Chapter 16: Mycoplasma

Question 1

What are mycoplasmataceae?

Answer 1

tiniest free-living organisms capable of self-replication
Lack peptidoglycan cell wall
Only protective layer is cell membrane packed with sterols to help shield cell organelles from exterior environment
Can contort into a broad range of shapes

Question 2

Mycoplasma penumonia causes what?

Answer 2

mild, self-limited bronchitis and penumonia

Question 3

What is the number one caue of bacterial bronchitis and pneumonia in teenagers and young adults?

Answer 3

Mycoplasma pneumoniae

Question 4

What is the pathogenesis of mycoplasma pneumoniae?

Answer 4

Transmission via respiratory route
Organism attaches to respiratory epithelial cells with the help of protein P1
2-3 week incubation period
Gradual onset of fever, sore throat, malaise, and persistent dry hacking cough

Walking pneumonia - do not feel very sick

Most symptoms resolve in a week, cough and infiltration 2 months

Question 5

Describe the chest x-ray of a pt with Mycoplasma pneumoniae

Answer 5

streaky infiltrate, seem more consistent with viral (atypical) pneumonia

Question 6

7% of pts infected with Mycoplasma pneumonia can develop what symptoms for unclear reasons?

Answer 6

erythema multiforme or Stevens-Johnson syndrome: severe skin reaction characterized by erythematous vesicles and bullae over the mucocutaneous junctions of mouth, eyes and skin

Question 7

What are the diagnostic tests for Mycoplasma pneumonia?

Answer 7

Cold agglutinins: IgM antibodies directed at common red blood cell antigen (I) that are modified with infection. clump at low temps
Complement fixation test: fourfold rise in antibody titer = recent infection
Sputum culture: artificial media rich in cholesterol, fried-egg appearance 3 weeks = mycoplasma
round bumpy mulberry with no halo = mycoplasma pneumonia
Mycoplasma DNA probe
PCR

Question 8

Describe Ureaplasma urealyticum. What does it commonly cause?

Answer 8

sometimes referred to as T-strain Mycoplasma (produces tiny colonies when cultured)
Ureaplasma is in urine and produces urease to break down urea
Normal flora in healthy sexually active women (60%)

Commonly infects lower urinary tract causing urethritis

Question 9

What is urethritis?

Answer 9

infection of urinary tract. Buring on urination (dysuria) and sometimes a yellow mucoid discharge from the urethra

Question 10

What causes urethritis?

Answer 10

Neisseria gonorrhoeae, Chlamydia trachomatis, and ureaplasma urealyticum