oral mycology

Oral Mycology
lectuer (17)

Dr.Baha,Hamdi.AL-Amiedie
Ph.D.Microbiology

Characteristic of fungi
1-• Eukaryotes
2- No chlorophyl (distinguishes them from
plants and algae)
3- Unicellular to filamentous
4- Rigid cell wall
5-Spore bearing stages in the life cycle

6-Usually reproduce by sexual and asexual
means
7-Insensitive to antibacterial antibiotics


Morphological types of fungi
Three major groups
1. Moulds
2. Yeasts
3. Mushrooms

Dimorphic fungi – fungi that have both a
yeast stage and a mould stage

In many cases vegetative cell of hypha contains more
than one nucleus – typical hypha is a nucleated tube

containing a cytoplasm ( a coenocytic) and no septa
(cross walls)
• Septate hyphae have one or two nuclei per cell


Asexual spores
Asexual reproduction
Asexual spore formation:
chlamydospores (formed within
sporangia)
conidia (formed naked at tips of
hyphae)
budding (cell division)
fragmentation (of mycelium)




Sexual spores
? Sexual spores are
? resistant to drying
heating, freezing, and
some chemical agents
Not as resistant to heat
as are bacterial
endospores
Either a sexual spore or
an asexual spore can
germinate and develop
into a new hypha and Mycelium

Fungal infection types
1-Rang from superfical infection to ovewhelming systemic infections that are rapidly fatal in the compromised host
2-they are increased in frequency as result of increased used of antibiotics
Corticostroids& cytotoxic drugs
3-classified into superfical, cutaneous
Subcutaneous&systemic infection;Systemic infection are subdivied into those caused by opportunistic fungi & by those caused by pathogenic fungi

Oral Aspect of fungal infections
Fungal infections in the oral and perioral regions occur either as primary localized lesions or as manifestations of systemic mycoses. By far the most common group of fungal infections that dental practitioners diagnose and treat are caused by Candida spp. Some of the rarer mycoses with oral manifestations
such as histoplasmosis, are found almost exclusively in the USA, while others such as mucormycosis are found particularly in immuno-compromised individuals.

Oral candidosis
Candida infections confined to the mouth are relatively common and “ Causes of generalized candidosis with oral manifestations, however, are uncommon. The laboratory diagnosis of oral candidosis is
The most common oral fungal infection is candidosis, caused by Candida spp., particularly C. albicans.
About 50% of the population are symptomless oral carriers of Candida spp., but only a small proportion of individuals have the signs and symptoms of infection.
The pathogenesis of oral candidosis involves a complex interaction between host defence mechanisms and fungal virulence factors

The common forms of oral candidosis
1.pseudomembranous,
2. erythematous (including HIV-associated infection and denture-related candidosis),
3. hyperplastic
4.angular cheilitis
Chronic mucocutaneous candidosis 5-.

Treatment :
consists of correcting predisposing factors and prescribing oral or systemic antifungal agents
The development of resistance in Candida spp. to azole drugs such as fluconazole may follow prolonged treatment and has been linked to treatment failure.
Oral lesions caused by fungi other than Candida spp. are rare and are usually secondary to primary infections of the lungs.

Laboratory diagnosis
1-microscopic examination:Direct examination with potassium hydroxide(KOH) a weat amount of skin scrapings break down the human cell enhancing the visibility of infected fungus.
2-laboratory culture: using special medium (sabourauds dextrose medium) enriched media.