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128 Cards in this Set
- Front
- Back
5 groups of human infectious diseases
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Bacteria, fungi, protozoa, helminthes, viruses
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3 Shapes of Bacteria
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Cocci, bacilli, spirochetes
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Arrangements of Cocci, ex.
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Diplococci: Neisseria, chains: Strep, clusters: Staph
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Smallest cell
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Mycoplasma
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Difference btw pro and euk cell wall
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Peptidoglycan
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General dif btw Gram – cell wall and Gram + cell wall
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-: Thin peptidoglycan layer, periplasmic space, outer membrane. + thick peptidoglycan layer, no outer membrane, (lipo)teichoic acid
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Dif btw lipo- and teichoic acid
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Lipo goes down to cell membrane, teichioic in wall
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Gram – cell wall characteristics
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Endotoxin LPS (Lipid A), periplasmic space (beta-lactamases), porins, O specific side chains
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How does Lipid A cause shock
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Released from dying bacteria, induces release of cytokines
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LPS is to gram – as ______ is to gram +
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Teichoic acid. (both can induce TSS)
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Parts of LPS and what they do
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Lipid A (induces fever/hypotension), O antigen: used for lab ID
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Functions of peptidoglycan
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Rigid support, protects against osmotic pressure
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Detailed morphology of Staph, strep, strep pneumoniae, Neisseria Bacillus, Salmonella, Corynebacterium, Fusobacterium, Vibrio, Borrelia, Treponena
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Clusters, chains, pairs w/pointed ends, kidney bean pair, rod w/square ends, rod w/rounded ends, club shaped, fusiform, comma-shaped, relaxed coil, tightly coiled
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Enzyme in peptidoglycan formation. Drug interaction?
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Transpeptidase, penicillins and cephalosporins inhibit this
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Describe mycobacterium cell wall and staining characteristics
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Mycolic acid à acid-fast stain. Don’t stain in gram stain
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What human enzyme kills bacteria, where is it, how does it work?
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Lysozymes: tears, secretions. Cleaves peptidoglycan
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Difference btw human/bact cell membrane
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Sterols in humans
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Gram + color, - color
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Purple. Pink.
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Steps in gram staining
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Thin film of suspension. Fix w/methanol. Flood w/crystal violet. Add iodine. Decolorize with alcohol. Flood w/counterstain. Rinse excess stain off
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Describe bacterial chromosome(s)
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Single, circular chromosome + plasmids
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What info do plasmids carry? Transposons?
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Plasmids: Antibiotic resistance, exotoxins, Transposons: antibiotic resistance genes
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What are plasmids?
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Extrachromosomal DNA
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Role of capsule, composition (w/exception)
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Antiphagocytic, polysaccharide, exception: anthrax (D-glutamic acid)
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Describe 2 fxns of pili
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Attachment, sex (conjugation)
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Describe fimbraie
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Adhesion protein
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Dif btw flagella and fimbraie/pili
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Flagella have directed movement
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How to flagella move. Define: monotrichous, amphitrichous, peritrichous, lophotrichous
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Rotate. One flagella, two. Flagella coming out all over. Tuft of flagella
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Describe motility of spriochete
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Flagella-like structure interwoven in spiral. Undulating motion
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What is glycocalyx. 2 kinds. What does it do?
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Gel like coating outside cell. Capsule and slime layer. Attaches bacteria to cells and prostheses
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Function of: inclusion bodies, nucleoid, ribosomes, mesosome
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Stored nutrients for later use. Location of bacterial chromosomes. Site of protein synthesis. Plasma membrane that fold into cytoplasm to increase surface area
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Why do spores form? How does form change? Killed by boiling? Any way to kill? Metabolically active?
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Lack of nutrients. Thick keratin-like coat. Survive for many years. No. Only at 121 degrees for at least 15 min. no.
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How do bacteria reproduce?
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Binary fission
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Fastest replicating bactera
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Clostridium perfringens
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#1 cause of diarrhea in US
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campylobactor
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Dif btw exotoxin and endotoxin
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Exotoxins are extraceullar proteins
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4 phase of bacterial growth cycle. describe
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Lag (incorporation of nutrients), log (exponential growth), stationary (equil btw death and new bacteria), death
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Dif btw aerobes, anaerobes, facultatives, microaerophilic in terms of enzymes. What do enzymes do
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Aerobes and facultatives have superoxide dismutase and catalase (break down toxic products of O2 use)
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T or F bacteria are haploid
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T
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2 processes to transfer DNA WITHIN bacteria
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Transposons and programmed rearrangements
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Medical importance of transposons. and programmed rearrangments
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Transposons: carry antibiotics resistance genes. Programmed rearrangments: evade immune system by putting new proteins (antigens on cell surface)
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3 processes to transfer DNA btw bacteria
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Conjugation, transduction, transformation
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Describe conjugation. What is required?
