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Yeasts are the mostly form of fungi usually found in the oral cavity of the human. A various types of yeasts are commonly found in commensalism relationship with the host. Candida albicans is the most common type of yeasts living in the oral cavity. Several factors can effects on the presence of yeasts in the oral cavity. This review tries to illustrate the most type of yeasts that can found in the oral cavity and the effective factors.
International Journal of Medical Science and Current Research (IJMSCR)
Available online at:
Volume2, Issue 4, Page No: 345-348
July-August 2019
International Journal of Medical Science and Current Research | July-August 2019 | Vol 2 | Issue 4
ISSN (Print): 2209-2870
ISSN (Online): 2209-2862
(International Print/Online Journal)
PUBMED-National Library of
Medicine ID-101739732
Yeasts: One member of the normal flora of the oral cavity
Ali Abdul Hussein S. AL-Janabi, Huda Ali S. Al-Mosawe, Karrar AI-Mosawi*
Dept. of Microbiology, College of Medicine, University of Karbala, Karbala-Iraq
* AI-Ammam Al-Hussein medical city hospital in Karbala
*Corresponding Author:
Professor Ali Abdul Hussein S. AL-Janabi
Dept. of Microbiology, College of Medicine, University of Karbala, Karbala-Iraq
Type of Publication: Review Paper
Conflicts of Interest: Nil
Yeasts are the mostly form of fungi usually found in the oral cavity of the human. A various types of yeasts are
commonly found in commensalism relationship with the host. Candida albicans is the most common type of
yeasts living in the oral cavity. Several factors can effects on the presence of yeasts in the oral cavity. This
review tries to illustrate the most type of yeasts that can found in the oral cavity and the effective factors.
Keywords: Yeasts, normal flora, oral cavity
Yeasts are one complex group of the community of
the oral flora [1]. They usually live in commensalism
relationship with the human and could be turn to
pathogenic in special conditions such as weakness in
the immune system [1-2]. The stable occurring of
yeasts in the orals cavity is usually under the control
by the competition with other microorganisms or by
the immune system of the human body [3]. Among
yeasts of the oral cavity, Candida albicans is found
as very common type of yeasts [4-5].
Oral normal flora
The oral cavity of the human contains a huge diverse
numbers of M.O. living as a residence complex
community with each other and in a commensalism
relationship with the human body [6]. This huge
number of oral microflora induce the scientists to
provide an informative design for collection all of
new information about such types of community like
what has done with the project of the human oral
microbiome database (HOMD) which designed to be
a reference for named and un-named, cultured or
non-yet-cultured bacteria [7]. However, several
methods are used to detect or identified the microbial
components of oral flora such as culturing of oral
swab [8] and molecular methods which is considers
the most important and significant methods in the
present time [9]. However, the full understanding of
the nature of the oral microflora that effect on the
human health and disease requires a holistic view that
emphasizes interactions among various residents
within the oral community and with the human body
There are many factors can effect on the diversity and
residence of oral microflora, especially yeast. Some
of these factors more relative to the survival and
distribution of most normal yeast flora such as age,
amount of saliva, pH, smoking, denture wearing,
while other factors consider less important such as
sensation of dry or burning mouth, taste disorders and
gender [5, 10]. The effects of age on the human oral
flora start from the first days of birth which are
affected by the type of diet, especially the
oligosaccharides present in formula and breast milk
and immunoglobulin A1 from the later [11]. This
colonization will establish the future flora for adult
and could be considers the potential trigger for future
disease in the oral cavity [12]. However, the number
of yeasts as part of normal oral flora is increased with
AL-Janabi, Huda Ali S et al International Journal of Medical Science and Current Research (IJMSCR)
Volume 2, Issue 4; July-August 2019; Page No.345-348
© 2019 IJMSCR. All Rights Reserved
the age [10]. Reduction in the saliva flow rate or pH
value of the mouth will increase the colonization rate
of the oral fungal flora and vice versa [10, 13].
Moreover, there are variable results about the effect
of smoking on the presence of fungal oral flora.
Smoking is mainly effective on the saliva and on oral
commensal bacteria and fungi, especially Candida
spp. [14]. Candida albicans found in higher number
in smokers independent on the type of smoking
(cigarette, water pipe, or electronic cigarette) [15].
