Basics of Microbiology: Special Growth Requirements

Question 1

Enzymes of aerobic organisms:

Answer 1

Superoxide Dismutase : Superoxide radical (O2 − ) produced by bacterial metabolism Catalyzed to O2 or hydrogen peroxide

Catalase: Converts hydrogen peroxide (H2O2 ) to oxygen and water

Need these enzymes to survive in oxygen environments!!

Question 2

Key Obligate Aerobes: (3)

contain_

Answer 2

Pseudomonas aeruginosa

Mycobacterium tuberculosis

Nocardia (opportunistic infections)

* Contain superoxide dismutase*

Question 3

Obligate Anaerobes:

lack_

common among_

often present in_

ineffective antibiotic:

Answer 3

Lack catalase or superoxide dismutase

Common among normal flora of gut and mouth

99% fecal flora • 100x more anaerobes than aerobes in mouth

Disease when surfaces breakdown

Often present in abscesses

Aminoglycosides ineffective (require O2 )

Question 4

Obligate Anaerobes key examples and unique feature:

Answer 4

Results in “foul smell”

Actinomyces (gums; dental abscesses)

Bacteroides (abdominal abscesses)

Clostridium (botulinum; perfringens; tetani)

Question 5

Key Anaerobic Infections (2) treatment?

Answer 5

Abdominal abscesses/perforations

Contain many gram (-) flora of GI tract

Also contain Bacteroides fragilis (anaerobe)

B. fragilis resistant to many antibiotics

Treatment: Metronidazole + gram (-) agent

Aspiration pneumonia

Mouth anaerobes enter lungs

Peptostreptococcus, Fusobacterium, Prevotella

Treatment: Clindamycin

Question 6

3 Facultative Anaerobes

Answer 6

Staph Strep E. Coli

Question 7

Obligate Intracellular Bacteria:

Answer 7

Rickettsia

dependent on host for ATP

Rocky Mountain spotted fever

Diagnosed clinically or with serology (antibody tests)

Chlamydia

Cannot synthesize their own ATP

Diagnosis: Nucleic Acid Amplification Testing (DNA testing)