Inclusion Criteria:  Physician referral Persistent symptomatic M. genitalium infection documented by a nucleic acid amplification test (NAAT) 14-90 days after completion of the prior antimicrobial regimen for M. genitalium Low risk of reinfection, defined as no unprotected sex with an untreated sex partner since completion of the prior antimicrobial regimen for M. genitalium Male or female sex at birth At least 18 years of age English-speaking Able to provide written informed consent Able to undergo a test of cure 21-28 days and 42-47 days after completion of the lefamulin Referring physician willing to complete case report form and supplementary data collection form Living in the United States  Exclusion Criteria:  Females with pelvic inflammatory disease (PID), pregnancy, or currently breastfeeding Females of reproductive age not on a highly effective method of contraception (i.e., intrauterine device (IUD), Nexplanon, progesterone only depot injection with last injection less than three months prior, oral contraceptive pill and last menstrual period less than 28 days prior) Known QT prolongation or ventricular arrhythmias including torsades de pointes Receiving concurrent drugs known to prolong QT interval (i.e., Class IA or III antiarrhythmics, antipsychotics, erythromycin, pimozide, moxifloxacin, tricyclic antidepressants) Receiving strong or moderate CYP3A or P-gp inhibitors or sensitive CYP3A4 substrates that prolong QT interval Moderate or severe liver impairment Known liver disease Renal failure requiring dialysis Known allergy to doxycycline and/or lefamulin Not willing or not able to undergo a test of cure 21-28 days and 42-47 days after completion of the lefamulin Not fluent in English and/or not able to provide written informed consent Referring physician not willing or not able to complete case report form and supplementary data collection form At the study physician's discretion, potential participant does not understand the risks and benefits and/or is not able to complete all study procedures