Increased growth rate of Candida spp. also found in
the oral of smoking patients and lead to candidiasis
[14]. Meanwhile, other study found a slightly
difference in number of Candida spp. between
smoker and non-smokers individuals [16]. The
difference in race of the human can also play a role in
the presence of fungal in the oral cavity. White males
show differed in their oral content of fungi than in
Asian males, while such difference was not clear
among females of both races [5].
Effect of diseases on the oral normal flora
Oral cavity is usually contented a wide diverse
number of organisms which are mostly associated
with the health and diseases in such part of the
human body [17]. Diseases are considered an
important effective factor on the health state of the
oral cavity and on its content of normal flora.
Immunocompromised conditions that mainly results
from cancer therapy and organs or cell
transplantation are the most effective factors on the
occurring of the oral flora [1-2]. The prevalence of
oral fungal flora in patients with cancer found to be
increased from 7.5% in pre-treatment of cancer to
32.6% at the therapy end [18]. Yeasts also found
increased in number in patients with
immunocompromised conditions [1-2]. However,
fungi represented by yeasts as a normal flora of the
oral cavity is usually occurred in low number than
bacteria [17]. Isolation of fungi from 20 healthy
individuals revealed that there was 74 culturable and
11 non-culturable fungal genera and the number of
species in each individual ranged from 9 to 23 [5].
Yeasts of the oral cavity
Yeasts are one of the most important groups of
commensalism organisms in the oral cavity of the
healthy individual [1]. They consider harmless
organisms unless the presence of predisposing host
factors [19] such as immunosuppressive conditions in
immunocompromised individuals [1], or in adult or
children patients with HIV infection [19-21]. The
occurring of fungi as normal microflora in healthy
individuals revealed more stability in number, but
with variable diversity over time as noted when
evaluated the oral fungi flora in 10 healthy
individuals after 28-30 weeks [22]. However, the
contents of oral cavity from fungi may be occurred as
a residence or temporary form. In the oral of 20
healthy individuals, about 74 culturable and 11 non-
culturable fungal genera had been isolated [5].
Candida spp. is the most frequency fungal species
found in the oral cavity as residence normal flora [4].
It found in 75% of healthy individuals followed by
Cladosporium spp. (65%), Aureobasidium spp.,
Saccharomycetales (50% for both), Aspergillus spp.
(35%), Fusarium spp. (30%), and Cryptococcus spp.
(20%) [5]. Candida albicans is the more common
member of Candida spp. lives in the oral normal
flora [1, 4-5]. It represented about 60-70% of all
isolates from healthy individuals, followed by C.
glabrata, C. tropicalis and genera of Rhodotorula,
Saccharomyces [1]. It also isolated more frequency
from the oral cavity of individuals with or without
dentures [4]. From 194 yeasts isolated from patients
with advance cancer, 95 of them (49%) are C.
albicans followed by C. glabrata [23]. The patients
with head and neck malignancy also had high
percentage of C. albicans (14.28%) as causative
agents of oral fungal infection followed by Candida
tropicalis (28.57%) and Candida
parapsilosis (14.28%)[24]. C. albicans also isolated
more frequently from patients with HIV infection
[20, 25]. The prevalence of C. albicans among other
species of Candida spp. is not always the case.
Although Chinese persons have greater number of
yeast in their oral cavity in comparison with those
live in North America, C. albicans was relatively rare
in number than other yeast types such as C.
parapsilosis, Candida guilliermondii, and C. famata
[26]. However, the variable results about the most
isolated species of yeasts can be depended on the
testing site and method used [1]. Most methods used
to isolate fungi from the oral cavity depending on
usage of oral swab [23, 27-28]. Whereas, molecular
method considers the powerful first step in detection
or identification of oral fungi [9].
