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Medical Microbiology
Medical Microbiology - immunology, diagnostic, clinical, tests
88
Microbiology
Undergraduate 4
08/02/2011

Additional Microbiology Flashcards

 


 

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Term
Medical Microbiology
Definition
human-microbe interactions: parasites, pathogens, virulence, host resistance, infection, disease, normal flora
Term
Parasites
Definition
organism living in or on host & causes damage; diagnostic micro: parasitic worms & protozoa (stool samples)
Term
Infection
Definition
such a rare process - amazing occurs at all
Term
Normal flora
Definition
necessary to keep pathogens or competing bacteria away; intimately intertwined in physiology; w/o it, we wouldn't last a week
Term
Skin
Definition
dry & acidic (from amino acids on surface & need water) - tough place to live; most w/I sweat glands & hair follicles, Gram (+) because more resistant to UV light
Term
Transient Flora
Definition
never stays in same place - transiently colonizing; can cause pathogenicity
Term
Resident Flora
Definition
always stays in same place
Term
Oral Cavity - Saliva
Definition
Saliva is hard place to live because lack of nutrients & lysozymes/lactoperoxidase destroy bacteria;
Term
Oral Cavity - Teeth
Definition
Teeth & gumline have most flora; most anaerobic or strict anaerobes; plaque buildup is biofilm & traps oral strep or bacilli; when eating, sugars attach & ferment acid on biofilm, eventually eroding teeth; not as diverse as other biofilms but not monotypic
Term
Intestinal Tract
Definition
gradient of pH increases & O2 decrease moving down tract; very complicated ecosystem; organisms stretch out on flora based on physiology (anaerobic bacteria closer to colon; more aerobic closer to esophagus); archaea bacteria in GIT; gas production (H2, CO2, CH4)
Term
IT Flora
Definition
B12 & K production, steroid mods; they create vitamins we can't but need; they modify basal compound steroids we made; process carbs first that we can't; they metabolize first then we absorb to digest; detoxify foreign chemicals
Term
Sloughing epithelial cells
Definition
Gram (-) help to slough epithelial cells to inhibit growth of pathogens
Term
Disruption of normal flora
Definition
antimicrobials disrupt normal flora, especially in lower tract, which affects chemostat; need to limit antimicrobials
Term
Upper respiratory tract
Definition
mucous membranes - do most work, keep inhaled particles from entering lower tract
Term
Lower respiratory tract
Definition
lungs have normal flora; ciliated epi cells keep out particles; 15% have pneumocystis controlled by macrophages but can cause disease; normal flora can cause disease if immune system defective
Term
Urogenital Tract - Bladder
Definition
Bladder is sterile - urine great medium for culturing; can get cystitis
Term
Urethra
Definition
facultative (-) rods & (+) cocci; can become opportunistic pathogens; nosocomial is infection from hospital from catheter
Term
Vagina
Definition
Pre-puberty & post-menopause: no glycogen & alkalinic, Gram (-); Adults have glycogen & acidic, Gram (+)
Term
Pathogenesis
Definition
creation of disease; bacteria has to enter, adhere, invade tissues, colonize & have virulence factors; w/o adherence, nothing will occur
Term
Adherence
Definition
Bacteria can adhere & not cause problems but must adhere if they are going to become pathogenic
Term
Colonization
Definition
bacteria can colonize w/o causing problems; just growth doesn't mean pathogenic yet; mycobacteria can off and on colonize but not cause harm
Term
Harmful interactions
Definition
exposure, adherence, invasion of tissues, further exposure, colonization/growth, production of virulence factors = pathogen; either toxicosis or invasiveness causes pathogenicity
Term
invasiveness
Definition
spreads all over to cause tissue damage; ability to gain access to & invade, colonize & become pathogenic
Term
toxicity
Definition
release of toxins to local or systemic areas to damage tissues
Term
Host entry - specific
Definition
breaks in skin or mucous membranes (wounds, trauma) allow easy entry but some can implant w/o aggressive entry (gonorrhea)
Term
Specific adherence
Definition
glycocalyx (capsule, slime layer), fimbrae (many small rods) & pili (few) allow bacteria to adhere like glue to tissues or cells; E. coli mainly causes pathogenicity from fimbrae in upper UT; pili are like grappling hooks
Term
Fimbrae & antibiotics
Definition
some antibiotics can strip pathogenic flora of its fimbrae, making it inactive & losing pathogenic status
Term
Host entry - invasion
Definition
penetration of epithelium, initiation of pathogenicity, growth on altered normal surfaces (burned skin, cuts); need plenty of bacterial cells to invade; can leave local sites & grow distantly (blood, lymph)
Term
Immune system & invasion
Definition
