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Microbiologists use three categories of techniques to diagnose infections:
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Observation of microbe’s microscopic and macroscopic morphology, physiology, and biochemical properties
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Microbiology ch 15
Micro 15
| Question | Answer |
|---|---|
| Microbiologists use three categories of techniques to diagnose infections: | phenotypic, genotypic, and immunologic. |
| Observation of microbe’s microscopic and macroscopic morphology, physiology, and biochemical properties | Phenotypic |
| Analysis of microbe’s DNA or RNA | Genotypic |
| Analysis of microbe using antibodies, or of patients’ antibodies using prepackaged antigens | Immunologic |
| The first step in clinical diagnosis (after patient observation) is obtaining a _____. | specimen |
| If obtaining a specimen is not performed correctly, specimen analysis will not be _____ no matter how “sensitive” the test. | accurate |
| Patient analysis for signs of microbial infection (i.e., fever, wound exudate, mucus production, abnormal lesion) comes first; after that, _____ are collected and analyzed. | specimens |
| The main _____ methods include the direct examination of specimens, observing the growth of specimen cultures on special media, and biochemical testing of pure cultures. | phenotypic |
| Direct microscopic observation of a fresh or stained specimen is one of the most _____ methods of determining presumptive and sometimes confirmatory microbial characteristics. | rapid |
| Such a wide variety of _____ exist for microbial isolation that a certain amount of preselection must occur, based on the nature of the specimen. | media |
| The physiological reactions of _____ to _____ and other substrates provide excellent indirect evidence of the types of enzyme systems present in a particular species. | bacteria to nutrients |
| The use of genotypic methods in microbial identification has ____ exponentially. | grown |
| _____ results in the production of numerous identical copies of DNA or RNA molecules within hours | polymerase chain reaction (PCR) |
| In some cases, where the microbial populations are relatively unknown, a form of PCR called _____ ______ _____ _____ may be used because it employs primers of random sequence in an attempt to pick a microbial needle out of a haystack. | random amplified polymorphic DNA (RAPD) |
| _____ is a technique that makes it possible to identify a microbe by analyzing segments of its genetic material. | Hybridization |
| Small fragments of single-stranded DNA (RNA) that are known to be complementary to the specific sequence of DNA being studied. | Probes |
| _____ testing can be performed on a variety of body fluids or tissues and is based on the principle that antibodies have extreme specificity for antigens. | Serological |
| Testing for microbial-specific antigens or antibodies is typically performed ___ ____, and antigen-antibody interactions are made macroscopically or microscopically visible. | in vitro |
| _____ reactions occur between antibody and antigens bound to cells, resulting in visible clumping. It is the basis of determining titer, or antibody concentration, in patient sera. | Agglutination |
| _____ reactions also occur between antibody and antigen and produce insoluble, visible precipitates, but they are typically made visible by adding radioactive or enzyme markers. | Precipitation |
| _____employs antisera against cellular antigens such as the capsule, flagellum, and cell wall to identify bacterial species and strains. | Serotyping |
| In the _____ _____ procedure, proteins that have been separated by electrical current are identified by labeled antibodies. | Western blot |
| _____ fluorescence antibody tests indicate the presence of microbial antigens and are useful in identifying infectious agents; _____ fluorescence tests indicate the presence of microbe-specific antibodies and are used to diagnose infection. | direct , indirect |
| ______ can detect very small quantities of antigen, antibody, or other substances and use dyes or radioactive isotopes to visualize antigen-antibody complexes. | immunoassays |
| The _____ test is widely used to detect antigens (direct method) or antibodies (indirect method) in patient samples. | ELISA |
| _____ _____ involves the complement-dependent action of lysins to detect antimicrobial antibodies and is used in diagnosing fungal and bacterial diseases. | Complement fixation |
| ___ ___ serological testing, such as the tuberculin reaction, involves injection of antigen to elicit a visible immune response in the host. | In vivo |
| The next 5 years are likely to bring many new technologies to the widespread diagnosis of _____ _____ | infectious diseases. |
| Whole-genome sequencing relies on ____ sequencing of microbes. | DNA |
| _____ _____ detects microbes via their protein fingerprints. | Mass spectrometry |
| infection of the bloodstream (septicemia) is a condition that can kill very _____. The critical time frame for appropriate management is estimated to be less than ___ hours. | quickly , 6 |
| _____ designed for infectious disease diagnosis are “chips” (absorbent plates) that contain gene sequences from potentially thousands of different possible infectious agents, selected based on the syndrome being investigated | Microarrays |
| An old way of diagnosing infections, which found use in only occasional infections, involves various _____ techniques. | imaging |
| imaging in the form of X rays has been used for centuries in the diagnosis of ______ | tuberculosis |
| PCR is used to: | Amplify the number of copies of genes. |
| Mass spectrometry identifies microbes via | protein fingerprints |