The important things about detection of the most
prevalence species of fungi in the oral cavity is
AL-Janabi, Huda Ali S et al International Journal of Medical Science and Current Research (IJMSCR)
Volume 2, Issue 4; July-August 2019; Page No.345-348
© 2019 IJMSCR. All Rights Reserved
related to determine the suitable curative agent for
treatment of any disease may results from abnormal
activities of such fungi in this part of the human
body. Antifungal resistance becomes serious problem
among patients with candidiasis infection, especially
to azole group which may also lead to recurrent oral
infection [29]. This type of resistance is clearer
among patients with malignant diseases [24]. About
34 (72%) isolates of C. glabrata from patients with
advance cancer were resistance to fluconazole and
Itraconazole [23]. Two isolates of C. albicans and C.
tropicalis from patients who undergoing radiotherapy
shown resistance to fluconazole [24]. Thus, a new
antifungal agent has become an important demand for
limiting the risk of fungal infection from the oral
cavity [19].
1- Stenderup A. Oral mycology. Acta
Odontologica Scandinavica. 1990, 48: 310.
2- Wong HM. Oral complications and
management strategies for patients
undergoing cancer therapy. The Scientific
World Journal. 2014. Article ID 581795, 1-
3- Baker JL, Bor B, Agnello M, Shi W, He X.
Ecology of the oral microbiome: beyond
bacteria. Trends in Microbiology. 2017,
25(5): 362374.
4- Zaremba ML, Daniluk T, Rozkiewicz D, et al.
Incidence rate of Candida species in the oral
cavity of middle-aged and elderly subjects.
Advances in Medical Sciences. 2006, 51:
5- Ghannoum MA, Jurevic R J, Mukherjee PK,
Cui F, Sikaroodi M, Naqvi A, Gillevet PM.
Characterization of the oral fungal
microbiome (mycobiome) in healthy
individuals. PLoS Pathogens. 2010, 6(1): 1-8.
6- Wade, WG. The oral microbiome in health
and disease. Pharmacological Research. 2013,
69, 137143.
7- Forsyth. expanded Human oral microbiome
Database (eHOMO). 2019.
8- Kulak-Ozkan Y, Kazazoglu E, Arikan A. Oral
hygiene habits, denture cleanliness, presence
of yeasts and stomatitis in elderly people.
Journal of Oral Rehabilitation. 2002,
9- Diaz P I, Hong B, Dupuy A K, Strausbaugh L
D. Mining the oral mycobiome: Methods,
components, and meaning. Virulence. 2017,
8(3): 313323.
10- Shimizu C, Kuriyama T, Williams DW,
Karasawa T, Inoue K, Nakagawa K,
Yamamoto E. Association of oral yeast
carriage with specific host factors and altered
mouth sensation. Oral Surgery, Oral
Medicine, Oral Pathology, Oral Radiology,
and Endodontology. 2008, 105(4): 445451.
11- Gomez A, Nelson KE. The oral microbiome
of children: development, disease, and
implications beyond oral health. Microbial
Ecology. 2017, 73(2): 492503.
12- Papaioannou W, Gizani S, Haffajee AD,
Quirynen M, Mamai-Homata E,
Papagiannoulis L. The microbiota on different
oral surfaces in healthy children. Oral
Microbiology and Immunology. 2009, 24(3):
13- Parvinen T, Larmas M. The relation of
stimulated salivary flow rate and pH to
Lactobacillus and yeast concentrations in
saliva. Journal of Dental Research. 1981,
60(12): 19291935.
14- Soysa NS, Ellepola AN. The impact of
cigarette/tobacco smoking on oral
candidosis: an overview. Oral Diseases. 2005,
11(5): 268273.
15- Mokeem SA, Abduljabbar T, AI-Kheraif AA,
Alasqah MN, Michelogiannakis D,
Samaranayake LP, Javed F. Oral Candida
carrage amoong cigarette-and waterpipe-
smokers, and electronic cigarette users. Oral
Diseases. 2019, 25: 319-326.
16- Oliver DE, Shillitoe EJ. Effects of smoking
on the prevalence and intraoral distribution of
Candida albicans. Journal of Oral Pathology.
1984, 13(3): 265270.
17- Chandra J, Retuerto M, Mukherjee PK,
Ghannoum M. The fungal biome of the oral
cavity. Methods Mol Biol. 2016, 1356: 107
135. doi: 10.1007/978-1-4939-3052-4_9.
