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bacteriology > GPC, HACEK, Spore-formers > Flashcards

GPC, HACEK, Spore-formers Flashcards

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1
Q

staph spp. characteristics

A

-skin & mucous membranes
-cocci in clusters
-gram pos
-no spores or flagella
-may have capsules (VISA)

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2
Q

MIC for staph spp.

A

MIC >2 & <8 is not considered officially resistant
-VISA is the range between 2 & 8 on E test

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3
Q

staph aureus

A

-large, round, opaque colonies
-facultative anaerobe
-can withstand high salt, ph, temp

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4
Q

staph aureus virulence factors

A

-hemolysins
-leukocidin: PVL produced from bacteriophage, PVL pos staph = deadly pneumonia
-enterotoxin: GI distress
-exfoliative toxin: epidermis from dermis
-TSST: fever, vomiting, shock, systemic organ damage

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5
Q

enzyme virulence of staph aureus

A

-coagulase
-hyaluronidase: digests connective tissue
-staphylokinase: digests blood clots
-DNAase
-lipases
-penicillinase: inactivates penicillin

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6
Q

local staphylococcal disease

A

-local to systemic
-localized cutaneous infections: invade through skin, wounds, follicles, or glands

*folliculitis
*furuncle- boil
*carbuncle- lesions from clusters of furuncles
*impetigo- bubble-like swelling (babies). herpes infection

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7
Q

systemic staphylococcal diseases

A

-osteomyelitis
-bacteremia (endocarditis)

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8
Q

toxigenic staphylococcal diseases

A

-food intoxication: heat stable enterotoxins, GI distress
-scalded skin syndrome: bright red flesh, blisters.
-TSS: shock & organ failure

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9
Q

other staphs

A

-epidermidis: skin & mucous membranes, endocarditis, UTI, bacteremia
-hominis
-capitis
-saprophyticus

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10
Q

ID of staph

A

-isolated from pus, tissue, sputum, urine & blood
-cultivation, catalase, biochemical testing, coagulase

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11
Q

catalase test

A

-staph is catalase pos
-strep is catalase neg

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12
Q

coagulase test

A

-coagulase pos: staph aureus
-coagulase neg: other staph spp.

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13
Q

MRSA

A

-methicillin resistant staph aureus
-contains mecA gene
-resistance to all beta-lactam antibiotics

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14
Q

general characteristics of strep

A

-gram pos, spherical/ovoid cocci in chains (pairs)
-non-motile
-can form capsules & slime layers
-facultative anaerobes
-catalase neg but have peroxidase system
-parasitic forms are fastidious
-small, non-pigmented colonies
-sens to drying, heat & disinfectants

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15
Q

alpha vs beta hemolysis in strep

A

-beta hemolysis; complete hemolysis (groups A, B, C, G, & D)
-alpha hemolysis; partial hemolysis (strep pneumoniae, viridans group strep)

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16
Q

strep pyogenes

A

-beta hemolytic
-most serious strep
-strict parasite
-inhabits throat & nose

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17
Q

virulence of strep pyogenes

A

-C-carbohydrates: protect against lysozyme
-fimbriae: adherence
-M protein: resistance to phagocytosis
-hyaluronic acid capsule: provokes no immune response

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18
Q

beta hemolytic strep pyogenes virulence factors

A

-streptolysin: hemolysins, SLO & SLS cause cell & tissue injury
-pyogenic toxin: fever & rash
-superantigens: mono & lymph stimulants- tissue necrotic factor

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19
Q

impetigo

A

superficial lesions that break & form highly contagious crust. epidemics in schools- associated with insect bites, poor hygiene, & crowded living conditions

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20
Q

erysipelas

A

pathogen that enters through a break in the skin and eventually spreads to the dermis & subcutaneous tissue

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21
Q

strep pharyngitis

A

strep throat

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22
Q

strep clinical disease

A

systemic infections:
-scarlet fever; strep pyogenes carrying a prophage that codes for pyrogenic toxin
-septicemia
-pneumonia
-streptococcal toxic shock syndrome

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23
Q

long term complications of group A strep

A

-rheumatic fever: manifests as carditis with extensive valve damage, arthritis, chorea, fever
-acute glomerulonephritis: increased bp, heart failure, chronic leading to kidney failure

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24
Q

group B strep

A

-normal human flora
-can be transferred to child during birth
-most prevalent cause of neonatal pneumonia, sepsis & meningitis
-33% fatal in infants