| Because they are sufficiently unique in their appearances, viruses can sometimes be identified at a family or genus level by which phenotypic method? | electron microscopy |
| Which method can identify different strains of a microbe? | Serotyping |
| In agglutination reactions, the antigen is a _____; in precipitation reactions, it is a _____. | whole cell; soluble molecule |
| Which type of methods is based on a microbe’s utilization of nutrients? | biochemical |
| tuberculin reaction is an ___ ___ immunologic method | in vivo |
| Genetic means of identification are being used as a sole resource for identifying ______. | bacteria |
| “Old-fashioned” techniques such as _____, _____, and _____ means are still very reliable. | biochemical, serological, and morphological |
| Other techniques that assist in disanosis are Computerized tomography (CT), Magnetic resonance imaging (MRI), and _____ _____ _____ | Positron emission tomography (PET) |
| Light microscopy aids in the observation of: | Cell shape, size, and arrangement; Gram stain reaction, acid-fast reaction; Endospores, granules, and capsules |
| Electron microscopy can pinpoint additional structural features such as: | Cell wall, Flagella, Pili, and Fimbriae |
| Appearance of colonies: texture, size, shape, and pigment, Speed of growth, and Patterns of growth in broth and gelatin media are all traits that can be assessed with the _____ _____ | naked eye |
| Dozens of diagnostic tests exist for determining the presence of specific enzymes and to assess nutritional and metabolic activities: | Fermentation of sugars, Capacity to digest complex polymers, Production of gas, Sensitivity to antibiotics |
| microbes that can’t be grown in the laboratory that are identified by genotypic methods | Viable noncultured (VNC) |
| Antibody response is exploited for diagnostic purposes when a patient sample is tested for the presence of specific antibodies to a suspected _____. | pathogen |
| _____ ____ are available for immediate identification of a number of pathogens. | Laboratory kits |
| Care should be taken with samples that contain resident microbiota. Only the infected site should be sampled, and not the ______ _______ | surrounding areas |
| ______ samples can be taken from the bladder with a catheter, by clean catch, dirty catch, or mucous lining of the urethra | urine |
| ______ can be swabbed or scraped with a scalpel to expose deeper layers | Skin |
| ______ are cleansed prior to swabbing for culture to avoid collecting normal microbiota | Wounds |
| Blood, cerebrospinal fluid, and tissue fluids must be taken by ____ ____ ____ | sterile needle aspiration. |
| ______ of the puncture site is extremely important | Antisepsis |
| ______ tests on patient sera can provide indirect evidence for specific pathogens through analysis of antibodies | Serological |
| _____ testing is important in identifying those who have had previous exposure to rubella or tuberculosis | Skin |
| Some ______ are identified solely on patient signs and symptoms. | pathogens |
| Direct observation of fresh or stained specimen is a _____ method of determining presumptive and sometimes confirmatory microbial characteristics. | rapid |
| Stains most often used: | Gram stain and acid-fast stain |
| used to enrich a pathogen present in small numbers or is easily overgrown | Specialized media |
| used for nonsterile specimens containing a diversity of bacterial species to encourage the growth of only the suspected pathogen | Selective media |
| Used to identify definitive characteristics and fermentation patterns | Differential media |
| Pure cultures must be obtained from ______ media so that subsequent steps in identification will be accurate | isolation |
| Physiological reactions of bacteria to nutrients and other substrates | Biochemical testing |
| Enzyme-mediated metabolic reactions often visualized by a _____ change | color |
| Microbe is cultured in a _____ with a special substrate, then tested for a particular end product. | medium |
| Microbial expression of the enzyme is made visible by a _____ _____ | colored dye. |
| No coloration means it ______ the enzyme for utilizing the substrate | lacks |
| Based on easily recognizable characteristics such as motility, oxygen requirements, Gram stain reactions, morphology, spore formation, and various biochemical reactions | Dichotomous keys |
| Flowcharts to trace a route of identification by offering pairs of opposing characteristics | Dichotomous keys |
| Eventually, an endpoint is reached, and the name of a genus or species that fits that particular combination of characteristics appears. | Dichotomous keys |
| Diagnostic tables that provide more complete information are preferred today by many laboratories | Dichotomous keys |
| Used when morphological and biochemical tests are insufficient | Phage typing |
| Bacteriophage infect bacteria in a species-specific and strain-specific way, which is useful in identifying some bacteria. | Phage typing |
| A lawn of bacterial cells is inoculated onto agar, mapped off into blocks, and phage are exposed to each block | Phage typing |
| Cleared areas corresponding to lysed cells indicate sensitivity to that phage. | Phage typing |
| _____ _____ are used to grow host-cell dependent rickettsias, chlamydias, and viruses. | Avian embryos |
| Useful in determining which drugs to be used in treatment | Antimicrobial sensitivity tests |
| useful in presumptive identification of species such as Streptococcus, Pseudomonas, and Clostridium | Antimicrobial sensitivity tests |
| A single colony of a true pathogen such as Mycobacterium tuberculosis in a sputum culture, or an opportunist in a sterile site, is highly suggestive of _____. | disease |
| Repeated isolation of a relatively pure culture of any microorganism can mean it is an agent of ______ | disease |
