Term
|
Definition
kills organism
(e.g. bactericide, fungicide) |
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Term
|
Definition
|
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Term
|
Definition
| an absolute process = killing/removal of all organisms (incl. bacterial spores) |
|
|
Term
| Will sterilization remove LPS? |
|
Definition
NO.
sterilization does not necessarily remove bacterial procuts, especially heat-stable ones like endotoxin |
|
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Term
|
Definition
| achieves clean w/ no pathogens (but does not imply sterilization or complete disinfection) |
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Term
|
Definition
| elevated temp, follow by rapid cooling (e.g. kills pathogens in milk) |
|
|
Term
| Will Pasteurized milk be sterile? |
|
Definition
NO.
pasteurization does not sterilize; some bacteria, spores, stable viruses may survive
pasteurization mainly used to preserve and prevent spoilage |
|
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Term
|
Definition
| chemical used to kill organisms on the surface of skin |
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Term
|
Definition
| means "without infection" |
|
|
Term
| What is the most effective means of preventing infection spread? |
|
Definition
|
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Term
|
Definition
| involves hand washing, gloves, gowns, masks, glasses, face shields, appropriate personal hygiene and cleaning of physician's equipment |
|
|
Term
| sterilization, disinfectant, preservatives list |
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Definition
|
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Term
|
Definition
| a substance that interferes with proliferation of microorganisms (viruses, bacteria, fungi, protozoa, etc.) |
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Term
|
Definition
a substance/compound of natural origin that demonstrates antimicrobial activity
the source of which is often soil microorganisms
(e.g. Streptomyces) |
|
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Term
| bacteriostatic vs. bacteriocidal |
|
Definition
"-static" agents inhibit growth, but do not kill the organism
"-cidal" agents kill the pathogen
bacteriostatic agents normally rely on a healthy immune system, where they can boost immune function; whereas bacteriocidal agents may be needed especially in immunodeficient pt's |
|
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Term
| narrow-spectrum antibiotics |
|
Definition
only affect certain classes
(e.g. Gram-positive bacteria, or anaerobic bacteria) |
|
|
Term
| broad-spectrum antibiotics |
|
Definition
effective against many types of pathogens (usually bacteria)
(e.g. both Gram-positive & Gram-negative bacteria) |
|
|
Term
| What are some situations when broad-spectrum antibiotics might be especially useful? |
|
Definition
| life-threatening situations (before being able to identify a more specific sensitivity treatment), or in prophylaxis pre-surgery |
|
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Term
|
Definition
| prevention of or protective treatment for disease |
|
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Term
| Kirby-Bauer (aka KB testing, aka disk diffusion) |
|
Definition
a test which uses "wafers" containing antibiotics to judge the susceptibility of a certain pathogen (bacteria) to relevant antibiotics; this is a qualitative test
the circles of poor bacterial growth ("zones of inhibition") around some of the wafers indicate antibiotic susceptibility
in general, larger zones correlate with smaller MIC |
|
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Term
| Minimum Inhibitory Concentration (MIC) |
|
Definition
a quantitative (#) measurement of the minimum antibiotic required to inhibit/prevent bacterial growth
MIC < or = MBC |
|
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Term
| Minimum Bactericidal Concentration (MBC) |
|
Definition
a quantitative (#) measure of the minimum concentration of antibiotic required to kill 99.9% of the patient's bacterial isolate; used to determine treatment regimens for life-threatening infections (e.g. meningitis)
MBC is an extension of MIC |
|
|
Term
| Antimicrobial Serumcidal Concentration |
|
Definition
similar to MBC
a quantitative (#) measurement of the minimum antibiotic required to kill a patient's isolate in their serum sample; this informs a patient-specific therapy |
|
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Term
| How would an antibiogram be helpful to a clinician or to a public health advocate? |
|
Definition
