Term
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Definition
| Yersinial infections are zoonotic infections that usually affect rodents, small animals and birds. Humans are accidental hosts. Gr |
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Term
| Important characteristics of Yersineae |
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Definition
Gram neg coccobacillary rod, but not true "straight" bipolar staining rod
MR: Positive
VP: Negative
Motile at 22 degrees Celsius, but not at 35 degrees Celsius
Urea: Positive (rapid) |
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Term
| Clinically important Yersineae spp. |
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Definition
Y. pestis
Y. enterocolitica
Y. pseudotuberculosis |
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Term
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Definition
Cause of the plague
Organisms are endemic in rodent populations in Southeast Asia and in the Southwestern U.S.
Transmission is by rodent flea or respiratory aerosols from infected humans |
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Term
| Yersinia pestis cell wall produces an endotoxin that |
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Definition
| Produces multiple organ failure which leads to death |
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Term
| Septicemia of Yersinia pestis |
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Definition
| Dissemination of bubonic form into the bloodstream. Large amounts of organisms are found in blood be transmitted by transfusions |
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Term
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Definition
| Caused by Yersinia pestis. It is the most serious form and is highly contagios, spread via respiratory droplets and rapidly fatal if left untreated. Can be treated using streptomycin |
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Term
| Lab identification of Yersinia pestis |
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Definition
Specimens: Aspirates from buboes, lmyph nodes and respiratory specimens
Biochemiccaly inert, need to be sent to the reference lab for ID. Rarely seen in the US. |
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Term
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Definition
Production of heat stable enterotoxin that causes diarrhea. May mimic appendicitis and cause septicemia and peritonitis
Transmitted through animal reservoirs (birds, pigs, cows) and contact with infected animals. It can also be seen in raw milk, water and other food sources. |
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Term
| Yersinia enterocolitica organisms can survive what? |
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Definition
| Pasteurization and multiply at 4 degrees Celsius |
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Term
| Yersinia enterocolitica lab identification |
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Definition
Done only on request
KOH broth (reduces the amount of NF. Place specimen in broth for 4-5 mins and transfer to CIN agar)
Incubate at 22 degrees Celsius for 48 hours. Colonies on CIN will be dark pink with translucent borders |
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Term
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Definition
Cefsulodin, irgasin, novobiocin: reduces NF
Mannitol: Carbohydrate source
Neutral red: pH indicator |
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Term
| Yersinia pseudotuberculosis |
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Definition
Primarily a disease of rodents and birds
More common in Europe than the US
Causes a penumonia-like illness that mimics TB in disease presentation; however organisms are not related at all |
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Term
| Differentiation between Yersinia pestis and Yersinia enterocolitica |
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Definition
Motility: Enterocolitica is positive for motility at 25 degrees Celsius while Pestis is not
ONPG: Enterocolitica is positive and pestis is negative
Urea: Enterocolitica is positive and pestis is negative
Ornithine: Enterocolitica is positive and pestis is negative
Sucrose: Enterocolitica is positive and pestis is negative |
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Term
| What is the only genus in the Tribe Citrobactereae |
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Definition
| Only genus is Citrobacter |
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Term
| What are the clinically significant species of the Citrobacter genus? |
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Definition
Citrobacter freundii
Citrobacter koseri (formerly c. diversus)
Citrobacter amalonaticus |
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Term
| Key biochemicals of the Citrobacter genus |
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Definition
MR: Positive
VP: Negative
Citrate: Positive
Motility: Positive
ONPG: Positive
Lysine decarboxylase: Negative |
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Term
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Definition
Found in soil/water
NF of stool
Opportunistic pathogen
Causes UTI's, pneumonia and septicemia |
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Term
| Colonial morphology of Citrobacter spp |
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Definition
BAP: Large, wet, mucoid colonies
MAC: Pink colonies "donuts" C. freundii looks like E. coli)
XLD: Yellow colonies (C. freundii is H2S positive yellow colonies with black centers) |
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Term
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Definition
Resistant to antibiotic therapy. Resistant to ampiciliin and cefazolin
H2S: Positive (May be initially confused with Salmonella spp in stool culture, but Salmonella spp is H2S positive and lactose negative)
Indole: Negative
Ornithine decarboxylase: Negative |
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Term
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Definition
Indole: Positive
Malonate: Positive
Adonitol: Positive |
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Term
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Definition
Indole: Positive
Malonate: Negative |
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Term
| Tribe Escherichiae includes what generas? |
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Definition
Eschericia spp
Shigella spp |
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Term
| Key biochemicals of Escherichiae |