immune system tries to keep bacterial infection local so it does not become systemic
Term
Growth limitations
Definition
physical (37oC), nutritional & trace elements (iron) needed; iron can be drawn in by acidophores from bacteria, allowing them to become pathogenic
Term
Dissemination
Definition
swollen lymph nodes signalling infection sites, inflammation causes sentinels to be called in to respond (WBC's, etc)
Term
Bacteremia
Definition
viable or living bacterial cells in blood, but not growing
Term
Septicemia
Definition
pathogenic bacterial cells from blood that have invaded & grown - can cause death
Term
Virulence
Definition
measure of how pathogenic a bacteria is or relative ability of parasite to cause disease; physiological factors allow them to be competitive in their environments helps to dominate body
Term
Virulence factors
Definition
extracellular proteins help establish & maintain disease; enzymes aid colonization & growth; fibrin clots allow pathogens to live in body and not get attacked; have to be effective because of energy cost or will be cut lose
Term
Attenuation
Definition
continuous re-growth of pathogen eventually loses pathogenicity
Term
VF - toxicity
Definition
how much toxins are needed to cause pathogenicity
Term
Exotoxins
Definition
extracellular proteins; cause damage far from infection site; botulinum loose - most virulent toxin; tetanus toxin clenched
Term
Enterotoxins
Definition
intestines; organ system failure; from food poisoning; massive secretion of fluid; E. coli and Shigella are same bug phylogenetically (shig has 4 diff species derived from non-pathogenic E. coli); shiga toxin causes more severe Shigellosis
Term
Endotoxin
Definition
Gram (-) lipopolysaccharide; release of endogenous pyrenogens; usually have low levels in circulation; causes fever, diarrhea, decrease in lymphocytes & leukocytes & platelets, inflammation; severe is septic shock; test levels with Limulus (horseshoe crabs)
Term
Host defense mechanisms
Definition
nonspecific, specific, natural resistance; amplitude of reaction for response rate: nonspecific attack anything (weak rate), specific only attacks one kind (strong rate)
Term
Nonspecific mechanism
Definition
always turned on, no prior stimulus from particular pathogen; can react towards anything (primary immune response)
Term
Specific mechanism
Definition
prior infection, body already built-up immune response for specific pathogen to be turned on (needs priming from repeated exposure to be more efficient) (secondary immune response)
Term
Natural host resistance
Definition
certain populations have resistance to diseases because they lack receptors for those pathogenic cells (bacteria, virus)
Term
Stress
Definition
can allow normal flora to become pathogenic, it harms immune system if too high
Term
Physical & Chemical defenses
Definition
these are independent of immune system; secretions, blood, cilia, mucous, normal flora, skin, acidity, flushing, pH
Term
Inflammation & fever
Definition
body's response to infection - low amounts can be good to rid bacteria; high or chronic amounts are bad; swollen, red & warm when fluid released & blood (RBC, WBC) at site of infection; fever either kills or stimulates blood to kill pathogen (pyrogenic compounds)
Term
Cytokines
Definition
chemical messengers produces by leukocytes to send signals & bring in reinforcement
Term
Clinical Microbiology
Definition
detection & ID of pathogens, antimicrobial susceptibility testing - determine if pathogen suspectible to what antibiotic; more important to figure out antimicrobial susceptibility than the ID of pathogen; can start broad spectrum AB's & switch once ID determined
Term
Clinical Micro Routes
Definition
microbiological route is classical: collect specimen; Conventional: culture & isolate specimen; Molecular: immunological or molecular; Immunological
Term
Molecular route
Definition
detect genetics, molecules or Ag's specific to that bug; can also do Ag-Ab test (PCR most common); amplification of nucleic acids
Term
Conventional Micro route
Definition
enrich, select or differentiate culture & isolate to identify & determine AB susceptibility
Term
Molecular micro route
Definition
search for genome of pathogen (nucleic acid hybridization or PCR)
Term
Molecular immuno route
Definition
search for pathogen's microbial cells or virus particles using fluorescent Ab test or ELISA
Term
Immuno route
Definition
blood sample - search for Ab against suspected pathogens Ag; Ab assay (agglutination, RIA, ELISA, etc)
Term
Specimen collection
Definition
most important step in clinical micro; asceptic collection; can get contamination or not enough of sample; transport
Term
culture media
Definition
general purpose (NA), enriched (BA), selective (EMB Gm -) or differential (EMB Lac +)
Term
Blood cultures
Definition
rule out bacteremia vs. septicemia; aerobic & anaerobic vials; amt/vol of sample VERY important (can increase or decrease sensitivity) incubate 5 days