antibiograms provide information (in table form) about antibiotic susceptibility and resistance trends of commonly used antibiotics, at a certain hospital
these published reports are designed to help minimize resistance spread and provide cost-effective antibiotic use (b/c they list dose $ prices) |
|
|
Term
| How is effective chemotherapy limited by abscess formation? |
|
Definition
abscesses are low O2, low blood perfusion, so drugs may not be able to penetrate
tissue necrosis favors replication of anearobic organisms
effectiveness of the host immune system (phagocytes, antibodies, sulfonamides) is also limited
the slowed-growth of the pathogens means drugs won't be as effective |
|
|
Term
| antibiotics & host immune system |
|
Definition
ideally, antibiotic agents should not harm the patient's immune system
antimicrobials generally work best in the presence of an intact immune system
drugs can't do it all |
|
|
Term
|
Definition
develop one infection on top of another (e.g. vaginal yeast infection)
this can be a limitation on the effectiveness of chemotherapy, since normal flora which were normally suppressed may be able to spread |
|
|
Term
|
Definition
| administration of a drug to a patient who is not infected but who is at increased risk of acquiring infection (e.g. erythromycin/tetracycline drops for prevention of opthalmia neonatorium, aka neonatal conjunctivitis) |
|
|
Term
| When is chemoprophylaxis justified? (list some) |
|
Definition
| (1) prevention of neonatal conjunctivitis, (2) for travelers facing malaria, (3) prevent Strept. In heart disease pt's, (4) against bacterial endocarditis in surgical procedures, (5) pre-surgery, (6) immunocompromised patents such as HIV, (7) UTI's, (8) animal and human bite wounds, (9) post-exposure to HIV, TB, or meningitis, (10) pre- and post-exposure in biological warfare |
|
|
Term
| What are some exaples of when chemoprophylaxis is not justified? |
|
Definition
| (1) just to prevent secendory pneumonia in influenza, (2) just for clean surgery which does not cross mucosal surfaces, (3) just because patient insists on antibiotics for them or their children |
|
|
Term
| What are the five major classes of antibacterial chemotherapy drugs? |
|
Definition
(1) metabolic analogs - e.g. sulfa drugs
(2) cell wall synthesis inhibitors - e.g. penicillins & cephalosporins
(3) cell membrane agents - e.g. Polymyxin B & E
(4) nucleic acid synthesis inhibitors - e.g. Rifampin
(5) protein synthesis inhibitors - e.g. erythromycin & tetracyclin |
|
|
Term
|
Definition
a combination therapy of trimethoprim and the sulfa drug sulfamtheoxazole used for uncomplicated UTIs and as the backbone therapy for pneumocystis jiroveci in HIV/AIDS
(can be dually classified as metabolic analogs and DNA synthesis inhibitors) |
|
|
Term
| How do penicillins and cephalosporins work as chemotherapy drugs? |
|
Definition
| by inhibiting the cross-linking of peptidoglycan in bacterial cell wall synthesis |
|
|
Term
|
Definition
30S ribosome inhibitors = AT = aminoglycosides & tetracyclines
50S ribosome inhibitors = SSCCCELL = streptomycin, streptogramins, chloramphenicol, clindamycin, clarithromycin, erythromycin, linezolid, lincomycin |
|
|
Term
| Dr. Spock and Mrs. Very against Strept |
|
Definition
Streptogramins (e.g. Synercid) used against:
vancomycin-resistant enterococci (VRE)
methicillin-resistant Staphylococcus aureus (MRSA)
drug-resistant Streptococcus pneumoniae (DRSP) |
|
|
Term
| What protein synthesis inhibitors are used against intracellular bacteria, malaria, and as an anti-inflammatory? |
|
Definition
| tetracyclines, minocycline, doxycycline, oxytetratcycline |
|
|
Term
|
Definition
| mupirocin used topically to eliminate nasal carriage of staphylococcus aureus (esp. MRSA) |
|
|
Term
|
Definition
metronidazole effective against anaerobic bacteria and certain protozoans
giardia lamblia
entamoeba histolytica
trichomonas vaginalis |
|
|
Term
| Foxy Lady, Stop Gyrating! |
|
Definition
| "floxacins" like ciprofloxacin and norfloxacin are used for UTIs (and lower respiratory tract infections) b/c they inhibit DNA packaging by DNA gyrase and promote cleavage of bacterial DNA |
|
|
Term
| Poly doesn't want a cracker |
|
Definition
| Polymyxin B (neosporin) and Polymyxin E (colistin) are only used topically for skin, ear, and eye infections |
|
|
Term
5-FC
5 fungi before Christ |
|
Definition
| 5-fluorocytosine is a cancer chemotherapeutic agent that inhibits nucleotide synthesis and interferes with fungal enzymes, also used for cryptococcal meningitis in AIDS patients |
|
|
Term
What drugs affect fungal sterols?
