Oral colonization: a possible source for candidemia in low-weight neonates

Rare Yeasts in Latin America: Uncommon Yet Meaningful

Systemic infections caused by rare yeasts are increasing given the rise in immunocompromised or seriously ill patients. Even though globally, the clinical significance of these emerging opportunistic yeasts is increasingly being recognized, less is known about the epidemiology of rare yeasts in Latin America. This review collects, analyzes, and contributes demographic and clinical data from 495 cases of infection caused by rare yeasts in the region. Among all cases, 32 species of rare yeasts, distributed in 12 genera, have been reported in 8 Latin American countries, with Trichosporon asahii (49.5%), Rhodotorula mucilaginosa (11.1%), and Saccharomyces cerevisiae (7.8%) the most common species found. Patients were mostly male (58.3%), from neonates to 84 years of age. Statistically, surgery and antibiotic use were associated with higher rates of Trichosporon infections, while central venous catheter, leukemia, and cancer were associated with higher rates of Rhodotorula infections. From all cases, fungemia was the predominant diagnosis (50.3%). Patients were mostly treated with amphotericin B (58.7%). Crude mortality was 40.8%, with a higher risk of death from fungemia and T. asahii infections. Culture was the main diagnostic methodology. Antifungal resistance to one or more drugs was reported in various species of rare yeasts.

Genetic diversity assessed using PFGE, MLP and MLST in Candida spp. candidemia isolates obtained from a Brazilian hospital

Candida spp. are the main causative agents of invasive fungal infections in immunocompromised patients. Candidemia has attributable mortality rates of 15 to 35% and increases hospitalisation time and costs, thus making this disease a public health concern. This study aimed to use pulsed-field gel electrophoresis (PFGE), microsatellite length polymorphism (MLP) and multilocus sequence typing (MLST) to analyse the genetic relationships among 65 Candida spp. bloodstream isolates, including 35 Candida albicans, 15 Candida glabrata and 15 Candida tropicalis isolates, all of which were obtained from patients in a Brazilian hospital. Moreover, patient clinical data were assessed. All techniques resulted in high discriminatory indexes. C. albicans and C. tropicalis isolates showed high genetic variability, while C. glabrata isolates had relatively low genetic variability. Moreover, a cluster of C. glabrata isolates was identified in a hospital unit. New MLST sequence types, diploid sequence types and alleles are described. Relationships were not observed between the molecular typing results and clinical characteristics. The molecular typing of clinical strains increases our understanding of candidemia epidemiology and promotes the development of strategies that can reduce the incidence of this disease. Moreover, this study is the first to combine these techniques to genotype these three species in Brazil.

Oral Candida colonization in xerostomic postradiotherapy head and neck cancer patients

OBJECTIVES

To evaluate (a) oral colonization of Candida species, especially for non-albicans Candida species (NACS), in xerostomic postradiotherapy head and neck cancer patients and (b) risk factors affecting their colonization.

MATERIALS AND METHODS

Subjective and objective dry mouth scores, stimulated salivary flow rates, pH and buffering capacity were measured in 72 xerostomic postradiotherapy head and neck cancer patients. Candida counts and species identification were performed using oral rinse samples cultured in Candida Chromagar, followed by polymerase chain reaction and API 20C AUX system.

RESULTS

Candida colonization was observed in 87.5% of subjects, with 80.6% and 48.6% of study population colonized by C. albicans and NACS, respectively. NACS was associated with high objective dry mouth scores, denture use, and females (p = .006, .009, and .036, respectively). In addition, Candida glabrata was detected more in females (p = .018) and denture wearers (p = .026), while Candida tropicalis was associated with high objective dry mouth scores (p = .022) and females (p = .027). Quantity of Candida colonization correlated positively with objective dry mouth scores (r = 0.599, p < .001) and negatively with salivary flow rates (r = -0.258, p = .041) and pH (r = -0.290, p = .022).

CONCLUSION

NACS colonization was common in xerostomic head and neck cancer patients. Increased signs of dry mouth, female and dental prostheses may promote NACS colonization.

Systemic hematogenous dissemination of mouse oral candidiasis is induced by oral mucositis

The causes of fungemia include immunosuppression and neutropenia stemming from diverse factors as well as the placement of central venous catheters. However, the relationship between fungemia and the oral cavity has not been substantiated. In this study, we explored the pathological conditions of Candida albicans—derived oral candidiasis in a mouse model, which always develops oral mucositis as a complication. In oral candidiasis, the hyphae of C. albicans are believed to primarily invade the stratum granulosum, but not the subepithelium, of the mucous membrane. We provide histological evidence that in concomitant oral mucositis, the hyphae infiltrate the subepithelium and blood vessels. Blood cultures and tissue samples revealed the onset of fungemia only in the mucositis-induced groups. Positive numbers of colony-forming units were found in groups A (chemotherapy), B (chemotherapy + mucositis) and C (mucositis), but were highest in group B. Some organs revealed positive CFU in groups B and C. The presence of fungal DNA in blood plasma and tissue was confirmed by PCR. The fungal DNA frequency was significantly higher in the mucositis group when compared with the non-mucositis group. The results suggest that fungi first invade the subepithelium and then the blood vessels, from which they disseminate throughout the body, and that oral mucositis is an important risk factor for fungemia. This study clearly demonstrates the relationship between oral mucositis, fungemia, and the potential systemic fungal dissemination, which has not been previously proven. Our findings highlight the importance of oral care for patients at risk of fungemia.

Candidemia in the Neonatal Intensive Care Unit: A Retrospective, Observational Survey and Analysis of Literature Data

We evaluated the epidemiology of Candida bloodstream infections in the neonatal intensive care unit (NICU) of an Italian university hospital during a 9-year period as a means of quantifying the burden of infection and identifying emerging trends. Clinical data were searched for in the microbiological laboratory database. For comparative purposes, we performed a review of NICU candidemia. Forty-one candidemia cases were reviewed (overall incidence, 3.0 per 100 admissions). Candida parapsilosis sensu stricto (58.5%) and C. albicans (34.1%) were the most common species recovered. A variable drift through years was observed; in 2015, 75% of the cases were caused by non-albicans species. The duration of NICU hospitalization of patients with non-albicans was significantly longer than in those with C. albicans (median days, 10 versus 12). Patients with non-albicans species were more likely to have parenteral nutrition than those with C. albicans (96.3% versus 71.4%). Candida albicans was the dominant species in Europe and America (median, 55% and 60%; resp.); non-albicans species predominate in Asia (75%). Significant geographic variation is evident among cases of candidemia in different parts of the world, recognizing the importance of epidemiological data to facilitate the treatment.

Admission to the Intensive Care Unit is Associated With Changes in the Oral Mycobiome

A prospective exploratory study was conducted to characterize the oral mycobiome at baseline and determine whether changes occur after admission to the intensive care unit (ICU). We found that ICU admission is associated with alterations in the oral mycobiome, including an overall increase in Candida albicans.