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194 Cards in this Set
- Front
- Back
Enterobacteriaceae (Enterics) are facultative (aerobes/anaerobes)
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anaerobes
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Fecal coliforms
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another name for the enterics found commonly as part of intestinal flora
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Pirmary intestinal pathogens
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Salmonella, shigella, yersinia
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Opportunistic pathogens
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Normally part of intestinal flora that may produce infection outside the intestine when the immune system is compromised
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Enterics produce lethal (endotoxin/exotoxin)
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Endotoxin, called LPS composed of 3 distinct parts
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What are the 3 parts of an LPS?
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O polysaccharide
Polysaccharide core Lipid A |
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The flagella is also called the _ Antigen
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H antigen (these are heat liable)
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The capsule is also called the _ antigen
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K antigen (overlay the surface O antigen and may block agglutination by O specific antisera)
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In salmonella, the envelope or capsule is called the
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Vi antigen
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What are the modes of infection for enterics?
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Contaminated food and water (Salmonella, Shigella, Yersinia enterocolitica, Escherichida coli)
Endogenous infection (UTI - esp female, bacterial peritonitis, abdominal abscess) Abnormal host colonization (nosocomial pneumonia) Transfer between debilitated patients Insect (flea) vector) - unique for Yersinia |
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Enterobacterieae opportunistic infections include
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Gram neg sepsis, UTI, pneumonia (older or kids), abdominal sepsis, meningitis, spontaneous bacterial peritonitis, endocarditis
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Why is selective media useful for identifying Gram neg bacteria
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Bile salts and dyes suppress growth of G+ org's, and differentiate species based on lactose fermentation or H2S production
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What are the charatacteristics for all enterobacterieae?
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All ferment glucose
All reduce nitrates to nitrites All are oxidase negative All (except Klebsiella and Shigella) are motile |
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Enterobacterieae opportunistic infections include
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Gram neg sepsis, UTI, pneumonia (older or kids), abdominal sepsis, meningitis, spontaneous bacterial peritonitis, endocarditis
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What is serotyping?
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Identification based on antigenic features
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How are enterics identified?
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Based on growth charactaristics (using SELECTIVE media)
Biochemical testing (based on matabolism and production of certain acids) Serotyping (antigenic testing) |
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What type of media should one begin with when dealing with enterics?
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Selective media (MacConkey, HE, XLD agars)
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Why are non-selective agars an issue for growing enterobacterieae?
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Colonies all look virtually identical on BAP or CBA and may or may not be hemolytic
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Why is selective media useful for identifying Gram neg bacteria
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Bile salts and dyes suppress growth of G+ org's, and differentiate species based on lactose fermentation or H2S production
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Why are non-selective agars an issue for growing enterobacterieae?
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Colonies all look virtually identical on BAP or CBA and may or may not be hemolytic
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Why is selective media useful for identifying Gram neg bacteria
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Bile salts and dyes suppress growth of G+ org's, and differentiate species based on lactose fermentation or H2S production
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What are three ways bacteria can utilize carbohydrates?
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oxidation (aerobic)
fermentation (anaerobic) both (facultative anaerobes) |
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What are the most common carbohydrates used by enterics?
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glucose, lactose, maltose, sucrose, arabinose and rhamnose
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What are the most common carbohydrates used by enterics?
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glucose, lactose, maltose, sucrose, arabinose and rhamnose
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What are three ways bacteria can utilize carbohydrates?
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oxidation (aerobic)
fermentation (anaerobic) both (facultative anaerobes) |
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Asacchrolytic bacteria
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Do not use carbohydrates for metabolism
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Asacchrolytic bacteria
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Do not use carbohydrates for metabolism
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What are the most common carbohydrates used by enterics?
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glucose, lactose, maltose, sucrose, arabinose and rhamnose
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Asacchrolytic bacteria
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Do not use carbohydrates for metabolism
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Oxidation-fermentation tests
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determine the ability of a bacteria to utilize a specific carbohydrate incorporated into a basal medium aerobically or anaerobically
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What are the two different pathways pyruvic acid enters after glycolysis?
