Mycology Exam Ii Candida Pathogenesis

Front 1

Describe the natural Candida environment

Back 1

Humans are primary reservior, inanimate objects, other mammals/ reptiles
not a significant soil source but can be found on fruits/ fruit trees

Front 2

Describe the C. albicans genome

Back 2

diploid, 8 chromosomes
hapoloid genome 16 Mb
usually lack introns

Front 3

What are some advantages to Candida's molecular biology

Back 3

genome sequence is complete
transformation is easy
reporter systems are available
Tet controlled promoter

Front 4

What are some disadvantages to Candida's molecular biology?

Back 4

Diploid genome, lack complete sexual cycle, codon misusage, no RNAi

Front 5

List some important components of Candida virulence

Back 5

adherance, morphogenesis, secreted enzymes, pheontypic switching, mating, drug resistance, biofilm formation

Front 6

What species of Candida is the most virulent

Back 6

C. albicans

Front 7

Describe the role of Candida adherance in its pathogenesis

Back 7

-promote host recognition and colonization
-adhere to a variety of host cells and inert materials

Front 8

What molecules does candida use to recognise host ligans or abiotic surfaces

Back 8

cell surface glycoprotein, glycan or other proteins

Front 9

Name some host molecules than can serve as ligands for Candida

Back 9

ECM proteins, laminin, fibronectin, collagen (epithelial and enodthelial cells)

Front 10

Which phases of Candida are pathogenic

Back 10

Both yeast and hyphal phase are pathogenic
The hyphal phase is formed only by albicans and dubliniensis, it is an apical extension with septae from behind the growing tip

Front 11

List some laboratory and in vivo triggers for Candida yeast => hyphae switch

Back 11

Lab- temp >30C, alakine pH, CO2/O2 ratio,specific nutrients, serum, nutrient poor media
in vivo- tissue, mucosa, devices

Front 12

What are the two classes of transcriptional regulation of Candida morphogenesis

Back 12

-inhibit transcription
-required for transcription

Front 13

What three signal transduction pathways are required for candida morphogenesis

Back 13

CPH1- MAP kinase pathway
-EFG1- RAS cAMP pathway
-HOG1- osmoregulation =PKC

Front 14

Describe candida phenotypic switching

Back 14

Normal colonies are smooth and white but they can swtich to opaque, star ring, wrinkle, etc
This is due to different proportions of budding, pseudohyphal, and mycelial growth, it is spontaneous and reversible, it is affected by histone deacetylases

Front 15

What is the signifcance of Candida phenotypic switching

Back 15

-Different viruence properties, drug susceptibilities, expression of surface antigens, tissue affinities, enzyme production, mating

Front 16

List three enzymes that are secreted by Candida

Back 16

SAPs
Phospholipases B
Lipases

Front 17

Describe the role of Candida SAPs

Back 17

Secreted Aspartyl Proteinase
broad substrate specificity, the type of SAP secreted can determine where Candida infects and what it does

Front 18

What is the most important treatment factor for treating device assocaited candida infections

Back 18

removal of the device, drug tx of candida biofilm is ineffective due to drug resistance

Front 19

what is the impact of growth rate on drug susceptibility in C. albicans biofilms

Back 19

the drugs had no impact on biofilm viability regardless of growth rate
conclusion- the drugs aren't stopping biofilm growth

Front 20

Describe the ability of antifungals to diffuse through C. albicans biofilm

Back 20

the drugs can diffuse
conclusion- the biofilm is not preventing drug entry

Front 21

T/F C. albicans cell walls are different in planktonic and biofilm forms

Back 21

true, they have more B 1,3 glucan and are much thicker

Front 22

What is the role of matrix B 1,3 glucan in C. albicans biofilm resistance

Back 22

-biofilm cells have more than planktonic
-intact biofilm and biofilm matrix bound or associated with higher concentrations of drugs also shown with radio-labeling
-disrupting the glucan makes the biofilm more susceptible
-Conclusion B 1,3 glucan sequesters the drug

Front 23

Describe the role of FKS1 in biofilm resistance

Back 23

-FKS1 is used for B 1,3 glucan synthesis
-FKS1 knockouts make less/ no glucan so the drugs are not sequestered
-TDH3-FKS1 strains make more glucan and are more resistant
-doxycyline repression of FKS1 increases susceptibility

Front 24

Does modulation of Candida FKS1 or enzymatic modification of glucan effect planktonic susceptibility

Back 24

No. This indicates a biofilm specific mechanism