Deck 37: Francisella

Question 1

One of the most common laboratory-acquired infections that is caused by a Biosafety Level 2 pathogen is caused by

A)Bordetella pertussis.
B)Francisella tularensis.
C)Pasteurella multocida.
D)Staphylococcus aureus.
E)All of the above are correct.

Answer 1

B
F. tularensis is a Biosafety Level 2 pathogen, a designation that requires technologists to wear gloves and to work within a biological safety cabinet (BSC) when handling clinical material that potentially harbors this agent. For cultures, the organism is designated Biosafety Level 3; a mask, recommended for handling all clinical specimens, is very important for preventing aerosol acquisition with F. tularensis. Because tularemia is one of the most common laboratory-acquired infections, most microbiologists do not attempt to work with infectious material from suspected patients. It is recommended that specimens be sent to reference laboratories or state or other public health laboratories that are equipped to handle Francisella.

Question 2

F.philomiragia differs from F.tularensis in that it

A)is oxidase-positive.
B)is hydrogen sulfide-positive.
C)hydrolyzes gelatin.
D)grows in 6% sodium chloride.
E)All of the above are correct.

Answer 2

E
F. philomiragia differs from F. tularensis biochemically. F. philomiragia is oxidase-positive by Kovac's modification, and most strains produce hydrogen sulfide in triple sugar iron agar medium, hydrolyze gelatin, and grow in 6% sodium chloride (no strains of F. tularensis share these characteristics).

Question 3

Tularemia, characterized by glandular, ulceroglandular, oculoglandular, oropharyngeal, systemic, and pneumonic presentations is caused by

A)Brucella species.
B)Bordetella species.
C)Pasteurella species.
D)Francisella species.

Answer 3

D
Francisella tularensis is the agent of human and animal tularemia. Worldwide in distribution, F. tularensis is carried by many species of wild rodents, rabbits, beavers, and muskrats in North America. Humans become infected by handling the carcasses or skin of infected animals, through insect vectors (primarily deerflies and ticks in the United States), by being bitten by carnivores that have themselves eaten infected animals, or by inhalation.

Question 4

F.philomiragia differs from F.tularensis in that it

A)is oxidase-negative.
B)is hydrogen sulfide-positive.
C)does not hydrolyze gelatin.
D)does not grow in 6% sodium chloride.
E)All of the above are correct.

Question 5

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

A)Cysteine and cystine
B)Blood and cysteine
C)Dopa-cysteine
D)Nicotinic adenine
E)All of the above are correct.

Question 6

Organisms belonging to the genus Francisella are

A)gram-positive diplococci.
B)gram-positive diphtheroid bacilli.
C)gram-negative coccobacilli.
D)gram-negative bacilli.