Candida albicans essay Flashcards
Introduction?
Rephrase question and provide my interpretation (not in 1st person)
Candida albicans is an opportunistic pathogen that is commonly found as a member of the human microflora. (Hogan DA, 2004)
Candidiasis is a common infection of the skin, oral cavity and esophagus, gastrointestinal tract, vagina and vascular system of humans. (Calderone RA, 2001)
Importance -
This microbial growth state has profound consequences for industry, the environment, and human health (Hall stoodley, 2004)
Candida bloodstream infection in adults are associated with longer stays in hospital, and larger costs the people in hospital without this infection, also an average person stays 1 month longer in hospital which $45,000 additional costs, excaerbating the problem of the infection. (Moran C, 2012)
Although most infections occur in patients who are immunocompromised or debilitated in some other way, the organism most often responsible for disease, Candida albicans, expresses several virulence factors that contribute to pathogenesis.
From host recognition biomolecules (adhesins) to morphogenesis (the reversible transition between unicellular yeast cells and filamentous, growth forms flexibility that results in the adaptation of the organism to the hostile conditions imposed not only by the host but also by the physician treating the infection. (Calderone RA, 2001)
Say how will answer this in the essay
Introduction to main paragraph 1 candida adhesins?
Hwp1 is a well-characterized Candida albicans cell surface protein, expressed only on hyphae, that mediates tight binding to oral epithelial cells
HWP1 expression is dependent upon Bcr1, a key regulator of biofilm formation (Calderone RA, 2001)
Main paragraph1 for candida adhesins (part 1)?
Allowing biofilm formation:
pre-conditioning of the adhesion surface either by macromolecules present in the bulk liquid or intentionally coated on the surface
; 2. Transport of planktonic cells from the bulk liquid to the surface;
3. Adsorption of cells at the surface;
4. Desorption of reversibly adsorbed cells;
5. Irreversible adsorption of bacterial cells at a surface;
6. Production of cell–cell signalling molecules;
7. Transport of substrates to and within the biofilm;
8. Substrate metabolism by the biofilm-bound cells and transport of products out of the biofilm. These processes are accompanied by cell growth, replication, and EPS production;
(breyers, 2004)
Main paragraph part 2 on adhesins?
Calderone RA, showed that in rats, Candida albicans mutated to not have Hwp1 severe biofilm defect, yielding only yeast microcolonies in the catheter lumen. equired for normal biofilm formation
Overexpression of HWP1 in a bcr1/bcr1 mutant background improves adherence in the in vivo catheter model.
Empathising that this is a possible therapeutic target, as well as the danger of mutations providing more HWP1 making the biofilms harder to get rid off
Conclusion on adhesins?
State overall findings, as well as who this affects (people, businesses)
Positive and negative of study
Introduction on morphogenesis?
The ability of C. albicans to alter its cellular morphology has been associated with its virulence; yeast cells are more prevalent in commensal interactions whereas filamentous cells appear important in opportunistic infections. (Hogan DA, 2004)
Main paragraph part 1 on morphogenesis?
Early studies on C. albicans morphological mutants suggested that hyphae are important for disease establishment. However, the lack of an exploitable sexual cycle in this fungus meant that it was not possible to associate the morphogenetic and virulence defects with a single genetic locus.
morphological mutants have been generated in C. albicans by knocking out specific target loci with a URA3-based cassette The analysis of these mutants has revealed a complex network of signal transduction pathways that control yeast→hypha morphogenesis in this fungus
The repressor CaTup1 regulates morphology, hence when inactivated causes c.albicans to grow in filamentous forms, which were less virulent suggesting they are less invasive
(Gow NA, 2002)
Put in conclusion (For example, hyperfilamentous microcolonies may not be disseminated efficiently in systemic models of infection when the cells are inoculated directly into the bloodstream.)
Main paragraph part 2 on morphogenesis?
However (Hogan DA, 2004) showed . albicans morphology is significantly affected by the presence of Pseudomonas aeruginosa, another opportunistic pathogen
3‐oxo‐C12 homoserine lactone, a cell–cell signalling molecule produced by P. aeruginosa, was sufficient to inhibit C. albicans filamentation without affecting fungal growth rates
microscopic analysis and real‐time reverse transcription polymerase chain reaction proved this
Hence the prevention of the filamentous form could be essential route in preventing infection in certain scenarios
In conclusion on morphogenesis?
Put in conclusion (For example, hyperfilamentous microcolonies may not be disseminated efficiently in systemic models of infection when the cells are inoculated directly into the bloodstream.) - for main paragraph part 1
State main findings, who this affects, positives and negatives of studies.
Overall conclusion?
state essay question and give answer
Say how ideas can be developed more in clinical trial
Describe weaknesses, but strengths as well
Practical application
Further study
Strong concluding sentence