PIZAZ MAT |
|
Definition
polyenes (e.g. amphotericin B, nystatin)
imidazoles & azoles (e.g. ketoconazole)
morpholines (e.g. amorolfin)
allyalmines & thicarbamates (e.g. terbinafie) |
|
|
Term
|
Definition
| fluconazole used for cryptococcal meningitis in AIDS patients, by inhibiting fungal sterol synthesis |
|
|
Term
| Tiny Turbo Ringworm infection |
|
Definition
| terbinafine used for tinea ringworm infections (and onychomycosis) |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
1 + 1 = 0.5
may be due to competition for a binding site or drug-drug interactions, opposing effects (e.g. tetracycline & penicillin) |
|
|
Term
|
Definition
|
|
Term
| When would combination chemotherapy be used? |
|
Definition
| polymicrobic infection, to cover both aerobes & anaerobes, to enhance -cidal activity (synergism), to decrease doses of a toxic drug (additive or synergistic), life-threatening infection (full coverage), or to decrease risk of emergent resistance |
|
|
Term
|
Definition
| Rifampin used to treat carriage of Hib and meningococcus, also MTB therapy; works b/c inhibits mRNA synthesis via DNA-dependent RNA polymerase |
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|
Term
|
Definition
used by bacteria to avoid antibiotics
the drug is actively pumped out of the cell, faster than it enters |
|
|
Term
|
Definition
organism that is unable to synthesize a particular organic compound
e.g. yeast mutant with an inactivated uracil pathway
e.g. auxotrophic humans must obtain vitamins and essential amino acids via diet |
|
|
Term
|
Definition
| a mechanism of bacterial resistance where there is no change in MIC but MBC is high; a rare phenomenon but may become more common in the future |
|
|
Term
|
Definition
| evasion of killing by depression of bacterial growth rate |
|
|
Term
|
Definition
| evansion of killing by depressed production of murein (peptidoglycan) hydrolases |
|
|
Term
| What are some ways in which bacteria exhibit resistance to antimicrobial agents? |
|
Definition
| (1) by altering the drug target site, (2) by preventing access of the drug to the target site, (3) by inactivating or destroying the drug, (4) by protecting the target site, (5) by overproducing the target, (6) bypassing antibiotic inhibition, (7) by developing tolerance |
|
|
Term
| What are examples of bacteria altering the target site of antimicrobial drugs? |
|
Definition
altering penicillin binding proteins (evades penicillin)
altering DNA gyrace (evades fluoroquinolones)
altering dihydrofolate reductase (evades trimethoprim) |
|
|
Term
| How do bacteria commonly acquire resistance? |
|
Definition
by mutation
by destruction and/or inactivation of the drug
by efflux of the drug |
|
|
Term
|
Definition
the "slimy football jersey" of bacteria
=> when a phagocyte tries to eat the bug, it can slip away
bacterial cell capsule is a very large structure consisting largely of polysaccharides that lies outside the cell wall of bacteria; it is not easily washed off and can cause various diseases, a virulence factor
some bacteria have capsule that resembles host polysaccharide, and this type of capsule is not immunogenic |
|
|
Term
| What do virulence factors enable bacteria to do? |
|
Definition
virulence factors are secreted by pathogens (bacteria, viruses, fungi, and protozoa) that enable them to:
(1) adhere to and colonize a niche in the host
(2) evade host immune response
(3) suppress host immune response
(4) enter/exit cells
(5) obtain nutrition from host |
|
|
Term
|
Definition
mucin glycoproteins are the main component of the first barrier that bacteria encounter in the intestinal tract
bacteria get stuck to the mucin because they have mucin-binding receptors,
but some bacteria do not and others have enzymes to degrade mucin (virulence) |
|
|
Term
|
Definition
small cationic proteins found in (in)vertebrates that act as natural bactericidal proteins (also act against fungi and some fungi)
defensins create pores in bacterial membranes, then diffuse through peptidoglycan to reach the cytoplasmic membrane
(note: endotoxin/LPS binds to defensins, preventing them from reaching cytoplasm) |
|
|
Term
|
Definition
secretory IgA is the main immunoglobulin found in mucous secretions (e.g. tears, saliva), protects against degradation from proteolytic enzymes
sIgA contributes to mucin, making it stickier and simultaneously bingding bacterial antigens
however, bacteria produce enzymes that cleave IgA, breaking the link between bacteria and mucin |
|
|
Term
|
Definition
cell-surface components/appendages that facilitate bacterial adhesion/adherence to other cells or to inanimate objects; they are a type of virulence factor
protein adhesins = fimbriae, pili, afimbrial, flagella, S-layer
polysaccharide adhesins = cell wall, capsule |
|
|
Term
|
Definition
part of the cell envelope that encloses the whole cell surface, resembles a tiled surface; can function as adhesins
in Gram-negative bacteria, S-layers are associated with endotoxin/LPS, protect against complement and phagocytosis |
|
|
Term
| What kinds of signal transduction occur after adhesion of bacterial pili/fimbriae? |
|
Definition
activation/repression of virulence genes in the bacteria;
or altering gene expression in the host |
|
|
Term
|
Definition
rod-shaped, hair-like structures on surface of bacteria
important for adherence, attach specifically to receptor, first initial "loose" contact, wait for tighter adherence
important for conjugation, gene exchange
mostly in Gram-negative bacteria
pili are constantly lost and reformed, allowing altered antigenicity
