Oral mycoses and other opportunistic infections in HIV: therapy and emerging problems - a workshop report

Pathophysiological microenvironments in oral candidiasis

Oral candidiasis (OC), a prevalent opportunistic infection of the oral mucosa, presents a considerable health challenge, particularly in individuals with compromised immune responses, advanced age, and local predisposing conditions. A considerable part of the population carries Candida in the oral cavity, but only few develop OC. Therefore, the pathogenesis of OC may depend on factors other than the attributes of the fungus, such as host factors and other predisposing factors. Mucosal trauma and inflammation compromise epithelial integrity, fostering a conducive environment for fungal invasion. Molecular insights into the immunocompromised state reveal dysregulation in innate and adaptive immunity, creating a permissive environment for Candida proliferation. Detailed examination of Candida species (spp.) and their virulence factors uncovers a nuanced understanding beyond traditional C. albicans focus, which embrace diverse Candida spp. and their strategies, influencing adhesion, invasion, immune evasion, and biofilm formation. Understanding the pathophysiological microenvironments in OC is crucial for the development of targeted therapeutic interventions. This review aims to unravel the diverse pathophysiological microenvironments influencing OC development focusing on microbial, host, and predisposing factors, and considers Candida resistance to antifungal therapy. The comprehensive approach offers a refined perspective on OC, seeking briefly to identify potential therapeutic targets for future effective management.

Ageing People Living with HIV/AIDS, PLWHA; More Dental Challenges; the Romanian Dental Professional's Point of View

BACKGROUND

In Romania, HIV (human immunodeficiency virus) and AIDS (acquired immunodeficiency syndrome) were first acknowledged in 1989. Getting older with HIV/AIDS is now possible due to antiretroviral treatment, but it can bring dental problems due to HIV itself or to the reluctance of dental professionals to treat dental problems. Our study aims to assess the attitudes, knowledge, and practices of Romanian dental professionals regarding aging PLWHA.

METHODS

An analytical cross-sectional observational survey based on a self-administered questionnaire was conducted for Romanian dental professionals from October 2022 to January 2023.

RESULTS

The responders' group profile was as follows: a mean age of 39.09 ± 0.36 years (limit: 19-75), a majority of 991 (90.01%) from urban dental offices, and 364 (33.06%) with more than twenty years' experience. A total of 517 (46.95%) responders had an unprofessional attitude and declared that, if possible, they would avoid taking part in performing dental treatments for people living with HIV/AIDS (PLWHA). There were 89 (8.08%) dental professionals that refused to work with PLWHA. Only 363 (32.97%) had worked with one previously. The dental professionals in rural areas refused PLWHA more frequently: 20% (N = 22) of rural dental professionals vs. 6.76% (N = 67) of urban dental professionals refused to work with PLWHA (OR = 0.30; 95% CI: 0.16-.56). The logistic regression applied for the 1101 responders revealed after stepwise selection that the most influential factor for their refusal to work with PLWHA in our study group was being previously exposed to HIV during dental practice (OR = 14.45; 95% CI: 8.55- 24.42; p = 0.000).

CONCLUSIONS

Dental educators and health care planners should promote the knowledge of prophylaxis and positive attitudes towards the treatment of PLWHA. Successful resolution of these concerns is time consuming and expensive but necessary if dentists are to satisfy their professional obligations to HIV/AIDS patients.

Oral Candidosis: Pathophysiology and Best Practice for Diagnosis, Classification, and Successful Management

Oral candidosis is the most common fungal infection that frequently occurs in patients debilitated by other diseases or conditions. No candidosis happens without a cause; hence oral candidosis has been branded as a disease of the diseased. Prior research has identified oral candidosis as a mark of systemic diseases, such as hematinic deficiency, diabetes mellitus, leukopenia, HIV/AIDS, malignancies, and carbohydrate-rich diet, drugs, or immunosuppressive conditions. An array of interaction between Candida and the host is dynamic and complex. Candida exhibits multifaceted strategies for growth, proliferation, evasion of host defenses, and survival within the host to induce fungal infection. Oral candidosis presents a variety of clinical forms, including pseudomembranous candidosis, erythematous candidosis, angular cheilitis, median rhomboid glossitis, cheilocandidosis, juxtavermillion candidosis, mucocutaneous candidosis, hyperplastic candidosis, oropharyngeal candidosis, and rare suppurative candidosis. The prognosis is usually favorable, but treatment failure or recurrence is common due to either incorrect diagnosis, missing other pathology, inability to address underlying risk factors, or inaccurate prescription of antifungal agents. In immunocompromised patients, oropharyngeal candidosis can spread to the bloodstream or upper gastrointestinal tract, leading to potentially lethal systemic candidosis. This review therefore describes oral candidosis with regard to its pathophysiology and best practice for diagnosis, practical classification, and successful management.

