Mycoplasmatales

Question 1

Mycoplasmataceae

What Genus of bacteria are in this family?

Answer 1

Mycoplasma

Ureaplasma

Eperythrozoon

Haemobartonella

Mycoplasma and Ureaplasma are pathogenic

Question 2

Mycoplasmataceae family

Morphology

Culture

Answer 2

The smallest free-living bacteria and smallest bacterial genome.

0.1-0.3 uM

Small enough to pass through filters most ‘sterilizing’ filters.

Strict aerobe

No peptidoglycan cell wall, and are thus pleiomorphic shaped.

Also are thus naturally resistant to beta lactams and glycopeptides like vancomycin.

With no cell wall the bacteria’s antigens are membrane glycolipids, whose antibodies often cross-react with human tissues.

Culture:

Very slow growth, takes weeks. On special synthetic media containing sterol, amino acid, nucleic acid, and selective antibiotic supplements.

Adhere strongly to epithelial cells: by the P1 adhesin protein.

Question 3

What are the pathogenic species of the Mycoplasmaceae family?

Answer 3

Mycoplasma pneumoniae and Ureaplasma urealyticum

Question 4

Mycoplasma pneumoniae

virulence factors

pathogenesis

Answer 4

P1 adhesin - protein which strongly adheres to respiratory epithelial cell membranes.

Cilostatic factors - Cilia are first immobilized, then the ciliated epithelial cells die.

Causes persistent cough, and exposes the airway to chronic infections of many other kinds, although the infection is resolved in a few weeks in individuals with a healthy immune system.

Question 5

M. pneumoniae

Habitat

Transmission

Clinical disease

Answer 5

Mild, self-limited bronchitis and pneumonia

The most common cause of bacterial bronchitis and pneumonia in school age children and teenagers.

Fever and persistent dry cough – ‘walking pneumonia’

Transmitted via respiratory droplets, which can be contaminated for months after the symptoms, or carried by asymptomatic individuals.

~5% of patients with M.p infection develop erythema multiforme aka Stevens-Johnson syndrome a severe skin reaction with erythematous vesicles and bullae over the mucous-cutanous junctions at the mouth, eyes, and skin.

Question 6

What are the significant species of the Mycoplasma genus?

What is their habitat?

Clinical diseases?

Answer 6

M. pneumonia - walking pneumonia described elsewhere. The most common pathogen of the group.

M. hominis and M. genitalium - normal vaginal flora

~15% of sexually active men and women have M. hominis colonization

Ureaplasma urealyticum also colonizes 50-75% of sexually active people of both sexes. (This is also of the Mycoplasmaceae family, but not of the Mycoplasma genus.)

Disease:

• M. Hominis:* Pylonephritis, Postpartum fevers, and systemic infections in immunocompromised patient
• M. genitalium:* Non-gonococcal urethritis. Pelvic inflammatory disease
• U. urealyticum:* Non-gonnococal urethritis. Pylonephritis, Spontaneous abortion or premature birth.

Question 8

Mycoplasmacea infection diagnosis

Treatment

Answer 8

Serology: Complement fixation test for circulating antibodies against mycoplasma. This is the standard test.

Cold agglutinin test: patients blood will contain antibodies against a modified RBC protein called “I” antigen. Which will cause RBCs to agglutinate at 4 degrees C.

PCR of patients sera for mycoplasma

ELISA

Sputum culture: takes several weeks. “fried egg” colonies. insensitive and slow.

Labeled DNA probe for mycoplasma DNA

Treatment:

Erthromycin (macrolide, inhibits 50S)

Tetracycline

Fluroquinolones

Question 9

Ureaplasma urealyticum

Habitat

Transmission

Clinical disease

Answer 9

Normal vaginal flora of 50-75% of women and men.

Transmitted during sexual activity and can infect the urinary tract of men or women.

Causes non gonococcal urinary tract infection, which may or may not produce pus and will cause painful burning urination.

It lives comfortably in the urinary tract due to its urease activity, producing ammonia and CO2.

Treatment:

Eryhtromycin.