Candida species from oral cavity of HIV-infected children exhibit reduced virulence factors in the HAART era

Comparative analysis of Candida spp. isolated from complete denture wearers with and without an HIV diagnosis

STATEMENT OF PROBLEM

Denture-related stomatitis (DRS), an inflammation frequently present in human immunodeficiency virus-positive (HIV+) individuals, can be attributable to colonization by Candida spp., which is considered a main factor. The virulence factors of these species are often modulated by the systemic condition of their hosts.

PURPOSE

The purpose of this clinical study was to evaluate the incidence, virulence, and morphology of Candida spp. isolated from biofilms of complete denture wearers with DRS, with and without an HIV diagnosis. In addition, the interaction of the systemic condition with the ability of Candida spp. to colonize was evaluated.

MATERIAL AND METHODS

Fifty-five complete denture wearers diagnosed with DRS were divided into 2 groups: experimental (HIV+) and control (human immunodeficiency virus-noninfected participants [HIV-]). Biofilm was collected by a standardized method of ultrasonification of prostheses. The incidence was evaluated by a chromogenic method and polymerase chain reaction (PCR). The virulence factors were assessed by using the capacity for biofilm formation by counting colony-forming units (CFUs/mL), biofilm metabolism by tetrazolium salt metabolization, and proteinase and phospholipase production by using a fluorimetric kit. Morphology was verified by using the hyphae-inducing test, and participants' health data were collected with a form. Data were analyzed by using the Student t, Mann-Whitney U, Spearman, and Fisher tests (α=.05).

RESULTS

The results of incidence were related to 55 participants (22 experimental and 33 control); in total, 63 Candida spp. samples were isolated, showing 28 Candida albicans and 36 nonalbicans strains. No significant difference was found between groups in baseline CFU/mL counts, biofilm formation capacity, cell metabolism, and phospholipase production. Proteinase production was higher for C. albicans in the control (P=.031) and for nonalbicans in the experimental (P=.016) groups. Relative to health data, the experimental group showed a moderate negative correlation between the CFU count/mL at baseline for nonalbicans and DRS classification (P=.020).

CONCLUSIONS

C. albicans was the most prevalent species. No difference was found in the Candida spp. of complete denture wearers with DRS, with and without an HIV diagnosis, with regard to virulence factors (except for proteinase production) and morphology.

Oral Microorganisms and Biofilms: New Insights to Defeat the Main Etiologic Factor of Oral Diseases

The oral cavity presents a highly diverse community of microorganisms due to the unique environmental conditions for microbial adhesion and growth [...].

Increased diversity, fungal burden, and virulence of oral Candida spp. in patients undergoing anti-tuberculosis treatment

Some studies have demonstrated a high prevalence of Candida species in patients with tuberculosis (TB). This is most likely due to long-term antimicrobial therapy. To date, no longitudinal studies addressed the effects of anti-TB treatment on the fungal burden and virulence of Candida spp. This study investigated the prevalence and virulence of Candida spp. in the oral cavity of 30 TB patients at different stages of treatment through a cohort study. These results were compared with those of 60 systemically healthy individuals in a cross-sectional study. Oral rinse samples from TB patients were collected before 45 and after 120 days of treatment. In the control group, the biological samples were collected only once. Candida spp. were identified by restriction fragment length polymorphism (RFLP) assays, and the following virulence factors were studied: phospholipase C and proteinase production, as well as Candida spp. biofilm and hyphae formation. The clinical diagnosis of TB and its treatment time were associated with the greater fungal burden (p < 0.0001), presence of non-albicans Candida (NAC) species (p = 0.0003), and increased virulence factors when compared with the Candida spp. isolated from systemically healthy individuals. The results showed that anti-TB treatment time was responsible for the increased fungal burden and isolation of NAC in TB patients (p = 0.0233). The increased prevalence, quantification, and virulence of Candida spp. isolated from the oral cavity of TB patients highlight the greater risk of oral lesions and cases of systemic dissemination in these patients.

Mucosal Bacteria Modulate Candida albicans Virulence in Oropharyngeal Candidiasis

Oropharyngeal candidiasis (OPC) is the most prevalent oral infection in immunocompromised patients, primarily associated with Candida albicans. Increasing evidence points to a significant role of mucosal bacteria on the transition of C. albicans from commensal to pathogenic. In this work, we hypothesized that changes in the abundance or composition of the mucosal bacterial microbiota induced by dietary sucrose during the development of OPC can modulate C. albicans virulence. C. albicans burdens and mucosal lesions were evaluated in a mouse cortisone immunosuppression model amended with sucrose. We also analyzed the mucosal bacterial composition using 16S rRNA gene sequencing and culture methods. In immunocompetent mice, sucrose significantly increased total bacterial burdens and reduced alpha diversity, by increasing the relative abundance of mitis group streptococci. In immunocompromised mice, C. albicans infection was associated with a significantly reduced bacterial alpha diversity due to an increase in the relative abundance of enterococci. When exposed to dietary sucrose, these mice had reduced C. albicans burdens and reduced bacterial alpha diversity, associated with an increase in the relative abundance of Lactobacillus. SparCC correlation networks showed a significant negative correlation between Lactobacillus and Enterococcus in all Candida-infected mice. Depletion of lactobacilli with antibiotic treatment partially restored C. albicans burdens in mice receiving sucrose. In coculture in vitro experiments, mouse oral Lactobacillus johnsonii isolates inhibited growth of Enterococcus faecalis isolates and C. albicans. These results support the hypothesis that the sucrose-induced attenuation of C. albicans virulence was a result of changes in the mucosal bacterial microbiome characterized by a reduction in enterococci and an increase in lactobacilli. IMPORTANCE By comparing Candida albicans virulence and the mucosal bacterial composition in a mouse oral infection model, we were able to dissect the effects of the host environment (immunosuppression), infection with C. albicans, and local modulating factors (availability of sucrose as a carbon source) on the mucosal bacterial microbiome and its role on fungal virulence. We showed that changes in endogenous microbial communities in response to sucrose can lead to attenuation of fungal disease. We also showed that Lactobacillus johnsonii may curtail Candida virulence both by inhibiting its growth and by inhibiting the growth of potentially synergistic bacteria such as enterococci. Our results support the concept that Candida pathogenesis should be viewed in the contexts of both a susceptible host and a mucosal bacterial microbiota conducive to virulence.

