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52 Cards in this Set
- Front
- Back
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What has a halo on india ink?
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Cryptococcus neoformans. The organism has amucopolysaccharide capsule that provides a "halo" around it that pushes away the india ink.
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When is Cryptococcus neoformans the answer?
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Answer india ink as the best initial test for cryptococcus, wehn you see a patient with AIDS with <100 CD4 cells who presents with fever, headache, and possibly a stiff neck. CSF will show a mild elevation of lymphocytes. the presentation is "subacute," which means it is slower in onset and milder than bacterial meningitis.
Caution: Normal CSF protein and white cell counts do not eclude cryptococcal meningitis. |
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What is the most accurate diagnostic test for cyrptococcus neoformans?
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The most accurate test for cryptococcal meningitis is either a cryptococcal antigen or fungal culture of the CSF.
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What are clue cells associated with?
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The smear is a wet mount and it shows clue cells. Clue cells are abnormal epithelial cells with ground-glass appearance and a hazy border. The tiny dark dots are bacteria stuck to the surface of the epithelial cells.
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When do you answer wet mount?
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Answer wet mount and clue cells when you see a woman with a thin, grayish/white vaginal discharge or vaginal itching. She may also describe dyspareunia. She may also describe a strong fishy odor (positive "whiff" test) adding KOH to slide. The pH in BV is usually >4.5.
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What is the most common organism causing bacterial vaginosis?
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Gardnerella vaginalis
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Why is it important to treat this disease in pregnant women?
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Pregnant women with BV are at increased risk for miscarriage, early (preterm) delivery, and infection after the pregnancy.
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Case: A 19-year-old sexually active female presents complaining of a yellowish-green discharge adn dyspareunia. The wet mount of her discharge shows cells with flagella.
What is her diagnosis? |
Trichomonas vaginitis
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Case: A 19-year-old sexually active female presents complaining of a yellowish-green discharge adn dyspareunia. The wet mount of her discharge shows cells with flagella.
What is the treatment? |
Trichomonas vaginitis is treated with oral metronidazole with concurrent treatment of the sexual partner. Single-dose therapy is preferred because of increased patient adherence.
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Case: A 19-year-old sexually active female presents complaining of a yellowish-green discharge adn dyspareunia. The wet mount of her discharge shows cells with flagella.
What is the treatment? |
the pelvic examination will show a "strawberry cervix," which is caused by multiple punctate hemorrhages visible on the cervix.
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Case: A 19-year-old sexually active female presents complaining of a yellowish-green discharge adn dyspareunia. The wet mount of her discharge shows cells with flagella.
What is different about the organism on wet mount from every other cause of STD? |
Trichomonas vaginalis is the only organism to be mobile on the wet mount as the flagella has it swim across the slide.
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When do you answer bone biopsy?
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Look for a patient with diabetes and peripheral vascular disease with leg pain, warmth, and an ulcer who has an abnormality on X-ray or MRI consistent wiht osteomyelitis.
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For which disease(s) is bone biopsy the gold-standard diagnostic test?
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A needle aspirate sample examined under a microscope is the gold-standard diagnostic test for the following diseases:
Osteomyelitis Bone tumors Metastatic osseous disease |
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What tests can replace bone biopsy if osteomyelitis is suspected?
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Radiographic evidence of osteomyelitis and positive blood cultures can replace the bone biopsy if osteomyelitis is suspected.
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What is Bone Scan or Technetium Pyrophosphate Nuclear Bone Scan?
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Bone scan is a method of detecting occult disease that has deposited in bone.
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How does Bone Scan or Technetium Pyrophosphate Nuclear Bone Scan work?
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Technetium is picked up by osteoblasts and deposited in teh bone as they lay down new matrix. You must have osteoblastic activity in order for it to light up.
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What makes Bone Scan or Technetium Pyrophosphate Nuclear Bone Scan abnormal?
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Bone scans can be abnormal from both infections and malignancies. Osteomyelitis and cancer are detected by bone scans. Bone scans lack specificity and often cannot distinguish soft-tissue infection nearby from involvement fo the bone.
