Which of the following growth characteristics is typical for Escherichia coli?
C) Beta-hemolytic on sheep blood agar (BAP)
Which of the following organisms produce a positive phenylalanine deaminase reaction?
A) All of the above
Identify the Gram-negative bacillus that can be described as:
lactose: negative
oxidase: negative
indole: negative
citrate: positive
methyl red: positive
urease: negative
H S: positive
clear colonies with black center on XLD
B) Salmonella enteritidis.
Which species of Shigella is most commonly associated with diarrheal disease in the USA?
A) sonnei
Shigella sp are genetically related to Escherichia coli but can easily be distinguished from each other using certain biochemical tests. List two biochemical tests you could perform to help you differentiate between these two organisms. Discuss the reactions you would expect to see for Shigella sp versus Escherichia coli for the biochemical tests you choose. *Note: ONE of your biochemical tests can be selective/differential plate media.
Shigella can be differentiated from E.coli with HE agar plates. E. coli's ability to ferment lactose would produce acid and cause oranging of the agar while Shigella would not. Shigella from E. coli can also be differentiated using the TSI test as the shigella result would be K/A, alkaline over acid as it utilizes the peptones and E. coli would be A/A plus gas as it ferments the carb's producing acid and gas.
A leg wound culture from a hospitalized 70-year-old diabetic man grew motile, lactose-negative colonies on MAC. Given the following biochemical reactions at 24 hours, what is the most probable organism?
H S: negative
Indole: negative
MR/VP: negative/positive
phenylalanine deaminase: negative
DNase: positive
citrate: positive
urease: negative
ornithine decarboxylase: positive
lysine decarboxylase: positive
arginine dehydrolase: negative
Gelatin hydrolysis: negative
C) Serratia marcescens
What amino acid is the substrate in indole test broth?
D) Tryptophan
Which genera of Enterobacteriaceae are usually nonmotile at 35°C?
D) Shigella, Klebsiella, and Yersinia
(T/F) The Moeller Decarboxylase Test requires an overlay of mineral oil to provide an anaerobic environment for decarboxylation, or hydrolysis of the amino acids to occur.
True
Three blood cultures taken from a 30-year-old cancer patient receiving chemotherapy and admitted with a UTI grew "swarming" colonies of lactose-negative, motile, Gram-negative rods prior to antibiotic therapy. Given the following biochemical reactions, which is the most likely organism?
H S: positive
indole: negative
MR/VP: positive/negative
phenylalanine deaminase: positive
DNase: negative
citrate: positive
urease: positive (rapid)
gelatin hydrolysis: positive
ornithine decarboxylase: positive
A) Proteus mirabilis
A number of vacationers who traveled outside the U.S. have had their vacations interrupted by a case of "traveler's diarrhea," which is commonly associated with which etiologic agent?
D) Enterotoxigenic E. coli (ETEC)
The medium used to determine whether an organism is oxidative or fermentative with respect to its metabolic activities is
A) OF medium
Four blood cultures were taken over a 24-hour period from a 20-year-old woman with severe diarrhea. The cultures grew motile Gram negativerods. A urine specimen obtained by catheterization also showed Gram-negative rods, 100,000 col/mL. Given the following results, which is the most likely organism?
TSI: A/A +gas
Indole: positive
MR/VP: positive/negative
H S: negative
citrate: negative
urease: negative
lysine decarboxylase: positive
phenylalanine deaminase: negative
A) Escherichia coli
(T/F) The purpose of the inverted Durham tube placed inside Carbohydrate Fermentation test tubes is to identify which organisms can grow anaerobically inside the Durham tube.
False
Which test is used to presumptively identify verotoxin-producing Escherichia coli such as O157:H7.
D) MUG
The most appropriate biochemical test to differentiate between K. pneumoniae and K. oxytoca is
A) Indole
Cefsulodin-irgasan-novobiocin (CIN) agar is recommended for the recovery of
B) Yersinia enterocolitica
Which of the following organisms is considered an "anaerogenic biotype of E. coli?"