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Mixed acid fermentation pathway
Butylene glycol pathway |
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Mixed acid fermentation pathway
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Pyruvic acid (and H+ + NADH + ATP) made after glucose fermentation is converted into lactose and NAD+ (that is fed back into glycolytic pathway)
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Butylene glycol pathway
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Pyruvate is converted into CO2, acetaldehyde, NAD+. Acetaldehyde is converted to ethanol.
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How would one test for mixed acid fermentation bacteria?
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Methyl red test (MR test):
positive: red (acidic) negative: yellow (neutral) |
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What test is used to test for butylene glycol pathways?
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alpha-naphthol and 40% KOH (VP test):
positive: red (presence of alcholol) negative: no color change or pink (little to no alcohol) |
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Durham tubes
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detect small amounts of gas production
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TSI or KIA slants
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detect only large amounts of gas production
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KIA agar is differentiated from TSI by the
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absence of sucrose (only lactose and glucose)
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MacConkey agar
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selects for gram negative organisms. pH<6.8 causes the dye to turn red.
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HE (Hektoen enteric) agar
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High bile salt inhibits nonenteric organisms - differentiates pathogenic salmonella and shigella
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XLD (Xylose Lysine Deoxycholate) agar
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Contains xylose, lactose, sucrose and lysine. Salmonella fermentates sugar, will have purple colonies
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On XLD agar, proteus vulgaris will show
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black on a yellow agar
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What two enzymes are necessary for lactose fermentation?
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beta-galactosidase and beta-galactose permease
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ONPG test
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Quickly detects lactose fermentation (Galactose-Glucose replaced by Galactose-Nitrophenyl)
negative: cloudy white positive: yellow |
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OPNG test detects beta-galactose permease activity (T/F)
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False, only detects beta-galactosidase activity
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Cytochrome oxidase
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tests for oxidase presence, enterics will all be negative
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Nitrate reducion test
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Addition of alpha-naphthylamine and sulfanilic acid
red: positive (nitrate is reduced) not red: negative (nitrate is not reduced) Negative tests must then be treated with zinc dust to test for a false negative (zinc reduces any residual nitrates to confirm a negative test) |
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IMViC test
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Detects presence of tryptophanase
Methyl red test looks for strong acids. Voges Proskauer test: detects acetoin and butylene glycol from glucose fermentation Citrate utilization: determines organisms ability to utilize sodium citrate |
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IMViC test results for E. coli?
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I: +
M: + V: - C: - |
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Urease test
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determines an organisms's ability to metabolize urea and release ammonia
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Phenylalanine deaminase test
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detects oxidative deamination
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IMViC results for E. coli?
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pos/pos/neg/neg
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What two tribes of pathogenic enterobacterieae are very similar?
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Eschirichiae and Shigella
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What antigens are used to test for E. coli?
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O antigen (LPS)
H antigen (flagella) K antigen (capsule) |
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TSI is A/A + gas
LIA is K/K IMViC: pos/pos/neg/neg Urea: neg Motility: pos Phenylalanine: neg |
E. Coli
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What is a very common site of infection for E. coli?
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Urinary tract
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What is an ETEC
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Enterotoxigenic: traveler's diarrhea, watery stool, abdominal cramps, (NO FEVER)
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EPEC
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Enteropathogenic E. Coli - seen commonly in babies, fever, vomiting, diarrhea, NO BLOOD IN STOOL
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EIEC
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Enteroinvasive E. coli - FEVER, blood in stool, mucus, white cells in stoll
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EaggEC
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Enteroaggregative e. coli - watery diarrhea, vomiting
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EHEC
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enterohemorrhagic e.coli - commonly 0157:H7
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O157:H7 produces what results on MAC?
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pink colonies
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What is the strain of E. coli currently spreading through Europe?
