Study On The Susceptibility And Resistance Mechanism Of Mycoplasma Hominis To Macrolides

Objective: To provide experimental data for clinical chemotherapy and understand the resistance mechanism of Mycoplasma hominis (Mh) to macrolides, the susceptibility of Mh clinical isolates to 5 macrolides was detected, and the correlation of nucleotide mutations in domain II and domain V of 23S rRNA and the resistance to josamycin in Mh clinical isolates was studied.Method: Susceptibility tests of 106 Mh clinical isolates to 5 macrolides were performed by using broth microdilution method ,according to the criteria of MICs being 4-fold or higher than the susceptible reference strain's counterparts. The specific primers of domain II and domain V of 23S rRNA of Mh clinical isolates resistant to josamycin were synthesized and DNA fragments were amplified by polymerase chain reaction(PCR) and amplicons were sequenced. The nucleotide sequences of Mh clinical isolates resistant to josamycin were compared with the reference strain's counterparts with Blast software, and the correlation of nucleotide mutation with the resistance to macrolides was analyzed.Results: In 106 Mh clinical isolates to 5 macrolides , josamycin was the most active agent against Mh, the MIC50 being 0.125 mg/L, MIC90 being 0.5 mg/L, roxithromycin, clarithromycin and azithromycin were less active against Mh, the MIC50 being 4 mg/L,32 mg/L and 64 mg/L, respectively; MIC90 being 32 mg/L,128 mg/L and 512 mg/L, respectively. Eryhthromycin had the least activity against Mh,with MIC50 and MIC90 being 64mg/L and 512 mg/L. Based on the accumulated inhibit bacteria rate at each concerntration, 4mg/L was required to inhibit 100% of Mh for josamycin ,whereas inhibit 100% of Mh required 64 mg/L for roxithromycin and required 512 mg/L for clarithromycin, azithromycin and erythromycin.Amplified DNA fragments of Mh clinical isolates resistant to josamycin in domain II and domain V of 23S rRNA by PCR. After sequencing, the DNA sequence...