Mycoplasma and chlamydia infections are common sexually transmitted infections caused by bacteria. The common causes of chlamydia infections are usually the following: First, chlamydia is caused by infection with bacteria, and the most common route of infection is through vaginal, oral and anal sex. Second, the mother may also transmit chlamydia to the child she delivers during delivery, resulting in pneumonia or a serious eye infection in the newborn. The most common causes of mycoplasma infections are the following: First, exposure of healthy people to droplets from coughing or sneezing of patients with mycoplasma infections. Second, long-term living in a substandard sanitary environment, or long-term living with patients with potential mycoplasma infection, or long-term eating together, using the same set of utensils, may lead to healthy people with mycoplasma infection.