8.4 Miscellaneous and Fastidious Gram - Rods

Question 1

A visitor to South America who returned with diarrhea is supected of being infected with V. cholerae. Select the best medium for recovery and identification of this organism.
A. MacConkey agar
B. Blood agar
C. TCBS agar
D. XLD agar

Answer 1

C. TCBS agar

Question 2

A curved gram-negative rod producing oxidase-positive colonies on blood agar was recovered form a stool culture. Given the following results, what is the most likely identification?
-Lysine decarboxylase=+
-Indole=+
-VP=Neg
-Urease=+/-
-TCBS=Green colonies
-Arginine decarboxylase=Neg
-KIA=Alk/Acid
-Lactose=Neg
-String test=Neg
A. Vibrio cholerae
B. Vibrio parahaemolyticus
C. Shigella spp.
D. Salmonella spp.

Answer 2

B. Vibrio parahaemolyticus

Question 3

A gram-negative S-shaped rod recovered form selective media for Campylobacter species gave the following results:
-Catalase=+
-Motility=+
-Growth at 42C=+
Grape odor=Neg
-Oxidase=+
-Hippurate hydrolysis=+
-Nalidixic acid=Susceptible
-Pigment=Neg
-Cephalothin=Resistant
The most likely identification is
A. Pseudomonas aeruginosa
B. Campylobacter jejuni
C. Campylobacter fetus
D. Pseudomonas putida

Answer 3

B. Campylobacter jejuni

Question 4

Which atmospheric condition is needed to recover Campylobacter sp.. from specimens inoculated onto a Campy-selective agar at 35C-37C and 42C?
A. 5% O2, 10% CO2, and 85% N2
B. 20% O2, 10% CO2, and 70% N2
C. 20% O2, 20% CO2, and 60% N2
D. 20% O2, 5% CO2, and 75% N2

Answer 4

A. 5% O2, 10% CO2, and 85% N2

Question 5

Which group of tests best differentiates Helicobacter pylori and C. jejuni?
A. Catalase, oxidase, and Gram stain
B. Catalase, oxidase, and nalidixic acid sensitivity
C. Catalase, oxidase, and cephalothin sensitivity
D. Urease, nitrate, and hippurate hydrolysis

Answer 5

D. Urease, nitrate, and hippurate hydrolysis

Question 6

Which of the following test should be done first in order to differentiate Aeromonas spp. from the Enterobacteriaceae?
A. Urease
B. OF glucose
C. Oxidase
D. Catalase

Answer 6

C. Oxidase

Question 7

Which is the best rapid test to differentiate Plesiomonas shigelloides form a Shigella species on selective enteric agar?
A. Oxidase
B. Indole
C. TSI
D. Urease

Answer 7

A. Oxidase

Question 8

Which are the best two tests to differentiate A. hydrophilia from P. shigelloides?
A. Oxidase and motility
B. DNase and VP
C. Indole and lysine decarboxylase
D. Growth on MacConkey and blood agar

Answer 8

B. DNase and VP

Question 9

Which genus (in which most species are oxidase and catalase positive) of small gram-negative coccobacilli is associated mainly with animals but may cause endocarditis, bacteremia, as well as wound and dental infections in humans?
A. Actinobacillus
B. Pseudomonas
C. Campylobacter
D. Vibrio

Answer 9

A. Actinobacillus

Question 10

Which of the following tests may be used to differentiate Cardiobacterium hominis from Actinobacillus spp.?
A. Gram Stain
B. Indole
C. Anaerobic incubation
D. Oxidase

Answer 10

B. Indole

Question 11

A mixture of slender gram-negative rods and coccobacilli with rounded ends was recovered from blood cultures following a patient’s root canal surgery. Given the following results after 48 hours, what is the most likely organism?
-Catalase=Neg
-Urease=Neg
-Oxidase=+
-Indole=Neg
-Ornithine decarboxylase=+
-Lysin decarboxylase=+
-X and V requirement=Neg
-Carbohydrates=Neg (no acid produced)
-Growth on blood and chocolate agar=+ (with pitting of agar)
-Growth on MacConkey agar=Neg
A. Eikenella corrodens
B. Actinobacillus spp.
C. Cardiobacterium hominis
D. Proteus spp.

Answer 11

A. Eikenella corrodens

Question 12

Kingella kingae can best be differentiated from Eikenella corrodens using which medium?
A. Sheep blood agar
B. Chocolate agar
C. MacConkey agar
D. XLD agar

Answer 12

A. Sheep blood agar

Question 13

Kingella kingae is usually associated with which type of infection?
A. Middle ear
B. Endocarditis
C. Meningitis
D. Urogenital

Answer 13

B. Endocarditis

Question 14

Cultures obtained form a dog bite wound produced yellow, tan, and slightly pink colonies on blood and chocolate agar with a margin of fingerlike projection appearing as a film around the colonies. Given the following results at 24 hours, which is the most likely organism?
-Oxidase=+
-Growth on MacConkey agar=Neg
-Catalase=+
-Motility=Neg
A. Actinobacillus spp.
B. Eikenella spp.
C. Capnocytophaga spp.
D. Pseudomonas spp.

