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Micro, Ass 12
HIV, Fungal Infx, and Opportunistic Infx
59
Microbiology
Graduate
01/22/2012

Additional Microbiology Flashcards

 


 

Cards

Term
p24
Definition

Core or Capsid protein in HIV, encoded by the gag gene;

 

p24 levels are used to determine viral load by ELISA which detects antibodies to the p24 protein capsid and HIV.

Term
gp120
Definition

HIV surface protein that mediates receptor binding;

Encoded by the env gene

Term
gp41
Definition

HIV surface protein that mediates membrane fusion activity;

Encoded by the env gene;

 

Drug target* of Enfuvirtide, a fusion inhibitor which binds to gp41 and pervents fusion of the viral and host membranes preventing viral entry into host cells.

Term
What gene encodes HIV reverese transcriptase, protease and integrase?
Definition
the pol gene
Term
T/F HIV is a - sense, enveloped, ssRNA genome
Definition

FALSE

 

+ Sense*

 

Is ssRNA and is enveloped

Term
Tat
Definition

HIV accessory protein;

 

Enhances the rate of proviral genes integrated into the host genome.

Term
Rev
Definition

HIV accessory protein;

Facilitates transport of unspliced viral mRNAs out of the nucelus for translation in the cytoplasm

Term
CXCR4
Definition
Chemokine receptor found on T cells (one of the possible second bindings, in addition to binding CD4+ receptors) which allows entry of viral entry into host.
Term
CCR5
Definition

Chemokine receptor on Macrophages;

Along with CXCR4, a possible secondary binding in addition to CD4+ to allow viral entry into host cells;

 

Drug Target* of Maraviroc which binds and inhbits viral fusion with host cell membranes;

 

Mutations in CCR5 are associated with resistance to HIV infection.

Term
T/F: Binding of CXCR4 chemokine receptor by HIV is necessary but not sufficient to allow viral entry into host cells.
Definition

True (though CCR5 can also work);

It is required that HIV bind CD4+ and one of the chemokine receptors (either CXCR4 or CCR5) in order for membrane fusion and viral entry into the host cell to take place.

Term
T/F: During the Asymptomatic/Latent phase of HIV CD4+ T cell levels rebound to normal and are maintained because the virus has slowed replication.
Definition

FALSE;

 

During the latent phase CD4+ T cells do rebound somewhat but then begin a steady decline. Also, during this period the virus is still replicating at a high level.

Term
What fluids are considered "high risk" for HIV transmission?
Definition

Blood, semen, cervical secretions, and breast milk;

 

 

CSF, urine, saliva and tears are low risk.

Term
What HLA type is associated with a status of being an Elite controller?
Definition
Elite controllers are long-term non-progressors who are more likely to be HLA-B57.
Term
T/F: HIV integration does not require host cell division.
Definition
TRUE
Term
What mutations are associated with being a long-term survivor?
Definition
Nef deletion (accessory protein);
Term
What are the 4 chief drug targets in in HIV treatment?
Definition

Fusion,

Reverse Transcription (NRTI and NNRTIs),

Integration,

Proteases (maturity)

Term
Atripla
Definition

The first combination, once a day AIDs treatment;

 

3 drug combo of efavirenz, emtricitabine and tenofovir.

Term
T/F: When resistance arises to a drug in an AIDS pt's HAART regimen, it is best to change every drug they are on and not just the one they became resistant to.
Definition
TRUE, better to change all drugs and not just one.
Term
What agents cause superficial fungal infections and what are the symptoms and treatments for such infections ?
Definition

Causitive agents: Malassezia Furfur (tinea versicolor), Exophiala werneckii (tinea nigra), blac and white piedra;

 

Sx: do not cause inflammation!
Piedra infx cause development of nodules of asci on hair shafts.

Piedra and tinea cause hyper and hypopigmented spots on the skin.

