Biofilm 3 - Candida

Question 1

What specific component distinguishes fungal cell walls from other organisms?

Answer 1

Chitin

polysaccharide

Question 2

What is the most abundant component of fungal cell walls?

Answer 2

Glucans

polysaccharide

Question 3

What are glycoproteins in the fungal cell wall?

Answer 3

Carbohydrates associated with proteins

Question 4

What provides stability and regulates compounds entering and exiting fungal cells?

Answer 4

Phospholipids in the cell membrane

Question 5

What is ergosterol and what is its function?

Answer 5

The fungal sterol equivalent of cholesterol; maintains structure and contributes to membrane-bound enzyme functions

Question 6

What comprises the plaques in pseudomembranous candidiasis?

Answer 6

Desquamated epithelial cells, hyphae, and fibrin

Question 7

In which conditions is pseudomembranous candidiasis common?

Answer 7

Immunocompromised patients and corticosteroid use

Question 8

What key characteristic distinguishes chronic hyperplastic candidiasis from pseudomembranous?

Answer 8

White patches that do not wipe away (unlike pseudomembranous which can be removed)

Question 9

Where does chronic hyperplastic candidiasis typically present?

Answer 9

On the buccal mucosa and border of the tongue

Question 10

What serious condition is chronic hyperplastic candidiasis classified as?

Answer 10

Oral potentially malignant disorder (OPMD)

Question 11

What condition is chronic hyperplastic candidiasis similar to?

Answer 11

Leukoplakia lesion

Question 12

Describe Newton’s type I denture-induced stomatitis.

Answer 12

Localized inflammation

Question 13

Describe Newton’s type II denture-induced stomatitis.

Answer 13

Diffuse inflammation

Question 14

Why are dentures conducive to candidiasis?

Answer 14

They provide a solid abiotic surface for Candida to adhere and proliferate on

Question 14

Describe Newton’s type III denture-induced stomatitis.

Answer 14

Granular inflammation

Question 15

What environmental factors promote denture-induced stomatitis?

Answer 15

Sub-optimal hygiene and a protected environment

Question 16

Which is the most common form of oral candidiasis?

Answer 16

Pseudomembranous (Thrush)

Question 17

Name three Candida species other than C. albicans that can cause oral infection.

Answer 17

Any three of: C. glabrata, C. tropicalis, C. krusei, C. parapsilosis, C. dubliniensis

oppurtunastic

Question 18

Define biofilm according to the lecture.

Answer 18

“Matrix-enclosed microbial populations adherent to each other and/or to surfaces or interfaces”

Question 19

What are the four stages of biofilm formation?

Answer 19

Adhesio
Initiation (proliferation)
Maturation
Dispersal

Question 20

List three protective benefits that biofilms provide to microorganisms.

Answer 20

Immune evasion, antimicrobial resistance, resistance to detergents and antiseptics

Question 21

Besides protection, what other two benefits do biofilms provide?

Answer 21

Nutrient sharing/metabolic cooperation and better usage of resources (reduced energy usage)

Question 22

What term describes C. albicans’ ability to exist in multiple forms?

Answer 22

Morphogenic yeast

Question 23

What two primary morphological states can C. albicans exhibit?

Answer 23

Yeast and hyphal cells

Question 24

List four virulence factors of C. albicans.

Answer 24

Any four of: biofilm formation, adhesion, morphogenesis, secreted proteinases, adaptability/heterogeneity, extracellular matrix (ECM)

Question 25

Name five triggers that can cause morphogenic switching in C. albicans.

Answer 25

Any five of: temperature, serum, pH, nutrient starvation, osmolarity, other stress

Question 26

What is the term for C. albicans' ability to switch between unicellular yeast and filamentous forms?

Answer 26

Polymorphic

Question 27

How does the morphogenic transition affect cell size?

Answer 27

It drastically increases cell size

Question 28

How might hyphal formation exert pressure on tissue?

Answer 28

Tight adhesion allows exerted pressure on tissue (mechanical force)

Question 29

What gene family is key in Candida adhesion?

Answer 29

ALS (Agglutinin-Like Sequence)

Question 30

Describe the key virulence factors of C. albicans.

Answer 30

Biofilm formation, adhesion (ALS gene family), morphogenesis, secreted proteinases (SAPs for tissue invasion/damage), HWP1 (covalent binding to buccal cells), adaptation/heterogeneity, extracellular matrix

Question 31

How does the mycobiome relate to oral health versus disease?

Answer 31

Malassezia mycotype predominates in health; Candida mycotype is selected for in disease; Candida interacts with various bacterial species (not limited to oral cavity)

Question 32

Compare the three main classes of antifungals by their mechanisms and examples.

Answer 32

Azoles (fluconazole, voriconazole): inhibit ergosterol synthesis; Polyenes (nystatin, amphotericin B): bind ergosterol creating membrane pores Echinocandins (caspofungin, micafungin): inhibit β-glucan synthesis

Question 33

Explain three mechanisms of antifungal resistance in Candida.

Answer 33

Overexpression of target components (ergosterol) Mutations in drug targets (e.g., Erg11 in C. glabrata causing azole resistance) Changes in drug transporter expression (CDR/MDR)

Question 34

Why are biofilms naturally resistant to antimicrobials and which antifungals remain effective?

Answer 34

Resistance due to: reduced permeability, matrix protection, persister cells, resource sharing Effective agents: polyenes, echinocandins, chlorhexidine (not azoles)

Question 35

Describe culture-based methods for identifying Candida species.

Answer 35

Media: Sabouraud agar or CHROMagar; Conditions: 30-37°C aerobic (cells remain yeast at 30°C); Identification: microscopic examination (germ tube formation)

Question 36

Compare molecular methods for identifying known vs. unknown Candida species.

Answer 36

Known species: qPCR with specific primers, MALDI-TOF, multi-locus sequence typing; Unknown species: 18S/ITS sequencing or whole genome sequencing