FastFung: A novel medium for the culture and isolation of fastidious fungal species from clinical samples

We developed a novel culture medium, referred to FastFung medium as suitable for the culture of clinical fungi, including fastidious ones, for both research and diagnostic studies. It is based on Schædler agar supplemented with many essential components for the growth of fastidious fungi. It also contains selective antibacterial agents for the inhibition of contaminant bacteria growth. In this preliminary study, the FastFung medium was compared to the gold standard Sabouraud medium for 98 fungal and 20 bacterial strains. The fungal strain positive culture rate was 100% vs. 95% and the bacterial strain inhibition was 100% vs. 20%, for the FastFung and Sabouraud media, respectively. When compared to the Sabouraud medium on 120 clinical samples, the FastFung medium displayed both a higher fungal colonies count, and a lower culture contamination rate. Storage at 4 °C for 4 weeks did not alter the FastFung culture medium performances for the six isolates of Candida, Cryptococcus, and Penicillium tested. These encouraging results suggest future development of using the FastFung medium in clinical mycology and in mycobiome characterization. Further prospective evaluation aiming at assessing whether implementing the FastFung medium in the routine workflow simplifies and strengthen fungal isolation capacities in the clinical laboratory is warranted.

Oral Candidiasis: A Disease of Opportunity

Oral candidiasis, commonly referred to as “thrush,” is an opportunistic fungal infection that commonly affects the oral mucosa. The main causative agent, Candida albicans, is a highly versatile commensal organism that is well adapted to its human host; however, changes in the host microenvironment can promote the transition from one of commensalism to pathogen. This transition is heavily reliant on an impressive repertoire of virulence factors, most notably cell surface adhesins, proteolytic enzymes, morphologic switching, and the development of drug resistance. In the oral cavity, the co-adhesion of C. albicans with bacteria is crucial for its persistence, and a wide range of synergistic interactions with various oral species were described to enhance colonization in the host. As a frequent colonizer of the oral mucosa, the host immune response in the oral cavity is oriented toward a more tolerogenic state and, therefore, local innate immune defenses play a central role in maintaining Candida in its commensal state. Specifically, in addition to preventing Candida adherence to epithelial cells, saliva is enriched with anti-candidal peptides, considered to be part of the host innate immunity. The T helper 17 (Th17)-type adaptive immune response is mainly involved in mucosal host defenses, controlling initial growth of Candida and inhibiting subsequent tissue invasion. Animal models, most notably the mouse model of oropharyngeal candidiasis and the rat model of denture stomatitis, are instrumental in our understanding of Candida virulence factors and the factors leading to host susceptibility to infections. Given the continuing rise in development of resistance to the limited number of traditional antifungal agents, novel therapeutic strategies are directed toward identifying bioactive compounds that target pathogenic mechanisms to prevent C. albicans transition from harmless commensal to pathogen.

Common oral opportunistic infections in Human Immunodeficiency Virus infection/Acquired Immunodeficiency Syndrome: Changing epidemiology; diagnostic criteria and methods; management protocols

There were 36.9 million in the world living with human immunodeficiency virus (HIV) infection/acquired immunodeficiency syndrome (AIDS) as of 2017, and new infections have seen a reduction by 18% since 2010. But this rate of decline is not sufficient for the goal of eradication of AIDS by 2030. Only 21.7  million people infected with HIV have accesses to antiretroviral therapy, with the rest at risk of the potential complications of HIV infection. It has been shown that oral lesions are diagnostic and prognostic of HIV infection, and many oral opportunistic infections continue to be a major problem, particularly in developing countries. It is therefore important that dental surgeons be aware and updated to recognize and manage the oral effects of HIV infection/AIDS. This chapter describes the classification, diagnosis, and management of oral lesions in these patients, based on our current understanding of the infection. This review also discusses the standardization of diagnosis of oral lesions in HIV infection/AIDS patients, immune reconstitution inflammatory syndrome case definition, and the research priorities formulated at the 7th World Workshop on Oral Health and Disease in AIDS.

