Morphology and Staining • Mycoplasma has many different shapes because the microbe is absent of cell wall.
Culture • Mycoplasma is the smallest (0.2-0.3 µm) microbe that can grow on artificial cell-free-media and form very small colony on plate. • Mycoplasma grow slowly in blood or serum contained media and produce "fried egg" colonies on agar plates. • Due to the slow growth, the colonies need 3 weeks to develop. The colonies are extremely small.
Human pathogens • There are many species in Mycoplasma in nature. Two genera are recognized as human pathogens: • Mycoplasma • Ureaplasma • Mycoplasma pneumoniae • Ureaplasma urealyticum
Mycoplasma pneumoniae • cause primarily atypical pneumonia in human
Virulent factors • P1 protein • an adhering membrane protein • Glycolipid antigen • Induce immunopathological injury • Capsule • resists phagocytosis and display cytotoxicity
Ureaplasma urealyticum • Causes non-gonococcal urethritis (NGU). NGU is a common STD with or without clinical symptoms.
Virulent factors • Phospholipase • Urease • IgA protease
◇ Laboratory diagnosis: Sample: Sputum or throat washings. Microscopy: Direct observation. Serological examination: Cold agglutinin test (IgM auto-antibody in sera of patients) and ELISA (P1 protein as the antigen).
◇ Treatment: Since Mycoplasma lacks cell wall, the penicillins and cephalosporins are ineffective. The common used antibiotics are tetracycline and erythromycin. ◇ Prevention:No vaccines are currently available