(see "fimbria") |
|
|
Term
|
Definition
|
|
Term
| Which would form a tighter adhesion - fimbrial or afimbrial? |
|
Definition
|
|
Term
|
Definition
in Gram-negative cell walls
LPS triggers an innate immune response characterized by cytokine production and inflammation, possibly leading to septic shock |
|
|
Term
|
Definition
| small cell-signalling proteins secreted from numerous cells in the body (unlike hormones), immunomodulating agents |
|
|
Term
| How do bacteria acquire iron to survive in the body? |
|
Definition
some use siderophores, which chelate iron complexes in the blood, internalizing it inside the bacteria to be cleaved
others bind and remove iron directly from host's transferrin and/or lactoferrin
bacterial toxins kill cells, releasing iron
finally, some bacteria exhibit "iron abstinence" or use substitute metals (e.g. Borrelia burgdorferi uses manganese) |
|
|
Term
| What is necessary for extracellular invasion of a host cell by bacteria? |
|
Definition
enzymes:
elastase degrades extracellular molecules
hyaluronidase cleaves proteoglycans
streptokinase & staphylokinase break down fibrin clots
lipase degrades host oils
nuclease digests RNA/DNA
haemolysins lyse RBCs |
|
|
Term
| What pathogens have obligate intracellular lifestyles? |
|
Definition
Chlamydia spp.
Rickettsia spp.
Mycobacterium lepra
Mycobacterium tuberculosis would be a factultative intracellular one, and it persists for years inside host |
|
|
Term
|
Definition
a common strategy for pathogens to induce uptake into a host cell
bacterial signalling proteins get injected into the cell, activating host to internalize the microbe
e.g. Salmonella spp. & Shigella spp. |
|
|
Term
| What three locations (intracellular niches) do bacteria generally inhabit while inside the cell? |
|
Definition
(1) phagolysosome - e.g. Coxiella burnetti,
(2) phagosome - e.g. Chlamydia & Salmonella,
(3) cytosol - e.g. Shigella & Rickettsia & Listeria |
|
|
Term
|
Definition
convert nitric oxide into NO3-, normally in the respiratory system
E. coli bacteria use this enzyme to develop resistance to nitric oxide (NO) |
|
|
Term
|
Definition
the presence of O antigen determines whether LPS is considered "rough" or "smooth", affects hydrophobic/hydrophilic nature
in Neisseria gonorrhoeae, a sialic acid is bound to the O antigen, which helps evade host immune response |
|
|
Term
| How do bacteria evade the antibodies of host immune response? |
|
Definition
| they can alter their pilus proteins, they can generate capsule which resembles host molecules, or they can coat themselves with host proteins such as firbonectin (which bind to the Fc portion of the antibodies, but do not lead to opsonization of bacteria => no complement activation) |
|
|
Term
| two component signal transduction systems (TCSTSs) |
|
Definition
bacterial systems which detect external signals and direct the organism to make a response
typically they have (1) a sensor protein and (2) a response regulator, which can either increase or prevent transcription of a gene
involved in regulating many diverse cellular functions (incl. chemotaxis, quorum sensing, toxins, virulence) |
|
|
Term
| T/F: in bacteria, transcription and translation occur in the same compartment so protein formation can occur immediately as soon as transcription starts |
|
Definition
|
|
Term
|
Definition
a ribosomal binding site in the mRNA, generally located 8 basepairs upstream of the start codon AUG
in E. Coli, the sequence is "AGGAGG"
participate in the formation of a polysome |
|
|
Term
|
Definition
| a cluster of ribosomes, bound to a mRNA molecule |
|
|
Term
|
Definition
a functioning unit of genomic DNA w/ a cluster of genes all under the control of a single regulatory signal or promoter
helps speed and coordinate bacterial response/adaptation |
|
|
Term
|
Definition
| a single mRNA can code for several different proteins |
|
|
Term
| bacterial mRNA vs. eukaryotic mRNA |
|
Definition
single compartment vs. nucleus-cytoplasm
unstable vs. stable for several hours
both have coding and non-coding regions
eukaryotic is transcribed from DNA first
5'3' of triphosphate P-P-P & last base vs. 5'3' of methylated cap & poly-A tail |
|
|
Term
|
Definition
collections of genes or operons under regulation by the same regulatory protein (e.g. vir regulon of Streptococcus Pyogenes under activator Mga)
multiple regulons can form a modulon |
|
|
Term
|
Definition
binds to core RNA polymerase, helping the core enzyme to recognize the promoter; sigma factor synthesis helps bacteria regulate gene expression
once transcription is initiated, the sigma factor is released and can attach to another core polymerase |
|
|
Term
| what are some examples of sigma factors in action? |
|
Definition
sigma-38 helps regulate nutrient deprivation, oxidative and osmotic stress in Salmonella, E. coli, and Pseudomonas Aeruginosa
sigma-32 is a heat shock protein important in the regulation of virulence of Vibrio cholerae |
|
|
Term
|
Definition
lies just 3' to the stop codon
short inverted repeats form a hydrogen-bonded, stem-loop structure that causes RNA polymerase to pause/stop transcription |
|
|
Term
|
Definition
| interfere with RNA polymerase, turning transcription off |
|
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Term
|
Definition
| bind to and block repressor molecules, turning transcription ON |
|
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Term
|
Definition
| bind directly to specific sequences adjacent to the promoter site or directly to RNA polymerase, to promote gene transcription (e.g. cAMP receptor) |
