lecture 5 greenberg
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| carbuncle | lateral and deep extension of S. aureus; several coalesced furuncles with several openings to the surface with discharging pus
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| abscess | central area of necrosis, infection with dead host cells and bacteria surrounded by reactive fibrosis
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| empyema | infection of thoracic cavity external to lung
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| erysipelas | infection of superficial skin with marked involvement of lymphatic vessels
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| exfoliatin | EC product of S. aureus responsible for intradermal splitting and necrosis seen with scalded skin syndrome (SSS)
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| furuncle | small abscess or boil; painful, indurated, erythematous and caused by S. aureus
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| impetigo | infection of the superficial layers of skin - epidermis and outer dermis
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| leucocidin | exotoxin of S. aureus that destroys PMN leukocytes (specifically Panton-Valentine leukocidin)
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| puerperal sepsis | bacteremia in mother following childbirth
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| shock | syndrome characterized by hypotension from systemic vasodilation
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| likely function of coagulase in S. aureus | makes it an invasive organism; allows it to wall off infection and stop blood supply thus inhibiting leukocyte entry into wound
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| function of protein A in S. aureus | bings IgG's Fc portion, allows bacteria to evade immune cells labeling it for phagocytosis
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| Name another Staphylococcus besides aureus that's resistant to methicillin | up to 98% of S. epidermidis and other coag neg spp.
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| Staphylococcus saprophyticus | the only coag neg Staphylococcus that is resistant to novobiocin disc on agar plates; causes 20-30% of symptomatic UTIs in young, sexually active females
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| L-pyrrolidonyl arylamidase (PYR) | diagnostic enzyme for Group A beta hemolytic strep (S. pyogenes)
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| important diagnostic tool to distinguish beta hemolytic strep bacteria apart | bacitracin resistance
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| M protein | major virulence factor within Streptococcus pyogenes; is antiphagocytic and allows them to bind to epithelial cells & keratinocytes; ~ 100 diff serotypes identified by M protein DNA sequencing
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| hyaluronate capsule | typical of group A beta hemolytic strep, barrier to complement components and binds CD44 on host tissues
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| methods of virulence for GABHS | M protein, EC matrix binding protein, hyaluronic acid capsule, Ig-binding protein, C5a peptidase, streptolysins, DNAases acting on lysed cells in pus, streptokinase, superantigens
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| streptokinase | GABHS - degrades clots by activating host plasminogens and allowing spread in tissues
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| name of GABHS proteases that degrade host and bacterial tissues | SpeA, -B and -C proteases
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| 2 important immune-mediated conditions caused by GABHS infection | acute post-streptococcal glomerulonephritis
acute rheumatic fever
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| tonsillopharyngitis/strep throat - mainly caused by this bacterial group | GABHS (sometimes groups C or G)
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| differences btwn TSS by S. aureus and GABHS | S. aureus - inapparent site of infection, lacks bacteremia and low fatality rate
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| description/mechanism of acute rheumatic fever | occurs 7-21 days post-strep infection of the PHARYNX; thought to be a cross-rxn to antibodies initially produced against Strep, affects heart and other tissues
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| signs of acute rheumatic fever | heart inflammation producing arrhythmias, polyarthritis, fever, skin abnormalities, choreiform movements
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| description/mechanism of acute poststreptococcal glomerulonephritis | occurs 7-21 days post-strep infection of either skin or pharynx; immune complexes to Strep antigens are deposited in glomerular subepithelium
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| signs of acute poststreptococcal glomerulonephritis | from simple proteinuria or microscopic hematuria to complete renal failure then death
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| mechanism of puerperal sepsis | GABHS (or GBBHMS) travel up vagina, invades endometrium and uterine lymphatics to cause bacteremia
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| the major virulence factor associated with GBBHS | type III capsule, allowing evasion of phagocytosis
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| abx of preference for treating GBBHS | PCN or ampicillin
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| environmental niche of GBBHS | vagina - causes many OB and neonatal infections
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| most prevalent causative agent of CAP | Streptococcus pneumoniae
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| niche of Strep pneumo | upper resp tract/oropharynx
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| 2 main spots Strep pneumoniae has specific adhesion factors for | NAG and 3-Gal disaccharides on epithelial cells; PAF in the plasma
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| phase variation - definition and example of bacteria that exhibits it | ability to up or downregulate adhesion factors in the cell wall according to the site of attachment or infection; pneumococci
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| 3 abx of choice for pneumococcal infection | PCN G, vanc and Rocephin
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| features on would look for when Gram-staining sputum for pneumococcal infection | GP, lancet or football-shaped diplococci, optochin-sensitive, alpha hemolytic
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| drug of choice to treat VRE | ampicillin
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| special features typical for growing Enterococcus | grow in presence of bile and 6.5% NaCl
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| niche of viridans Streptococci like species mutans, sanguis and salivarius | mouth, on surface of teeth and gums
