Pathogens for Lecture Exam 1

Question 1

Clostridium (Clostridioides) difficile:

Gram stain results:
Relationship to oxygen:
Standard Biochemical test:
Significant features:
Medical Relevance:
Type:

Answer 1

Gram Stain Results
- Gram positive
- rod/ bacillus
-diplo / strepto-

Relationship to Oxygen
- Obligate Anaerobe

Standard Biochemical Test
-Catalase: -

Other Significant Features
- ONLY endospore formation
- pleomorphic
-

Medical Relevance
- causes colon cancer
- Diarrheal agent

Type
-bacteria

Question 2

Escherichia coli

Gram stain results:
Relationship to oxygen:
Standard Biochemical test:
Significant features:
Medical Relevance:
Type:

Answer 2

Gram Stain Results
-Gram negative
-small
-rods/coccobacilli
-random

Relationship to Oxygen
-Facultative anaerobe

Standard Biochemical Test
-Catalase: +
-Oxidase: -
-Indole: +

Other Significant Features
-Motile
-Ferments glucose and lactose with production of acidic wastes and gas
-Member of the family Enterobacteriaceae

Medical Relevance
-Produces toxins that can cause diarrheae
-Common cause of UTIs

Type
-Bacteria

Question 3

Naegleria fowleri

Stages:
Relationship to oxygen:
Significant features:
Medical Relevance:
Type:

Answer 3

Stages:
-trophozoite
-flagellate
-cyst

Relationship to Oxygen
- facilitative aerobic

Other Significant Features
- ONLY PROTOZOA
-

Medical Relevance
- “Brain eating”
- free-living (bacteria eating)

Type
- protozoa

Question 4

Staphylococcus aureus

Gram stain results:
Relationship to oxygen:
Standard Biochemical test:
Significant features:
Medical Relevance:
Type:

Answer 4

Gram Stain Results
- Gram positive
- coccus
- irregular clusters (staphylo)
-

Relationship to Oxygen
- facultative anaerobe (can grow without the need for oxygen)

Standard Biochemical Test
-Catalase: +

Other Significant Features
- found in upper respiratory tract and skin
- Beta-hemolytic
-coagulase +

Medical Relevance
-SSTI (skin and soft tissue infection)
-

Type
- bacteria

Question 5

Staphylococcus saprophyticus

Gram stain results:
Relationship to oxygen:
Significant features:
Medical Relevance:
Type:

Answer 5

Gram Stain Results
- Gram positive
- irregular clusters
-coccus
-

Other Significant Features
- coagulase -
- non-hemolytic
-

Medical Relevance
- UTI (honeymoon itch)
-

Type
- bacteria

Question 6

Treponema pallidum

Gram stain results:
Relationship to oxygen:
Significant features:
Medical Relevance:
Type:

Answer 6

Gram Stain Results
- Gram negative
- spirochete

Relationship to Oxygen
- aerobic (oxidative phosphorylation)

Other Significant Features
- ONLY SPIROCHETE (inside)

Medical Relevance
- causes syphilis

Type
-bacteria

Question 7

Trichophyton mentagrophytes

Significant features:
Medical Relevance:
Type:
Types cont’:

Answer 7

Other Significant Features
- ONLY FUNGUS

Medical Relevance
-causes ringworm

Type
-fungi

Types cont’
-ascomycota
-basidomycota
-zygomycota

Question 8

What are the 4 gram stain results?

Answer 8

Size, Shape, Arrangement, Stain

Question 9

Facultative

Answer 9

organisms can survive with the presence or absence of oxygen.

Question 10

Obligate

Answer 10

aerobes can survive in the presence of oxygen

anaerobes can survive in the absence of oxygen