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Donor sex pilus attaches to recipient. DNA moves along sex pilus. Requires F plasmid. At the end, both have a copy of transferred genetic material
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Describe transduction. What is lysogenic conversion
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DNA transferred via bacteriophage. If new protein made: lysogenic conversion
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Describe transformation. 2 ways it can happen.
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DNA itself transferred: via dying cells or experimentally
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Normal flora of skin
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S. epidermidis, Propionibacterium, Peptococcus, Candida
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How can candida cause disease
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IV drug use, gets into bloodstream. Endocarditis
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How can S. epidermidis cause disease
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It gets on prostethic devices: heart valves, joints
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Major normal flora of the nose
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Staph aureus
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3 normal flora of throat and bacteria they inhibit
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Viridans strep (Strep pyogenes), Neisseria spp (N. meningitides), S. epidermidis (S. aureus)
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Normal flora of mouth – what problem do they cause.
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Viridans (Strep mutans): dental caries. Most common cause of subacute infective endocarditis. Anaerobes (Bacteriodes, Fusobacterium, Clostridium, Peptostreptococcus): cause lung abscess if aspirate
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Major site of bacteria in the body
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Colon
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What is the normal role of E. coli, aberrant role
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Normal GI flora, leading cause of UTI
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Normal flora of GI
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E. coli, Bacteriodes fragilis, Enterococcus faecalis, Pseudomanas aeruginosa
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What extraintestinal disease to these case: B. fragilis. E. faecalis. P. aeruginosa
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Peritonitis following trauma, appendicitis, diverticulitis. UTI, endocarditis. Various nosocomial infections
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Role of antibiotics in normal GI flora
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Can wipe out normal flora and allow rare bacteria to overrun (clostridium difficile)
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Major normal flora of GU tract, what happens when it’s suppressed
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Lactobacillus – keeps pH low.. Candida infection
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Bacteria on skin around GU tract
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S. saprophyticus
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Bacteria that can infect urine as it comes out urethra
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S. epidermidis, coliforms, diphtheroids, nonhemolytic streptococci
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Bacteria around urethra of women and uncircumcised men
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Mycobacterium smegmatis
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Female urethra can get bacteria from what area
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Fecal flora
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Define colonization resistance and give an example
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Normal flora take up receptor sites so pathogens can’t attach. Ex. Viridans strep on throat prevent GAS from binding
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Does E. coli produce a vitamin. If yes, what
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Yes, vitamin A
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Diseases caused by Staphlyococcus aureus
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Abscesses, various pyogenic infections (endocarditis, septic arthritis, osteomyelitis), food poisoning, TSS, nosocomial pneumonia, septicemia, surgical-wound infection. Meningitis, UTI, abscess formation of any organ
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T or F. gram + cocci are motile
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F
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T or F. gram + cocci do not form spores
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T
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Gram, catalase, coagulase status of staph spp
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Staph aureus: all +, S. epidermidis, saprophyticus: coagulase -
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What is catalase, why is it good for bacteria
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Degrades H2O2 into O2 and H2O, prevents peroxide from microbicidal activity of letting neutrophils kill
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What is coagulase
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Causes plasma to clot by activating prothrombin à thrombin
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T or F. s. aureus ferments mannitol
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T
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T of F. s. aureus is beta hemolytic
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T
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90% of what bacteria have beta-lactamase. What is that?
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s. aureus. Degrades many penicillins
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How can s. aureus be resistant to beta-lactamase resistant penicillin
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Changes in penicillin binding protein
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6 important cell wall components and antigens
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Protein A, teichoic acids, polysaccharide capsule, phage surface receptors, microcapsule, peptidoglycan
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Describe protein A
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Bind Fc portion of IgG, antiphagocytic
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Describe teichoic acid in staph
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Adherence to mucosal cells + play a role in septic shock
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Describe role of peptidoglycan in strep
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Endotoxin-like properties
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Role of staph as normal flora (3 kinds of staph)
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s. epidermidis: skin + hair follicles. S. aureus: nose. S. saprophyticus: skin around GU tract
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T or F. S. aureus disease thrives in heavily contaminated environment and immunocompromised people.
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T
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Typical lesion of s. aureus
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Abscess
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What happens to abscesses
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Central necrosis and drain to the outside
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Important predisposing factor in s. aureus infection
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Foreign bodies (sutures, IV catheters)
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3 clinically important exotoxins in s. aureus
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Enterotoxin, toxic shock syndrome toxin, exfoliatin
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Describe what enterotoxin does and clinical manifestations
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Superantigen: release of IL-1 from macros, IL-2 from T helper cells. food poisoning. Prominent vomiting (signals enteric n.s. to stimulate vomiting center in brain) + watery, non-bloody diarrhea.
