Candida Dubliniensis: Infection, Transmission & Diseases

Candida dubliniensis is a yeast fungus and is often found in the oral cavity of HIV or AIDS patients. In addition, it often co-occurs with Candida albicans in candidiasis. The similarity between Candida dubliniensis and Candida albicans makes correct identification of the microorganism difficult.

What is Candida dubliniensis?

In 1995, scientists distinguished Candida dubliniensis from the very similar fungus Candida albicans. In the context of candidiasis, Candida dubliniensis often occurs together with Candida albicans or other species of this genus. The species designation “dubliniensis” goes back to the Irish capital Dublin, as researchers first recognized the yeast fungus as a new species in this part of Europe. Within this classification, different types of Candida dubliniensis can be distinguished, one of which may have pathogenic properties. However, because the fungus occurs almost exclusively in association with other Candida species, experts have difficulty assessing its general significance for medical practice.

Occurrence, distribution, and characteristics

Although Candida dubliniensis was not described until the 1990s, studies subsequently detected the microorganism for a period of at least 40 years. Presumably, therefore, Candida dubliniensis is not a new species or mutation. Instead, researchers assume that it was often confused with Candida albicans in the past. The microorganism has a worldwide distribution. In 1998, scientists Sullivan and Coleman found that the frequency of different Candida species was shifting. Proportionally, the number of Candida albicans infections was decreasing, while other species were gradually taking their place. Nevertheless, Candida albicans is still the most common pathogen causing Candida infections. Oral mucosal swabs from people with HIV or AIDS contain spores of Candida dubliniensis more often than average. However, an outbreak of candidiasis does not necessarily occur because a strong immune system forms a natural protection against the pathogens. Since it is precisely this defense system that is weakened in people with AIDS (or other significant infections), the fungus succeeds in spreading. Candida dubliniensis forms a whitish coating on infected surfaces when seen with the naked eye. Initially, it often forms a two-dimensional colonization, but especially after a longer period of time, the fungus can form small colonies that are separated from each other. Chlamydospores and tubes similar to them are formed by the microorganism in some cases, but not constantly. Chlamydospores are capsules or vesicles that form on branches of the fungal tissue and initially remain in contact with the rest of the organism. The vesicle consists of the cell wall, which thickens to form a resistant protective layer. If the environment dries out or does not provide enough nutrients, the organism can survive in these sheaths. The surrounding tissue dies, but from the retreat in the chlamydospore, the fungus can grow anew. For medicine, this can mean more difficult treatment because the organism may be temporarily inactive but still present. The fungus multiplies optimally at 30-37°C, but not above 42°C. Laboratories take advantage of the maximum growth temperature by establishing cultures with spores and allowing them to rest at 42° C for 48 hours. If the spores are Candida dubliniensis, no coating will grow on the prepared culture medium. If, on the other hand, it is the very similar Candida albicans, the fungus multiplies and a characteristic whitish layer develops. In this way, the distinction between the two microorganisms can be made. On special culture media, Candida dubliniensis and Candida albicans also develop different colorations. The two microorganisms also differ in terms of their genetic material. Candida dubliniensis usually has a diploid chromosome set, in which each chromosome appears twice, but temporarily the fungus may take on a haploid form.

Diseases and ailments

Candida dubliniensis is particularly common in the oral cavity of patients infected with the HIV virus or those suffering from AIDS. The latter describes a specific syndrome that disrupts and progressively disintegrates the human immune system as a result of HIV infection, whereas infection with HIV in itself can be asymptomatic (initially).Candida dubliniensis is also involved in the formation of candidiasis in many cases. Symptoms include white coating in the mouth (for example on the tongue or in the esophagus), on fingernails or in skin folds. In the case of systemic candidiasis, Candida dubliniensis can affect numerous organs. The disease occurs mainly in people whose immune system is not fully functional. The cause may also be the temporary use of antibiotics, cancer and related medication, diabetes mellitus, sepsis or another underlying disease. However, Candida dubliniensis has so far played a minor role in candidiasis. Various antifungal drugs are used in the treatment of the infectious disease. This group of drugs fights the microorganisms and prevents their further spread in the tissue. “Candidiasis due to HIV disease” represents a separate diagnosis in the International Classification System of Diseases (ICD) (B20.4). Fungal infection often manifests in affected individuals as one of the first visible signs of the increasingly weakened immune system. In addition, an investigation in an individual case demonstrated colonization with Candida dubliniensis in the lungs of a deceased individual. Whether the infection contributed to death or was incidental is unknown.