Makindo Medical Notes

Related Subjects: |Herpes Varicella-Zoster (Shingles) Infection |Chickenpox Varicella Infection |Varicella Cerebral Vasculopathy |Herpes Viruses |Herpes Zoster Ophthalmicus (HZO) Shingles |MonkeyPox |Mumps |Measles |Rubella (German Measles) |Epstein-Barr Virus infection |Cytomegalovirus (CMV) infections |CMV retinitis infections |Toxoplasmosis

Mycoplasmas are the smallest free-living microorganisms, lacking a cell wall and capable of replicating independently outside of host cells. While most Mycoplasma species are harmless, a minority are pathogenic, causing a range of infections primarily affecting the respiratory and urogenital tracts. Understanding the characteristics, pathogenic species, diagnostic methods, and management strategies is essential for effective treatment and prevention.

About

• Characteristics: Mycoplasmas are small organisms that lack a cell wall but can replicate independently outside of host cells. They are the smallest free-living microorganisms.
• Pathogenicity: Most Mycoplasma species are harmless; only a minority are disease-producing. They are usually non-invasive, causing local mucosal damage or stimulating autoimmune responses in the host.
• Diseases Caused: Mycoplasmas may cause pneumonia, urethritis, and pelvic inflammatory disease (PID).

Pathogenic Mycoplasmas

• Mycoplasma pneumoniae:
  • Infects the upper respiratory tract (URTI) and spreads via coughs.
  • Incubation period of 2-3 weeks, commonly seen in 5-20-year-olds.
  • Causes bronchitis and pneumonia.
  • Host produces IgM antibodies to the 'I' antigen on red cells, leading to hemolysis and a direct Coombs positive result.
  • Generally not severe and rarely life-threatening.
  • Associated complications include bullous myringitis, erythema multiforme, Stevens-Johnson syndrome, Raynaud's phenomenon, internal carotid artery occlusion, strokes, aseptic meningitis, transverse myelitis, Guillain-Barré syndrome (GBS), and polyarthralgias.
• Mycoplasma hominis: Causes vaginitis and pelvic inflammatory disease (PID); infections are not sensitive to erythromycin.
• Mycoplasma genitalium: Associated with urethritis and PID.
• Ureaplasma urealyticum: Hydrolyzes urea and causes urethritis.
• Mycoplasma fermentans: Can cause overwhelming infections in immunocompromised individuals.

Investigations

• Cold Agglutinins: These antibodies clump erythrocytes at 4°C and dissociate upon reheating to 37°C. They can be caused by Mycoplasma infections, Epstein-Barr Virus (EBV) (anti-i), Cytomegalovirus (CMV) (anti-I), other viruses, and lymphomas.
• Polymerase Chain Reaction (PCR): Highly sensitive method for detecting Mycoplasma DNA in clinical specimens.
• Serology: Detection of specific antibodies against Mycoplasma species.
• Culture: Difficult and time-consuming due to the fastidious nature of Mycoplasmas.

Management

• Antibiotic Therapy:
  • Mycoplasmas lack a cell wall, making them resistant to antibiotics that target cell wall synthesis, such as penicillins and cephalosporins.
  • Effective antibiotics include macrolides (e.g., azithromycin, erythromycin) and tetracyclines (e.g., doxycycline, tetracycline).
  • Avoid tetracyclines in pregnant women and children under 8 years old due to the risk of tooth discoloration and bone growth inhibition.
  • Be cautious with erythromycin as it can cause theophylline toxicity by inhibiting its metabolism.
  • Typical course of antibiotic therapy ranges from 7 to 14 days.
• Supportive Care: Includes rest, hydration, and symptomatic treatment for fever and pain.
• Prevention:
  • Good hygiene practices to prevent the spread of infections.
  • Avoiding close contact with infected individuals.
• Management of Complications: Address any autoimmune or severe systemic complications as they arise.

Conclusion

Mycoplasma infections, though often mild and self-limiting, can lead to significant clinical complications, especially in vulnerable populations such as children, young adults, and immunocompromised individuals. Accurate diagnosis and appropriate antibiotic therapy are essential for effective management. Preventive measures, including good hygiene practices, play a crucial role in controlling the spread of these infections.

References

• Glenney, J. A., Fox, J. G., & Moore, M. R. (2005). Mycoplasma Infections in Clinical Practice. Springer.
• Mayo Clinic. Mycoplasma Infections. Available at: https://www.mayoclinic.org
• National Institutes of Health (NIH). Mycoplasma Infections. Available at: https://www.ncbi.nlm.nih.gov
• World Health Organization (WHO). Antibiotic Resistance Threats in the United States. Available at: https://www.who.int
• Centers for Disease Control and Prevention (CDC). Mycoplasma pneumoniae. Available at: https://www.cdc.gov