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25
group D strep
-enterococcus faecalis, faecium, durans -strep gallolyticus; colon cancer -opportunistic
26
endocarditis
subacute bacterial endocarditis -preexisting heart disease at high risk -colonization of heart by forming biofilms -meningitis -intra-abdominal infections -gingivitis & dental abscesses
27
strep pneumoniae
-60-70% of all bacterial pneumonias -small, lancet shaped cells in pairs & chains -blood or chocolate agar -die in O2 -all pathogenic strains form large capsules -alpha hemolytic & P disk
28
viridan strep
-oral or bowel flora -alpha (green) hemolytic
29
human bite and the organism pits sheep blood agar
Eikenella corrodens
30
HACEK acronym
-fastidious gram neg cocccobacillary organism -Haemophilus aphrophilus (not true haemophilus- does not need X or V) **now called Aggregatibacter aphrophilus -Aggregatibacter spp -cardiobacterium hominis -Eikenella corrodens -Kingella spp frequently affect damaged valves & case emboli
31
infective endocarditis
-majority of cases caused by strep, staph, enterococcus, or fastidious gram neg cocco-bacillary -staph aureus causes most cases of IE
32
HACEK general characteristics
-slow growing -fastidious -gram neg bacilli -require increased CO2 (5-10%) -usual flora in oropharyngeal cavity -opportunistic in immunocompromised patients
33
HACEK clinical significance
-IE -peridontal disease -dental caries -infections following dental procedures
34
lab ID for aggregatibacter (haemophilus) aphrophilus
-small convex white-grey, non-hemolytic colonies on BA -yellow convex, entire, smooth colonies on chocolate -poorly staining coccobacilli -KIA- acid/acid -only xylose & mannitol are neg -nitrite; strong reduction
35
Haemophilus spp
-require hemoglobin for growth --factor X (hemin)- heat stable --factor V (NAD)- heat-labile, coenzyme, NAD found in blood -pleomorphic gram neg bacilli
36
haemophilus species
-true haemophilus require both X & V -parainfluenzae only uses factor V -aphrophilus only used factor X
37
swollen joints revealing cloudy fluid & gram neg bacilli:
kingella kingae -septic arthritis
38
lab ID of aggregatibacter actinomycecomitans
-slow growing, tiny, non hemolytic colonies on BA -pale-staining gram neg cocco-bacilli -KIA: acid/acid -lactose & sucrose neg -ornithine decarboxylase neg -nitrate reduced -indole neg
39
c. hominis
-endocarditis in patients with underlying valvular heart disease or with prosthetic valves -aortic valve -septic arthritis -gram stain in rosettes
40
lab ID of c. hominis
-small, clear, smooth, non hemolytic colonies on BA -gram variable slender bacilli with distinct poles in rosettes -KIA: acid/acid -xylose & lactose neg -nitrates reduced to gas -indole pos
41
eikenella corrodens
-soft tissue infections in teeth & trauma -clenched fist & bite injuries -exists in dental plague of healthy people
42
eikenella corrodens characteristics
-gram neg bacillus -non motile -non spore forming -cytochrome pos -reduced nitrate -facultative anaerobe -stimulated growth by 3-10% CO2
43
lab ID of kingella kingae
-small, entire, transparent colonies on BA with soft beta hemolysis -gram neg, short, plump coccobacilli -KIA: alk/alk (non-fermenter) -oxidase utilization of dextrose & maltose (the rest are neg)
44
bacillus anthracis
-large, spore-forming aerobic, gram pos in pairs or long chains -nonmotile, nonhemolytic -grows rapidly in host & culture -vegetative & spore
45
anthrax
-disease of herbivores -inhalation, cutaneous, GI -bioterrorism
46
b. anthracis spores
sporulation requirements: poor nutrient condition, presence of oxygen spores: very resistant -lethal dose: 2500-55000 spores
47
b. anthracis virulence
2 active chains (EF, LF) & one binding chain (PA) -capsule: poly-D-glutamic acid. antiphagocytic -EF: increases intracellular cAMP. hypersecretion (edema) -LF: Zn-dependent peptidase. induced apoptosis & cell necrosis PA: binding component, combines & delivers EF or LF
48
b. cereus misc.
-normal in soil -food-borne intoxications -in sushi rice if not stored properly (vinegar)
49
b. cereus characteristics
-large, spore forming, aerobic, gram pos bacillus -non hemolytic -motile -box-car shaped -stain with malachite green -food borne transmission (undercooked rice) -resistant to penicillin
50
importance of spores
-resistant to heat, drying, pressure & disinfectants -antibiotic resistant -survive in hospital environment -spores are not reproductive (survival)
51
diagnostic spore form for c. tetani & c. botulinum
tetani: terminal spore botulinum: sub-terminal spore
52
lab ID b. cereus
