Genotyping of Candida albicans and Candida dubliniensis by 25S rDNA analysis shows association with virulence attributes in oral candidiasis

Supragingival mycobiome of HIV-exposed-but-uninfected children reflects a stronger correlation with caries-free-associated taxa compared to HIV-infected or uninfected children

IMPORTANCE

Globally, caries is among the most frequent chronic childhood disease, and the fungal component of the microbial community responsible is poorly studied despite evidence that fungi contribute to increased acid production exacerbating enamel demineralization. HIV infection is another global health crisis. Perinatal HIV exposure with infection are caries risk factors; however, the caries experience in the context of perinatal HIV exposure without infection is less clear. Using high-throughput amplicon sequencing, we find taxonomic differences that become pronounced during late-stage caries. Notably, we show a stronger correlation with health-associated taxa for HIV-exposed-but-uninfected children when compared to unexposed and uninfected children. This aligns with a lower incidence of caries in primary teeth at age 6 or less for exposed yet uninfected children. Ultimately, these findings could contribute to improved risk assessment, intervention, and prevention strategies such as biofilm disruption and the informed design of pro-, pre-, and synbiotic oral therapies.

Co-Infection of Oral Candida albicans and Porphyromonas gingivalis Is Associated with Active Periodontitis in Middle-Aged and Older Japanese People

Background and Objectives: Candida albicans can be detected in subgingival sites of patients with periodontitis. However, the association between oral Candida albicans and periodontitis has not been fully elucidated in Japanese adults. The aim of this study is to clarify the relationship between oral Candida albicans infection/co-infection of oral C. albicans and Porphyromonas gingivalis and periodontitis among middle-aged and older Japanese people. Materials and Methods: Eighty-six patients (mean age 70.4 years) who visited the Hiroshima University Hospital from April to September 2021 were investigated in this study. Oral swab samples were collected from the tongue surface. C. albicans and P. gingivalis DNA was detected by real-time PCR using specific DNA primer sets. C. albicans-positive participants were classified into two groups according to the presence or absence of intron insertion of C. albicans DNA by PCR analysis. Results: C. albicans was detected in 22 (25.6%) of the 86 patients. Patients in their 80s recorded a higher C. albicans-positive rate (35.3%) compared with other participants. However, there was no significant association between the C. albicans positivity rate and clinical parameters such as sex, age, systemic disease, denture use, or oral health status. Of the 22 C. albicans-positive participants, 10 participants (45.5%) had C. albicans with intron insertion; 70% of participants who had C. albicans with intron insertion exhibited ≥6 mm probing depth. C. albicans/P. gingivalis co-infection was found in 12 patients (14%). Importantly, binomial logistic regression analysis revealed that C. albicans/P. gingivalis co-infection was significantly associated with ≥6 mm periodontal pockets with bleeding on probing (p = 0.02). Conclusions: Co-infection of C. albicans and P. gingivalis is involved in active periodontitis in middle-aged and older people.

Analysis of pathogenic factors of Candida albicans and the effect of vaginal immunization on recurrent vulvovaginal candidiasis in mice

BACKGROUND

The role of fungal pathogenic factors and the immune response of the vaginal epithelium in vulvovaginal candidiasis (VVC) and recurrent vulvovaginal candidiasis (RVVC) are still unclear. Our study wants to clarify whether there are differences in pathogenic factors between VVC and RVVC strains, confirm the roles of pathogenic factors in the pathogenesis of RVVC, and analyze the influence of pathogenic factors on vaginal host immunity.

METHODS

VVC- and RVVC-causing Candida albicans strains were genotyped with 25S rDNA. Drug susceptibility assays using a modified alamarBlue broth microdilution method were carried out. Milk culture medium and egg yolk culture medium were used to measure the secreted aspartate protease (Sap) and phospholipase (Plb) activity of the samples. We used C. albicans with different Sap activity levels to induce RVVC in mice and measured interleukin 4 (IL4), interleukin 8 (IL8), and interleukin 17 (IL17) in vaginal lavage fluid at different stages of RVVC infection.

RESULTS

There were no significant differences between VVC and RVVC fungi except that the Sap activity was lower for RVVC-causing C. albicans than for VVC-causing C. albicans. C. albicans with both strong Sap and weak Sap induced RVVC in mice. C. albicans with strong Sap had a reduced RVVC infection rate. In addition, C. albicans with strong Sap stimulated the vaginal epithelium to secrete more IL4, IL8, and IL17.

CONCLUSION

Compared with that of VVC-causing C. albicans, the Sap activity of RVVC-causing C. albicans was lower. C. albicans with strong Sap was less capable of causing repeated vaginal infections than that with weak Sap and stimulated the vaginal epithelium to produce more cytokines.

Antimicrobial photodynamic therapy for oral Candida infection in adult AIDS patients: A pilot clinical trial

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) using methylene blue (MB) plus potassium iodide (KI) has been shown to be effective in killing Candida albicans in many in vitro and in vivo studies, however, there are limited reports of clinical investigations. This study aimed to explore the clinical application of aPDT with MB plus KI for the treatment of oral infection caused by C. albicans in adult acquired immune deficiency syndrome (AIDS) patients.