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O104:H4: shigella like toxins
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All species of Shigella possess which antigen?
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O antigen. Shigella never has an H antigen and sometimes has K antigen.
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How are Shigella species divided?
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Four serologic groups based on the kind of O antigen.
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What are the four clinically significant species of Shigella?
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S. dysenteriae (serogroup A), S. flexneri (B), S. boydii (C), S. sonnei (D)
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Characterize Shigella sonnei based on lactose fermentation, motility, gas production, ureaase, H2S, lysine, arginine and ornithine decarboxylation.
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Lactose negative
Nonmotile No gas production No urease activity No H2S production Do not decarboxylate lysine or arginine DO decarboxylate ornithine (slowly ferment lactose) |
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What are some symptoms of genums Shigella?
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dysentery, seizures, HUS (hemolytic uremic syndrome)
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Dysentery
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High fever, chills, abdominal cramps, pain and TENESMUS (unique to shigella)
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Tenesmus
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Feels like constipation but there is no actual stool is in intestine
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Shigella sonnei
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Organism most commonly associated with diarrheal disease in the US. Asymptomatic or mild symptom.
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S. dysenteriae
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Rare in developed nations, but very virulent and common in 3rd world. Cannot ferment mannitol.
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S. flexneri
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Mild to asymptomatic, difficult to distinguish
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How would a person commonly contract Edwardsiella tarda?
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Usually contracted from fresh water fish or reptiles.
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Pathogenesis and symptoms of E. tarda
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Bacteremia, wound infection (usually water related) Septicemia seems to be more severe when iron is abundant
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What are the biochemical charactaristics of Edwardsielleae?
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No lactose fermentation
H2S producer **Lysine and ornithine decarboxylation** |
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How do Edwardsielleae look on HE and MAC agar?
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MAC: Black
HE: colorless |
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What are the two species of Salmonelaa?
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S. enteritica and S. bongori
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What happened to the many species of Salmonella?
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Many were rolled into S. enterica and are now subspecies strains of that species. (ie. S. typhi is now S. enterica ss serotype typhi)
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Does Salmonella ferment lactose?
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No
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Is Salmonella motile?
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Yes
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Does Salmonella decarboxylate lysine or ornithine?
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Lysine for both
Salmonella: Non-typhi is pos for ornithine, typhi is neg |
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Is Salmonellla Citrate positive or negative?
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Positive
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Virulence factors of Salmonellae?
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Endotoxins - play a role in intracellular survival
Capsule - anti-phagocytosis Adhesions - attach to epithelial cells Type III secretion systems |
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What type of disease is caused by Salmonella?
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Enterics fevers (typhoid fever) and gastroenteritis (food poisoning) - also non-typhoidal septicemia. Salmonella can be a carrier.
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What is the most common cause of food poisoning in the US?
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Salmonella enterica ss enterica (formerly S. enteritidis)
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What is commonly contaminated by S. enterica ss enterica (S. enteritidis)
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Contaminated food, water and milk. Common: uncooked eggs
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Typhoid fever
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Caused by Salmonella enterica ss enterica serotype typhi and serotype paratyphi. First 2 weeks: fever, constipation, bacteria in blood but not in stool.
After 2 weeks: diarrhea begins, blood culture negative and stool positive |
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What's the difference between gastroenteritis and enteric fevers?
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Enteric fever (typhoid) involve the spread of the bacteria into the blood, causing bacteremia.
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Non-typhoidal bacteremia or septicemia
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Occurs without GI symptoms; high fever and positive blood culture
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Carrier state (salmonella)
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Organisms centralized in gall bladder (removal necessary) and patient will have organism in stool for up to a year after having typhoid fever
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Salmonella:
H2S: Citrate: Ornithine: Gas: |
H2S: trace
Citrate: neg Ornithine: neg Gas: none |
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What media are best for Salmonella isolation?