Oral Microbiome in HIV-Infected Women: Shifts in the Abundance of Pathogenic and Beneficial Bacteria Are Associated with Aging, HIV Load, CD4 Count, and Antiretroviral Therapy

Human immunodeficiency virus (HIV)-associated nonacquired immunodeficiency syndrome (AIDS) conditions, such as cardiovascular disease, diabetes, osteoporosis, and dementia are more prevalent in older than in young adult HIV-infected subjects. Although the oral microbiome has been studied as a window into pathogenesis in aging populations, its relationship to HIV disease progression, opportunistic infections, and HIV-associated non-AIDS conditions is not well understood. We utilized 16S rDNA-based pyrosequencing to compare the salivary microbiome in three groups: (1) Chronically HIV-infected women >50 years of age (aging); (2) HIV-infected women <35 years of age (young adult); and (3) HIV-uninfected age-matched women. We also examined correlations between salivary dysbiosis, plasma HIV RNA, CD4⁺ T cell depletion, and opportunistic oral infections. In both aging and young adult women, HIV infection was associated with salivary dysbiosis characterized by increased abundance of Prevotella melaninogenica and Rothia mucilaginosa. Aging was associated with increased bacterial diversity in both uninfected and HIV-infected women. In HIV-infected women with oral coinfections, aging was also associated with reduced abundance of the common commensal Veillonella parvula. Patients taking antiretroviral therapy showed increased numbers of Neisseria and Haemophilus. High plasma HIV RNA levels correlated positively with the presence of Prevotella and Veillonella, and negatively with the abundance of potentially beneficial Streptococcus and Lactobacillus. Circulating CD4⁺ T cell numbers correlated positively with the abundance of Streptococcus and Lactobacillus. Our findings extend previous studies of the role of the microbiome in HIV pathogenesis, providing new evidence that HIV infection is associated with a shift toward an increased pathogenic footprint of the salivary microbiome. Taken together, the data suggest a complex relationship, worthy of additional study, between chronic dysbiosis in the oral cavity, aging, viral burden, CD4⁺ T cell depletion, and long-term antiretroviral therapy.

In Vitro Effect of Cinnamomum zeylanicum Blume Essential Oil on Candida spp. Involved in Oral Infections

The present study demonstrates the antifungal potential of chemically characterized essential oil (EO) of Cinnamomum zeylanicum Blume on Candida spp. biofilm and establishes its mode of action, effect on fungal growth kinetics, and cytotoxicity to human cells. The minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) values varied from 62.5 to 1,000 μg/mL, and the effect seems to be due to interference with cell wall biosynthesis. The kinetics assay showed that EO at MICx2 (500 μg/mL) induced a significant (p < 0.05) reduction of the fungal growth after exposure for 8 h. At this concentration, the EO was also able to hinder biofilm formation and reduce Candida spp. monospecies and multispecies in mature biofilm at 24 h and 48 h (p < 0.05). A protective effect on human red blood cells was detected with the EO at concentrations up to 750 μg/mL, as well as an absence of a significant reduction (p > 0.05) in the viability of human red blood cells at concentrations up to 1,000 μg/mL. Phytochemical analysis identified eugenol as the main component (68.96%) of the EO. C. zeylanicum Blume EO shows antifungal activity, action on the yeast cell wall, and a deleterious effect on Candida spp. biofilms. This natural product did not show evidence of cytotoxicity toward human cells.

Overview and research agenda arising from the 7th World Workshop on Oral Health and Disease in AIDS

The Research Agenda generated by the 7th World Workshop on Oral Health and Disease in AIDS (WW7) is delivered in this paper. Panels of international experts presided over nine workshops that constituted the conference held in November 2014 in Hyderabad, India. The main goal of the Workshop was to bring together clinician and scientists interested in the subject to debate with world-wide perspectives current issues related to the oral manifestations in HIV/AIDS. The workshops were structured around three themes; basic science, clinical/translational science and social science and were attended by 135 participants from 31 countries. The research questions debated at the workshops are presented in nine consensus papers published in this issue and are summarised in this paper along with an outline of the identified research needs in the field.