AL-Janabi, Huda Ali S et al International Journal of Medical Science and Current Research (IJMSCR)
Volume 2, Issue 4; July-August 2019; Page No.345-348
© 2019 IJMSCR. All Rights Reserved
18- Lalla RV, Latortue MC, Hong CH, et al. ;
Fungal Infections Section; Oral Care Study
Group; and Multinational Association of
Supportive Care in Cancer
(IMASCC)/International Society of Oral
Oncology (ISOO). A systematic review of
oral fungal infections in patients receiving
cancer therapy. Support Care Cancer. 2010,
18(8): 985992.
19- Ngo HX, Garneau-Tsodikova S, Green KD. A
complex game of hide and seek: the search
for new antifungals. Med Chem Commun.
2016, 7(7):12851306.
20- Vargas KG, Joly S. Carriage frequency,
intensity of carriage, and strains of oral yeast
species vary in the progression to oral
candidiasis in human immunodeficiency
virus-positive individuals. Journal of Clinical
Microbiology. 2002, 40(2): 341350.
21- Blignaut E. Oral candidiasis and oral yeast
carriage among institutionalised South
African paediatric HIV/AIDS patients.
Mycopathologia. 2007, 163(2): 6773.
22- Monteiro-da-Silva F, Araujo R, Sampaio-
Maia BInterindividual variability and
intraindividual stability of oral fungal
microbiota over time. Medical Mycology.
2014, 52(5): 496503.
23- Bagg J, Sweeney MP, Lewis MA, Jackson M
S, Coleman D, AI Mosaid A. High prevalence
of non-albicans yeasts and detection of anti-
fungal resistance in the oral flora of patients
with advanced cancer. Palliative Medicine.
2003, 17(6): 477481.
24- Raj S, Sharma D, Mate P, Capoor MR,
Bhowmik KT. A study of changes in the oral
fungal flora of patients on radiotherapy for
head and neck malignancies and their
correlation with funguria and fungemia.
Indian Journal of Cancer. 2017, 54(1): 39-42.
25- Akpan A, Morgan R. Oral candidiasis.
Postgraduate Medical Journal. 2002, 78(922),
26- Xul J, Mitchell TG. Geographical differences
in human oral yeast flora. Clinical Infectious
Diseases. 2003, 36(2): 221224.
27- Martin MV, Al-Tikriti U, Bramley PA. Yeast
flora of the mouth and skin during and after
irradiation or oral and laryngeal cancer.
Journal of Medical Microbiology. 1981, 14:
28- Kulak-Ozkan Y, Kazazoglu E, Arikan A. Oral
hygiene habits, denture cleanliness, presence
of yeasts and stomatitis in elderly people.
Journal of Oral Rehabilitation. 2002,
29- Rautemaa R, Ramage G. Oral candidosis
clinical challenges of a biofilm disease.
Critical Reviews in Microbiology. 2011,
37(4): 328336.
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Background: Patients of head and neck malignancies often develop oral mucositis and invite various pathogens to colonize over it. Objectives: The objective of this study is to identify the fungi isolated from patients undergoing radiotherapy (RT) for head and neck cancer, to determine the antifungal susceptibility of these isolates and to determine the time and week of fungal colonization. Patients and methods: Three specimens (throat, urine, and blood) were collected from each of the head and neck cancer patients, who were advised RT. These specimens, which were collected before the start of RT, during RT (2nd and 6th week), and post-RT (8th week) were inoculated into fungal culture media. Candida species were identified by standard methods and antifungal susceptibility of the candidal isolates was done. Results: Candida infection was found in 24/42 patients (57.14%) out of which Candida albicans was isolated in 14.28%, Candida tropicalis (28.57%) and Candida parapsilosis (14.28%). Maximum isolation of yeast was in the 6th week of RT. Fungemia was found in 3/42 patients. All the yeast isolates were sensitive to fluconazole except two. Conclusion: Prophylactic antifungal therapy in patients undergoing RT for head and neck malignancy is particularly important to prevent intraoral colonization and infection by Candida. Screening of such patients on RT for fungal infections can prevent fatal mold infections.