| ____ results in the production of numerous identical copies of DNA or RNA molecules within hours | Polymerase Chain Reaction (PCR) |
| Used when microbial populations are relatively unknown | Random amplified polymorphic DNA (RAPD) |
| Makes it possible to identify a microbe by analyzing segments of its genetic material | Hybridization |
| small segments of DNA or RNA known to be complementary to the specific sequences of the nucleic acid isolated from a microbe | Probes |
| Similar to genetic fingerprinting | Pulsed-Field Gel Electrophoresis |
| Involves the separation of DNA fragments that are too large for conventional gel electrophoresis methods | Pulsed-Field Gel Electrophoresis |
| One of the most viable indicators of evolutionary relatedness and affiliation is the comparison of One of the most viable indicators of evolutionary relatedness and affiliation is the comparison of 16S rRNA sequences____ ____ sequences | 16S rRNA |
| rRNA is isolated, sequenced, and analyzed from _____ _____ | patient samples |
| The _____ method used for rRNA analysis can rapidly identify 16S rRNA sequences without first culturing the organism | FISH |
| ______ Involves in vitro testing of serum | Serology |
| ______ determines the immunologic status of patients | Serology |
| The most effective serological tests have a high degree of _____ and _____ | specificity and sensitivity |
| property of a test to focus only on a certain antibody or antigen, and not react with an unrelated or distantly related antigen | Specificity |
| detection of even minute quantities of antibodies or antigens in a specimen; reflects the degree to which a test will detect every positive person | Sensitivity |
| The basis of immunologic testing is the binding of antibody (Ab) to a specific site or ______ of an antigen (Ag) | epitope |
| ______ tests were developed to produce an endpoint reaction visible to the naked eye or with light microscopy. | Serological |
| Smaller Ab-Ag interactions can be observed using _____ or _____ reagents. | dyes or fluorescent |
| In both Agglutination and Precipitation Reactions, one antigen is interlinked by several antibodies to form insoluble ______. | aggregates |
| antigens that are whole cells or organisms such as red blood cells, bacteria, or viruses | Agglutination |
| used to identify antibodies to syphilis | Rapid plasma reagin (RPR) test |
| Precipitation: Antigen is a _____ molecule | soluble |
| Used to diagnose autoimmune disorders and determine past exposure to certain diseases | titer |
| Reflection of the highest dilution of serum that still produces agglutination | titer |
| Ag-Ab technique for identifying, classifying, and sub-grouping certain bacteria into categories called ______ | serotypes |
| involves a precipitation reaction against capsular polysaccharide antigens | Quellung test |
| The _____ ______ test involves the electrophoretic separation of proteins, followed by antibody-mediated detection of these proteins | Western blot |
| Monoclonal antibodies labeled by a fluorescent dye | Fluorescent antibodies (FAbs) |
| Unknown test specimen or antigen is fixed to a slide and exposed to a FAb solution | direct testing |
| FAbs used in _____ testing recognize the Fc region of antibodies in patient sera | indirect |
| Alternative methods that employ monoclonal antibodies and permit rapid, accurate measurement of trace antigen or antibody levels | Immunoassays |
| Antibodies or antigens labeled with a radioactive isotope used to pinpoint minute quantities of a corresponding antigen or antibody | Radioimmunoassay (RIA) |
| Uses an enzyme-linked indicator antibody to visualize Ag-Ab reactions | Enzyme-Linked Immunosorbent Assay (ELISA) |
| Relies on a solid support such as a microtiter plate that can adsorb the reactions | Enzyme-Linked Immunosorbent Assay (ELISA) |
| Common test used for antibody screening for HIV, various rickettsial species, hepatitis A and C, and Helicobacter | indirect ELISA |
| Known antibody is adsorbed to the bottom of a well and incubated with an unknown antigen. | direct ELISA |
| Used to detect antigens to hantavirus, rubella virus, and Toxoplasma. | direct ELISA |
| antibody that causes the lysis or rupture of target cells and requires complement | Lysin |
| antibodies that interact with complement system components on red blood cells, causing cells to hemolyze | Hemolysins |
| ____ ______ tests employ principles similar to serological tests, but antigen or antibody is introduced to a patient to elicit a visible reaction | In vivo |
| test where a small amount of purified protein derivative (PPD) from Mycobacterium tuberculosis is injected into the skin. | Tuberculin test |
| Culturing takes ____ hours or more. | 18 |
| Many infections are ______ | polymicrobial |
| bloodstream infection | septicemia |
| Identifying the cause of septicemia can take _____ hours, but the critical time frame for appropriate management is less than 6 hours. | 18 – 24 |
| Contain gene sequences from potentially thousands of different possible infectious agents | Microarrays |
| The development of high-throughput nucleic acid sequencing has revolutionized the analysis of the human _____ | genome |
| The cost of whole-genome sequencing, in terms of time and money, is becoming so _____ that this technique may become commonplace in clinical and epidemiological laboratories around the world | low |
| Used to determine the structure and composition of various chemical compounds and biological molecules. | Mass Spectrometry |
| used for rapid and highly accurate microbial identification | Mass Spectrometry |
| ____, ____, and ____scans have been increasingly employed to find areas of localized infection in deep tissue. | MRI, CT scans, and PET |
| Imaging in the form of X-rays has been used for centuries in the diagnosis of ______ | tuberculosis. |
Created by:
alucero