Infants and the IC can develop fungemia;

 

Tx: Selenium sulfide (topical dandruff shampoo), shaving effected area, topical azoles.

Term
What fungal agents have a "Spaghetti and Meatballs" appearence on KOH mount?
Definition

Superficial fungal infections

 

Tinea versicolor, tinea nigra, black and white piedra.

Term
What fungi can be visualized under Woods Lamp and what is their appearance?
Definition

Superficial fungal infections

 

Tinea versicolor, tinea nigra, black and white piedra.

 

Show a Coppery Orange Fluorescence

Term
What is the agent of Tiena infections of the skin and hair?
Definition
Microsporum
Term
What is the chief symptom of a microsporum infection?
Definition
Puritis (cutaneous fungal infection)
Term
What do Trichophytan and Epidermophyton cause?
Definition
Cutaneous fungal infections effecting the skin, hair, and nails.
Term
What is the treatment for cutaneous fungal infections?
Definition

Topical azole antifungals (topical imidazoles);

 

Tx tinea capitis (scalp) with Griseofulvin (which inhbitis the mitotic spindle);

 

Treatment of these is required for weeks to months as relapses are common.

Term
T/F: Fungal infections passed from person to person show more inflammation than those passed form animal to person.
Definition

FALSE;

Animal to person = more inflammation;

Person to person = less inflammation.

Term
What fungus exibits "rosette-shaped conidia"?
Definition

Sporothrix schenckii - Agent of subcutaneous fungal infection known as Sporotrichosis or "rose gardeners disease" (aslo seen in handlers of sphagnum moss and in ulcerous lesions of cats);

Pulmonary form seen in alcoholics;

 

Cigar-shaped yeast in sputum or lesions.

Term
How would you treat Sporotrichosis?
Definition

Subcutaneous fungal infection caused by sporothrix schenckii (dimorphic fungus);

 

Tx with Itraconazole or Amphotericin B + Potassium Iodide

Term
What does it mean to say that a fungus is "dimorphic"?
Definition

They assume 2 different morphologies based on their location;

 

"Mold in the Cold, Yeast in the Beast"

 

Cutaneous fungal infections are monomorphic as they only assume the mold form.

Term
What are the symptoms, agents, and treatment of systemic fungal infections?
Definition

Sx: Acute pulmonary infections ("Fungus Flu") that do not respond to antibiotics and can progress to chronic pulmonary issues or dissiminate;

 

Etiologic agents: Histoplasma, Coccidioides, Blastomyces, and Cryptococcus;

 

Treatment: is typically with Amphotericin B which punches a hole in the cell membrane,

Ketoconazole is also often used and Flucytosine is used in cryptococcal infections.

Term
What fungal infection(s) can be confused with TB?
Definition
Histoplasmosis (calcified lesions in the lung) and Aspergillus (fungus ball in the lung).
Term
What two key things are helpful in the diagnosis of histoplasmosis?
Definition
In sputum cytology and blood culture (remember it is in macrophages) seeing macrophages with yeast inside + Tuberculate Macroconidia
Term
What diseases is called "spelunkers" or "chicken farmers" disease?
Definition

Histoplasmosis;

 

Found in soil/dirt/dust enriched with bat and bird droppings;

 

Is an intracellular yeast that resides within macrophages.

Term
What fungus has an environmental (arthrocondia) form that is inhaled and forms a spherule inside the body?
Definition
Coccidioides, the etiolgical agent of "Desert Valley Fever"
Term
What fungus causes "Desert Valley Fever"?
Definition
Coccidioides
Term
How do you make a diagnosis of Coccidioides?
Definition
See spherules with endospores
Term
What fungus can disseminate in the third trimester of pregnancy or in IC pt?
Definition
Coccidioides
Term
Where are infections of Coccidioides commonly seen?
Definition
The Southwestern United States
Term
For which fungus is visualization of "Broad based budding blastomyces" diagnostic?
Definition
Blastomyces dermatidis
Term
What is the agent of Dermatitidis?
Definition
Blastomyces dermatidis, infection disseminates to the skin and to mucocutatneous areas.
Term
What fungi are endemic to the Ohio and Mississippi River Valley areas?
Definition
Histoplasmosis and Blastomyces dermatidis
Term
What fungus is transmitted through pigeon droppings?
Definition
Cryptococcus neoformans
Term
What is the microscopic appearence of Cryptococcus neoformans?
Definition

