Deck 33: Legionella

Question 1

A febrile and pneumonic illness first named in 1976 by scientists at the Centers for Disease Control and Prevention (CDC)who were investigating an epidemic of pneumonia among Pennsylvania State American Legion members attending a convention in Philadelphia is known as:

A)Philadelphia pneumonia.
B)legionnaires' disease.
C)tuberculosis.
D)rheumatic fever.

Answer 1

B
Legionella is the causative agent of legionnaires' disease,a febrile and pneumonic illness with numerous clinical presentations.Scientists at the CDC,who were investigating an epidemic of pneumonia among Pennsylvania State American Legion members attending a convention in Philadelphia,discovered Legionella in 1976.Retrospective serologic evidence of Legionella infection has,however,been recognized as far back as 1947.

Question 2

Organisms belonging to the genus Legionella are:

A)gram-positive diplococci.
B)gram-positive diphtheroid bacilli.
C)gram-negative coccobacilli.
D)faintly staining,thin gram-negative bacilli.

Answer 2

D
All members of the genus Legionella are faintly staining,thin,gram-negative bacilli.

Question 3

To cultivate Legionella in the laboratory,a medium supplemented with what ingredient(s)is necessary?

A)L-cysteine and iron
B)Blood and cysteine
C)Dopa-cysteine
D)Nicotinic adenine

Answer 3

A
Only one genus,Legionella,exists in the Legionellaceae family.All members of this genus are faintly staining,thin,gram-negative bacilli that require a medium supplemented with iron and L-cysteine and buffered to pH 6.9 for optimal growth.

Question 4

A direct immunofluorescent antibody (DFA)test was performed on a sputum sample that yielded a positive test.The organism grew on BCYE medium and was a thin gram-negative,faintly staining bacillus.What is the drug of choice for this organism?

A)Fluoroquinolones
B)Erythromycin
C)Penicillin
D)Aminoglycosides

Question 5

The natural habitat of L.pneumophila is:

A)freshwater streams.
B)the upper respiratory tract of humans and animals.
C)the large intestine of humans and animals.
D)foods contaminated by soil.

Question 6

An elderly man with chronic heart and lung disease develops Legionella pneumonia.By what route was the infection most likely to have been acquired?

A)Respiratory route,from an infected person
B)Inhalation of aerosolized water from a source containing protozoa
C)Inhalation of spores from moldy hay
D)Exposure to livestock or animal products

Question 7

Who is at most risk to develop legionnaires' disease?

A)65-year-old transplant recipient
B)14 year old swimming in a lake
C)90 year old living in an apartment complex
D)Newborn baby to a mother infected with hepatitis

Question 8

The medium or media of choice used to recover Legionella is:

A)buffered charcoal yeast extract (BCYE).
B)Regan-Lowe agar.
C)Löwenstein-Jensen medium.
D)blood and chocolate agars.