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Oral microbiota is one of the most complex and diverse microbial communities in the human body. In the present study, we aimed to characterize oral fungi biodiversity and stability over time in a group of healthy participants with good oral health. Oral health and oral fungal microbiota were evaluated in 40 healthy individuals. A follow-up of 10 participants was carried out 28 weeks and 30 weeks after the first sampling. Oral rinse was collected and incubated in a fungal selective medium at 25ºC and 37ºC for 7 days. Fungi were identified based on macro- and microscopic morphology. API/ID32C was used for yeast identification, and molecular techniques were used to identify the most prevalent nonidentified moulds, mainly by sequencing 18S and internally transcribed spacer regions. Moulds were recovered from all participants and yeast from 92.5%. The most frequently isolated fungi were Candida spp., Rhodotorula spp., Penicillium spp., Aspergillus spp., and Cladosporium spp. The oral fungal community presented a high interindividual variability, but the frequency and quantification of each fungal taxon was constant over the 30-week observation period, showing a consistent intraindividual stability over time. The intraindividual stability opposed to interindividual variability may suggest a common and a variable group of fungi in the oral cavity.
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Candida samples were taken over a period of 2 years from 54 human immunodeficiency virus (HIV)-positive asymptomatic subjects to evaluate changes in yeast carriage, intensity of carriage, and genotype over time. Overall, we found that HIV-positive patients with CD4+-cell counts of between 200 and 400/μl had significantly more yeast colonization than healthy control subjects. Of the 54 patients, 11 developed thrush. We found that intensity of carriage in these 11 patients increased significantly in the progression from asymptomatic yeast carrier to an episode of oral thrush. Also, the most common yeast species isolated was Candida albicans; however, we did see a number of patients harboring multiple species at the same time. Using the C. albicans-specific probe Ca3, we found that 54% (n = 6) of the 11 patients who developed thrush maintained genetically similar strains throughout the study period, with minor genetic variations in all patients except one. Forty-six percent of these patients had either multiple strains throughout the study period (n = 2), strain replacement (n = 1), or species replacement (n = 2). Of the patients who had multiple strains, one (I4) was infected by two different strains of Candida dubliniensis distinguished by a recently developed species-specific probe. These results suggest that commensal strains colonizing HIV-positive individuals can undergo alterations prior to producing an episode of thrush.
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Oral candidiasis is a common opportunistic infection of the oral cavity caused by an overgrowth of Candida species, the commonest being Candida albicans. The incidence varies depending on age and certain predisposing factors. There are three broad groupings consisting of acute candidiasis, chronic candidiasis, and angular cheilitis. Risk factors include impaired salivary gland function, drugs, dentures, high carbohydrate diet, and extremes of life, smoking, diabetes mellitus, Cushing's syndrome, malignancies, and immunosuppressive conditions. Management involves taking a history, an examination, and appropriate antifungal treatment with a few requiring samples to be taken for laboratory analysis. In certain high risk groups antifungal prophylaxis reduces the incidence and severity of infections. The prognosis is good in the great majority of cases.
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The oral yeast flora of healthy humans from eastern North America and China were sampled and compared. Chinese persons harbored a greater number and diversity of yeast species in the mouth. Furthermore, Candida albicans, which is the predominant commensal and etiologic species of candidiasis in Europe and the Western Hemisphere, was relatively rare in China.
Fungal infections directly affect millions of people each year. In addition to the invasive fungal infections of humans, the plants and animals that comprise our primary food source are also susceptible to diseases caused by these eukaryotic microbes. The need for antifungals, not only for our medical needs, but also for use in agriculture and livestock causes a high demand for novel antimycotics. Herein, we provide an overview of the most commonly used antifungals in medicine and agriculture. We also present a summary of the recent progress (from 2010-2016) in the discovery/development of new agents against fungal strains of medical/agricultural relevance, as well as information related to their biological activity, their mode(s) of action, and their mechanism(s) of resistance.