Are Candida albicans isolates from the oral cavity of HIV-infected patients more virulent than from non-HIV-infected patients? Systematic review and meta-analysis

Candida albicans is the main causative agent of oral lesions in HIV-infected patients and its oral colonization is a potential source of systemic dissemination. Although the high prevalence of lesions in HIV patients can be explained by the immunosuppressive condition, several studies have reported that natural selection can make C. albicans more virulent in this group of patients. Comparisons of the activity of exoenzymes (phospholipase, proteinase and hemolysin) in C. albicans isolated from HIV-infected and uninfected patients have yielded conflicting results. This study aimed, through a systematic review and meta-analysis, to answer the question: "Is the hydrolytic enzymatic activity of C. albicans, isolated from the oral cavity, different in individuals infected and not infected with HIV?" The question was addressed using the PECO framework: P (Population): children and adults, E (Exposure): HIV infection, C (Comparator): non-HIV-infected patients; O (Outcomes): exoenzymes activity i.e. phospholipase, proteinase and hemolysin. We conducted a systematic search on Pubmed, Embase, Scopus, Livivo, Lilacs, Web of Science, and Science Direct databases, and Google Scholar. The MAStARI tool was used to evaluate the risk of bias in the selected studies. From 2259 studies, 19 were included in this review and 11 comprised the meta-analysis. The activity of phospholipase (M-H = 0.15; Z = 2,76; p = 0.0006) and hemolysin exoenzymes (M-H = 0.07; z = 1,94; p = 0.05) was higher in C. albicans isolated from the oral cavity of HIV-infected patients, whereas the levels of protease activity were not different compared with non-HIV-infected individuals. This study showed a higher phospholipase and hemolysin activity in C. albicans isolates from the oral cavity of HIV-infected patients.

Current Aspects in the Biology, Pathogeny, and Treatment of Candida krusei, a Neglected Fungal Pathogen

Fungal infections represent a constant and growing menace to human health, because of the emergence of new species as causative agents of diseases and the increment of antifungal drug resistance. Candidiasis is one of the most common fungal infections in humans and is associated with a high mortality rate when the fungi infect deep-seated organs. Candida krusei belongs to the group of candidiasis etiological agents, and although it is not isolated as frequently as other Candida species, the infections caused by this organism are of special relevance in the clinical setting because of its intrinsic resistance to fluconazole. Here, we offer a thorough revision of the current literature dealing with this organism and the caused disease, focusing on its biological aspects, the host-fungus interaction, the diagnosis, and the infection treatment. Of particular relevance, we provide the most recent genomic information, including the gene prediction of some putative virulence factors, like proteases, adhesins, regulators of biofilm formation and dimorphism. Moreover, C. krusei veterinary aspects and the exploration of natural products with anti-C. krusei activity are also included.

Isolation of pathogenic Candida species from oral cavity of postpartum females, and its association with obstetric and dental problems

OBJECTIVE

The aim of the current study was to investigate pathogenic Candida spp. Colonization in oral cavity of postpartum females and its association with adverse pregnancy outcomes (APOs) and dental issues.

METHODS

Saliva samples and clinico-demographic data were collected from 267 postpartum females along with 54 non-pregnant females (Jan 2016-March 2018). Isolation of Candida was carried out by using standard microbiological methods and different virulence factors (Esterase activity, phospholipase activity and biofilm formation) were evaluated.

RESULTS

Candidacolonization was high in postpartum females (p<0.001, OR = 4.28). This colonization was not significant among females with APOs, however, one to three folds risk was seen with different obstetric and dental factors. High esterase activity was seen among Candida isolates from postpartum females in comparison to control group (p = 0.01). Phospholipase activity of C.albicans isolates from this group was also high (p = 0.001). Majority of the Candida isolates (66.87%) from postpartum females were biofilm formers. Increase in antifungal activity was seen among isolates from postpartum females, with 85% isolates resistant to Fluconazole and Voriconazole (p<0.001) and Amphotericin B resistance was present in 64.38% isolates (p<0.001).

CONCLUSION

Postpartum females are more susceptible to oral Candida colonization, which exhibit enhanced virulence characteristics and its carriage are associated with increased risk for development of APOs and dental problems.

Modulation of the Fungal-Host Interaction by the Intra-Species Diversity of C. albicans

The incidence of human infections caused by the opportunistic fungal pathogen Candida albicans is on the rise due to increasing numbers of immunosuppressed patients. The importance of the immune system in preventing overgrowth of the colonizing fungus and thereby limiting infection is well recognized and host protective mechanisms widely investigated. Only recently, it was recognized that the natural diversity in the fungal species could also influence the outcome of the interaction between the fungus and the host. C. albicans strain-specific differences are complex and their regulation at the genomic, genetic, and epigenetic level and by environmental factors is only partially understood. In this review, we provide an overview of the natural diversity of C. albicans and discuss how it impacts host-fungal interactions and thereby affects the balance between commensalism versus disease.