WEX 3B – Microbiology – Flashcards
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| Why is it necessary for RBs to reorganize into EBs before they are released from the host cell? |
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| EBs are the extracellular form; RBs will not survive outside the host cell |
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| How do we culture for Chlamydia trachomatis? |
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| Centrifugation enhances endocytosis into monolayer of cells, usually mouse fibroblasts (McCoy cells) then incubate 48-72 hrs at 35*C |
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| What is the life cycle of the genus Chlamydia? |
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| 1) Within 8 hrs of endocytosis, EB converts to RB 2) RB reproduces by binary fission 3) 18-24 hrs, RB reorganize to EB 4) Cycle complete 24-40 hrs after endocytosis |
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| What species of Chlamydia is zoonosis that causes cold or flu like upper respiratory illness? |
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| Chlamydia psittaci |
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| What species of Chlamydia causes diseases of the eye and most frequent STD? |
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| Chlamydia trachomatis |
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| What species of Chlamydia is an etiologic agent of walking pneumonia and brochitis? |
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| Chlamydia pneumoniae |
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| What are 3 specimen sources for laboratory testing for Chlamydia? |
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| 1. Ocular and genital tract 2. Bubo pus (LGV) 3. Sputum and throat washings |
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| What are 4 detection methods for Chlamydia? |
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| 1. Fluorescent Antibody Technique (FA) 2. Enzyme Immunoassay (EIA) 3. Nucleic Acid Amplification 4. Nucleic Acid Probes |
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| What is the purpose of darkfield microscopy? |
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| To permit observation of live, moving spirochetes that are unstained |
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| What are some of the general characteristics of the Genus Borrelia? |
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| 1. Loosely coiled spirochete 2. Gram-negative type cell wall 3. Wright's or Giemsa stain 4. Not easily or reliably cultured |
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| What does Borrelia recurrentis cause and how is it transmitted? |
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| Causes epidemic louse-borne relapsing fever in humans, transmitted by lice from a smashed or scratched contaminate into the bite site |
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| What does Borrelia spp. causes and how is it transmitted? |
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| Causes endemic tick-borne relapsing fever in humans transmitted by various species of soft-shelled ticks of the Genus Ornithodoros |
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| Describe the lesion that is seen in the initial phase of Lyme disease. |
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| Skin lesion is called erythema chronicum migrans, a flat reddened area near the bite site that slowly expands with central clearing |
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| What are some of the general characteristics of the genus Leptospira? |
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| 1. Tightly coiled, thin, flexible spirochete 2. Resembles a "Shepherd's hook" 3. Gram-negative type of cell wall 4. Cultivated in protein-rich, semi-solid media (below surface of medium) 5. Primarily associated with occupational exposure |
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| Briefly describe the epidemiology for leptospirosis. |
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| Organism carried by rodents in their urine, spread by direct exposure to infected animal urine or contaminated soil or water |
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| Briefly describe the mode of infection for leptospirosis. |
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| Ingestion of contaminated water or food or through mucous membranes of the eye, mouth, genitals, or through abraded skin |
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| How can Leptospira biflexa be differentiated from other Leptospira spp? |
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| Leptospira biflexa's ability to grow at 13*C |
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| What are some of the general characteristics of the Genus Treponema? |
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| 1. Moderately tightly coiled 2. Gram-negative type cell 3. Not culturable on laboratory media |
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| Give a brief description of the medical importance and epidemiology of Treponema pertenue. |
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| Medical importance - infectious tropical skin disease Epidemiology - non-venereal disease transmitted by direct contact |
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| Give a brief description of the medical importance and epidemiology of Treponema carateum. |
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| Medical importance - contagious skin disease prevalent in tropical America Epidemiology - non-venereal infection transmitted by direct contact |
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| What are the modes of infection for syphilis? |
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| Acquired - contact with chancre or lesion Congenital - infant is born with the disease (can cross the placenta) |
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| What are the clinical features for the primary stage of syphilus? |
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| 1. Chancre (usually heals spontaneously) 2. Enlarged lymph glands |
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| What is the method of diagnosis of syphilis during the primary stage? |
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| 1. Darkfield microscopic examination 2. Serological test (about 80% of untreated cases) |
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| What are the clinical features for the secondary stage of syphilis? |
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| 1. Secondary mucocutaneous rash 2. Fever 3. Malaise (feeling ill) 4. Alopecia (hair falls out) |
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| What are the methods of diagnosis during the secondary stage of syphilis? |
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| 1. Clinical features 2. Examination of rash scrapings 3. Serological tests |
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| What are the clinical features for the latent stage of syphilis? |
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| NONE |
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| What are the methods of diagnosis during the latent stage of syphilis? |
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| NONE |
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| What is the clinical significance of syphilis testing? |
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| 1. Control of venereal disease 2. Prevention or detection of congenital syphilis 3. Routine screening 4. Treatment will reduce non-treponemal test titers |
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| What are the contents of the "antigen ampoule" of the RPR test and what purpose do they serve? |
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| 1. Cardiolipin-lecithin-cholesterol (CLC) complex (antigen) 2. Charcoal carbon particles (indicator) 3. Choline chloride (deactivation of complement that may interfere with test) |