|
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Term
|
Definition
| native repressors have no affinity for the operator site, so the default mode of gene transcription is ON, but when a co-repressor binds to the repressor, this actually leads to repression of gene transcription (e.g. trp operon) |
|
|
Term
| accidental gene rearrangements |
|
Definition
| e.g. repair, mutation, transposition, plasmid, phage, foreign DNA |
|
|
Term
| programmed gene rearrangements |
|
Definition
are part of a genetic program, largely predictable
genes must be moved to an active "expression locus"
repeating the program over and over is the source of consistent antigenic variation
e.g. amplification, deletion, assembly of genes from gene segments
e.g. moving a gene from silent storage to an active site |
|
|
Term
|
Definition
| must be moved to an active site where transcription and translation occur before they can express 'new gene' |
|
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Term
|
Definition
| switches on/off the expression of some component, like surface proteins |
|
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Term
|
Definition
| alters the antigenic nature of component such as surface proteins |
|
|
Term
|
Definition
a type of phase variation for gene expression
vvv = ON. ^^^ = OFF. |
|
|
Term
| slipped-strand mispairing |
|
Definition
a type of phase variation for gene expression
strand slippage leads to frame shift, premature termination, truncated protein product |
|
|
Term
|
Definition
a type of antigenic variation for genes
uses homologous recombination to "suffle" the antigenic make-up of product (e.g. type IV pilus of N. gonnorhoeae) |
|
|
Term
|
Definition
a type of antigenic variations for gene expression
simple mutations can give rise to antigenic variants no longer recognizable to host immune system (e.g. HIV & influenza A virus) |
|
|
Term
|
Definition
a type of antigenetic variation
where variation occurs in the phenotype of the organism, but not the genotype (e.g. methylation of surface structures) |
|
|
Term
|
Definition
| hugh mutation rates associated with viruses, produces variants, some of which may not be reactive to antibodies anymore (virulence) |
|
|
Term
|
Definition
large scale change in a particular pathogen
now, prior exposure will yield no beneficial sensitivity advantage b/c the pathogen appears as "new" (e.g. influenza pandemics of 1918) |
|
|
Term
|
Definition
are non-chromosomal/extrachromosomal genetic elements that usually encode traits that are not essential for viability and replicate independently of the chromosome, most are supercoiled & linear
cell-to-cell transfer, direct contact = conjugation
intentional uptake of "naked" gene = transformation
=> horizontal gene transfer |
|
|
Term
|
Definition
the average number of molecules of a given plasmid per bacterial chromosome is called its copy number
smaller plasmids usually are nonconjugative, and have high copy numbers
large plasmids are often conjugative, have small copy numbers, carry other genes as well as the operon, and code for all functions required for their replication |
|
|
Term
|
Definition
a DNA molecule used as a vehicle to transfer foreign genetic material into a cell
the four major types of vectors are plasmids, viruses, cosmids, and artificial chromosomes |
|
|
Term
|
Definition
| mediate conjugation, usually large, autonomous replication and transfer of DNA to recipient (e.g. genes for sex pilus) |
|
|
Term
|
Definition
| do not mediate conjugation, usually smaller, they lack one or more of the genes needed for transfer of DNA |
|
|
Term
|
Definition
a conjugative plasmid that controls sexual functions of bacteria
the first episome discovered |
|
|
Term
|
Definition
aka bacteriocinogenic plasmids
code for substances that kill other bacteria (bacteriocins or colicins) |
|
|
Term
|
Definition
aka resistance plasmids
carry antibiotic resistance genes |
|
|
Term
|
Definition
| enable the digestion of unusual substances |
|
|
Term
|
Definition
| turn the bacterium into a pathogen (e.g. siderophores for iron uptake, toxins) |
|
|
Term
| What is the medical significance of plasmids? |
|
Definition
| they control many important properties of pathogens (resistance, toxin production, adherence, colonization) and compairing profiles can help identify pathogens epidemiologically |
|
|
Term
|
Definition
toxic bacterial proteins
found in both Gram-positive and Gram-negative bacteria
important for survival and propagation (e.g. evasion or iron acquisition) but some toxins have no known benefit (e.g. botulinum toxin)
some have been used in vaccines, some used in treatment |
|
|
Term
| T/F: toxin genes are not normal components of the bacterial genome |
|
Definition
TRUE (for many bacteria)
carried in on bacteriophages (e.g. diptheria toxin) or found on plasmids from other bacterial species |
|
|
Term
|
Definition
Type I toxins = Superantigens
Type II toxins = Membrane-acting
Type III toxins = A-B toxins |
|
|
Term
|
Definition
| Type I toxins bind to MHC and receptors on T cells to stimulate a super-normal immune response of excessively high levels of IL-2 cytokines (e.g. toxic shock syndrome toxin from Staph. Aureus) |
|
|
Term
|
Definition
| Type II toxins that insert into host membrane and make an open channel, swelling and rupture |
|
|
Term
|
Definition
| Type II toxins that destabilize host cell membrane, by removing charged groups on phospholipids or cleave at other sites (e.g. Staph. Aureus alpha-hemolysin used to kill host phagosomes) |
|
|
Term
| How do A-B toxins exert effect? |
