FASTIDIOUS GRAM NEGATIVE RODS. PART 6

Question 1

Where does Pasteurella spp. colonize in mammals and birds?

Answer 1

Pasteurella spp. colonize the mucous membranes of the upper respiratory tract and gastrointestinal tracts of mammals and birds.

Question 2

How do human infections with Pasteurella spp. typically occur?

Answer 2

Human infections occur from bites and scratches inflicted by animals, primarily felines.

Question 3

What type of infection does Pasteurella spp. cause?

Answer 3

Pasteurella spp. results in a localized, pus-producing infection.

Question 4

Which species of Pasteurella is most commonly isolated

Answer 4

Pasteurella multocida

Question 5

What is the morphology of pasteurella multocida

Answer 5

P. multocida is a short, encapsulated gram-negative rod that exhibits bipolar
staining

Question 6

what other infections are caused by pasteurella multocida

Answer 6

Causes wound infections associated with cat and dog bites.

Question 7

Where is Pasteurella spp. part of the normal flora?

Answer 7

mouths of animals, particularly domestic cats and dogs.

Question 8

How is Pasteurella spp. transmitted to humans?

Answer 8

Pasteurella spp. is transmitted by biting (e.g., through animal bites or scratches).

Question 9

What is known about the pathogenesis of Pasteurella spp.?

Answer 9

The pathogenesis of Pasteurella spp. is not well understood. However, it is known that the capsule serves as a virulence factor, and endotoxin is present in the cell wall.

Question 10

what toxins are produced by pasteurella species

Answer 10

no toxins are produced

Question 11

What is the typical clinical presentation at the site of an animal bite?

Answer 11

After an animal bite, there is often rapidly spreading cellulitis (inflammation of the skin and underlying tissues) at the bite site

Question 12

How long is the incubation period for these infections?

Answer 12

The incubation period for infections from animal bites is brief, usually less than 24 hours.

Question 13

Why can cat bites in particular lead to complications?

Answer 13

Cat bites can lead to osteomyelitis (infection of the bone) because cats’ sharp, pointed teeth can implant the organism under the periosteum (the outer layer of bone).

Question 14

explain the culture characteristics of pasteurella multocida on blood or chocolate agar

Answer 14

1. Shows small, smooth, grayish, convex colonies
2. Non-hemolytic “Musty” or earthy odor
   (No growth on Mac. Conkey agar)

Question 15

Microscopic examination of pasteurella multocida

Answer 15

1. Very small gram negative rods
2. Bipolar staining with Giemsa or methylene blue “Safety-pin” appearance

Question 16

biochemical test results for pasteurella multocida

Answer 16

1. Oxidase positive
2. Indole positive
3. Nonmotile
4. Catalase positive
5. Glucose fermenter

Question 17

Treament of pasteurella multocida

Answer 17

Penicillin G

Question 18

what is the prevention of pasteurella multocida

Answer 18

1. people who have beeen bitten by a cat should be given ampicilin to prevent pateurella multocida infection
2. Animal bites, especially cat bites, should not be sutured