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What is the most accurate test for osteomyelitis and cancer?
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The precise etiology of the abnormality on a bone scan often requires a bone biopsy to confirm the diagnosis.
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What is a CD4 (T-cell) count?
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CD4 count is used to monitor HIV-positive patients. Serum measurement of CD4 (T-cell_ markers is representative of the number of helper T lymphocytes in the blood count. CD4 is used to determine the need for prophylactic antibiotics and to monitor the response to treatment. Start antiretrobiral therapy: CD4,350 or viral load >55,000.
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When is CD4 count the right answer?
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Answer CD4 count as the best test to determine the severity of immunosuppression in HIV/AIDS.
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What prophylactic medications should be started based on a CD4 cell count?
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Prophylaxis should be initiatd in the following scenarios:
CD4 counts less than 200 cells/ul: TMP/SMX for pneumocystis jiroveci CD4 counts less than 100 cells/ul: TMP/SMX for Toxoplasma and itaconazole for Histoplasmosis in endemic areas CD4 counts less than 50 cells/ul: azithromycin for Mycobacterium avium complex (MAC) |
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What is darkfield microscopy?
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The darkfield is the most accurate test of primary syphilis.
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How is darkfield microscopy done?
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A scraping of swab from the syphilitic chancre is rubbed on a slide.
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When do you answer darkfield microscopy?
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Answer darkfield microscoopy for primary syphilis when the question asks for the most accurate diagnostic test. In primary syphilis, there is a false negative rate of about 25% for the RPR or VDRL. The darkfield is more sensitive than an RPR.
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How does a callium scanning test work?
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Gallium is a nuclear scan that detects infection and some cancers. Gallium builds up in areas where white blood cells are present and there is increased iron metabolism. Gallium is transported on transferrin Gallium is a nonspecific test that can help localize teh site for subsequent CT or MRI scanning.
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when is gallium scan the answer?
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Answer gallium scan when you see a patient with persistent fever without localizing symptoms and the initial blood cultures, chest X-ray, and urinalysis are negative. Gallium detects the source of fevers of unknown origin, lymphoma, and abscesses.
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What is the most accurate test to confirm an abnormal gallium scanning result?
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Ultimately, a biopsy is the most accurate way to determine the etiology of an abnormal gallium scan. Cancers require histology and infections require that the culture be confirmed.
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What is Herpes Simplex PCR?
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Herpes simplex PCR is done on cerebrospinal fluid and is the single most accurate test for herpes encephalitis.
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When is Herpes Simplex PCR the answer?
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Look for a patient wit fever, headache, and confusion of less than 2 weeks' duration. The PCR of CSF is more accurate than an EEG, head CT, MRI, or even brain biopsy.
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How does Indium-Labled Leukocyte Scan work?
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Indium is a nuclear medicine test of occult infection or FUO. A sample of the patient's blood is drawn and incubated with indium. The indium-tags the white cells. The blood is re-injected into teh patient. The indium-tagged white cells then localize to the site of infection.
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When is an indium scan the right answer?
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Look for a case of occult infection not found on routine testing such as blood cultures, chest X-ray, or urinalysis. Indium is also useful when gallium is inaccurate, such as with intra-abdominal infections.
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What is the most accurate test for FUO or occult infection.
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Biopsy is more accurate.
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What is KOH (Potassium Hydroxide) Prep?
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KOH is the best initial test to diagnose superficial fungal infections. KOH is applied to a wet mount sample of vaginal discharge/secretions or to a skin scraping to identify fungi. This is seen under a microscope. Epithelial cells dissolve and the fungal structures remain behind and are visible.
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When do you answer KOH?
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KOH prep is indicated for the following:
Tinea (pedis, manus, corporis, cruris, capitis) Onychomycosis Tinea versicolor Candidiasis |
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In which infection is the test associated with an amine odor?
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Applying KOH to a wet mount and smelling/whiffing immediately after yield a fishy (amine) in bacterial vaginosis.