|
Definition
| B subunit binds to membrane receptor, then translocates the A portion into the host cell, catalyzing an ADP-ribosylation reaction which either inactivates or damages the host cell protein (e.g. diptheria toxin does this to elongation factor EF-2) |
|
|
Term
|
Definition
a Type III A-B toxin that targets heparin-binding epidermal growth factor (HB-EFG) to inactivate enlongation factor EF-2, stopping protein synthesis
=> diptheria involves damage to heart & neurological symptoms (difficulty swallowing) |
|
|
Term
|
Definition
a Type III A-B toxin that does not involve colonization, but rather intoxication, targets neurons and peripheral nerve endings, blocking Ach release, causing
=> generalized "flaccid paralysis" where muscles don't get stimulated, atrophy (e.g. food-borne botulism) |
|
|
Term
| Which type of botulinum toxin is used off-label for cosmetic treatment of wrinkles? |
|
Definition
C1 = botox
C2 and C3 = are less toxic |
|
|
Term
|
Definition
a Type III A-B toxin that targets the CNS, blocking the release of inhibitory interneurons that would normally be responsible for relaxing muscles after contraction
=> tetanus "lockjaw" is a spastic paralysis, constant contraction |
|
|
Term
| zinc-requiring endopeptidases |
|
Definition
cleave a set of proteins called "synaptobrevins" that are normally found in synaptic vesicles of neurons responsible for release of neurotransmitter and inhibitory mediators
botulism & tetanus toxin share a considerable amount of genetic similarity to the enzymes that cleave these proteins |
|
|
Term
| Why do botulinum toxin and tetanus toxin cause such different effects? |
|
Definition
botulinum toxin targets peripheral neurons;
while tetanus toxin acts on the CNS |
|
|
Term
|
Definition
a Type II membrane-disrupting toxin that targets many cell types, hydrolyzing the lipid "lecithin" and has phospholipase activity
=> kills host cells and causes tissue damage (aka gangrene) w/ an expanding zone of dead tissue |
|
|
Term
| toxic shock syndrome toxin (TSST) |
|
Definition
a Type I superantigen toxin that targets T cells and macrophages
=> causes nonspecific binding of T cells and macrophages; elicits cytokine production by T cells, which help produce fever and other symptoms of toxic shock syndrome |
|
|
Term
|
Definition
a Type III A-B toxin that binds ganglioside receptors and enters cells via endocytosis, turns on G protein permanently, disrupting hormone regulation of cellular activities
=> causes bone loss, weight loss, destruction of lung |
|
|
Term
|
Definition
| collection/mixture of microorganisms (bacteria, fungi, and/or protozoa, with associated bacteriophages and other viruses) embedded in a polysaccharide matrix, which is secreted by one or more member(s), attached to a solid biologic or non-biologic surface |
|
|
Term
| T/F: more than 99% of all bacteria live in biofilm communities |
|
Definition
|
|
Term
| extracellular polymeric substances (EPS) |
|
Definition
| slimy substance secreted into biofilms to facilitate attachment and matrix formation and to become irreversibly attached (permanent adherence) |
|
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Term
| how is microorganism behavior more complex in a biofilm community? |
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Definition
| they break down complex nutrients by pooling their biochemical resources; they alter their phenotype (growth rate, gene regulation); and they demonstrate enhanced survival with nutrition availability, defense mechanisms, resistance to physical force, evasion of phagocytosis & antibiotics & disinfectants |
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Term
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Definition
in the first attachment phase of a biofilm life cycle, a sediment of organic molecules help to form a "conditioning layer" on the biofilm surface;
the first colonists are usually bacteria |
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Term
| how can biofilms propagate? |
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Definition
biofilms can spread around and creep along a surface
they can propagate through detachment of clumps or by a type of "seeding dispersal" that releases individual cells |
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Term
| T/F: the susceptibility of biofilms to antimicrobial agents can be determined by MIC/MBC |
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Definition
FALSE!!!!!!
These tests rely on the response of planktonic ("free") microorganisms rather than biofilm-associated ones |
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Term
| how do biofilms affect chronic wounds? |
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Definition
they prevent wound healing
biofilms are especially found on many medical devices and pieces of hospital equipment such as catheters, prostheses, heart vales, shunts, dental implants, ventilators, hemodialysis machines, etc. |
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Term
| What are the ways in which biofilms are intrinsically resistant to antimicrobials? |
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Definition
| it's difficult for drugs to diffuse through the EPS matrix ("capsule"); biofilms have a lower growth rate, minimizing the rate that antimicrobial agents would be taken in effectively; and the environment surrounding biofilms may provide further protection |
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Term
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Definition