Answer 14

C. Capnocytophaga spp.

Question 15

Smooth gray colonies showing no hemolysis are recovered from an infected cat scratch on blood and chocolate agar but fail to grow on MacConkey agar. The organisms are gram-negative pleomorphic rods that are both catalase and oxidase positive and strongly indole positive. The most likely organism is:
A. Capnocytophaga spp.
B. Pasteurella spp.
C. Proteus spp.
D. Pseudomonas spp.

Answer 15

B. Pasteurella spp.

Question 16

Which media should be used to recover Bordetella pertusis from a nasopharyngeal specimen?
A. Chocolate agar
B. Blood agar
C. MacConkey agar
D. Bordet-Gengou agar

Answer 16

D. Bordet-Gengou agar

Question 17

Which medium is recommended for the recovery of Brucella spp. from blood and bone marrow specimen?
A. Biphasic Castenada bottles with Brucella broth
B. Blood culture bottles with Brucella broth
C. Bordet-Gengou agar plates and THIO broth
D. Blood culture bottles with THIO

Answer 17

A. Biphasic Castenada bottles with Brucella broth

Question 18

In addition to CO2 requirements and biochemical characteristics, Brucella melitensis and Brucella abortus are differentiated by growth on media containing which two dyes?
A. Basic fuchsin and thionin
B. Methylene blue and crystal violet
C. Carbol fuchsin and iodine
D. Safranin and methylene blue

Answer 18

A. Basic fuchsin and thionin

Question 19

Which of the following amino acids are required for growth of Francisella tularensis?
A. Leucine and ornithine
B. Arginine and lysine
C. Cysteine and cystine
D. Histidine and tryptophan

Answer 19

C. Cysteine and cystine

Question 20

Which medium is best for recovery of Legionella pneumophila from clinical specimens?
A. Chocolate agar
B. Bordet-Gengou agar
C. New yeast extract agar
D. Buffered charcoal-yeast extract (CYE) agar

Answer 20

D. Buffered charcoal-yeast extract (CYE) agar

Question 21

Haemophilus influenzae causes ocular infections (pinkeye) and requires X and V factors in the primary medium for growth. The subspecies Haemophilus influenza (biogroup) aegyptius can further be identified and differentiated by which two test?
A. Indole and xylose
B. Glucose and urease
C. Oxidase and catalase
D. ALA test and oxidase

Answer 21

A. Indole and xylose

Question 22

Haemophilus species that require the V factor (NAD) are easily recovered on which primary agar plate?
A. Blood agar made with sheep red cells
B. Blood agar made with horse red cells
C. Chocolate agar
D. Xylose agar

Answer 22

C. Chocolate agar

Question 23

Which of the following products is responsible for satellite growth of haemophilus spp. around colonies of Staphylococcus and Neisseria spp. on sheep blood agar?
A. NAD
B. Hermin
C. Indole
D. Oxidase

Answer 23

A. NAD

Question 24

Which of the following plates should be used in order to identify Haemophilus haemolyticus and haemophilus parahaemolyticus?
A. Chocolate agar an Mueller-Hinton agar with X factor added
B. Horse blood agar and Mueller-Hinton agar with X and V strips
C. Brain-heart infusion agar with sheep red cells added
D. Chocolate agar and Mueller-Hinton agar with X factor added

Answer 24

B. Horse blood agar and Mueller-Hinton agar with X and V strips

Question 25

The majority of Haemophilus influenzae infections are caused by which of the following capsular serotypes?
A. a
B. b
C. c
D. d

Answer 25

B. b

Question 26

Which Haemophilus species is generally associated with endocarditis?
A. H. influenzae
B. H. ducreyi
C. H. aphrophilus
D. H. haemolyticus

Answer 26

C. H. aphrophilus

Question 27

Which Haemophilus species is difficult to isolate and recover from genital ulcers and swollen lymph nodes?
A. H. aphrophilus
B. H. ducreyi
C. H. haemolyticus
D. H. parahaemolyticus

Answer 27

B. H. ducreyi

Question 28

Which of the following is a characteristic of strains of Haemophilus influenzae that are resistant to ampicillin?
A. Production of B-lactamase enzyme
B. Hydrolysis of chloramphenicol
C. Hydrolysis of urea
D. All of these options

Answer 28

A. Production of B-lactamase enzyme

Question 29

A small, gram-negative coccobacillus recovered from the CSF of a 2-year-old child gave the following results:
-Indole=+
-X requirement=+
-Urease=Neg
-Glucose=+(acid)
-V requirement=+
-Lactose=Neg
-Hemolysis=Neg
Which is the most likely identification?
A. Haemophilus parainfluenzae
B. Haemophilus influenzae
C. Haemophilus ducreyi
D. Haemophilus aphrophilus

Answer 29

B. Haemophilus influenzae

Question 30

The g-ALA test (fro porphyrins_ is a confirmatory procedure for which test used for identification of Heamophilus species?
A. X factor requirement
B. V factor requirement
C. Urease production
D. Indole production

Answer 30

A. X factor requirement

Question 31

An elderly woman who cared for several domestic cats was hospitalized with suspected cat-scratch disease (CSD). Blood culture appeared negative, bur a small, slightly curved pleomorphic gram0negative bacillus grew on BHI agar (brain, hear infusion agar with 5% horse or rabbit blood). What is the most likely identification?
A. Bartonella spp.
B. Brucella spp.
C. Kingella spp.
D. Haemophilus spp.