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Definition
PAD: Negative
Urea: Negative
MR: Positive
VP: Negative
H2S: Negative
Citrate: Negative |
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Term
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Definition
Only 1 clinically significant species: E. coli
NF of stool
Most common cause of community-acquired UTI's (esp. females)
Also causes wound infections, pneumonia, septicemia and meningitis |
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Term
| E. coli is usually not considered a pathogen if isolated from stool. However, there are some what? |
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Definition
| Extremely virulent strains that may cause intestinal disease |
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Term
| Enteropathogenic E. coli (EPEC) |
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Definition
Causes diarrhea, esp in infants
Disease is caused by toxin
Toxin production is carried on a plasmid which may be transferred to other organisms |
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Term
| Enterotoxigenic E. coli (ETEC) |
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Definition
Causes profucse, watery diarrhea
Resembles cholera
Due to production of enterotoxin
Also known as "Traveler's diarrhea" |
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Term
| Enteroinvasive E. coli (Alkalens-dispar) |
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Definition
Causes dysentery-like illness similar to Shigella
Stool contains increased WBC's, RBC's and mucus |
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Term
| Hemorrhagic colitis (E. coli O 157:H7) |
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Definition
Causes severe diarrhea with bloody stools
Undercooked ground beef (and other foods) are a source
Can cause hemolytic uremic syndrome (HUS)
MAC with sorbitol: clear colonies
(E. coli O 157:H7 is sorbitol negative) |
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Term
| Escherichia coli colonial morphology |
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Definition
MAC: 95% are rapid lactose fermenters; pink "donuts"
BAP: Large, wet, gray, Beta-hemolytic colonies (most)
XLD: Yellow colonies
EMB: Green colonies with metallic sheen |
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Term
| Key biochemicals for Escherichia coli |
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Definition
Donuts on MAC
Indole: Postive
ONPG: Positive
MR: Positive
VP: Negative
Citrate: Negative
Sensitive to most antibiotics (Except ampicillin, SXT) |
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Term
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Definition
Always considered a pathogen
Causes bacillary dysentery (severe ab cramps with blood and mucus in stools)
Organism does not penetrate past the intestinal mucosa
Rarely causes extra-intestinal infections unlike Salmonells app. |
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Term
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Definition
| Production of a heat stable enterotoxin (Shigatoxin) |
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Term
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Definition
No animal reservoir
Infection is obtained through fecal oral route (usually water)
Organism can survive temperature and pH extremes (stomach acids) |
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Term
| Shigella spp are highly infectious. Infection occurs with how many organisms? How long is the incubation period? |
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Definition
Infection can occur with as little as 50-100 orgnaisms
Inc. period is 36-72 hours |
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Term
| Shigella colonial morphology |
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Definition
BAP: Large, wet, gray colonies
MAC: Clear colonies
XLD: Clear colonies |
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Term
| Key biochemical characteristics of Shigella spp |
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Definition
ONPG: Negative
Motility: Negative
MR: Positive
VP: Negative
H2S: Negative
PAD: Negative
Mannitol: Positive (except S. dysenteriae) |
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Term
| Serological identification of Shigella spp |
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Definition
Antisera available for all 4 types ("o" antigen)
Organisms may need to ne boiled for 10-15 mins to remove the "k" antigen |
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Term
| Clinically significant Shigella spp. |
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Definition
S. dysenteriae (serogroup A)
S. flexneri (Serogroup B)
S. boydii (Serogroup C)
S. sonnei (Serogroup D) 80% of all US isolates |
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Term
| Clinically important features of Shigella spp |
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Definition
Always considered pathogen
Very low inoculum needed
Non-motile |
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Term
| Tribe Edwardsielleae contains only one genus with three clinically significant species |
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Definition
Edwardsiella spp
Edwardsiella tarda
Edwardsiella hoshinae
Edward ictaluri |
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Term
| Edwardsiella spp resembles E. coli, but is different how? |
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Definition
| Edwardsiella is H2S positive and lactose negative |
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Term
| How can Edwardsiella spp be pathogenic |
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Definition
Natiral reservoir occurs in reptiles and freshwater fish
May be a cause of diarrhea
Seen in wound infections associated with trauma related to aquatic accidents |
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Term
| Edwardsiella tarda key biochemicals |
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Definition
H2S: Positive
MR: Positive
VP: Negative
Indole: Positive
Motility: Positive
Lysine: Positive
Ornithine: Positive
TSI: K/A H2S
ONPG: Negative |
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Term
| Edwardsiella colonial morphology |
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Definition
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Term
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Definition
| Natural reservoir occur in reptiles and freshwater fish. Seen in wound infections associated trauma related to aquatic accidents |
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