A) Shigella spp
Which pathogen can exhibit the stain characteristics shown in the photograph
C) Yersinia spp
A foot wound from a nursing home patient was cultured and grew on MAC as pink to dark pink, oxidase-negative mucoid colonies. Further results were:
Indole: negative
MR/VP: negative/postiive
Citrate: positive
Urease: positive
Motility: negative
H S: negative
The most likely organisms is:
C) Klebsiella pneumoniae
Which of the following media and/or biochemical tests may be used to distinguish E.coli O157:H7 from commensal E.coli?
D) MAC and SMAC
Plesiomonas shigelloides is a relatively new member of the Enterobacteriaceae. What characteristic separates it from other members of the Enterobacteriaceae?
D) it is oxidase positive
A 64-year-old male with lymphoma has a positive blood culture at 18 hours incubation. The organism is a non-lactose fermenting Gram negative bacillus on MAC. Further testing gives the following reactions:
oxidase=negative
motility=positive
indole=positive
MR/VP=positive/negative
citrate=positive
urease=positive
ornithine decarboxylase=negative
phenylalanine deaminase=positive
The genus is:
D) Providencia
Infection with the bubonic form of plague disease occurs by which route?
A) flea bite
The Methyl Red test detects which end product of glucose fermentation?
D) mixed acids
What substance is added to triple sugar iron (TSI) to detect the production of hydrogen sulfide gas?
B) Ferrous sulfate
Match the statement from the left column with the best corresponding organism(s) in the right column.
+Enterotoxigenic E. coli (ETEC)
+Shigella infection
+Salmonella enterica ss typhi
+Enterohemorrhagic E. coli (EHEC)
+Klebsiella spp.
+Uropathogenic E. coli
-Can lead to hemolytic uremic syndrome (HUS), produces Shiga toxin
-Scant stool with blood, mucus and pus
-Traveler's diarrhea
-Major nosocomial pathogen; non-motile
-Can lead to hemolytic uremic syndrome (HUS), produces Shiga toxin
-Associated with eggs, dairy products, and cold-blooded animals
-Iron chelation
Enterotoxigenic E. coli (ETEC): Traveler's diarrhea
Shigella infection: Scant stool with blood, mucus and pus
Salmonella enterica ss typhi: Associated with eggs, dairy products, and cold-blooded animals
Enterohemorrhagic E. coli (EHEC): Can lead to hemolytic uremic syndrome (HUS), produces Shiga toxin
Klebsiella spp.: Major nosocomial pathogen; non-motile
Uropathogenic E. coli: Iron chelation
Which of the pathogenic E.coli is known for its stacked brick colony formation on the intestinal mucosa?
C) EAEC
Yersinia pestis is characteristically
A) Urease negative
Which of the following organisms would produce a yellow slant and a yellow butt plus gas on TSI agar after incubating 18 hours?
B) Escherichia coli
The K antigen of the family Enterobacteriacea is
C) Heat labile
The majority of clinical isolates of Klebsiella are
A) K. pneumoniae
Which of the following is not true of Shigella?
A) Large numbers of organisms must be ingested to produce disease.
Hemolytic uremic syndrome is a complication after infection with
C) E. coli O157:H7
Which member of the Enterobacteriaceae is a causative agent of caseous swellings called pseudotubercules?
D) Yersinia pseudotuberculosis
One of the most common etiologic agents of community-acquired uncomplicated cases of cystitis is
A) Escherichia coli
Reptiles kept as pets are sometimes associated with the transmission of
D) Salmonella
(T/F) These organisms are always considered pathogens, not commensal organisms, when they are isolated from patient specimens: Salmonella, Shigella, Yersinia.
True
Which test is performed on isolates of Klebsiella pneumoniae to identify if the isolate is a potential cause of pyogenic liver abscesses