prevents detachment, stay in a favorable niche, more opportunities for gene exchange, more cell-to-cell communication and/or cooperation, more exposure to moving water, more nutrient adsorption;
plus defense against mechanical force, predation, and immune response |
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Term
| What are some "good biofilms"? |
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Definition
| in earth's sediment and bedrock, there are recycling elements and leaching minerals and soil-forming bacterial biofilms that help; there is mutual exchange of nutrients among plant roots and microbes; and we could use bioremediation in sewage treatment and/or toxic waste sites |
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Term
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Definition
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Term
| Does direct testing involve cell culture? |
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Definition
NO.
direct testing involves microscopic (e.g. gram stain) and macroscopic (e.g. agglutination) techniques to get rapid identification of a pathogen |
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Term
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Definition
the aggregation by antibodies of suspended cells or similar-sized particles (agglutinogens) into clumps that settle
(immunological/serological method of pathogen identification, where epitope + Ab = clumps) |
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Term
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Definition
extremely sensitive tests that permit rapid and accurate measurement of trace Ag or Ab
(incl. RIA, ELISA, EIA) |
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Term
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Definition
| selective media for anaerobic bacteria (e.g. Clostridium, Bacterioides) |
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Term
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Definition
| selective media for fastidious organisms (e.g. Haemophilus) |
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Term
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Definition
selective media for Neisseria
addition of antibiotics kill off other organisms |
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Term
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Definition
| differential media that differentiates b/w alpha, beta, and gamma hemolysis of Streptococcus |
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Term
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Definition
| both selective and differential media, used a lot for Salmonella & Shigella |
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Term
| Eosin Methylene Blue (EMB) |
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Definition
| both selective and differential media, produces metallic green sheen for lactose-positive |
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Term
| How is phage typing used to identify pathogens? |
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Definition
only certain kinds of phages infect certain bacteria
this method is good for outbreak scenarios, identify down to subspecies |
|
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Term
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Definition
a procedure for separating and identifying Ag or Ab mixtures by electrophoresis in polyacrylamide gel, followed by immune labeling
identifies specific antigen, detects proteins |
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Term
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Definition
immunological method of testing for certain antibodies or specific antigen
uses Ab + Ag + complement + sheep RBC |
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Term
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Definition
enzyme-linked ammuno-sorbent assay
a very sensitive serological test used to detect Ab's in such diseases as AIDS |
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Term
| Why would you order immunoelectrophoresis? |
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Definition
this test can detect disorders in Ab production
serum samples are electrophoresed, then proteins are reacted with antibodies, diffuesion produces arc pattern representing major serum components |
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Term
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Definition
polymerase chain reaction
specific DNA gene amplification |
|
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Term
| why is DNA hybridization called "checkerboard hybridization"? |
|
Definition
large DNA samlpes are hybridized against large numbers of DNA probes on a single support
can identify bacterial species contained in a sample with many species |
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Term
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Definition
restriction fragment length polymorphism
aka "DNA fingerprinting"
where DNA is digested, fragmented, electrophoresed, labeled probes => only a few strains will be genetically similar |
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Term
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Definition
pulsed-field gel electrophoresis
large segments of DNA separated by rotating the electric field, does not require special fluorescent dyes
good for when you have a lot of DNA |
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Term
