Microbiology 2 Flashcards
What are the two types of microscopic fungi?
Mould and yeast
In which 2 ways can microscopic fungi grow?
As single cells (yeasts) or as multi-branched hyphae forming a filamentous mycelium (moulds)
What are the 3 ways to classify fungal infections?
Superficial (candida-> thrush) subcutaneous and deep mycoses
What causes thrush and how is it treated?
Candida albicans. Treated with a topical azole cream (clotrimazole)
What fungi cause ringworm?
Dermatophytes
What are the medical names for ringworm of the scalp, skin, foot and groin?
Tinea capitis, tinea corporis, tinea pedis and tinea cruris
How is ringworm treated?
Topical clotrimazole or terbinafine
Give 3 antifungals with an indication each
Fluconazole - vaginal candidiasis
Clotrimazole - candidiasis
Nystatin - oropharyngeal candidiasis
How does clotrimazole and fluconazole work?
They cause decreased synthesis of ergosterol, stopping cell membrane synthesis
What adverse effects does fluconazole cause?
Prolongs QT interval. hepatotoxicity, GI upset, headache
3 warnings of fluconazole
Given in caution with liver disease
Don’t give with QT prolonging drugs
Not to be given in pregnancy
Give 3 ways HIV is transmitted. What is the commonest way worldwide and in the U.K?
Sex Needles Mother to child Worldwide: heterosexual sex UK: gay sex
Describe the structure of HIV
Outer envelope with gp120 and gp41.
Inner core with RNA, reverse transcriptase, integrase, proteases
Matrix with p17 and p24
Describe how HIV enters the cell
Gp120 binds to CD4, action of CCR5 and CXCR4 allow HIV to fuse membranes
How does HIV’s RNA get turned into new HIV viruses?
Reverse transcriptase -> RNA to DNA
Integrase -> DNA incorporated into cell
Describe the primary HIV infection
Macrophages infected, presents HIV to CD4 cells in lymph nodes. Macrophages move into the blood and spread HIV around the body. Sharp spike in viral load.
What are 5 symptoms of HIV?
Lethargy Malaise Depression Rash Headache
Why does the viral load continue to increase during clinical latency?
Because the immune system cannot produce antibodies fast enough to keep up with the rate of the antigen formation by HIV
Give 2 areas in which HIV develops reservoirs
Memory cells and immune privileged areas
What is associated with early HIV infection?
Rise in viral load and fall of CD4 to <350mm^3
What are key symptoms to be aware of?
Recurrent infections (shingles), candidiases, oral hairy leukoplakia and upper respiratory tract infections
Give 5 AIDS defining conditions
Kaposi's sarcoma Deep candidiases TB Invasive cervical carcinoma Cytomegalovirus
What are the 2 ways to diagnose HIV and when would you do each?
Antibody assay test and antigen test. Antigen assay test has a window period of 6-12 weeks after infection so if -ve but clinical suspicion, do antigen test
How are patients monitored?
3 monthly CD4+ and viral load counts