Answer 31

A. Bartonella spp.

Question 32

A 5-year-old nonimmunized male with a persistent cough, fever, and flulike symptoms was admitted to the hospital. Nasopharyngeal swabs were cultured on 15% blood, chocolate, Bordet-Genjou, and Regan-Lowe (with 10% charcoal) agars. All media grew a gram-negative coccobacillus. Carbohydrate and biochemical tests were negative. What is the most likely identification?
A. Haemophilus influenza
B. Bordetalla pertusis
C. Haemophilus parainfluenzae
D. Bordetella bronchiseptica

Answer 32

B. Bordetalla pertusis

Question 33

A 29-year-old male who often hunted rabbits and spent a lot of time in the woods was admitted to the hospital with skin ulcers on his upper extremities. At 48 hours, a small coccobacillus was recovered from the aerobic blood culture bottle only. The organism stained poorly with Gram stain, but did stain with acridine orange. Cultures taken from the ulcers did not grow on primary media. What is the most likely identification?
A. Pseudomonas aeruginosa
B. Pseudomonas fluorescens
C. Chryseobacterium spp.
D. Francisella tularensis

Answer 33

D. Francisella tularensis

Question 34

A neonate was readmitted to the hospital with a diagnosis of meningitis. The CSF revealed gram-negative straight rods. At 24 hours, the organism grew on 5% sheep blood and chocolate agars displaying a yellow pigment. On MacConkey agar, it appeared as a non-lactose fermenter. Colonies were oxidase, DNase, and gelatinase positive, and oxidized glucose and mannitol. what is the most likely identification?
A. Haemophilus influenza
B. Chryseobacterium meningosepticum
C. Stenotrophomonas maltophilia
D. Acinetobacter baumannii

Answer 34

B. Chryseobacterium meningosepticum

Question 35

A 46-year-old dog warden was admitted to the hospital with several puncture bite wounds encountered while wrangling with a stray dog. Culture at 48 hours produced small yello colonies on 5% sheep blood and chocolate agars in 10% CO2, but no growth on MacConkey agar. Gram stain showed gram0negative curved, fusiform rods. Colonies were oxidase and catalase positive. What is the most likely identification?
A. Capnocytophaga canimorsus
B. Francisella tularensis
C. Legionella pneumophila
D. Pseudomonas aeruginosa

Answer 35

A. Capnocytophaga canimorsus

Question 36

The HACEK group of organisms (Haemophilus apharophilus, actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella spp.) are all known for which type of infections?
A. Urinary tract
B. Endocarditis
C. Pharyngitis
D. Tonsillitis

Answer 36

B. Endocarditis

Question 37

A suspected case of Legionnaires’ disease was noted on the request form a culture and sensitivity ordered on a sputum sample. The patient was a 70-year-old male who presented with a positive serological test for Legionella spp. what is the most efficient way to confirm the infection using the submitted sample?
A. Culture the sputum on MacConkey agar
B. Gram stain of the sputum
C. Acid-fast staining
D. Direct immunofluorescent microscopy

Answer 37

D. Direct immunofluorescent microscopy

Question 38

The test used most often to separate the Micrococcaceae family from the Streptococcaceae family is:
A. Bacitracin
B. Catalase
C. Hemolysis pattern
D. All of these options

Answer 38

B. Catalase

Question 39

Micrococcus and Staphylococcus species are differentiated by which test(s)?
A. Fermentation of glucose (OF tube)
B. Catalase test
C. Gram stain
D. All of these options

Answer 39

A. Fermentation of glucose (OF tube)

Question 40

Lysostaphin is used to differentiate Staphylococcus from which other genus?
A. Streptococcus
B. Stomatococcus
C. Micrococcus
D. Planococcus

Answer 40

C. Micrococcus

Question 41

Which of the following tests is used routinely to identify Staphylococcus aureus?
A. Slide coagulase test
B. Tube coagulase test
C. Latex agglutination
D. All of these options

Answer 41

D. All of these options

Question 42

Which of the following enzymes contribute to the virulence of S. aureus?
A. Urease and lecithinase
B. Hyaluronidase and B-lactamase
C. Lecithinase and catalase
D. Cytochrome oxidase

Answer 42

B. Hyaluronidase and B-lactamase