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214 Cards in this Set
- Front
- Back
Replication enzyme prokaryotes?
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DNA Pol III
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Replication error rate prokary
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1 in 10 million
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Transcription enzyme prokary
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RNA Pol
No primer required |
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Bacterial Ribosome
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50S + 30S = 70S
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Eukaryotic Ribsome
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60S + 40S = 80S
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Function of aminoacyl-tRNA synthetase
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add amino acid to anticodon
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Function of peptidyl transferase
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forms peptide links between adjacent amino acids using tRNAs during the translation process of protein biosynthesis
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Transformation
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-uptake of naked DNA by recipient cell
-active process requiring specialized machinery -usually transfers small amt of DNA |
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Transduction
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-mediated by bacteriophage
1-2% of chromosome (30-60 genes) ... a large amount |
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Generalized transduction
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any fragment of bacterial chromosome transferred
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specialized transduction
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one genes next to insertion site transferred (lysogeny)
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Lytic transduction
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life cycle of bacteriophage that ends in lysis of bacterial host cell and release of viral progeny
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lysogeny
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alternate life cycle of some bacteriophages where the viral genome is integrated into the bacterial chromosome
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prophage
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bacteriophage integrated into bacterial chromosome
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Lysogenic conversion/phage conversion
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toxin genes added to prophage
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Conjugation
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plasmid mediated
can transfer large amounts of genetic information physical contact between cells (Pilus) must be F+ for pilus formation |
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Plasmids
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extra-chromosomal genetic material
replicon- can be replicated independent of chromosome encode toxins, Ab resistance, heavy metals |
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Transposons
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"jumping genes"
conservative or duplicative can cause insertional mutation |
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IS element
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insertional sequence
inverted terminal repeats encodes transposase |
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Composite transposon
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IS elements flanking internal sequence (e.g. drug resistance gene)
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Mutation frequency
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10^-7
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Types of mutations
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base substitution
-AA change -nonsense -silent frameshift mutation -deletion -insertion |
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UV light causes
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thymine-thymine dimers
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Transition
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Replace purine w/ purine or pyrimidine w/ pyrimidine
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Transversion
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Replace purine w/ pyrimidine or vice versa
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Restriction endonucleases
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originally a defense against bacteriophage
cuts DNA from any source cuts at specific restriction sites |
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Cloning
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cut and paste
amplify gene of interest vector -unique restriction site origin of replication selectable marker often plasmid or viral |
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Southern Blot
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Fractionation of DNA fragments on gel by size (electrophoresis)
Transfer to membrane Hybridization Use probe to find DNA of complementary sequence |
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Types of Blots
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Southern- DNA, probe is oliqonucleotide, used to see if gene is present/ identify organism
Northern- mRNA, probe is oligonucleotide, looks to see if gene is expressed Western Blot- SDS gel, proein, probe is Ab, looks to see if protein produced |
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Array hybridization
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Looks at expression of hundreds of genes at once
Oligos to each gene arranged on blot Probe with cDNA (mRNA) |
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Peptidoglycan
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Cell wall material (murein)
Crosslinked NAG-NAM-NAG formed by transpeptidases |
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Gram + cell wall characteristics
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Thick peptidoglycan wall w/ teichoic and lipoteichoic acid
Single inner cell membrane |
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Gram - cell wall characteristics
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Thin cell wall between outer and inner membranes.