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MAC, HE, XLD
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Biochemical results of S. enterica ss arizonae
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Malonate positive
Dulcitol neg OPNG pos Lactose fermentation (some) |
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Citrobactereae
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grow on citrate medium
methyl red positive lactose fermenter urease pos looks similar to E. Coli on MAC |
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Lactose fermenters show up which color on MAC agar?
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pink
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What diseases are associated with C. freundii?
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Nosocomial infection
UTI Pneumonias |
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C. koseri?
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Associated with infant meningitis and brain abscess. Most infants will not survive infection and those that do will have neurological damage.
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What tests can be used to differentiate C. freundii?
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H2S positive
Urease activity Lysine decarboxylase negative |
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What are the most common species of Klebsiella?
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K. pneumonieae and K oxytoca
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Klebsiella is motile (T/F)
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False
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Some characteristics of Klebsiella?
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H2S negative
MR negative VP positive Growth on citrate and KCN Urease activity positive Most do not produce indole (K. oxytoca does) |
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K. pneumonieae ss pneumonieae
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frequently recovered lower resp. tract infection.
Classic pneumoni: necrosis, hemorrhage, thick brick red sputum |
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K. oxytoca
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similar symptoms to K. pneumonieae
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What is special about Klebsiella?
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Produces large mucoid colonies on primary isolation media (because of polysaccharide capsule)
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How does one differentiate K. oxytoca and K. pneumonieae?
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K. oxytoca: Indole positive
K. pneumonieae: Indole negative |
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What is ESBL?
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Extended spectrum beta lactamase - antibiotic resistance encoding plasmid present in non-K. pneumonieae species of Klebsiella
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What is an important test to perform when dealing with Klebsiella for patient treatment?
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Identification of antibiotic susceptability and resistance
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Two common species of Enterobacter?
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E. aerogenes and E. cloacae
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Is Enterobacter ornithine decarboxylase positive or negative? Is it motile?
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Positive; Motile
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How are E. aerogenes and E.cloacae differentiated?
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E. aerogenes
Lys: + arg: - E. cloaceae: lys - arg: + |
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Cronobacter sakazakii
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Related to infant meningitis. Bright yellow on TSA.
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Most common species of Pantoea?
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P. agglomerans
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Where is P. agglomerans commonly isolated from?
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P. agglomerans is commonly isolated from plant matter and animal and human waste.
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What is the pathogenesis of P. agglomerans?
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Opportunist; causes septicemia, UTI, wound infection
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How does P. agglomerans utilize lysine arginine or ornithine?
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Does not produce any of these.
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How does P. agglomerans frow on MAC and SBA?
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MAC: pimply red
SBA: yellow |
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what are the two Hafnia (Klebsielleae) species?
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one species but two biotype Hafnia alvei and Hafnia alvei biotype 1
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Common species of Serratia?
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S. marcescens
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What enzymes are charactarized by Serratia
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Lipase, gelatinase and DNAase
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Color of S. marcescens on MAC?
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pink to red pigmented colonies on mac
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Proteus are (normal/abnormal) in intestinal flora
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normal flora
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Proteus is a lactose fermenter (T/F)
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False; proteus does not ferment lactose.
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Proteus is phenylalanine deamninase (positive/negative)
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positive
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Which species of Proteus are commonly pathogenic?
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P. mirabilis and P. vulgaris
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Proteus are commonly found in nosocomial cases (T/F)
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True. Proteus are responsible for ~3% of nosocomial infections in the US.
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What colony morphology is charactaristic of Proteus on SBA?
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Swarming colonies on non-selective media with a distinct odor.
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Proteus are H2S (positive/negative)
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Positive
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Proteus are urease (pos/neg)
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pos
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What test is used to diff P. mirabilis and P. vulgaris?
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Indole and ornithine
P. mirabilis is indole neg and orn pos P. vulgaris is indole pos and orn neg |
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What are the two subspecies of Morganella morganii?
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M. morganii ss morganii
M. morganii ss sibonii |
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What are the common charactaristics of Providencia?
