Myco/Ureaplasma General Characteristics
1. Smallest bacteria. So small, they were initially mistaken to be viruses.
2. No cell wall. This makes them inherently resistant to antimicrobials that affect cell wall synthesis (penicillins, cephalosporins, vancomycin, etc.)
3. Membranes made up of Sterols.
4. Pleomorphic rods and cocci.
5. Facultative Anaerobes
6. Mycoplasma pneumoniae is a STRICT AEROBE.
7. Require sterol supplementation from animal serum to grow.
8. Slow growers, and hard to discern that growth had actually occurred (small).
9. Antigens are typically membrane Glycolipids and Proteins.
1. Mycoplasma pneumoniae attaches to Respiratory Epithelial Cells using a specialized structure composed of different Adhesins. The most important one is P1 Adhesin. This structure interacts with Sialated Glycoprotein Receptors of the cilia, causing destruction of the Cilia and then the Ciliated Epithelial Cells (same goes for Erythrocytes). No Ciliated Epithelial Cells = poor clearance of pathogens from Upper Respiratory Tract. This causes the cough associated with infection.
2. Mycoplasma pneumoniae, itself, acts as a Superantigen, causing cytokine release of TNF-α, IL-1, and IL-6 from inflammatory cells. This causes the disease features of infection.
1. P1 Adhesin attaches pathogen to ciliated epithelial cells of UR Tract and Erythrocytes, to their Sialated Glycoprotein Receptors, causing cell death.
2. The pathogen itself acts as a superantigen, leading to TNF-α, IL-1/6 release.
1. Mycoplasma pneumoniae is a STRICT HUMAN PATHOGEN. Causes disease year round, but proportionally moreso during Summer and Fall. Epidemics happen every 4-8 years. Most common in children.
2. Mycoplasma pneumoniae spreads via aerosols from the cough. Prolonged carriage can occur after infection.
3. Mycoplasma hominis, Mycoplasma genitalium, and Ureaplasma Spp. are commonly present in infant females as well as sexually active people, in the genitalia. Ureaplasma is the most common species found in these cases.
1. Mycoplasma pneumoniae is typically an asymptomatic carriage, as it is so common worldwide that most adults have developed immunity. For children, the infection is typically a Tracheobronchitis with Low Fever, Malaise, Headache, and a Dry Cough for 2 to 3 weeks (possibly with Pharyngitis occurring as well), followed by worsening symptoms for 2 weeks or more, which MAY lead into Atypical Pneumonia with PATCHY BRONCHOPNEUMONIA SEEN ON CHEST RADIOGRAPHS. Secondary complications include Paralysis, Myelitis (spinal cord), Pericarditis (heart membrane), Hemolytic Anemia (no erythrocytes in blood), Arthritis, and Mucocutaneous Lesions.
2. Mycoplasma genitalium typically causes Nongonococcal Urethritis (NGU) or Pelvic Inflammatory Disease.
3. Ureaplasma urealyticum typically causes NGU, Pyelonephritis (kidney), or SPONTANEOUS ABORTION.
4. Mycoplasma hominis typically causes Pyelonephritis, Postpartum Fevers, and Systemic Infections in the Immunocompromised.
1. Microscopy is useless (can't stain, no cell wall!).
2. Culturing is error-prone (they are SO small).
3. PCR is good.
4. P1 Adhesin Immunoassays are very useful for Mycoplasma pneumoniae.