-large, flat, grey-yellow colonies on BA, matte to granular consistency, fimbriated edges & beta hemolysis -short, gram pos bacilli, singularly or short chains, central or subterminal spores -catalase pos -lecithinase produced on egg yolk agar -casein, starch, gelatin hydrolyzed
53
lab ID of bacillus anthracis
-flat, spreading, non hemolytic, grey-yellow colonies on BA with ground-glass surface & irregular margins -tenacious consistency that stands up like whipped egg -long, gram pos bacilli in chains. -terminal & subterminal spores -catalase pos -reference lab for ID
54
clostridium perfingens
-gram pos, non motile, obligate anaerobes, spore forming, capsulated, rounded end bacilli -spores are oval, central or subterminal, not bulging -grows best on glucose or glucose blood agar -self limiting gastroenteritis or clostridial myonecrosis -produce alpha, beta, epsilon toxins -all types produce alpha-toxin (phospholipase) gangrene causative agent
55
c. perfringens pathogenesis
cellulitis: subcutaneous tissue infection, discolored skin, gas formation, edema, no necrosis suppurtative myostits: fascilitis, pus in muscles, no necrosis clostridial myonecreosis: gas gangrene, life-threatening, muscle necrosis, fast spreading, tachycardia & systemic fever, intravascular hemolysis, shock, organ failure -super fatal
56
camp reactions
-regular arrow head is strep streaked with staph aureus -gram pos bacilli have a synergistic zone that is small & rectangular (Listeria identification)
57
c. perfringens ID
-double zone of hemolysis -robertson's media(cooked meat medium): blackening of meat with strict anaerobes -clots litmus milk (stormy fermentation: acid gas curd)
58
c. difficile
-gram pos, spore forming bacillus -grows on selective media in 2 days & smells like horse poop -strict anaerobe, motile, difficult to culture -normal gut flora -relatively drug resistant
59
cdif & antibiotics
antibiotics (vanco, clindamycin, cephalosporins, penicillins, beta-lactams) reduce all other bacteria in the intestinal track and allow for overgrowth of c. difficile, leading to CDI
60
c. dificille virulence
-toxigenic strains produce 2 large protein exotoxins that are associated with virulence (toxins A & B) -toxin A (enterotoxin) damages tight junctions which increase the permeability of gut epithelial layer. chemoattractant for PMNs -toxin B (cytotoxin) destroys cytoskeleton, kills enterocytes
61
pseudomembranous colitis (antibiotic resistant colitis)
-fever, abdominal pain, bloating, cramping -fulminant watery diarrhea with WBC -inflammatory plaque on gut wall -progresses to toxic megacolon (fatal)
62
anaerobic bacteria
-toxic forms of oxygen get neutralized by superoxidase dismutase, catalase, peroxidase -anaerobic bacteria do not produce these and cannot survive in the toxic oxygen
63
c. botulinum
-strict anaerobe, gram pos bacillus, -found in soil, animal feces
64
c. botulinum virulence
-botulinum toxin -toxins A, B, E, & F cause human disease -A & B associated with foods -E associated with fish products
65
c. botulinum pathogenicity
-absorbed through gut, carried via blood, binds presynapses of motor neurons in PNS & CNS -block release of acetlylcholine -protease that cleaves proteins
66
infant botulism
-first month of life -ingestion of honey causes botulism in infants
67
lab diagnosis of botulinum
-culture from feces -definitive diagnosis = detection of toxin -ELISA & PCR
68
c. tetani
-anaerobic, gram pos, slender bacilli -spherical, terminal spores giving drum stick appearance -no capsules -motile with flagella
69
c. tetani virulence
-2 exotoxins: tetanolysin, tetanospasmin -tetanolysin: damages tissues surrounding infection and optimizes conditions for bacterial multiplication -tetanospasmin (tetanus toxin): plasmid-coded neurotoxin responsible for disease -released upon cell lysis after bacterial overgrowth (anaerobic conditions). -antigenic and neutralized by its antitoxin. toxoid form used for vaccine
70
c. tetani pathogenicity
-unlike c. perfringens, c. tetani is not invasive -remains localized -germination of spores aided by: necrotic tissue, calcium salts, pyogenic infections -tetanopasmin blocks GABA causing muscle spasms (spastic paralysis)
71
c. tetani lab diagnosis
-anaerobic culture of tissues, not required for ID -RCM broth: tetani turns meat particles black -blood agar with polymyxin B
72
clostridia spores & ID of organism
central spore: c. bifermentans sub-terminal: c. perfringens oval & terminal: c. tetrium spherical & terminal (drum stick): tetani

bacteriology (2 decks)

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