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What is the monospot test?
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The monospot test is the initial test used to diagnose infectious mononucleosis (IM). It detects heterophile antibodies that are characteristic of EBV.
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When do you answer monospot test?
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Monospot test is the best initial test when the question shows a patoent with sore throat, fever, lymphadenopathy, and malaise. A total of 50% of patients will have splenomegaly. Rash is present in 15% unless they have been given ampicillin, when it is present in closer to 90% of patients. Exudative pharyngitis may occur.
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What is the most accurate test for EBV?
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The most accurate test acutely is the IgM to EBV viral capsid antigen (VCA). Antibodies to EBV nuclear antigen (EBNA) rise in 3-4 weeks.
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What is Legionella Urine Antigen?
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Legionella urine antigen is the antigen found in Legionella pneumonia. It is the best initial test to make a specific diagnosis of Legionella.
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What is the best test for legionella?
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Legionella urine antigen has 100% specificity with L. pneumophilia type 1. Only 70-80% of disease is caused by L. pneumophilia type 1. Sputum culture or a culture of hte tracheal aspirate on specialized charcoal/yeast extract remains the definitive test.
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When do I answer legionella urine antigen?
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Answer Legionella antigen when you are shown a nursing home resident admitted for pneumonia that presents with fever, confusion, diarrhea, and hyponatremia. CPK, liver function tests, and creatinine can also be elevated.
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What is polymerase Chain Reaction HIV RNA Viral Load (PCR HIV RNA VL)?
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The PCR HIV viral load is a quantitative measurement of the amount of virus in circulation in the patient's blood.
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When (PCR HIV RNA VL) is in the question, what should you think of?
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This test is the first thing to change in response to treatment. PCR HIV viral load is also the first thing to become bnormal if the patient stops taking medication or the treatment fails. The viral load test tells how fast the CD4 cells will drop. The higher the viral load, the faster the person's disease will progress. Thelower the viral load, the slower the disease progresses.
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When do you answer (PCR HIV RNA VL)?
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Measurements should be made at the time of the HIV diagnosis and every 3-4 months therafter. The PCR viral load is also the basis of HIV sensitivity testing in order to determine the presence of resistance in failing regimen.
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for which disease(s) are VDRL/RPR used?
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Serum measurement for these nontreponemal examinations are used for thediagnosis or screening of syphilis.
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Whe signs/symptoms would you epect the patient to have in a case where you needed to use VDRL or RPR?
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In the primary stage, you would expect the patient to present with a chancre and painless regional lymphadenopathy. In the secondary stage, rash, lymphadenopathy, condylomata lata, and alopecia can be expected. Tertiary syphilis is characterized by cardiac or neurological disease.
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In what cases can you get false negative and false positive tests?
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False positives: CT diseases, infectious mononucleosis, malaria, leprosy, IV drug use, Hepatitis C, infective endocarditis, and pregnancy
False negatives: Prozone phenomenon (very high antibody titers are present) |
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Which test would you do if your clinical suspicion for the disease is high but the VDRL/RPR is negative?
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When your clinical suspicion si high yet the nontreponemal tests are negative, you would want to do the darkfield examination in primary syphilis and the FTA-ABS test for the other stages.
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What is the response to treatment?
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The RPR and BDRL decrease or disappear in response to treatment. The FTA can remain positive lifelong.
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What is the Tzanck Smear?
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Tzanck preparation is used to diagnose the skin manifestations of either Herpes simplex or Varicella Zoster. You are looking for multinucleated giant cells. Tzanck smear cannot distinguish betwen varicella (zoster) and herpes simplex.
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When is Tzanck smear the answer?
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Answer Tzanck smear as the best initial diagnostic test for skin or genital infections that might be herpetic in nature. Tzanck smear is NOT necessary if the diagnosis is clinically clear from the presence of vesicles.
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What is the most accurate diagnostic test for herpes?
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The most accurate test for a herpetic infection of the skin or genitals is a viral culture.
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