Term
UTI's
Definition
very common & from normal flora, most common is nosocomial infection (from hospital); (-) rods or (+) cocci
Term
Urine specimens
Definition
bacturia - infection 105; culture on blood agar or MacConkey agar; MA selective gram (-) & differential for Lac (+); Blood is both Gram (+) & Gram (-)
Also blood specimen for nitrite production, or high WBC; dipstick
Term
Fecal specimens
Definition
preservation necessary; Selective & Differential media required; Campylobacter most common cause of GTI's; H10157 big outbreak from variation of Enterohemorrhagic E. coli (cause shiga toxins); Parasites (worms, protozoa)
Term
Fecal Parasites
Definition
worms like tapeworms or protozoa like nematodes
Term
Wound/Abscess cultures
Definition
wound - superficial, deep; specimens - tissue, fluid aspirate, swab; anaerobes
tissue sample or fluid aspirate from outside of wound (not swab of tissue); "jelly donut story"; most likely polymicrobic infection (do anaerobic & aerobic cultures)
Term
Abscess treatment
Definition
antimicrobials hard to disseminate abscesses so masses have to be excised
Term
Genital cultures
Definition
STD's; some hard to culture, Neisseria, Chlamydia, Treponema pallidum (syphillis) & HIV
Term
Neisseria
Definition
enriched, selective agar w/ increased CO2 & humidity
Term
Chlamydia
Definition
very hard to culture; cell culture & Ag detection or nucleic acid sequencing tests (can also determine if other infections)
***for sexually abused - cannot run nucleic test bcz false (+); only cell culture for legal purposes
Term
Polymorphonuclear cells
Definition
Gram (-) diplococci Neisseria - can see only one form for males but different morphology for females
Term
Growth-dependent ID methods
Definition
selective & differential media; conventional biochemical tests; rapid biochemical tests; automated biochemical tests
Term
Antimicrobial susceptibility testing
Definition
disk diffusion methods & liquid dilution methods
Term
Disk diffusion methods
Definition
Kirby-Bauer, Zones of inhibition, interpretation: sensitive, intermediate
Term
Liquid dilution methods
Definition
minimum inhibitory concentration (MIC)
Term
Immunological ID methods
Definition
serology: Ag-Ab reactions, IgM, IgG, agglutination, fluorescent Ab's, ELISA (enzyme-linked immunosorbant assay)
Term
IgM, IgG
Definition
IgM key because it's quickly increased during infection (current or recent infection); IgG harder to test for
Term
Agglutination
Definition
Ag-Ab binding to form lattice = + result
Term
Fluorescent Ab's
Definition
tag Ab's w/ fluorescent dye & wash; see binding with color
Term
ELISA (don't focus on - might not be on test)
Definition
direct enzyme-linked immunosorbant assay; Ab's to virus on plate; add patient sample (serum, etc) which possible virus particles or Ag's; Add antivirus Ab with conjugated enzyme; wash w/ buffer; add substrate for enzyme; + results are colored; quantitation proportional to Ag
Term
Molecular diagnostic methods*
Definition
based on analysis of pathogen-specific nucleic acid (NA); can use PCR's or other technology to amplify sequences; because complimentary DNA is stable
Term
Benefits of molecular diagnostic methods
Definition
readily extracted, visualized & detected; sequences unique to each pathogen & can be amplified; DNA stable
Term
Mol diagnostic methods: NA (nucleic acid) probes & PCR*
Definition
NA probes: ssDNA, specific to particular pathogen, hybridization reactions
PCR: amplify NA targets, increasity sensitivity, qualitative PCR, quantitative PCR (viral load), reverse transcriptase PCR (RT-PCR); PCR uses two NA primers, one is cell & one is ssDNA
Term
NA probes - Detection*
Definition
place specimen cells on filter; lyse cells & generate ss target DNA; add reporter-labeled probe; allow for reannealing to target; measure hybridization directly if reporter radioactive or fluorescent; add enzyme substrate if reporter enzyme; detect using radioactive detector, fluorimeter or colorimeter/visual inspection
Term
NA probes - Measure Reporter*
Definition
lyse & denature sample in NaOH; region complementary to target DNA with reporter probe & capture probe; hybridize sample DNA to probes in solution; nucleases destroy unhybridized probe; target DNA against complementary DNA - capture w/ dipstick; measure reporter.
Term
Qualitative PCR
Definition
Used for mycobacterium TB
Term
RT-PCR*
Definition
HIV is RNA virus so RT needed, then do PCR
Term
clinical micro - diagnostic virology*
Definition
cytopathogenic effect on cell lines; electron microscopy; ELISA, virus-specific PCR
Term
clinical micro - diagnostic virology*
Definition
selective media, non-selective media, direct microscopic observation
Term
Exotoxins - Gram (+) or (-)?
Definition
Gram (+)
Term
Endotoxins - Gram (+) or (-)?
Definition
Gram (-)
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