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| What kind of needle is used to dispense the antigen in the RPR test and how many drops should it be calibrated to deliver? |
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| Blunt 20-gauge needle calibrated to deliver 60 drops of antigen per mL |
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| The rotator should be calibrated to how many rpms for the RPR test? |
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| 100 rpms |
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| How are both the specimen and antigen dispensed onto the 18 mm circle when performing the RPR test? |
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| One "free falling" drop |
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| How long should the test card of an RPR test rotate? |
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| 8 mins (at 100 rpm) |
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| True/False? The RPR test is a "non-specific" or "non-treponemal" test used to detect the presence of reagin in a patient's serum or plasma. |
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| True |
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| True/False? Results for the RPR test are reported as either positive or negative. |
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| False. RPR test results are reported as either Reactive or Non-reactive |
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| True/False? The Fluorescent Treponemal Antibody Absorption Test (FTA-ABS) is a "specific" or "treponemal" test used to confirm a reactive RPR test. |
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| True |
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| What is the definition of "antigen"? |
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| A "foreign" substance that induces an immune response and reacts with antibodies or T-cell receptors. |
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| What is Indirect FA used for? |
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| To detect the presence of a specific antibody to serum following exposure to a microorganism. |
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| ELISA concept is similar to FA, but uses an ____________ instead of a fluorochrome. |
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| enzyme utilizing substrate |
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| Give one example of a membrane-bound EIA. |
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| Home pregnancy tests |
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| True/False? Thermus aquaticus is heat labile. |
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| False. Thermus aquaticus' Taq polymerase's optimal temperature is 72*C but can be stable at 94*C |
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| C-reactive protein is aptly named because it reacts with the C-polysaccharide of what bacteria? |
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| Streptococcus pneumoniae |
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| In antigen-antibody testing, a __________________ test results when a cloudy line of reacted material appears in the area of the agar where an optimal ratio of antigen to antibody exists. |
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| Precipitin ring |
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| The counter-immune electrophoresis, precipitin ring, and Ouchterlony diffusion tests are examples of antigen-antibody technology that use _____________________ reactions. |
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| Precipitation |
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| This test detects antibodies against relatively large cellular antigens. |
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| Direct agglutination |
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| This test detects antibodies against soluble antigens adsorbed onto large particles such as RBCs or latex beads. |
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| Indirect agglutination |
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| These reactions are Antigen-Antibody reactions in which harmful effects of baterial toxins or a virus are blocked by specific antibodies found in the patient's serum. |
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| Neutralization reactions |
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| These are fluorescent dyes that are attached to specific antibodies for detection. |
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| Fluorescent antibody. |
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| Name 2 fluorochromes used to label antibody for fluorescent microscopy. |
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| 1. Auramine 2. Rhodamine |
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| Name 2 fluorochromes that are not antibody related and explain how they produce the fluorescence needed for fluorescent microscopy. |
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| 1. Acridine orange - binds directly to nucleic acid 2. Calcofluor white - binds to the polysaccaride in the fungal cell wall |
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| In _________________ FA testing the antibody is supplied by the patient serum |
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| Indirect |
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| In _________________ FA testing the antibody to the antigen is tagged with a fluorochrome. |
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| Direct |
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| In _________________ FA testing the fluorochrome is labeled to a specific antiserum. |
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| Indirect |
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| What is the principle of the ELISA test? |
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| An automated spectrophotometer reads the color change in the reaction which results from the enzyme utilizing substrate |
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| How is color developed in the ELISA test? |
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| By the reaction which results from the enzyme utilizing substrate |
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| In direct ELISA testing, the microtiter plate suppplied by the test kit has the ___________ adsorbed to the wells. |
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| antibodies |
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| In direct ELISA testing, the conjugate contains what two essential parts? |
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| 1. Enzyme 2. Antibody |
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| In indirect ELISA testing, the microtiter plate supplied by the test kit has the ___________________ adsorbed to the wells. |
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| antigen |
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| The first step in DNA replication is to temporarily ___________ the double strand forming two moving fork replication sites. |
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| unzips |
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| ___________________ molecules move along each fork formed in the second step of DNA replication adding complimentary bases. |
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| Polymerase |
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| Define Denaturation. |
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| The process of disrupting the double helix to yield two molecules of single stranded DNA. |
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| Define Annealing. |
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| Lowering the temperature slowly allows the strands (of DNA) to reassociate into the double helix with the proper base pairing |
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| Define Hybridization. |
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| Annealing two strands derived from different types of sources. |
