What Are Mycoplasmas and How Do They Affect Human Health?

Mycoplasmas are a unique group of microorganisms known for being the smallest free-living prokaryotes capable of self-replication. Unlike most bacteria, they lack a rigid cell wall, which gives them high flexibility in shape—a characteristic referred to as pleomorphism. This structural feature also makes them naturally resistant to many common antibiotics that target cell wall synthesis, such as penicillins.

Understanding the Biology of Mycoplasmas

Due to their minimal cellular structure, mycoplasmas have one of the smallest genomes among known organisms. They thrive in environments rich in cholesterol and other nutrients, commonly inhabiting mucous membranes in humans and animals. While many species exist as harmless commensals, several types are recognized as significant human pathogens.

Key Pathogenic Mycoplasma Species

Mycoplasma pneumoniae is one of the most well-known species, primarily affecting the respiratory system. It spreads through airborne droplets and is a leading cause of atypical or "walking" pneumonia, especially in school-aged children and young adults. Symptoms often include persistent dry cough, low-grade fever, sore throat, and fatigue. In some cases, it can lead to bronchitis or more severe lower respiratory tract infections.

Other clinically important species include Mycoplasma hominis and Mycoplasma genitalium, both associated with urogenital tract infections. These organisms can cause urethritis, cervicitis, pelvic inflammatory disease, and prostatitis. Notably, M. genitalium has been increasingly linked to non-gonococcal urethritis and is considered a sexually transmitted pathogen.

Transmission and Reproductive Health Risks

These microbes can be transmitted through sexual contact or from mother to child during childbirth. There is growing evidence suggesting that certain mycoplasmas—along with Ureaplasma urealyticum—may cross the placental barrier, potentially contributing to complications such as preterm labor, spontaneous abortion, and congenital abnormalities. As a result, screening and proper management are recommended in high-risk pregnancies or cases of unexplained infertility.

Diagnosis and Treatment Challenges

Diagnosing mycoplasma infections can be difficult due to their slow growth and inability to be detected by standard culture methods. Modern approaches rely on nucleic acid amplification tests (NAATs), such as PCR, for accurate identification. Treatment typically involves antibiotics that target protein synthesis, including macrolides, tetracyclines, or fluoroquinolones, depending on patient age and resistance patterns.

Because of their role in chronic and sometimes asymptomatic infections, awareness of mycoplasmas is essential for effective clinical management. Ongoing research continues to uncover their impact on immune function and long-term health outcomes, making them an important focus in infectious disease medicine.