Microbes of the Day (Exam Two)

Question 1

Saccharomyces cerevisiae

Answer 1

Yeast (single-celled eukaryotic fungi)
Used in baking and brewing, model organism.

Question 2

Candida albicans

Answer 2

Yeast (single-celled eukaryotic fungi)
Most prevalent cause of fungal infections in humans. Opportunistic pathogen.

Types (Bloodstream, internal organs, thrush, vaginal candidiasis/yeast infection).

Question 3

Herpes simplex virus (HSV 1/2 or HHV 1/2)

Answer 3

Linear dsDNA virus, enveloped.
HSV-1: generally causes cold sores.
HSV-2: genital herpes.

Characteristics:
- infection (epithelial cells and neurons)
- primary infection
- latency
- transmission (through direct contact with herpes sores, until they heal, and by asymptomatic carriers)
- No cure

Question 4

Rabies virus

Answer 4

ssRNA genome.
Untreated mortality rate is almost 100%.
Vaccine available for prevention and early treatment. Worldwide zoonotic disease with many animal reservoirs.

2 lethal forms:
Furious: (80%) involves the brain, characterized by aggressiveness, excitability, and foaming at the mouth.
Dumb/Paralytic: primarily involves the spinal cord; animals have weak limbs and are unable to raise their heads or make sounds due to paralysis of the neck and throat muscles.

Question 5

Psuedomonas aeruginosa

Answer 5

Gram negative bacillus bacterium.
Opportunistic infection.
Hospital acquired infections.
Antibiotic resistance strains.

Question 6

Answer using: Saccharomyces cerevisiae, Candida albicans, HHV-1/HHV-2, none, or all

1. Gram negative bacterium.
2. May cause cold sores
3. Has a dsDNA genome.
4. Used in baking.
5. The causative agent behind thrush/yeast
   infection.

Answer 6

1. None
2. HHV-1/HHV-2
3. All
4. Saccharomyces cerevisiae
5. Candida albicans

Question 7

Chlamydia trachomatis

Answer 7

Gram negative, coccobacillus.
Most reported nationally notifiable STD (1.6 million cases reported in 2022).
Obligate intracellular parasite.
Easiest to treat, often asymptomatic.
May cause PID.

Question 8

Neisseria gonorrhoeae

Answer 8

Gram-negative, diplococcus.
Known as clap or drip.
Carries often remain without symptoms but transmit the disease for years.
PID: occurs in about 50% of untreated females.
Antibiotic-resistant strains are becoming an issue.

Question 9

Treponema pallidum

Answer 9

Gram-negative, spirochete bacterium.
Stages of disease:
Primary- painless chancre (sore)
Secondary- systemic, rash dispersed on body (characteristically palms and soles).
Tertiary- 1/3 of untreated progress to tertiary, developed over 10-30 years.
Neurosyphilis can result in shuffling walk, paralysis, and insanity.
Gummas: tumor-like lesions may develop

Question 10

Mycobacterium tuberculosis:

Answer 10

Acid fast, bacillus.
Tuberculosis (communicable disease).
Second leading cause of infectious death.
Multi-drug resistant strains.

Question 11

Borrelia burgdorferi:

Answer 11

Gram-negative spirochete.
Lyme disease.
Most common vector-borne disease in the U.S, deer tick.
Symptoms are vague, flu-like, with fever.

Question 12

Plasmodium spp:

Answer 12

Protozoan, cause of malaria.
Most common: P. falciparum, P. malariae, P. ovale, P. vivax.
* Transmitted: female Anopheles mosquitoes
* Was endemic in U.S. until 1950’s
* Symptoms occur after 2-4 weeks, up to a year later – shaking, chills, and fever due to destruction of red blood cells and release of toxins
* ~249 million cases in 2022 and 608,000 deaths/yr worldwide
* Preventable and treatable
* Drug resistance is a serious problem; currently no vaccine

Question 13

Match the microbe with the description. Use All, None,
Mycobacterium tuberculosis, Borrelia burgdorferi, and
Plasmodium spp. to answer the questions

1. Second leading cause of infectious death worldwide
   in 2022, after SARS-CoV-2.
2. Protozoan.
3. Spirochete that moves like a corkscrew with axial
   filaments.
4. DNA genome.
5. Cause of communicable disease, not transmitted by
   an arthropod

Answer 13

1. Mycobacterium tuberculosis
2. Plasmodium spp
3. Borrelia burgdorferi
4. All
5. Mycobacterium tuberculosis