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| The principle behind ______________ is to use known fragments of DNA to detect complimentary sequences of DNA in an unknown specimen. |
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| Nucleic Acid Probes |
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| What is the temperature used to denature? |
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| 94*C |
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| What is the temperature used to anneal? |
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| 50*C |
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| What is the temperature used to extend? |
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| 72*C |
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| What is the template/target for the probes or primers related to polymerase chain reaction technology? |
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| Specimen DNA |
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| What reapeatedly heats and cools the sample in polymerase chain reaction technology? |
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| Thermocycler |
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| What extends specific primers into a complementary strand of DNA in polymerase chain reaction technology? |
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| Thermus aquaticus polymerase |
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| True/False? C-reactive protein is a non-specific antigen-like substance supplied by test kits that use latex agglutination testing to detect the presence of IgG immunoglobulins produced by the patient during an inflammatory response. |
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| False. It detects C-Reactive Protein, an amino acid composition similar to that of IgG |
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| What are 3 general shapes of animal viruses? |
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| 1. Helical - rod-like 2. Icosahedral - ball-like 3. Complex |
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| Why are viruses considered to be "obligate intracellular parasites"? |
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| Viruses replicate only in living cells and cannot replicate outside of a host cell. The host cell must provide the energy, synthetic machinery, precursors, enzymes, and ribosomes for the synthesis of viral protiens and nucleic acids |
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| What is the correct sequence of steps in the virus lytic replication cycle? |
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| 1. Attachment 2. Penetration and Uncoating 3. Eclipse or Synthesis Phase 4. Assembly/maturation 5. Release |
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| What is the correct sequence of steps in the virus lysogenic cycle? |
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| 1. Viral DNA is incorporated into the host DNA immediately upon entering the cell 2. Genes coded by the prophage are transcribed and replicated as if they were normal host DNA 3. Upon certain stimuli, the prophage/provirus is removed from the host DNA |
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| What are the characteristics of the acute phase of a virus infection? |
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| 1. Virus is detectable 2. IgM may be detectable 3. IgG is usually not detectable |
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| What are the visual effects or abnormalities seen in cells that are infected by a virus (Cytopathic effects)? |
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| 1. Inclusion body 2. Giant cells |
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| How many days after onset of symptoms should serum samples for acute and convalescent phases be collected? |
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| Acute - 7 days after onset of symptoms Convalescent - 14-30 days after onset of symptoms |
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| How long may a serum specimen for virology testing be stored at 4*C - 6*C? |
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| Up to several weeks |
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| True/False? Virus specimens for virus isolation and growth are usually processed and inoculated onto cell cultures |
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| True |
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| Which hepatitis viruses are transmitted fecal-oral? |
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| Hepatitis A virus |
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| Which herpes family member causes recurring oral or genital lesions? |
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| Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) |
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| Which herpes family member causes chicken pox and herpes zoster? |
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| Varicella zoster virus (VZV) |
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| Which respiratory virus causes a disease in infants and young children and requires isolation of the patient? |
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| Paramyxoviridae family, genus pneumovirus |
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| What virus family are Influenza viruses type A, B and C members of? |
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| Orthomyxoviridae |
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| Which respiratory virus has caused outbreaks of Adult Respiratory Disease in military recruits? |
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| Adenoviridae family, genus Mastadenovirus |
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| What type of immune cells does HIV infect? |
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| CD4 (T-Cell) lymphocyte |
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| Although the Picornaviruses are best known for mild diseases such as the common cold, what is the most serious disease a member may cause? |
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| Poliomyelitis |
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| Which family includes the virus which causes rabies? |
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| Rhabdoviridae |
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| Are live virus vaccines "attenuated" or "inactivated" viruses? |
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| Attenuated |
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| What aspect of viral growth do most of the currently prescribed antiviral drugs affect? |
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| Inhibits viral activities within the host cells, but with minimal harmful side effects to the host. |
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| What direct preparation is used a CSF specimen? |
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| India Ink |
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| What are the three macroscopic morphologies used mold culture? |
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| Texture, Color and Reverse |
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| What is the causative agent of Black piedra? |
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| Piedraia hortae |
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| Which thermally dimorphic fungal pathogens causes "rose handlers' disease"? |
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| Sporothrix schenckii |
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| Name the three genera causin chromoblastomycosis. |
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| Phialophora, Cladosporium, Fonsecaea |
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| Blastomyces dermatitidis is the etiological agent of what disease process? |
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| North American Blastomycosis |