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| name diseases from toxins of Clostridia: difficile, tetani, botulinum, perfringens | C-diff diarrhea (nosocomial usually)
tetanus - spastic neurological dz
perfringens - gas gangrene, necrotizing skin infections
botulism - paralyzing neurological dz
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| name diseases from toxins of Bacillus genus: cereus and anthracis | anthrax - non-hemolytic type
food-borne diarrhea, is hemolytic
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| 2 most medically important non spore-forming GP rods | Corynebacterium and Listeria (both are non-filamentous also)
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| the most likely people to be affected by anthrax spores | abbatoir or slaughterhouse workers who are exposed to the hides or meat of animals who were previously infected
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| 3 clinical syndromes that could result from anthrax spore intoxication | cutaneous - from open wounds, trauma
GI - from eating contaminated meat
inhalational - from inhaling aerosolized spores
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| 3 virulence factors of Bacillus anthracis | edema toxin, lethal toxin and protective antigen
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| B. anthracis virulence factors are A-B toxins | protective antigen - B
edema and lethal factor - A (EF = calmodulin-dependent adenylate cyclase = anti-inflammatory cytokines; LF = MAPK kinase that stops cell growth)
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| best abx to treat B. anthracis | doxycycline and cipro (if naturally occuring, PCN hopefully)
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| pneumococcus vaccines | 13-valent polysaccharide version for children
23-valent " " " adults
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| 2 types of illneses produced from B. cereus intoxication | emetic and diarrheal illness
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| Contrast the 2 syndromes from B. cereus intoxication | emetic - from heat-stable endotoxin, improperly heated fried rice, sx within 1-6 hours
diarrheal - heat-labile endotoxin, from ingesting spores in cream sauce, vegetative cells germinate in gut, sx in 12-24 hrs
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| Clostridium species/type associated with gas gangrene | perfringens type A (a in both gas and gangrene)
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| Clostridium species/type associated with necrotizing enterocolitis | perfringens type C (C in colitis)
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| How does C. perfringens gain access to soft tissues and skin? | usually through trauma/dirty wounds where clostridia were in soil or feces and contacted wound
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| T/F Inflammatory cells are usually intermixed with C. perfringens when looking at gas gangrene tissue histologically. | no, they release toxins to lyse WBCs = no inflammatory cells
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| method of contracting C. perfringens gastroenteritis/specific pathogenic substance | ingesting meat that was stored at high temps allows spores to germinate and release heat-labile enterotoxin once in the body
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| mechanism of action of C. difficile toxins | toxins A/B - combo of enterotoxin that causes massive fluid secretion and cytotoxin that causes death and sloughing of intestinal epithelium
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| possible deadly outcome of C. difficile diarrhea | toxic megacolon
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| abx of choice to kill any remaining C. tetani bacteria at site of infection in tetanus pt | metronidazole (NOT!! PCN)
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| functions of the two chain toxin of C. tetani | heavy - specific binding to GABA-containing inhibitory nerves
light - endopeptidase that cleaves synaptobrevin = no vesicle release
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| neurotoxin that causes tetanus | tetanospasmin
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| mechanism of C. botulinum toxin | has light chain endopeptidase that prevents ACh release from NMJ = flaccid paralysis
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| most typical circumstance in which person comes into contact with C. botulinum | home canned products, eating food that wasn't cooked well enough and heat-labile toxin persists
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| why no raw honey to infants? | infant botulism from possible clostridial spores in honey
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| tx for tetanus | equine antitoxin
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| how C. diphtheriae become virulent | by acquiring the diphtheria toxin from a lysogenic phage
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| niche of C. diphtheriae | resp tract and skin
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| mechanism of A-B toxin of diphtheroids | B binds cell surface, A ADP-ribosylates EF-2 (elongation-factor 2) effectively stopping eukaryotic protein synthesis
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| vaccines available? tetanus, botulism, diphtheria, C. difficile infection | tetanus - yes
botulism - no
diphtheria - yes
C. diff - no
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| cause of death from diphtheria | toxin-induced cell death of throat epithelium, formation of pseudomembranes, obstruction of throat and resp failure from inability to get air or diaphragm paralysis
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| primary route of infection of Listeria | fecal-contaminated foods like milk or queso fresco, even when properly refrigerated
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| abx of choice for Listeria | ampicillin, possibly also Bactrim for some isolates
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| Listeria's preferred method for growing in host | intracellularly, induces phagocytosis then escapes into cytoplasm to replicate
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| tests to differentiate btwn Listeria and Streptococci | Listeria - catalase +, beta-hemolytic
Streptococci - catalase -, all types of hemolysis
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| erysipelothrix | caused by Erysipelothrix rhusiopathiae - erysipelas-like rash on hands of fisherman/abattoirs
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| causes severe acne | Propionibacterium acnes
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| diseases caused by Listeria monocytogenes | meningitis or bacteremia in immunocompromised and neonates, most typically though self-limited diarrheal illness
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| psychrophilic | able to live in refrigerator temps
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