glabrata biofilm (p=0.0001). Agreeing with CFU in vitro count, C. glabrata CFU/mL values recovered from oral cavity of mice were statistically higher in the group with single infection (p=0.0001) than the group with mixed infection. We concluded that C. krusei inhibits C. glabrata and takes advantage to colonize the oral cavity and to form biofilms.

Fungal contribution in chondroradionecrosis of the larynx

OBJECTIVE

To assess the prevalence of invasive fungal elements in the specimens of patients who underwent salvage total laryngectomy for chondroradionecrosis (CRN) in the absence of recurrent or persistent malignancy.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary academic medical center.

METHODS

One hundred fifty-nine patients were identified who underwent salvage total laryngectomy. Pathology reports were reviewed, and all laryngectomy specimens that did not contain residual malignancy were reevaluated for evidence of invasive fungal elements.

RESULTS

Twelve of 159 (7.5%) patients who underwent total laryngectomy after primary radiotherapy or chemoradiotherapy had no evidence of residual malignancy. Each of these specimens contained histopathologic evidence of CRN; invasive fungal elements were identified in 25%. There was no statistical difference in demographic or treatment-related variables between patients who underwent salvage total laryngectomy with evidence of persistent or recurrent malignancy in the laryngectomy specimen versus patients without evidence of tumor on final histopathologic analysis. Patients with evidence of ulceration or necrosis in the laryngectomy specimen had reduced overall survival, irrespective of the presence of persistent malignancy (hazard ratio = 2.923, 95% confidence interval = 1.023-8.352, P = .045).

CONCLUSION

Among salvage total laryngectomy patients, no difference was identified between patients who underwent total laryngectomy for recurrent or persistent malignancy after primary radiotherapy and those who received total laryngectomy without evidence of malignancy in their specimens. Invasive fungal elements were detected in several laryngectomy specimens that did not contain residual malignancy. Empiric antifungal therapy may therefore benefit patients diagnosed with CRN who are at risk for progression to nonfunctional larynx. Patients with evidence of ulceration or necrosis in the salvage laryngectomy specimen had worse overall survival.

LEVEL OF EVIDENCE

4. Laryngoscope, 127:E159-E165, 2017.