What Causes a Positive Mycoplasma Test Result?

Testing positive for Mycoplasma—commonly referred to as a “mycoplasma infection”—indicates the presence of one of several bacterial species within the Mycoplasma genus, most frequently Mycoplasma pneumoniae, Mycoplasma genitalium, or Mycoplasma hominis. Unlike typical bacteria, mycoplasmas lack a rigid cell wall, rendering them resistant to beta-lactam antibiotics such as penicillins and cephalosporins. Their small size and minimal genome allow them to adhere tightly to host epithelial cells—particularly in the respiratory or urogenital tracts—where they trigger localized inflammation and tissue damage.

Mycoplasma pneumoniae is a leading cause of atypical community-acquired pneumonia, especially among children and young adults. Transmission occurs via respiratory droplets during close personal contact; outbreaks are common in schools, dormitories, and military barracks. Symptoms often develop gradually over several days and may include persistent dry cough, low-grade fever, sore throat, headache, and malaise—sometimes with extrapulmonary manifestations such as rash, hemolytic anemia, or neurologic complications.

In contrast, Mycoplasma genitalium and Mycoplasma hominis are sexually transmitted organisms associated with urethritis in men and cervicitis, pelvic inflammatory disease (PID), and infertility in women. Diagnosis typically requires nucleic acid amplification testing (NAAT) from urine, urethral, or cervical specimens—culture is rarely used due to technical difficulty and slow growth. Asymptomatic carriage is common, particularly in women, which can complicate epidemiologic interpretation and clinical management.

A positive test result does not always equate to active disease. Clinical correlation is essential: clinicians must assess symptomatology, exposure history, physical findings, and laboratory markers—including elevated cold agglutinins (in M. pneumoniae) or elevated white blood cell count—to distinguish colonization from clinically significant infection. Treatment is guided by species identification and local resistance patterns; macrolides (e.g., azithromycin), tetracyclines (e.g., doxycycline), or fluoroquinolones (e.g., moxifloxacin) are commonly employed, though rising antimicrobial resistance—especially to macrolides in M. genitalium—necessitates judicious use and, when appropriate, confirmatory susceptibility testing.