**7. Epidemiological markers**

As we have already pointed out, yeasts (especially those of the genus *Candida*) have emerged as important pathogens in humans and animals and the interrelation between both is of great relevance, gaining prominence today.

Several markers can be used to detect new yeast species as well as their genotype. Based on the data, we can determine the presence of these microorganisms, the same species/genotype, in one or more anatomical areas of the host, as well as of different ecological niches.

Confirming the colonization/infection area has often been an arduous task. Therefore, the use of these markers shows to be of great importance for the epidemiological study of yeasts.

Among the phenotypic markers, we can highlight those based on colony morphology (morphotyping), enzyme production (enzyme typing), sensitivity to "Killer" toxins and antifungal agents. They are simple and easy to perform techniques.

Genotypic markers are more sophisticated and safer; however, they require more elaborate techniques. The technique is based on short sequential repetition of bases throughout the yeast genome and its reading is performed on a specific sequencing apparatus. The patterns of the visualized DNA bands function as true "fingerprints" of the microorganism, leading us to the recognition of the colonization/infection area of the host. This technique can be used both for use in clinical isolates and for environmental samples (**Figure 17**).

With increasingly interconnected ties between man and his dog, the use of these markers is a valuable technique for detecting epidemiological transmission between

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barrier [36].

*Importance of Yeasts in Oral Canine Mucosa DOI: http://dx.doi.org/10.5772/intechopen.95905*

fungicidal actions [34].

susceptible yeast species.

biochemical and/or molecular responses.

logical analysis of the agent's transmitter [33].

**8. Antifungals, sensitivity tests and treatment**

these species and a facilitator for taking therapeutic actions based on the microbio-

Currently, yeast mycoses have increased substantially, and it can be considered an important public health problem, especially in systemic clinical conditions and hospital infections. The antifungal drugs used in human and veterinary medicine have special characteristics regarding the chemical structure and the mechanism of action, interfering directly or indirectly in the fungal cell, with fungistatic or

Among the existing antifungal drugs, the most widely used and known are polyenic, imidazolic, pyrimidine, sulfamide, benzofurenic and other compounds with varying degrees of success, such as iodides, thiosulfates, sulfides and tolnaftates. In the treatment of invasive fungal infections, classes of polyene antifungals (amphotericin B), azoles (fluconazole, voriconazole, ketoconazole, itraconazole, posaconazole), pyrimidines (5-fluorocytosine) and echinocandin, caspofungin, micafungin) are mainly used [35]. The increasing incidence of yeast infections, such as those present in the oral mucosa, has been a target of constant concern in the search for increasingly effective treatments and safer drugs. The use in the treatment and prophylaxis of antifungals such as fewer toxic azoles, especially fluconazole, has given rise to cases of resistance among

The resistance of fungi to antifungal agents can be classified into clinical and microbiological resistance. The concept of clinical resistance is defined when there is a persistence or progression of a fungal infection even with the administration of the drug chosen as appropriate. In this case, "in vitro" tests may indicate the sensitivity of the agent to the antifungal. Usually, the occurrence of clinical resistance is associated with host, iatrogenic, pharmacological factors and factors related to the fungus virulence [36]. Microbiological resistance is a phenomenon in which the etiologic agent can develop in the presence of therapeutic concentrations of antifungals, a capacity verified "in vitro". Resistance can be intrinsic, primary or secondary, or extrinsic. This aspect is of real importance since we are increasingly faced with resistant yeasts, especially the "critical" species, highlighting *C. auris* and *C. haemulori,*

Intrinsic resistance is so called when no member of a species is sensitive to the antifungal, being primary, when in a species normally sensitive to an antifungal we find a resistant strain (without exposure to it) or secondary or acquired, when a previously sensitive strain develops resistance after exposure to a drug, due to phenotypic or genotypic changes [37]. The mechanism of resistance to antifungals by fungi, both for clinical or microbiological resistance, is involved with cellular,

In the cellular mechanism, strains or sensitive specimens are exchanged for resistant endogenous ones, genetic alteration, a fact that guarantees secondary resistance, transient genetic expression and alteration in the cell type. Regarding the biochemical mechanism, phenotypic changes in fungi occur, allowing the absorption of the drug to be slower, altering the target site and increasing the excretion of the drug. The changes from the molecular point of view causing a genetic amplification to occur, mutations, among other modifications in the gene involved in the defense against the antifungal. In addition to these changes, another molecular alternative of resistance is the ability to form biofilms, an efficient physical

whose findings should be immediately reported to the treatment team.

**Figure 17.** *Chromosomal bands of yeasts obtained by electrophoresis pulsed field - PFGE.*

*Canine Genetics, Health and Medicine*

examples (**Figure 16**).

**7. Epidemiological markers**

different ecological niches.

miological study of yeasts.

environmental samples (**Figure 17**).

*Chromosomal bands of yeasts obtained by electrophoresis pulsed field - PFGE.*

techniques.

**6.3 Chromogenic medium: CHROMagarCandida®**

blue/green and *C. krusei* light pink, for example (**Figure 15**).

between both is of great relevance, gaining prominence today.

Sowing in chromogenic media, such as CHROMagarCandida®, can provide presumptive identification according to the color developed by the yeast. In this medium, the specie *Candida albicans* develops a light green color; *C. tropicalis* it is

In addition to these identification methods, there are several automated and manual systems that facilitate the laboratory routine, such as Vitek and API20C, as

As we have already pointed out, yeasts (especially those of the genus *Candida*) have emerged as important pathogens in humans and animals and the interrelation

Several markers can be used to detect new yeast species as well as their genotype.

Genotypic markers are more sophisticated and safer; however, they require more elaborate techniques. The technique is based on short sequential repetition of bases throughout the yeast genome and its reading is performed on a specific sequencing apparatus. The patterns of the visualized DNA bands function as true "fingerprints" of the microorganism, leading us to the recognition of the colonization/infection area of the host. This technique can be used both for use in clinical isolates and for

With increasingly interconnected ties between man and his dog, the use of these markers is a valuable technique for detecting epidemiological transmission between

Based on the data, we can determine the presence of these microorganisms, the same species/genotype, in one or more anatomical areas of the host, as well as of

Confirming the colonization/infection area has often been an arduous task. Therefore, the use of these markers shows to be of great importance for the epide-

Among the phenotypic markers, we can highlight those based on colony morphology (morphotyping), enzyme production (enzyme typing), sensitivity to "Killer" toxins and antifungal agents. They are simple and easy to perform

**102**

**Figure 17.**

these species and a facilitator for taking therapeutic actions based on the microbiological analysis of the agent's transmitter [33].