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Heat resistance, stomach acid, jejunum enzymes - reaction of enterotoxin
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Fairly heat resistant, resistant to stomach acid, jejunum enzymes
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Describe toxic shock syndrome toxin
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Causes toxic shock, esp in women w/tampon, nose tampon. Superantigen à IL-1, IL-2, TNF released
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Describe exfoliatin
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Causes “scalded skin syndrome”. Epidermolytic.
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What is alpha toxin?
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Kills leukocytes à skin necrosis and hemolysis.
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Name some virulence enzymes in s. aureus
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Coagulase, fibrinolysin, hyaluronidase, proteases, nucleases, lipases
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Proteins that disable host immunity in s. aureus
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Protein A, coagulase, hemolysins, penicillinase
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Proteins tunneling through tissue in s. aureus
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Hyaluronidase, staphylokinase, lipase
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Pathogenic mechanisms of s. aureus
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Toxins and inflamm due to multiplying in tissues
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T of F. All spp of staph produce exotoxin
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F: S. epidermidis and S. saprophyticus don’t – also means no food poisoning or septic shock
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What are 2 divisions of clinical manifestations of s. aureus
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Pyogenic and toxin-mediated
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Pyogenic diseases of s. aureus
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Skin infections, septicemia, endocarditis (esp R. sided tricuspid in IV drug uses), osteomyelitis, arthritis, postsurgical wound infection, pneumonia, abscesses
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What does staph pneumonia often lead to?
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Empyema and lung abscess
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Toxin-mediated diseases of s. aureus
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Food poisoning – ingest enterotoxin. TSS, scalded skin syndrome
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Clinical manifestation of TSS
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Hypotension; macular, sunburn like rash, 3+ organ involvement
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Clinical manifestation of scalded skin syndrome. Age group often affected
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Fever, large bullae, erythematous rash, skin slough, serous fluid exudes, electrolyte imbalance, skin and hair loss. Recovery takes 7-10 d. young children
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Diseases caused by S. epidermidis
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Infect protheses, neonatal sepsis, peritonitis in renal pts with catheter, cerebrospinal fluid shunt infection
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What is the most common cause of cerebrospinal fluid shunt infection
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s. epidermidis
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What determines if S. epidermidis adheres well to prostheses?
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Presence of glycocalyx
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Diseases caused by S. saprophyticus
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UTI.
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Top two causes of community acquired UTI
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E. coli, S. saprophyticus
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Lab Dx: gram, culture, coagulase, mannitol
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+. golden-yellow, beta hemolytic. +. +
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Lab dx: culture of coagulase - staph
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White colonies, non hemolytic
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Role of novobiocin in staph
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s. epidermidis sensitive, s. saprophyticus not
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Bacteriophages and lab dx for staph
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Staph can be divided into groups based on their lysis
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T or F. 90% of s. aures resistant to penicillin
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T
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Why are most s. aureus resistant to penicillin?
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Contain beta lactamase
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what meds are some s. aureus resistant to?
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Penicillin, methicillin, nafcillin, partial vancomycin
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Tx of staph toxic shock syndrome
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Correct hypotension w/fluids. Pressor drugs, inotropes, beta lactamase resitant penicillin.
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Topical antibiotic for staph
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Mupirocin
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Definition of tolerance
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Bacteria can’t grow but not killed by med
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Treatment of abscesss
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Surgical drainage
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T or F. S. epidermidis is highly resistant to antibiotics
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T. use vancomycin +/- another drug. Remove prosthesis
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Prevention of staph infections
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Hygiene!!!, remove shedders from high-risk areas, peri-op antibiotics
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Are viruses cells
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Y
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What is the only group that has a nucleus
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Eurkaryotes
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Which group has DNA or RNA
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Viruses
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Describe chromatin of euk, arch, pro and viruses
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Many, complexed w/histones. Single loop. single, circular chromatin + plasmids, none
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Describe ribosomes of euk, arch, pro, viruses
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80S, 70S, 70S, none
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Which group has mitochondria
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Euks only
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Outer surface of euk, arch, pro, viruses
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Euk: cell membrane w/sterols. Chitin wall, ergosterol. Arc: glycerol/isoprene derivatives. Pro: peptidoglycan + cell membrane, maybe capsule. Viruses: naked protein capsid + lipoprotein envelope
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Motility: euk, arc, pro, viruses
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Flagella, cilia, pseudopods. Flagella, flagella. None
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Difference btw bacteriostatic and bactericidal
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Inhibits bacterial growth (host defenses need to kill). Kill bacteria.
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Reasons for antibiotic failure
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Delay in dx, tx. Wrong dx. Errors in susceptibility testing. Inadequate concentration of bacteria at infection site. other factors at site. immunocompromised pt. superinfection. resistance.
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How can you distinguish btw N. gonorrhea and N. meningitidis
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Fermentation of glucose or maltose
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How you distinguish E. coli from Shigella and Salmonella
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Fermentation of lactose
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