Diagnostic Microbiology Exam 2- Enteric Pathogens & more tests
LDC
+,V,+
trehalose
-,+,+
arabinose
-,+,-
Name the 4 species of Shigella grouped by major O antigens
1) A- Shigella dysenteriae 2) B- Shigella flexneri 3) C- Shigella boydii 4) D- Shigella sonneii
List the three common forms of Yersinia and their diseases,
1) Yersinia pestis- plague 2) Yersinia enterocolitica-Enlarged mesenteric lymph nodes 3)Yersinia pseudotuberculosis- Septicemia
What three results can an amino acid medium detect?
1) decarboxylation 2) deamination 3) no interaction
The pH indicator for XLD is
phenol red
The amino acids all use bromocresol purple as the pH indicator EXCEPT _________; it requires the addition of ________ to test for deamination
phenylalanine (PDA); FeCl3
Salmonella is LDC
positive
Uninoculated amino acid tests and alkaline amino acid tests are both
purple (acidic is yellow)
Describe a decarboxylation tube result
purple, alkaline butt, K/K
the pH indicator of LIA is
Bromocrescol purple
_________________________ is the pH indicator in LIA
Bromocresol purple
The pH indicator for Hektoen agar is
Bromthymol blue
media used to distinguish Yersinia from other Enterobacteriaceae
CIN
The sulfur source in XLD is
sodium thiosulfate
(T/F) Y. pestis can be motile
False
The primary plate for stool cultures are
Hektoen and XLD
Describe a test in which there is no interaction with the amino acid (but fermentation of glucose)
K/A
ate three tests that can be used to distinguish S. typhi from S. cholerasuis and S. paratyphi.
LDC, Trehalose, Arabinose
What does LIA stand for
Lysine Iron Agar
Group C Shigella
S. boydii
Group B Shigella
S. flexneri
Group D Shigella
S. sonnei
What pathogen did typhoid Mary have
Salmonella typhi (Typhoid fever)
Group a Shigella
Shigella dysenteriae
-Most common isolate in US of Shigella
Sonnei (D)
(T/F) Y. pseudo and Y. enters can be motile
True
What test would you use to distinguish Citrobacter and Salmonella?
Urea OR LDC
Describe a deamination tube result
acidic, yellow butt, red slant, R/A
Decarboxylation is (anaerobic/aerobic)
anaerobic
Yersinia enterocolitica mimics _____________
appendicits
Amino acid decarboxylation results in a change of pH to
basic
Safety pin staining is also called ________ staining and is characteristic of which species?
bipolar; Y. pestis
Salmonella colonies are ______ on HE
black
Yersinia colonies look like a ________ on blood agar
bullseye
The element of a CIN plate are
cefsulodin, irgasan, novobioicn, hbile salts and crystal violet
The malonate test is similar to which other biochemical test?
citrate
What does it mean if the results are K/K? K/A? R/A?
decarboxylation; no interaction w amino acids; deamination
The sulfur source in HE is
ferric salts
Shigella colonies are ______ on HE
green
Citrobacter is LDC
negative
Proteus mirabilis is indole _________
negative
Salmonella is urease
negative
Yersiniz pests is urease
negative
Morganella is citrate __________, Providencia is citrate ___________
negative, positive
(T/F) Yersinia is motile at 25 degrees Celsius
true
E. coli colonies are _______ on HE
yellow
Virulence factors of Salmonella
•Fimbriae •Ability to traverse intestinal mucosa •Enterotoxin production
