The Research Of Mechanism Of Drug-resistance Of Mh To Macrolides And Conditions On Infection Of Mycoplasma

IntroductionHuman mycoplasmas are common pathogens of urogenital and respirat- ory tract infections. They can cause non-gonococcal urethritis,cervicitis,pelvic inflammatory disease,spontaneous abortion,infertility and other diseases. Due to unsuitable treatment after infection,more and more drug-resistance had been reported recent years .we also can find that the resistance of mycoplasmas to microlide are increasing year by year by the detection of susceptibility test. It was even worse in the mixed infection by Mycoplasma hominis(Mh) and ureaplasma urealyticum(Uu) and Mh alone.Mh is one of the main pathogens of urogenital tract infections, some antibiotics such as penicillin,cephalosporin are inefficacious to it because it lacks of cell wall;and also there is Tet M gene in its genome, tetracycline are inefficacious too. In clinical, doctor usually use macrolides and quinolones.In this research, we had analysised the drug- resistance conditions of the clinical samples by susceptibility test , meanwhile, we had explored the mechanism of drug-resistance of Mh to the. Macrolides.MethodsUrogenital specimens from 4846 (male:1726,female:3120, age:2-69) outpatients were assayed by the susceptibility test according to the instructions of kits which were provided by Lizhu company.To choose 20 Mh specimens from above metioned samples for the research of drug-resistance. All of them are cultured in liquid medium and purified by the solid medium to exclude other microorganisms.To assay the Erm A,Erm B,Erm C and Mef A by polymerase chainreaction and the domain V of 23s rRNA where the binding site of Mh to macrolides are also amplified. The product are detected by agarose gel electrophoresisComparing the sequence of the products of 23s rRNA with correspon- ding sequence in genebank ,and analysis the mutation .ResultsInfections by Uu are common in clinical, it occupied 40% of NGU, and infection by Mh alone are rare appearance, all of them were mearly resistance to the 14,15 ring macrolides but sensitive to 16 ring macrolide, Josamycin. In mixed infection cases, it should be treated without 14,15 ring microlide to prevent the Mh infection coming worse.In this research, we didn't find the Erm A,Erm B,Erm C and Mef A gene after PCR detection.After comparing to sequence of Mycoplasma pneumonia Genebank ,we can find a G2057A mutation.Refer to the induced resistant strain, the MIC is 64mg/L and 128mg/L respectively.In this research, we can find a A2059G mutation in common. ConclusionThe resistance of Mh to macrolides are not caused by the methylase (ErmA,Erm B,Erm C) and Mef A but caused by the mutant of binding site to the drug. And to acquired resistance to 16 ring macrolide, the mechanism may be the A2059G mutant in 23s rRNA domain V.