Jointly conducted by UM1 and IRD, this research reveals unprecedented data on fungal infections in Cameroon.
Thierry Ngouana Kammalac, researcher at TransVIHMI (Université Montpellier 1).
Thesis defended in 2014 at the doctoral school École doctorale Sciences Chimiques et Biologiques pour la Santé (Montpellier ; 1992-....).
This research is the result of an international co-supervision between several partner institutions.
Referenced in the ABES/STAR network, this thesis meets the rigorous criteria of French higher education.
The research conducted by Thierry Ngouana Kammalac at the University of Montpellier 1 and the University of Yaoundé I highlights the genetic diversity of Cryptococcus and Candida isolates in people living with HIV in Yaoundé. This study is of paramount importance as it addresses a little-explored topic in the region, where opportunistic fungal infections pose a major public health challenge. Indeed, fungal infections, particularly those caused by C. neoformans and yeasts of the genus Candida, are common among PLHIV, but data on their molecular epidemiology and antifungal susceptibility are scarce.
Opportunistic fungal infections, such as those caused by C. neoformans, are particularly concerning in the context of HIV, as they can lead to serious, even fatal complications. Immunocompromised patients, such as those living with HIV, are more vulnerable to these infections, underscoring the urgency for in-depth research in this area. In West Africa, and more specifically in Cameroon, the lack of data on the prevalence and diversity of these pathogens makes it difficult to implement effective prevention and treatment strategies.
The results of this study are striking. A total of 25 strains of C. neoformans and 317 Candida isolates, including 113 C. albicans, were isolated. The observed genetic diversity is significant, with 14 molecular types identified for C. neoformans and 65 for C. albicans. This raises questions about the evolution of these pathogens in a context where antifungal treatments are increasingly used. This genetic diversity could also have implications for the virulence of the strains and their ability to evade treatments, which is a major public health issue.
The variable susceptibility of the isolates to antifungals, particularly partial resistance to 5-fluorocytosine and fluconazole, raises concerns about the effectiveness of current treatments. These results highlight the need for regular monitoring of the susceptibility of isolates to antifungals in order to adapt treatment protocols. In a context where antifungal resistance is on the rise, it is crucial to develop treatment management strategies that take this variability into account.
Furthermore, the study also explored the antifungal activity of three medicinal plants, Terminalia mantaly, Terminalia catappa, and Monodora tenuifolia. The results show that these extracts exhibit promising inhibitory activity against the tested yeasts, thus paving the way for new therapeutic alternatives. Traditional medicine, which is widely practiced in many African communities, could play a key role in the fight against fungal infections.
The combination of certain subfractions even showed synergistic effects, which could revolutionize the treatment of fungal infections. For example, the combined use of these plant extracts with conventional antifungals could not only improve treatment efficacy but also reduce the side effects associated with high doses of antifungals. This could also help decrease the selective pressure that favors the emergence of resistant strains.
It is essential to consider how these findings can be translated into concrete actions to improve public health in Cameroon and the region. Policymakers must take these results into account to strengthen prevention and treatment strategies for fungal infections. The integration of traditional medicine, such as the use of plant extracts, could offer viable solutions in the face of increasing antifungal resistance.
Moreover, it would be wise to encourage collaborations between researchers, healthcare practitioners, and local herbalists to better understand and value the available phytotherapeutic resources. This could also promote awareness among populations about fungal infections and the importance of prevention.
In summary, this research provides crucial data on the molecular epidemiology of fungal infections in Cameroon and underscores the importance of an integrated approach to combat these pathogens. The results should be used to guide public health policies and encourage research on new antifungal therapies. By integrating traditional knowledge and scientific advancements, it is possible to significantly improve the management of fungal infections in people living with HIV, thereby contributing to the reduction of morbidity and mortality associated with these infections.
Key Facts
- 25 strains : Number of strains of C. neoformans isolated in the study.
- 317 isolates : Total number of Candida isolates, including 113 C. albicans.
- 14 molecular types : Number of molecular types identified for C. neoformans.
- 65 molecular types : Number of molecular types identified for C. albicans.
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Sources and Access
Thierry Ngouana Kammalac. Diversité génétique d'isolats de Cryptococcus et Candida issus des patients VIH positifs à Yaoundé et étude de leur sensibilité aux antifongiques et aux extraits de plantes. Parasitologie. Université Montpellier I; Université de Yaoundé I, 2014. Français. ⟨NNT : 2014MON13512⟩. ⟨tel-01132146⟩