It is a monomorphic, heavily encapsulated yeast that can be cultured from the CSF and visualized using India Ink;

 

Note that india ink is insensitive and latex agglutination should be used to confirm as well as culture as Cryptococcus is a Urease Positive Yeast.

Term
What fungus has the appearence of having a "halo" around it when cultured?
Definition
Cryptococcus neoformans
Term
What is a common agent of meningitis in AIDS patients?
Definition
Cryptococcus neoformans
Term

What are the opportunistic fungi that are a concern for IC pts?

Which is the leading cause of death in AIDS pts?

Definition

Aspergillus, Candida, Zygomycoses, and Pneumocystis jioveci;

 

Pneumocystis jioveci is a leading cause of death in AIDS patients.

Term
What fungus can be described as an acute-angled fungus with septate hyphae?
Definition

Aspergillus Fumigatus;

Is also monomorphic (always in its fungal form);

 

A is for Asperigullus, Acute angles, and Amphotericin (used to tx aspergillus)

Term
What are risk factors for Aspergillus infection?
Definition
IC status, prior use of steroids or transplants.
Term
Infection with which fungus can lead to the development of a "fungus ball" visualized on CXR?
Definition
Aspergillus
Term
What can invasive aspergillosis in a severely IC pt cause?
Definition

Nasal Congestion,

Meningitis,

MI and many other manifestations

Term
How can Candida be cultured?
Definition

On Sabouraud's agar - contains peptones and dextrose at pH 5.6;

 

Candida forms germ tubes if incubated @ 37 degrees in serum.

Term
Who is at risk for Cutaneous candida infections?
Definition

The IC, diabetics, obese pt, pregnant pt, IV drug users;

 

Infection occurs where skin touches skin and can lead to gastritis, sepsis and endocarditis (esp in the IC and IV Drug users)

Term
Who is at risk for Chronic Mucocutaneous Candidiasis (CMC)?
Definition

Immunocomprimised patients and

Pt with DiGeorge's Syndrome

Term
How is Candidiasis treated?
Definition

Nystatin (topical or oral polyene antifungal);

 

Nystatin + Amphotericin B for dissiminated infx;

 

Flucytosine (which inhibits DNA synth) and capsofugin could be used.

Term

What are the Zygomycoses?

What do they look like and what do they cause?

Definition

Zygomycoses are opportunistic fungi = Mucor, Rhizopus, Absidia;

 

Non-septate hyphae typically at 90 degree angles

 

Cause severe infections that lead to tissue necrosis and attacking of the brain (rhinocerebral form of mucor can be fatal, man without a face story).

Term
What type of fungal infection are ketoacidotic patients prone to? What other group of pt are at risk for this infx?
Definition

Zygomycoses

 

Pt with leukemia are also succeptible to this infection.

 

Tx: Amphotericin and removal of all necrotic tissue.

Term
What fungus has a "dented helmet/condom/soccer ball" appearence?
Definition
Pneumocystis jiroveci
Term
PCP Pneumonia
Definition

Caused by Pneumocystis jiroveci infection (PneumoCystis Pneumonia, PCP);

Fever, shortness of breath, non-productive cough;

 

H&E stain of lung tissue shows honeycomb appearence, patchy infultrates on CXR;

 

Dx: silver-stained cysts on BAL;

 

Tx: Trimethoprim (inhibits DHFR)

Term
How do you treat a pneumocystis infx?
Definition
Trimethoprim* (inhibits DHFR)
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