LPS on outermembrane Lipoprotein connects outer membrane to cell wall |
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Lipoteichoic acid
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anchors cell wall to membrane in gram +'s
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Lipoprotein
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Anchors cell wall to outer membrane in gram -'s
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Periplasm
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space between membranes in gram - bacteria. organization and degradation of cell wall occurs here
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Functional barrier of gram - bacteria
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inner cell membrane
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Siv like barrier of gram - bacteria
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outer membrane
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Lipopolysaccharide
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Only found in gram -
Consists of Lipid A, Core poly, and O-antigen repeating subunits Lipid A forms toxic portion of endotoxins |
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Gram stain procedure
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1. Fix cells to slide
2. Add crystal violet 3. Add iodine solution 4. Wash w/ mild solvent 5. Counter-stain with safranin |
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Site of action of penicillins and cephalosporins, also can be degraded by lysozyme
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Cell wall peptidoglycan
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Site of action of aminoglycosides, erythromycin, tetracyclines, and chloramphenicol
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Bacterial ribosome
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Chemical composition of endospore
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Keratinlike coat with dipicolinic acid, provides resistance to dehydration, heat, and chemicals
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Bacterial repoduction
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Binary fission
-DNA replication -Chromosome segregation -Septum formation -Cytokinesis |
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Bacterial growth phases
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Lag phase
Exponential growth phase (log) Stationary phase Decline and death |
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Glycolysis
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Sugar converted to pyruvate yielding 2 ATP per glucose
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Superoxide dismutase
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converts oxygen free radicals to peroxide (h202)
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Catalase or Peroxidase
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Decomposes peroxide to H20
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Aerobe
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Need 02 for terminal electron receptor
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Facultatives
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Can use 02, but can also use fermentation or other e- acceptors
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Aerotolerant
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Dont use 02, but are OK with it
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Strict anaerobes (obligate)
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Lack SOD and catalase
Ferment or use another e- acceptor |
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Microaerophiles
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Thrive is low 02 (5%)
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Pathogen
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any organism capable of producing dz
normal flora becoming pathogenic are termed opportunistic |
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ID50/LD50
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number of organisms required to infect or kill 50% of exposed individuals
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incidence
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number of cases
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prevalence
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percentage of population at a given time
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endemic
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always present
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epidemic
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outbreak through a population
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pandemic
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epidemic of global proportions
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Incubation
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time between exposure and symptoms
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Prodromal period
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onset of non-specific symptoms
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Acute period
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characteristic symptoms of dz
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Pathogen characteristics
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Transmission
Adherence Invasiveness Toxigenesis |
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Methods of invasion
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Penetration (collagenases/hyaluronidases)
Coagulation IgA protease Leukocidins- knock off phagocytic cells |
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Endotoxin found in
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Gram - bacteria only
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Exotoxin found in
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Gram - and +
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Sampling
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aspirated pus, swab, paperpoint
microscopic eval culture |
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Antibiotic screening
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Bacteria spread in lawn on plates
Seeded with Ab discs Zones of inhibition reflect sensitivity to Ab Can be done in liquid culture as well |
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Traveler's diarrhea cause
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Enterotoxigenic E. coli (ETEC)
Emerged in 60s |
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ETEC Toxins
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Heat-stable (ST) - ^cGMP, increased fluid secretion
Heat-labile (LT) - ^cAMP, electrolyte shift |
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ETEC clinical findings
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diarrhea, cramps, fever, nausea
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ETEC incubation/resolution
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1-3 days, 3-4 days
Dx by culture |
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ETEC Tx
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Tx symptoms
No Rx needed |
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E. coli 0157:H7 toxin
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Lysogenic phage encodes Verotoxin
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E. coli 0157:H7 Epidemiology
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73,000 cases and 60 deaths a year in US
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E. coli 0157:H7 Transmission
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Oral/fecal contamination
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E. coli 0157:H7 clinical findings
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Bloody diarrhea/cramps/no fever
