Question 1

What test is useful in the initial differentiation of Proteus, Morganella, and Providencia species from the rest of the Enterobacteriaceae?

Accepted Answer

A) Oxidation-fermentation 
B) Methyl red 
C) Amino acid decarboxylase 
D) Phenylalanine deaminase 
A) Oxidation-fermentation 
B) Methyl red 
C) Amino acid decarboxylase 
D) Phenylalanine deaminase

Question 2

The chemical reaction for the Ortho-nitrophenyl-b-D-galactopyranoside (ONPG) test is:

Accepted Answer

A) b-galactosidase hydrolyzes lactose into glucose and galactose. 
B) glucose ® pyruvic acid ® acetoin. 
C) b-galactosidase hydrolyzes o-nitrophenyl-b-D-galactopyranoside into galactose and o-nitrophenol (a yellow compound). 
D) O-nitrophenyl-b-D-galactopyranoside is oxidized into acetoin and glucose. 
A) b-galactosidase hydrolyzes lactose into glucose and galactose. 
B) glucose ® pyruvic acid ® acetoin. 
C) b-galactosidase hydrolyzes o-nitrophenyl-b-D-galactopyranoside into galactose and o-nitrophenol (a yellow compound). 
D) O-nitrophenyl-b-D-galactopyranoside is oxidized into acetoin and glucose.

Question 3

Rapid identification of clinical isolates often involves commercially packaged identification kits and fully automated instruments.What do these kits use to assess the preformed bacterial enzymes?

Accepted Answer

A) Extraction kits 
B) Volatile benzenes 
C) Chromogenic or fluorogenic substrates 
D) Chemiluminescent substrates 
A) Extraction kits 
B) Volatile benzenes 
C) Chromogenic or fluorogenic substrates 
D) Chemiluminescent substrates

Question 4

Extracellular DNase can be produced by:

Accepted Answer

A) Staphylococcus aureus. 
B) Streptococcus agalactiae. 
C) Micrococcus luteus. 
D) Haemophilus influenzae. 
A) Staphylococcus aureus. 
B) Streptococcus agalactiae. 
C) Micrococcus luteus. 
D) Haemophilus influenzae.

Question 5

To inoculate triple sugar iron (TSI) agar or Kligler's iron agar (KIA), the laboratory scientist should pick a well-isolated colony with an inoculating needle and:

Accepted Answer

A) touch the bottom of the needle to the bottom of the slant portion of the agar and move the needle back and forth across the surface of the slant all the way to the top of the tube. 
B) touch the bottom of the needle to the top of the slant portion of the agar and move the needle back and forth across the surface of the slant all the way to the bottom of the tube. 
C) touch the bottom of the needle to the bottom of the slant portion of the agar and move the needle up the slant in a straight line all the way to the top of the tube. 
D) stab the butt almost all the way to the bottom of the tube, then move the needle back and forth over the surface of the slant all the way to the top of the tube. 
A) touch the bottom of the needle to the bottom of the slant portion of the agar and move the needle back and forth across the surface of the slant all the way to the top of the tube. 
B) touch the bottom of the needle to the top of the slant portion of the agar and move the needle back and forth across the surface of the slant all the way to the bottom of the tube. 
C) touch the bottom of the needle to the bottom of the slant portion of the agar and move the needle up the slant in a straight line all the way to the top of the tube. 
D) stab the butt almost all the way to the bottom of the tube, then move the needle back and forth over the surface of the slant all the way to the top of the tube.

Question 6

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

Accepted Answer

A) Amino acidase 
B) Amylase 
C) Deaminase 
D) Decarboxylase 
A) Amino acidase 
B) Amylase 
C) Deaminase 
D) Decarboxylase

Question 7

Which system provides rapid identification of gram-negative bacteria through the use of cards?

Accepted Answer

A) MicroScan 
B) BD Phoenix 100 
C) Vitek AutoMicrobic system 
D) Sherlock Microbial Identification system 
A) MicroScan 
B) BD Phoenix 100 
C) Vitek AutoMicrobic system 
D) Sherlock Microbial Identification system

Question 8

Which test determines if an organism is a delayed lactose-fermenter?

Accepted Answer

A) b-Galactosidase 
B) Dihydroxylase 
C) Nitrate 
D) Ortho-nitrophenyl-b-D-galactopyranoside (ONPG) test 
A) b-Galactosidase 
B) Dihydroxylase 
C) Nitrate 
D) Ortho-nitrophenyl-b-D-galactopyranoside (ONPG) test

Question 9

The lysine iron agar (LIA) slant is also useful in differentiating:

Accepted Answer

A) Acinetobacter and Alcaligenes. 
B) Klebsiella and Enterobacteriaceae. 
C) Proteus, Morganella, and Providencia. 
D) Escherichia, Salmonella, and Campylobacter. 
A) Acinetobacter and Alcaligenes. 
B) Klebsiella and Enterobacteriaceae. 
C) Proteus, Morganella, and Providencia. 
D) Escherichia, Salmonella, and Campylobacter.