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Lactose negative
PDA positive Indole positive Citrate positive H2S negative |
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P. stuartii is commonly isolated from?
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From burn unit patients
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P rettgeri
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Common in nosocomial, traveler's diarrhea and
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How does one diff P. stuartii and P. rettgeri?
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Urease and arabitol fermentation
P. stuartii: arabitol neg and urease neg P . rettgeri: arabitol pos and urease pos |
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Yersinia pestis is caused by..
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Caused by fleas carried by rats (bubonic plague)
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What are the two forms of Yersinia pestis infection in humans?
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Bubonic (glandular) - 2 - 5 days after infection, high fever, swollen lymph nodes, black spots on skin
Pneumonic - secondary to bubonic: bacteremia, sepsis, respiratory infection |
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What is the optimal temperature for Y. pestis growth?
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25 - 30 C
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Y. pestis is ornithine (neg/pos)
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Negative (also urease negative)
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How is Y. entercolitica transmitted?
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Via pets, contaminated food (esp. meat, chocolate milk, water), infected infusion
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Why is Y. entercolitica so dangerous?
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Can survive in colder temperatures
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What four conditions are associated with Y. entercolitica?
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Acute enteritis: *fever*, abd. pain, nausea, diarrhea, bloody stool (TODDLERS AND CHILDREN)
Mimic acute appendicitis (ADULTS) Arthritis - most common extraintestinal form (usually followed by GI) Erythema nodosum - tender red itchy nodules |
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What are some special ID charactaristics of Y. entercolitis?
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Growth at 25 - 30 C, loses motility at 35+ C. Better growth with cold enrichment (4 C)
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What selective media is used for Y. entercolitica?
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CIN: produces red "bull's eye" colonies
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Why is Y. pseudotuberculosis so dangerous?
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Causes mesenteric lymphadenitis, very high mortality rate in children.
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HACEK
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Haemophilus aphrophilus/paraphrophilus
Actinobacillus actinomycetemcomitans Cardiobacterium hominis Eikenella corrodens Kingella spp |
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General char's of HACEK
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gram neg bacilli, oropharyngeal and urogenital flora
Pathogenicity: endocarditis, bacteremia, mixed-flora wound infections |
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How long do HACEK organisms take to grow?
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at least 2-3 days sometimes 2 weeks
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What medium is used to grow HACEK?
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SBA or chocolate agar; MAC, HEK, etc do not work
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What are causes and symptoms of H. aphrophilus/paraphrophilus infection?
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endocarditis, brain abscess, meningitis, osteomyelitis, soft tissue infection - caued by dental disease, animal bites and skin piercing
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ONPG, catalase and acid for H. aphrophilus
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Positive; negative; positive
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A. actinomycetemcomitans symptoms
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Abscesses, bacterial endocarditis, periodontitis, Papillion-Lefevre syndrome
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Papillon-Lefevre syndromeassociated with A. actinomcetemcomitans
|
Hyperkeratosis of palms and soles, and periodontal destruction
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Portals of entry for A. actinomcytemcomitans
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oral lesions, skin abrasions, pulmonary infection, thoracotomy, UT instruments (ie. catheter, cystoscope)
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A. actinomcytemcomitans virulence factors
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Leukotoxin - kill neutrophils, monocytes and T-lymphocytes by damaging chromosomal DNA
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What is special about A. actinomcyetomcomitans colonies?
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Star-shaped area after 1 wk on SBA/chocolate
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A. ureae colonies show
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distinct filaments
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Cardiobacterium hominis is mainly associated with which condition?
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endocarditis primarily,followed by dental disease
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How do you get a good gram stain of C. hominis? good culture?
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Must be spun down first; requires subcultures since initial culture growth is usually weak
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Eikenella corrodens route of infection?
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human bite, head and neck infection, frequent in the immunosuppressed and IV drug users.
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Eikenella virulence factors?
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Pili, slime layer (prevents phagocytosis) proteins for adherence
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Eikenella cultures do what to agar?