Resolves in 5-10 days Hemolytic uremic syndrome (HUS) in young/old |
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E. coli 0157:H7 Dx
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Growing on sorbitol-MacConkey agar
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E. coli 0157:H7 Tx
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Treat symptoms, No Rx
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E. coli O104:H4 toxin
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Shiga toxin
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Salmonella enteritidis clinical findings
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Gastroenteritis, diarrhea, fever, cramps, bacteremia can develop
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Salmonella enteritidis transmission
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oral-fecal, person to person, contaminated food (beef/poultry)
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Salmonella enteritidis morphology
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gram - rod
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Escerichia coli morphology
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gram - rod
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Salmonella typhi morphology
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gram - rod
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Salmonella typhi/paratyphi causes
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enteric fever (typhoid fever)
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Salmonella typhi/paratyphi clinical findings
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headache, malaise, anorexia, diarrhea/constipation, inflammation of liver/spleen lasting for 3-4 weeks
(12-30% mortality w/o tx) |
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Salmonella typhi/paratyphi clinical exam findings
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rose-colored spots on chest
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Salmonella typhi/paratyphi tx
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Ab tx but resistance is high
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Salmonella typhi/paratyphi transmission
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contact, food, sewage, lives only in people
chronic carriers |
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Salmonella Newport
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emerging, Ab resistant strain of S. typhi
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Most common Shigella
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S. sonnei 72% of cases
S. flexneri most of rest |
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Shigella toxin
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Shiga
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Shigella clinical findings
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diarrhea, fever, cramps
1-2 day incubation may cause seizures in kids resolves 5-7 days 2% of S. flexneri develop Reiter's syndrome |
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Reiter's syndrome
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develops in 2% of S. flexneri cases
joint pain, eye irritation, painful urination |
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Shigella tx
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Antibiotics
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Shigella transmission
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oral-fecal, p2p
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Shigella morphology
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non motile, gram - rod
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Pathogen in "Hot tub rash"
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Pseudomonas aeruginosa
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Pseudomonas aeruginosa morphology
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Gram - rod
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Pseudomonas aeruginosa clinical findings
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Dermatitis/folliculitis
Itchy/red bumpy rash Pus-filled blisters at hair follicles Can cause pneumonias in immunocompromised and infections in burns |
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Pseudomonas aeruginosa transmission
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heavily contaminated water contact
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Haemophilus influenzae morphology
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Gram - rod, opportunist (Upper resp tract infection)
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Haemophilus influenzae pathology
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HiB
-Bacteremia -Epiglotittis -Meningitis (5% mortality, 10-30% brain damage) -HiB vaccine |
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Neisseria morphology
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Aerobic gram - diplococci
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Neisseria gonorrhea transmission
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contact
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Neisseria gonorrhea clinical findings
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burning sensation, discharge
sore throat in oral infection infects reproductive tract, mouth, throat, and eyes |
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Neisseria gonorrhea effects if untreated
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PID/infertility in women
Infertility in men Risk of bacteremia |
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Neisseria gonorrhea Tx
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Antibiotics
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Neisseria meningitidis pathology
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Meningococcus
Meningococcemia 10-15% fatality rate |
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Neisseria meningitidis symptoms
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fever, headache, stiff neck
nausea, vomiting seizures |
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Neisseria meningitidis resides in
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nasopharynx
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Neisseria meningitidis dx
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Spinal tap
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Neisseria meningitidis tx
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IV antibiotics, MUST tx rapidly!
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Rickettsiaceae morphology
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Gram -, pleiomorphic, non-sporulating rods
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Rickettsiaceae transmission
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Ticks, fleas, lice
Obligate intracellular parasites |
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Rickettsiaceae pathology
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RMSF
Typhus |
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Rickettsia richettsii pathology and transmission
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Rocky Mountain Spotted Fever transmitted by ixodid (hard) ticks, Dermacentor
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Rickettsia richettsii symptoms
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Rapid
Fever, headache, muscle pain Rash, abdominal/joint pain Fatal if untreated |
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Rickettsia richettsii Treatment
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Antibiotics (Doxycycline or Chloramphenicol)
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Rickettsia prowazekii causes
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Epidemic Typhus