Question 10

In the Voges-Proskauer test, you are testing for the metabolic by-products of which pathway?

Accepted Answer

A) Glucose ® formic acid ® formaldehyde 
B) Glucose ® pyruvic acid ® mixed acid fermentation 
C) Lactose ® glucose ® 2,3 butanediol 
D) Glucose ® pyruvic acid ® acetoin ® diacetyl KOH 
A) Glucose ® formic acid ® formaldehyde 
B) Glucose ® pyruvic acid ® mixed acid fermentation 
C) Lactose ® glucose ® 2,3 butanediol 
D) Glucose ® pyruvic acid ® acetoin ® diacetyl KOH

Question 11

If a bacterium utilizes lactose or sucrose and produces H₂S, what will the triple sugar iron (TSI) reaction look like?

Accepted Answer

A) Acid/acid, black butt 
B) Acid/alkaline, black butt 
C) Alkaline/alkaline, black slant 
D) Alkaline/acid, black slant 
A) Acid/acid, black butt 
B) Acid/alkaline, black butt 
C) Alkaline/alkaline, black slant 
D) Alkaline/acid, black slant

Question 12

Oxidative/fermentative (O/F) basal medium is a medium that will test the oxidative and fermentative capabilities of a microbe.The pH indicator is:

Accepted Answer

A) sudan IV. 
B) phenolphthalein. 
C) bromcresol green. 
D) bromthymol blue. 
A) sudan IV. 
B) phenolphthalein. 
C) bromcresol green. 
D) bromthymol blue.

Question 13

Why does the Moeller decarboxylase base medium contain glucose if it is testing the decarboxylation of amino acids?

Accepted Answer

A) The decarboxylation of the amino acids takes place during the glucose metabolic pathway.Once glucose is broken down into pyruvic acid, then the amino acid is modified. 
B) To get the energy needed to take the carboxyl group off the amino acid, the bacteria must have glucose. 
C) When glucose is fermented, one of the by-products is acetoin.This acetoin is part of the mechanism that cleaves the carboxyl group from the specific amino acid. 
D) Decarboxylases are inducible enzymes produced in an acid pH. 
A) The decarboxylation of the amino acids takes place during the glucose metabolic pathway.Once glucose is broken down into pyruvic acid, then the amino acid is modified. 
B) To get the energy needed to take the carboxyl group off the amino acid, the bacteria must have glucose. 
C) When glucose is fermented, one of the by-products is acetoin.This acetoin is part of the mechanism that cleaves the carboxyl group from the specific amino acid. 
D) Decarboxylases are inducible enzymes produced in an acid pH.

Question 14

What reagent is used to demonstrate a positive phenylalanine deaminase test?

Accepted Answer

A) 10% Ferric chloride 
B) Methyl red 
C) a-Naphthol 
D) 40% Sodium hydroxide 
A) 10% Ferric chloride 
B) Methyl red 
C) a-Naphthol 
D) 40% Sodium hydroxide

Question 15

Bacteria can use carbohydrates by:

Accepted Answer

A) oxidation. 
B) synthesis. 
C) reduction. 
D) induction. 
A) oxidation. 
B) synthesis. 
C) reduction. 
D) induction.

Question 16

A positive test for motility:

Accepted Answer

A) turns the motility media blue. 
B) shows hazy appearance throughout or movement away from a stab. 
C) appears as a scum on the top of the media. 
D) will turn blue after the addition of the indicator bromthymol blue. 
A) turns the motility media blue. 
B) shows hazy appearance throughout or movement away from a stab. 
C) appears as a scum on the top of the media. 
D) will turn blue after the addition of the indicator bromthymol blue.

Question 17

What does the oxidase test determine?

Accepted Answer

A) If the bacteria have the enzyme, oxidase, to reduce oxygen to carbon dioxide 
B) If the bacteria have oxidase, which will allow for the oxidation of carbohydrates 
C) If the bacteria can hydrolyze urea to ammonia and carbon dioxide 
D) The presence of the cytochrome oxidase system that oxidizes reduced cytochrome with molecular oxygen 
A) If the bacteria have the enzyme, oxidase, to reduce oxygen to carbon dioxide 
B) If the bacteria have oxidase, which will allow for the oxidation of carbohydrates 
C) If the bacteria can hydrolyze urea to ammonia and carbon dioxide 
D) The presence of the cytochrome oxidase system that oxidizes reduced cytochrome with molecular oxygen

Question 18

The principle of the citrate test includes all the following except:

Accepted Answer

A) bacteria able to use citrate will use the ammonium salts releasing ammonia. 
B) the alkaline pH that results from use of the ammonium salts changes the pH indicator. 
C) the pH indicator changes from red to bright yellow. 
D) the pH indicator changes from green to blue. 
A) bacteria able to use citrate will use the ammonium salts releasing ammonia. 
B) the alkaline pH that results from use of the ammonium salts changes the pH indicator. 
C) the pH indicator changes from red to bright yellow. 
D) the pH indicator changes from green to blue.

