Doxycycline is an effective drug for the treatment of Mycoplasma solium infection, but there are different clinical reports on the duration of doxycycline treatment, so the author designed this study to investigate the optimal duration of doxycycline treatment for Mycoplasma solium. The following is reported: 1 Data and methods 1.1 General data: 100 patients with Mycoplasma solani infection were from two hospital specialist clinics, Sanming First Hospital affiliated to Fujian Medical University and Sanming Third Hospital affiliated to Fujian University of Traditional Chinese Medicine, aged 21-46 years, with an average of 25.8 years, including 69 males and 31 females. 1.2 Diagnostic criteria: Male patients’ specimens were collected with reference to the Three Sampling Methods 1.3 Test method: All patients were given oral doxycycline 0.1g, bid, the first dose was doubled, and the specimens were taken for PCR testing after 1 week of treatment. Those with negative results ended treatment, those with positive results continued the original regimen for 1 week and took specimens for testing after 2 weeks, those with negative results ended treatment, those with positive results continued treatment for the third week and were retested by PCR at the end of 3 weeks. After 4 weeks of discontinuation, all patients were retested by PCR.1.4 Efficacy criteria: Referring to the “Efficacy observation of 40 cases of semen mycoplasma infection treated by combined Chinese and Western medicine” [2], PCR test for Mycoplasma solium negative was considered effective; positive was considered ineffective.2 Results See Table 1 Table 1 Efficacy observation (cases) Item N Negative Positive Total cure rate Recurrence Recurrence rate % After 1 week of treatment 100 8 92 8.00% 7 87.5% After 2 weeks of treatment 92 53 39 61.00% 18 33.96% After 3 weeks of treatment 39 35 4 96.00% 3 8.57% Note: The total cure rate is the ratio of the number of PCR negative cases to the total number of cases; the relapse rate is the ratio of the number of PCR negative cases to the number of PCR positive cases in patients treated with this course of treatment.3 Discussion: Doxycycline Doxycycline is a tetracycline broad-spectrum antibiotic that inhibits most gram-positive and negative bacteria and has a bactericidal effect at high concentrations, and can inhibit rickettsiae, Chlamydia trachomatis and mycoplasma. Its pharmacological mechanism is to inhibit the growth of bacteria and mycoplasma by binding specifically to the 30S subunit of the bacterial nucleoproteasome, in the A unit, preventing the linkage of aa-tRNA at this position and preventing the growth of peptide chains and the synthesis of mycoplasma proteins [3]. Doxycycline is well absorbed orally, about 93%, with a protein binding rate of 93% and a half-life of 12-20 h. 42% of the drug can be recovered from the urine. The author reviewed the relevant literature reports on the clinical application of doxycycline in the past 10 years, in which observations related to the treatment course mostly from 7 to 15 days and no recurrence were reported. The results of this study suggest that a 3-week course of doxycycline has the best efficacy and the lowest relapse rate, which further confirms that doxycycline is a concentration-dependent antibiotic, while a 1-week or 2-week course has a low cure rate and a high relapse rate due to the insufficient duration of drug concentration.