Pre Lecture Quizzes: Exam 2

Enteric bacteria

If a bacterium utilizes lactose or sucrose, what will the TSI reaction look like?

A/A

The LIA slant is also useful in differentiating

Proteus, Morganella, & Providencia

The methyl red test detects metabolic by-products from what pathway?

Mixed acid fermentation pathway

Using Moeller’s decarboxylase base medium, what color is a positive reaction and what causes this color to be produced?

Purple, alkaline environment produced

The two reagents used in the Voges–Proskauer test are:

40% KOH and α-naphthol.

A technician is reading the O/F biochemical test for identifying a particular gram-negative rod. The organism has produced acid, indicated by a color change, in the closed tube only. This indicates that the organism is

a fermenter.

Decarboxylase tests exist for all the following amino acids, except

tyrosine.

Amino acids can be metabolized by these substances that remove an amine group. What is this substance?

Deaminase

Biochemical tests are based on the _____ of microorganisms.

phenotype

A positive test for motility

shows hazy appearance throughout or movement away from a stab.

The medium used in the decarboxylase test is called

Moeller’s decarboxylase base medium.

Extracellular DNase can be produced by

Staphylococcus aureus.

This reagent is used to demonstrate a positive phenylalanine deaminase test.

10% ferric chloride

What two reagents can be used to visualize indole in indole test broth?

Ehrlich’s and Kovac’s

The decarboxylase tests determine

whether the bacteria possess enzymes capable of removing the carboxyl group of specific amino acids in the test medium.

All the following are biochemical features of Salmonella, except

lactose positive.

You have isolated a bacterium from a stool culture that produces clear colonies on sorbitol MacConkey (SMAC) agar. Which of the following would be the most appropriate test to perform next?

Rapid methylumbelliferyl-β-D-glucuronide (MUG)

What organism possesses the Vi antigen?

Salmonella typhi

Which of the following agars is not selective for Enterobacteriaceae?

Buffered charcoal yeast extract

Escherichia coli strains have all the following properties, except

can use citrate as a sole carbon source.

A microbiologist is reading stool culture plates. She sees an organism that has a dry, pink colony with a surrounding “halo” of pink on MAC. What is a good presumptive identification of this organism?

Escherichia/Citrobacter-like organism

A microbiologist is reading a stool culture and notices a mucoid pink colony on MAC agar. What is the most likely organism?

Klebsiella pneumoniae

Why is it that most cases of salmonella food poisoning are not treated with antibiotics?

The disease is self-limiting and will subside on its own.

What genus has the following characteristics: urea negative, positive for lysine decarboxylase, hydrogen sulfide, and indole, and does not grow on Simmon’s citrate?

Edwardsiella

What bacterium is the causative agent of the plague?

Yersinia pestis

Which organism is the most common cause of urinary tract infections (UTIs) in humans?

Escherichia coli

A microbiologist is reading stool culture plates. She is looking for enteric pathogens on the MAC plate. What do they look like?

Clear, colorless colonies

In the carrier state, where are pathogenic salmonella carried?

Gallbladder

The primary pathogens of the Enterobacteriaceae include all the following, except

Proteus mirabilis.

What bacterium produces swarming colonies on nonselective media, such as sheep blood agar (SBA)?

P. mirabilis

All of the following are symptoms of salmonellosis that may appear 8 to 36 hours after ingestion of contaminated food, except

headache.

What is the name of the organism that has been a documented cause of nursery outbreaks of neonatal meningitis and brain abscesses?

C. koseri

What organism in the genus Providencia is incriminated in nosocomial outbreaks in burn units and has been isolated from urine cultures?

Providencia stuartii

Which animals are a common source of Salmonella serotypes?

Cold-blooded animals (fish)

All of the following are categories of diarrhea-causing Escherichia coli, except

EMEC.