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Enterobacteriaceae Citrobacter Cronobacter Essentials
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Enterobacteriaceae Citrobacter Cronobacter Essentials
Enterobacteriaceae Citrobacter Cronobacter Essentials
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1
Question
Which family do Citrobacter, Cronobacter, Enterobacter, Klebsiella, Proteus, and Serratia belong to?
Answer
Enterobacteriaceae
2
Question
What type of bacteria are Enterobacteriaceae in terms of Gram stain and oxygen requirement?
Answer
Gram-negative bacilli or coccobacilli; typically oxidase-negative
3
Question
Are Enterobacteriaceae generally commensals in the human GI tract?
Answer
They are true pathogens, not normally commensals (except Yersinia pestis in plague context?)
4
Question
Name three overt enteric pathogens listed in the content.
Answer
Salmonella enterica, Shigella spp., Yersinia spp.
5
Question
What glucose fermentation capability do the listed pathogens share?
Answer
They ferment glucose
6
Question
Which species are indicated as catalase positive except Shigella dysenteriae type 1?
Answer
All listed Enterobacteriaceae except Shigella dysenteriae type 1
7
Question
What is the nitrate reduction capability of these organisms (excluding Photorhabdus and Xenorhabdus)?
Answer
They reduce nitrates to nitrites
8
Question
Which two genera are exceptions to oxidation or catalase traits mentioned for some species?
Answer
Plesiomonas sp. and Shigella dysenteriae type 1
9
Question
Which species within Citrobacter are listed as indole-variable and melibiose-positive?
Answer
Citrobacter freundii is indole-variable and melibiose-positive
10
Question
Which Citrobacter species is indole- and sucrose-variable and melibiose-negative?
Answer
Citrobacter koseri
11
Question
Which Citrobacter species is positive for ODC and variable for indole, dulcitol, and melibiose?
Answer
Citrobacter braakii
12
Question
Which Citrobacter species is positive for indole, ODC, melibiose, and sucrose?
Answer
Citrobacter farmeri
13
Question
What is the general habitat for Citrobacter organisms according to the text?
Answer
Inhabitants of the intestinal tract
14
Question
What medium do all Citrobacter species grow on, as indicated by the genus name?
Answer
Simmons citrate medium
15
Question
What key biochemical test result is positive for Citrobacter species according to the text?
Answer
Methyl red test
16
Question
Which Cronobacter species is associated with neonatal infections and metabolizes sialic acid found in breast milk?
Answer
Cronobacter sakazakii
17
Question
Which Cronobacter species is associated with adult infections?
Answer
Cronobacter malonaticus
18
Question
How can Cronobacter be differentiated from Enterobacter in terms of metabolic tests?
Answer
Voges-Proskauer, arginine dihydrolase, and ODC positive; raffinose and L-rhamnose patterns; sorbitol, melibiose, and sucrose reactions
19
Question
What is a defining pigment trait mentioned for Cronobacter?
Answer
Yellow pigment
20
Question
What is a notable antibiotic resistance trait of Cronobacter spp.?
Answer
Intrinsically resistant to ampicillin and first- and second-generation cephalosporins
21
Question
Which Cronobacter species is tied to adult infections in the text?
Answer
Cronobacter malonaticus
22
Question
What is the clinical relevance of Citrobacter freundii in terms of growth and tests?
Answer
Indole-variable; acid test results: melibiose positive; ODC positive; grows on Simmons citrate; methyl red positive
23
Question
Which Biochemical trait distinguishes Citrobacter koseri from others in indole/dulcitol/sucrose reactions?
Answer
Variable for dulcitol and sucrose; negative for melibiose
24
Question
Which genus includes species previously classified as Enterobacter sakazakii?
Answer
Cronobacter
25
Question
What is a major clinical concern with Cronobacter sakazakii in neonates?
Answer
Neonatal infections
26
Question
What is the common property of Proteus, Klebsiella, Enterobacter, Serratia regarding oxidase?
Answer
Oxidase-negative
27
Question
Are Citrobacter species considered opportunistic pathogens or true pathogens in the text?
Answer
Opportunistic pathogens
28
Question
Name two clinical specimens where Citrobacter can be recovered as per the classification?
Answer
Blood and wound specimens
29
Question
What is a shared trait of the Enterobacteriaceae regarding connection to the GI tract?
Answer
Many are true pathogens not normally commensals in GI tract
30
Question
Which species is noted as misidentified with Kluyvera ascorbata or Salmonella enterica in commercial systems?
Answer
Citrobacter spp.