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Pitting
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Eikenella smells like...
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bleach
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Kingella denitrificans can be confused with N. gonorrheae. What test is used to distinguish the two?
|
K. dentrificans ans catalase neg and superoxol neg
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K. dentrificans colonies are
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smooth and opaque
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Kingella kingae
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Associated with child-to-child transmission
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K. kingae morphology on SBA
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Plump GN rods, Beta hemolytics, pitting
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Suttonella indologenes
|
similar to K. kingae except for indol positive
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S. indologenes is resistant to which antibiotics
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clinidamcyin, erythromycin, lincomycin, vancomycin
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HACEK stands for?
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H = Haemophilus aphrophilus/paraphrophilus
A = Actinobacillus actinomycetomcomitans C = Cardiobacterium hominis E = Eikenella corrodens K = Kingella spp |
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HACEK organisms generally cause which disorders?
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Endocarditis, bacteremia, mixed-flora wound infections
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HACEK is a normal flora of what part of the body?
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Oropharyngeal and urogenital tracts
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What are the growth requirements for HACEK?
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Enriched media (ie. SBA, chocolate) capnophilic (5-7% CO2) and time (2-3 day minimum, sometimes weeks)
|
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What is the normal habitat of H. aphrophilus/paraphrophius in humans?
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Oral cavity (dental plaque) and upper resp. tract
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What conditions are assocaited with H. aphrophilus/paraphrophilus?
|
Endocarditis (esp. with valvular heart disease) brain abscess, meningitis, osteomyelitis, soft tissue infection
|
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What is mode of transmission for H. aphrophilus/paraphrophilus?
|
Dental disease, dog bites, piercings
|
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What distinguishes H. aphrophilus/paraphrophilus from other HACEK?
|
ONPG positive
catalase negative acid producer |
|
How does one distiguish H. aphrophilus from paraphrophilus?
|
H. aphrophilus does NOT require X or V factor
H. paraphrophilus requires V factor Neither require X factor |
|
What are H. aphrophilus/paraphrophilus susceptible to/resistant to?
|
Tetracycline, chloramphenical, streptomycin, 2nd generation cephalosporins, quinolones
Resistant to PCN and ampicillin. |
|
Actinobacillus actinomycetmcomitans is involved in what diseases/conditions?
|
Subactute bacterial endocarditis (with hx of heart disease)
Juvenile periodontitis |
|
What organism is associated with Papillon-Lefevre syndrome?
|
Actinobacillus actinomycetmcomitans
|
|
What are the portals of entry for Actinobacillus actinomycetmcomitans?
|
Oral lesions, skin abrasions, pulomary infections, thoracotomy, catheters
|
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Virulence factors of Actinobacillus actinomycetmcomitans
|
Leukotoxins that inhibit immune response by killing WBC's
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Growth requirements of Actinobacillus actinomycetmcomitans?
|
Enriched media, at least 48 hrs, capnophilic env.
No X or V factor required. |
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Which bacteria is commonly found canine oral cavities?
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C. canimorsus
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What are the symptoms of Capnocytophaga?
|
Fulminant septicemia and peripheal gangrene
|
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How can Capnocytophaga cause juvenile periodontitis?
|
When it's with an actinomycetemcomitans infection
|
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Salidases/aminopepsidases
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Capnocytophaga virulence proteins
|
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What mode of xmission is associated with Streptobacillus moniliformis
|
Rodent
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Is Streptobacillus motile?
|
No
|
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What special measures need to be taken to culture Streptobacillus moniliformis?
|
Need to be cultured in live host
|
|
Haverhill fever
|
Caused by S. moniliformis. Fever, GI symptoms, rash. MIMICS LYME'S DISEASE
|
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The selective agar used for Bordatella is..
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Bordet-Gengot (high starch)
Regen-Lowe agar (mother of pearl colonies on this) |
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The slective agar for Francisellais...
|
BCYE
|