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Rickettsia prowazekii transmission
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Human body louse
May be flying squirrel vector |
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Rickettsia prowazekii symptoms
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Headache, chills, fever, prostration, confusion, photophobia, vomiting, rash
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Rickettsia prowazekii Tx
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Antibiotics
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Vibrio cholera morphology
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slender, gram - rod
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Vibrio cholera causes
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Cholera
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Vibrio cholera fatality rate if untreated
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25-50%
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Vibrio cholera transmission
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oral/fecal
lives only in humans |
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Vibrio cholera symptoms
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"rice water" stool
electrolyte gradient disrupted by cholera toxin circular collapse and shock occur eventually |
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Vibrio cholera Tx
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Rehydrating electrolytes, reduces fatality to 1%
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Campylobacter morphology
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Curved, gram - rods
microaerophilic/thermophilic |
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Campylobacter jejuni reservoirs
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livestock/pets
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Most common cause of bacterial diarrhea
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Campylobacter jejuni
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Campylobacter jejuni symptoms
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Fever, cramps, diarrhea
Resolves in a week 0.1% of cases develop Guillain-Barre syndrome Becoming resistant to Antibiotics |
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Chlamydia trachomatis symptoms
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Ocular infections
-neonatal conjunctivitis -blindness General infections -"silent epidemic" PID Damage may be irreversible Pneumonia in neonates |
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Chlamydia pneumoniae symptoms
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Acute respiratory infection
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Chlamydia Dx
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Fab test
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Chlamydia Tx
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Tetracycline
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Treponema morphology
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Spirochaetes
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Treponema in oral cavity
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Strict anaerobes, role in perio
T. denticola, vincentii, etc |
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Causitive agent of Sphyilis
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Treponema pallidum
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Treponema pallidum symptoms
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Syphilis
Primary -smooth, round chancre resolves after 3-6 weeks Secondary -rash and lesions, fever, swollen lymph, sore throat, patchy hair loss, headaches, weight loss, muscle aches, fatigue Late stage -brain, nerves, eyes, heart, blood vessels, liver, bones, and joints |
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Treponema pallidum tx
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antibiotics (IM penicillin G)
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Borrelia burgdorferi causes
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Lyme dz
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Borrelia burgdorferi transmission
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black legged ticks
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Borrelia burgdorferi symptoms
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Lyme dz
70-80% develop erythema migrans 3-30 days post bite "Bell's" palsy, meningitis, heart arrythmia, arthritic symptoms |
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Borrelia burgdorferi dx
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Serology
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Borrelia burgdorferi Tx
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antibiotics
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Borrelia burgdorferi morphology
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spirochete
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Borrelia burgdorferi morphology
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spirochete
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Mycoplasma morphology
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tiny, pleomorphic, no cell wall
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Mycoplasma pneumoniae symptoms
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Atypical pneumonia
can cause oral erythematous patches |
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Mycoplasma pneumoniae transmission
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p2p
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Mycoplasma pneumoniae dx and tx
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difficult to dx, antibiotics
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Helicobacter morphology
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Gram -, spiral, microaerophile
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H. pylori symptoms
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peptic ulcers
most common chronic infection |
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H. pylori dx
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serology, endoscopy
|
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H. pylori tx
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antibiotic
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Legionella pneumophilia morphology
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thin, pleomorphic gram -
|
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Legionella pneumophilia transmission and diseases
|
Respiratory
Causes Legionnaires' dz and Pontiac fever Often contracted after overnight stay out of home, often associated with water reservoir |
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Pontiac Fever symptoms
|
short incubation followed by flu-like illness without pneumonia in a majority of people
|
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Legionnaires' dz symptoms
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Longer incubation followed by enigmatic pneumonia in <5% of those exposed
High fatality rate (5-40%) |
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Legionella pneumophilia dx
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Serology
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Clostridia morphology
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Gram +, anaerobic, sporulating rods
Normally found in soil, noted for production of toxins |
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Clostridium perfringens transmission
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ubiquitous in the environment
|
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Clostridium perfringens causes
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necrotizing infections and gas gangrene
fever, pain, myonecrosis, gas |