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Definition
radioactive isotope label
used in immunoassays, very sensitive |
|
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Term
|
Definition
detects the Ab to a specific Ag
w/ radioactive labels or enzyme labels |
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Term
|
Definition
detects the Ag
w/ radioactive labels or enzyme labels |
|
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Term
| what is the goal of most genome projects? |
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Definition
| to produce a finished contiguous DNA sequence of the chromosome (or genome) |
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Term
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Definition
open reading frame
any stretch of codons (longest) that does not contain chain termination (STOP) codon |
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Term
| what is the challenge now facing scientists studying genomics/bioinformatics? |
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Definition
| how to organize and catalog the vast amount of information, interpret large amounts of information into a usable form (e.g. identifying and characterizing genes or identifying the combination of genes that make an organism pathogenic) |
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Term
| is bioinformatics studied in vivo or in vitro? |
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Definition
in vitro
it's biologically-derived information, statistical analysis |
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Term
|
Definition
using computers to carry out biological experiments virtually
allows researcher to look at the bigger picture |
|
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Term
| what are the three components of basic genomic information? |
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Definition
gene content
gene organization
gene dynamic (e.g. horizontal gene transfer in bacteria) |
|
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Term
|
Definition
the entire gene pool for a pathogen sp.
(incl. genes that are not shared by all strains)
core = all strains
dispensable = more than 1
strain-specific = only 1 |
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Term
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Definition
segments of DNA that can move/jump within a genome/plasmid, propagation depends on physical integration with a genome replicon (unlike plasmid)
in the process, they may cause mutation or decrease the amount of DNA in genome
(aka mobile genetic elements or "jumping genes") |
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Term
| what is the simple structure of a transposon's insertion elements (IS)? |
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Definition
| simple structure of a transposon includes a gene producing an enzyme that catalyzes insertion, a repeated sequence ("inverted terminal repeat") marking the end of insertion, and a short stretch of genomic DNA ("target site repeat") that's repeated on either side of the insertion element |
|
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Term
|
Definition
first transcribe the DNA into RNA
then use reverse transcriptase to make a DNA copy of the RNA to insert to a new location
as opposed to the Cut + Paste mechanism where DNA moves directly from place to place |
|
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Term
| 1,2,3 = Classy Retro hairCUT MINI-me! |
|
Definition
Class I transposons = RETROtransposons (copy + paste mechanism)
Class II transposons = (CUT + paste mechanism)
Class III transposons = Miniature Inverted-repeats Transposable Elements (aka MITEs) |
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Term
|
Definition
| transposons that carry a selectable marker (such as antibiotic resistance) have been used to make random mutations in the genome of a pathogen; the mutant is screened for loss of virulence |
|
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Term
| pathogenicity islands (PAIs) |
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Definition
genomic islands acquired by horizontal gene transfer which collectively contribute to virulence of the pathogen; similar to transposons in that they carry functional genes
associated with tRNA genes, targets for DNA integration
high in C's and G's
found mainly in Gram-negative, but a few Gram-positive
e.g. adhesins, toxins, iron uptake systems, invasins, etc. |
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Term
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Definition
single nucleotide polymorphisms are small genetic changes, sources of variation within a person's DNA sequence
serve as biological markers ("SNP profiles") |
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Term
|
Definition
analyze host and microbe gene expression during infection to tentatively identify the genes whose expression is turned on (or off) under certain conditions;
the array is hybridized with mRNA, DNA or cDNA from the organism grown under different conditions;
can help identify expression of virulence factors
advantage = largen number of genes in small space |
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Term
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Definition
| a technique that uses fluorescently labelec nucleic acid molecules as "mobile probes" to identify complementary molecules (sequences that are able to base-pair with one antoher) |
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