This review summarizes the impact of biofilms in oral candidosis with special emphasis on medically compromised patients. The concept of oral candidosis as a mixed candidal-bacterial biofilm infection has changed our understanding of its epidemiology and diagnosis as well as approach to its treatment. Candida albicans is the most common causative agent of oral candidosis although Candida species other than C. albicans are often seen in medically compromised patients with a history of multiple courses of azole antifungals. Although C. albicans is usually susceptible to all commonly used antifungals when tested in vitro, their biofilm form are highly resistant to most antifungals. Therefore, treatment consists of mechanical destruction of the biofilm in combination with topical drugs. Azole antifungals should be avoided for patients suffering from recurrent oral yeast infections due to a risk of selection and enrichment of resistant strains within the biofilm. Oral candidosis can also be a symptom of an undiagnosed or poorly controlled systemic disease such as HIV infection or diabetes. If the response to appropriate treatment is poor, other causes of oral mucositis should be excluded. Oral candidosis arises from the patient's mixed candidal-bacterial biofilm, i.e., dental plaque, whereby good self-care is important for successful therapy.
The purpose of this study was to determine oral hygiene habits, denture cleanliness, presence of yeasts and denture stomatitis in elderly people. Seventy complete denture wearers were investigated clinically and mycologically. Subjects were evaluated according to, presence of denture stomatitis, presence of yeasts, denture cleanliness, frequency of denture brushing and denture cleaning methods. Swabs were taken from the palate investigated mycologically in order to identify the yeast colonies. No statistical relationship was found between denture stomatitis and frequency of denture brushing and denture cleaning methods. However, there was a statistically significant relationship between denture stomatitis, yeasts' presence and denture cleanliness.
Oral fungal infections frequently develop in individuals with advanced cancer. This study examined the oral mycological flora of 207 patients receiving palliative care for advanced malignant disease. Demographic details and a clinical history were documented from each participant. A tongue swab was collected and cultured on CHROMAgar Candida (CHROMAgar Paris, France). All yeasts were identified by germ tube test, API ID 32C profiles and, for Candida dubliniensis, by species-specific PCR. Susceptibility to fluconazole and itraconazole was determined by a broth microdilution assay according to the National Committee for Clinical Laboratory Standards (NCCLS). At time of sampling, 54 (26%) of the 207 subjects had clinical evidence of a fungal infection and yeasts were isolated from 139 (67%) individuals. In total, 194 yeasts were isolated, of which 95 (49%) were Candida albicans. There was a high prevalence of Candidia glabrata (47 isolates) of which 34 (72%) were resistant to both fluconazole and itraconazole. All nine isolates of C. dubliniensis recovered were susceptible to both azoles. No relationship was established between anti-fungal usage in the preceding three months and the presence of azole resistant yeasts. This study of patients with advanced cancer has demonstrated a high incidence of oral colonization with non-C. albicans yeasts, many of which had reduced susceptibility to fluconazole and itraconazole. The role of improved oral care regimes and novel anti-fungal drugs merits further attention, to reduce the occurrence of fungal infection in these patients.
South Africa currently has an estimated 500,000 AIDS orphans, many of whom are HIV-positive. Oral candidiasis commonly occurs in both adult and paediatric HIV/AIDS patients. Published information on HIV-positive children in Africa mainly concerns hospitalised patients. The objective of this study was to determine the prevalence of oral candidiasis and oral yeast carriage among paediatric HIV/AIDS patients residing in orphanages in Gauteng, South Africa, and to compare the prevalence of isolated yeast species with species obtained from adult HIV/AIDS patients. Eighty-seven paediatric HIV/AIDS patients residing in five homes were examined and a swab taken from the dorsal surface of the tongue, cultured on CHROMagar and yeast isolates identified with the ATB 32C commercial system. The species prevalence of 57 identified isolates was compared with that of 330 isolates from adult HIV/AIDS patients. Twelve (13.8%) children presented with clinically detectable candidiasis. Yeasts were isolated from 0% to 53% of children in the individual homes, with Candida albicans (40.4%) and C. dubliniensis (26.3%) constituting the most frequently isolated species. Gentian violet prophylaxis was administered in one particular home and a higher carriage rate (66.6%) of non-C. albicans and non-C. dubliniensis was observed among these children. The prevalence of C. albicans was lower while the prevalence of C. dubliniensis, C. glabrata and C. tropicalis was significantly higher (p < or = 0.001) among the children than among adult HIV/AIDS patients. These findings indicate a role for yeast culture and species determination in cases with candidiasis in institutionalized paediatric HIV/AIDS patients.