Question 19

The medium used in the decarboxylase test is called _____ decarboxylase base medium.

Accepted Answer

A) Clark's 
B) Voges' 
C) Moeller's 
D) OF 
A) Clark's 
B) Voges' 
C) Moeller's 
D) OF

Question 20

The decarboxylase tests determine:

Accepted Answer

A) whether the bacteria possess enzymes capable of removing the carboxyl group of specific amino acids in the test medium. 
B) whether the bacteria can further metabolize the acids formed during fermentation to 2,3 butanediol. 
C) if bacteria can maintain an acid pH if only sucrose is present in the media. 
D) to see if a-naphthol can be broken down into its constituent parts: acetoin and diacetyl KOH. 
A) whether the bacteria possess enzymes capable of removing the carboxyl group of specific amino acids in the test medium. 
B) whether the bacteria can further metabolize the acids formed during fermentation to 2,3 butanediol. 
C) if bacteria can maintain an acid pH if only sucrose is present in the media. 
D) to see if a-naphthol can be broken down into its constituent parts: acetoin and diacetyl KOH.

Exam 9: Biochemical Identification of Gram-Negative Bacteria

What test is useful in the initial differentiation of Proteus, Morganella, and Providencia species from the rest of the Enterobacteriaceae?

The chemical reaction for the Ortho-nitrophenyl-b-D-galactopyranoside (ONPG) test is:

Rapid identification of clinical isolates often involves commercially packaged identification kits and fully automated instruments.What do these kits use to assess the preformed bacterial enzymes?

Extracellular DNase can be produced by:

To inoculate triple sugar iron (TSI) agar or Kligler's iron agar (KIA), the laboratory scientist should pick a well-isolated colony with an inoculating needle and:

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

Which system provides rapid identification of gram-negative bacteria through the use of cards?

Which test determines if an organism is a delayed lactose-fermenter?

The lysine iron agar (LIA) slant is also useful in differentiating:

In the Voges-Proskauer test, you are testing for the metabolic by-products of which pathway?

If a bacterium utilizes lactose or sucrose and produces H₂S, what will the triple sugar iron (TSI) reaction look like?

Oxidative/fermentative (O/F) basal medium is a medium that will test the oxidative and fermentative capabilities of a microbe.The pH indicator is:

Why does the Moeller decarboxylase base medium contain glucose if it is testing the decarboxylation of amino acids?

What reagent is used to demonstrate a positive phenylalanine deaminase test?

Bacteria can use carbohydrates by:

A positive test for motility:

What does the oxidase test determine?

The principle of the citrate test includes all the following except:

The medium used in the decarboxylase test is called _____ decarboxylase base medium.

The decarboxylase tests determine:

Bacterial Cell Structure, Physiology, Metabolism, and Genetics

Host-Parasite Interaction

The Laboratory Role in Infection Control

Control of Microorganisms

Performance Improvement in the Microbiology Laboratory

Specimen Collection and Processing

Microscopic Examination of Materials From Infected Sites

Use of Colony Morphology for the Presumptive Identification of Microorganisms

Immunodiagnosis of Infectious Diseases

Applications of Molecular Diagnostics

Antimicrobial Agent Mechanisms of Action and Resistance

Antimicrobial Susceptibility Testing

Staphylococci

Streptococcus, Enterococcus, and Other Catalase-Negative, Gram-Positive Cocci

Aerobic Gram-Positive Bacilli

Neisseria Species and Moraxella Catarrhalis

Haemophilus and Other Fastidious Gram-Negative Bacilli

Enterobacteriaceae

Vibrio, Aeromonas, Plesiomonas, and Campylobacter Species

Nonfermenting and Miscellaneous Gram-Negative Bacilli

Anaerobes of Clinical Importance

The Spirochetes

Chlamydia, Rickettsia and Similar Organisms

Mycoplasma and Ureaplasma

Mycobacterium Tuberculosis and Nontuberculous Mycobacteria

Medically Significant Fungi

Diagnostic Parasitology

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Agents of Bioterror and Forensic Microbiology

Biofilms: Architects of Disease

Upper and Lower Respiratory Tract Infections

Skin and Soft Tissue Infections

Gastrointestinal Infections and Food Poisoning

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