Is doxylag considered a suitable antibiotic to treat a mycoplasma genitalium infection? if not, please advise which antibiotic is more preferred

Not reliable: Doxycycline (Doxylag and other brands) sometimes works against M. genitalium but is not reliable. However, doxy is one of the best treatments for nongonococcal urethritis (NGU), even though 10-15% of NGU is due to MG. If you have a proved MG infection (positive test) or have NGU that didn't respond to doxy or azithromycin, ask your doctor about moxifloxacin.