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Clostridium perfringens toxin
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Alpha toxin
catalytically disrupts membranes leading to edema |
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Clostridium perfringens symptoms
|
fever, pain, myonecrosis, gas
tissue damage can lead to amputation progression to bacteremia can prove fatal |
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Clostridium perfringens dx
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Culture, microscopy, tissue imagaing
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Clostridium perfringens tx
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surgery, antibiotics, hyperbaric 02
|
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Clostridium botulinum found
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in soil
|
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Clostridium botulinum toxins
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Seven types
Alpha type most deadly biological toxin known Blocks ACh release leading to flaccid paralysis |
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Clostridium botulinum pathologies
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Three that vary w/ transmission
Food borne- toxin produced by growth in improperly preserved food. Non-acidic foods (beans, corn, hot peppers) Wound botulism- bacteria introduced into wound, increased incidence w/ heroine use Infant botulism- infant ingests contaminated food. Bacteria reproduces in gut, produces toxin. From honey, corn syrup, etc |
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Clostridium botulinum dx
|
By symptoms and patient hx
|
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Clostridium botulinum tx
|
antitoxin (human for infant, equine for others)
respiratory assistance |
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Clostridium tetani symptoms
|
causes tetanus "lock jaw"
|
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Clostridium tetani transmission
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introduced into deep wounds (anaerobic)
|
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Clostridium tetani toxins
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produces tetanolysin and tetanospasmin
Tetanospasmin blocks GABA -cause intense muscle spasm |
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Clostridium dx and tx
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Dx- symptoms
Tx- antitoxin and antibiotics |
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Clostridium difficile transmission
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Found in soil, occasionlly part of normal gut flora for some
|
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Clostridium difficile toxins
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A toxin- exotoxin that acts enterically
B toxin- cytotoxin |
|
Clostridium difficile symptoms
|
Causes pseudomembraneous colitis (PMC), toxic megacolon, perforations of the colon, sepsis
Watery diarrhea, fever, anorexia, nausea, abdominal pain and occasionally death |
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Clostridium difficile tx
|
antibiotics, GI surgery, long stay in health care facilities, immunocompromised
|
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Clostridium difficile dx
|
stool culture, antigen detection, toxin detection
|
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Streptococci morphology
|
gram positive, chain forming cocci
wide distribution |
|
Streptococci dx and culture
|
Hemolytic characterization
-grown on blood agar plates Three posibilities -No hemolysis -Alpha-hemolysis --narrow zone of partial lysis and discoloration - beta-hemolysis --wide, clear zone of complete hemolysis |
|
Streptococcus pneumoniae characteristics
|
alpha-hemolytic
gram +, chain forming cocci |
|
Streptococcus pneumoniae symptoms
|
Pneumonia and meningitis in adults, otitis media, and sinusitis in children
Can cause: -hearing loss -neurological impairment -death during invasive dz (14% of hospitalized adult) |
|
Streptococcus pyogenes characteristics
|
Group A Streptococci (GAS)
Beta-hemolytic, hemolysins, hyaluronidase gram +, chain forming cocci |
|
Streptococcus pyogenes pathologies
|
non-invasive strep throat and impetigo
red sore throat, may have white/yellow patches can cause scarlet fever (scarlatina) Invasive necrotising faciitis, toxic shock (STSS), cellulitis, >35% STSS, 25%NF, Death in 10-15% of invasive cases |
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Streptococcus agalactiae characteristics
|
Group B streptococci
beta-hemolytic gram+ chain forming cocci |
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Streptococcus agalactiae pathologies in neonates
|
Sepsis, pneumonia, meningitis in neonates
|
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Streptococcus agalactiae pathologies in adults
|
Sepsis and soft tz infections
|
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Streptococcus agalactiae pathologies during pregnancy
|
Sepsis, amnionitis, UTI, stillbirth
|
|
Staphylococci characteristics
|
Gram+, cluster forming cocci
|
|
Staphylococcus epidermidis pathologies
|
normal flora
can cause wound, catheter infections |
|
Staphylococcus aureus pathologies
|
superficial infections
food poisoning toxic shock syndrome deep infections |
|
S. aureus superficial infections symptoms
|
boils, carbuncles, abscesses, conjunctivitis
|
|
S. aureus food poisoning
|
Enterotoxins
produced in food and consumed very fast reduced w/ proper handling |
|
S. aureus toxic shock syndrome
|
replication and production of specific enterotoxin in body
wounds and burns pharynx tampons Sx: fever, malaise, stupor, organ failure |
|
Resistance in Staphylococcus aureus
|
MRSA
VISA/VRSA -resistance to penicillin related drugs Nosocomial infections are most transmissions/infections |
|
Listeriosis morphology
|
Gram+ rod
|
|
Listeria monocytogenes transmission
|
Gram+ rod,
food borne transmission -meat, poultry, dairy, vegetables -rarely reported noscomial |
|
Listeria monocytogenes pathologies
|
Long incubation
Gastroenteritis Pregnancy related and neonatal infection -fetal sepsis/meningitis leading to stillbirth Sepsis and meningitis in adults |
|
Bacillus anthracis characteristics
|
Gram+ sporulating rod
|
|
Bacillus anthracis toxins
|
Edema factor- alters cAMP levels in MOs
Lethal factor- triggers apoptosis Protective factor- shuttle EF and LF to cell |
|
Bacillus anthracis transmission and symptoms
|
Associated w/ large herbivores, most human infections are related to animal contact
Cutaneous -cuts/abrasions raised, itchy bump that ulcerates edema and swelling fatal in 20% of cases w/o tx |
|
Anthrax pathologies
|
Intestinal
-ingests contaminated meat -nausea, anorexia, vomiting, fever, pain, sever diarrhea -fatal 25-60% Inhalation -inhalation of spores followed by cold-like symptoms -progesses rapidly to respiratory collapse and shock -Usually fatal w/o tx |
|
Anthrax dx and tx
|
Culture/serology
Treated w/ heavy course antibiotics |
|
Mycobacterium tuberculosis characteristics
|
slender rods, do not take up gram stain (acidfast) because of mycolic acid in cell wall
|
|
Mycobacterium tuberculosis pathologies
|
Primary infection
-local lesions (Ghon focus), local lymphs enlarge -usually becomes dormant upon cell mediated response -left untreated it can reemerge after months or years causing fatal pathology Post-primary infections -miliary TB --spread to multiple foci -meningitis, bone/joint, renal -Tubercular bronchopneumonia --75% emergent infection anorexia, fatigue, fever, night sweats, cough, bloody sputum pleural effusion and lung collapse |
|
Mycobacterium tuberculosis dx
|
Mantoux test (TST)
-intradermal injection of purified protein derivative (PPD) -hard lesions form due to immune reaction |
|
Mycobacterium tuberculosis tx
|
Combination drug therapy
-multiple antibiotics over long course Vaccine w/ live vaccine somewhat effective -Bacillus Calmette-Guerin (BCG) |