Mycoplasma Serology Methods

Mycoplasmas Overview

• Over 150 species of cell wall-free bacteria exist, with four being of primary importance in humans.
• Mycoplasma pneumoniae is linked to pneumonia, joint issues, and can manifest in individuals aged 5-20 years.
• Mycoplasma hominis is involved in postpartum fever and uterine tube infections.
• Ureaplasma urealyticum is associated with nongonococcal urethritis and lung disease in low birth weight infants.
• Mycoplasma genitalium relates to urethral and other infections.

Colony Appearance

• Cultures may exhibit a distinctive "fried egg" appearance on agar, with colonies measuring 20-500 μm.

Serological Diagnostics

• Antibodies can be detected in infected humans using various methods, including:
  • Complement fixation (CF) tests with glycolipid antigens from cultured mycoplasmas.
  • Hemagglutination inhibition (HI) tests using tanned red cells.
  • Indirect immunofluorescence techniques.
  • Specific tests measuring growth inhibition by antibodies.

Treatment Approaches

• Mycoplasmas show resistance to penicillins, cephalosporins, and vancomycin.
• Tetracyclines and erythromycins are effective both in vitro and in vivo for treating mycoplasmal pneumonia.
• Some strains of ureaplasmas may be resistant to tetracyclines.

Mycoplasma pneumoniae and Atypical Pneumonias

• Typically presents as mild disease with a clinical spectrum from asymptomatic to serious pneumonitis, possibly affecting other systems (neurological, hematologic).
• Symptoms include insidious onset with fever, headache, sore throat, and cough that may progress to blood-streaked sputum.
• Incubation period lasts from 1 to 3 weeks.

Laboratory Tests for Diagnosis

• Diagnosis relies heavily on clinical recognition; laboratory tests provide secondary support.
• Slightly elevated white cell count may appear; sputum Gram stain helps rule out other pathogens (e.g., Streptococcus pneumoniae).
• Mycoplasmas are rarely cultured due to the need for specialized tests.
• Cold agglutinins appear in about 50% of untreated cases, peaking in the third or fourth week of illness.
• Specific antibodies can be detected through CF tests with acute and convalescent phase sera.

Mycoplasma hominis Specifics

• Associated with a range of diseases, particularly in the urinary tract.
• Found in 10% of pyelonephritis patients and linked to infections such as salpingitis and tubo-ovarian abscesses.
• Isolated from blood in women with postabortal or postpartum infections.

Ureaplasma urealyticum Characteristics

• Implicated in various diseases, particularly nongonococcal urethritis in men, though Chlamydia trachomatis is the primary cause.
• Commonly resides in the female genital tract with a weak association to disease.

Culture and Microscopy

• Mycoplasma cultures require serum, growth factors, and metabolic substrates for growth.
• Culture methods involve special solid media incubated under specific conditions for several days.
• Direct microscopic examination is generally considered ineffective.

This quiz focuses on the serological techniques used to detect antibodies in humans infected with mycoplasmas. It covers various methods such as CF tests, HI tests, and indirect immunofluorescence, and explains their specificity in measuring immune response. Test your understanding of these critical diagnostic approaches!