METHODS

A total of 21 adult AIDS patients with C. albicans oral candidiasis were divided into two groups according to MB concentration and received two consecutive aPDT treatments. Immediately before and after the aPDT treatments, C. albicans yeast isolates were recovered to measure the colony-forming units per mL (CFU/mL), biofilm formation, and to analyze the 25S rDNA genotype. Patients were assessed for the clinical recovery of oral lesions and improvement of symptoms.

RESULTS

The Log₁₀ CFU/mL of C. albicans decreased significantly after the second aPDT but not the first aPDT. There was no significant difference between the two MB concentrations. Both aPDT protocols decreased the oral lesions and clinical symptoms with no significant difference after 2-fraction aPDT. The biofilm formation of C. albicans isolates did not change before and after aPDT. The killing efficiency of 2-fraction-aPDT was not associated with either biofilm formation or 25S rDNA genotype.

CONCLUSIONS

Two-fraction-aPDT with MB plus KI could reduce the number of viable C. albicans fungal cells and improve the clinical symptoms of oral candidiasis in adult AIDS patients, regardless of the biofilm formation or 25S rDNA genotype of infected C. albicans isolates.

Lack of relationship between genotype and virulence in Candida species

BACKGROUND

The virulence of isolates among different Candida species causing candidemia may play a role in the prognosis of the patients. Furthermore, the potential relationship between genotype and virulence is still unclear and need to be further studied.

AIMS

We aim to assess the relationship between genotype and virulence in Candida species using a Galleria mellonella larvae infection model.

METHODS

One hundred and ninety-four isolates from 68 clusters (Candida albicans, 114/41; Candida parapsilosis, 74/24; Candida tropicalis, 6/3) were compared against the same number of each species singleton genotypes in terms of survival of G. mellonella larvae.

RESULTS

The median of survival and the IQR ranges of clusters and singleton were as follows: C. albicans (2 days, IQR 1.5-2 vs. 2 days, IQR 1-2.25), C. parapsilosis (2 days, IQR 1.5-2.6 vs. 2 days, IQR 2-3.3), and C. tropicalis (1 day, IQR 1-3.5 vs. 2 days, IQR 2-3.5; p<0.05). High intra-cluster variability in terms of median of survival was found regardless the species.

CONCLUSIONS

No relationship between genotype and virulence in Candida was observed with the G. mellonella model.

Development and in vitro evaluation of buccal mucoadhesive films for photodynamic inactivation of Candida albicans

Candidiasis is one of the most common diseases that occur in the oral cavity, caused mainly by the species Candida albicans. Methylene blue (MB) has a potential for microbial photoinactivation and can cause the destruction of fungi when applied in Photodynamic Therapy (PDT). Mucoadhesive films are increasingly being studied as a platform for drug application due to their advantages when compared to other pharmaceutical forms. The aim of this work was to develop mucoadhesive buccal film containing poloxamer 407 (P407), alcohol polyvinyl (PVA) and polyvinylpyrrolidone (PVP) for the release of MB aiming the photoinactivation of Candida albicans in buccal infections. Different amounts of P407 were added to the binary polymeric blends composed PVA and PVP. Formulations were characterized as morphology, thickness, density, bending strength, mechanical properties, water vapor transmission, disintegration time, mucoadhesion, DSC, ATR-FTIR, in vitro drug release profile and photodynamic inactivation. The films displayed physicochemical characteristics dependent of polymeric composition, mucoadhesive properties, fast MB release and were effective in photo inactivate the local growth of Candida albicans isolates. The formulation containing the lowest PVA and P407 amounts displayed the best performance. Therefore, data obtained from the film system show its potentially useful role as a platform for buccal MB delivery in photoinactivation of C. albicans, showing its potential for in vivo evaluation.

Evaluation of Antifungal Activity of Naja pallida and Naja mossambica Venoms against Three Candida Species

In contrast to comprehensively investigated antibacterial activity of snake venoms, namely crude venoms and their selected components, little is known about antifungal properties of elapid snake venoms. In the present study, the proteome of two venoms of red spitting cobra Naja pallida (NPV) and Mozambique spitting cobra Naja mossambica (NMV) was characterized using LC-MS/MS approach, and the antifungal activity of crude venoms against three Candida species was established. A complex response to venom treatment was revealed. NPV and NMV, when used at relatively high concentrations, decreased cell viability of C. albicans and C. tropicalis, affected cell cycle of C. albicans, inhibited C. tropicalis-based biofilm formation and promoted oxidative stress in C. albicans, C. glabrata and C. tropicalis cells. NPV and NMV also modulated ammonia pulses during colony development and aging in three Candida species. All these observations provide evidence that NPV and NMV may diminish selected pathogenic features of Candida species. However, NPV and NMV also promoted the secretion of extracellular phospholipases that may facilitate Candida pathogenicity and limit their usefulness as anti-candidal agents. In conclusion, antifungal activity of snake venoms should be studied with great caution and a plethora of pathogenic biomarkers should be considered in the future experiments.