Macrolide resistance and molecular mechanisms in Mycoplasma pneumoniae

Objective To investigate status of macrolide resistance and determine molecular mechanisms in Mycoplasma pneumoniae.Nethods All of 370 throat swab specimens were cultured to isolate Mycoplasma pneumoniae.Mycoplasma pneumoniae isolates were identified by nested PCR for specific 16SrRNA gene.Antibiotic susceptibility test was done to identify acrolide resistant strains.23SrRNA gene wag amplified by nested PCR followed by direct automatic sequencing method.The DNA sequences were compared to the sequence of Mycoplasma pneumoniae M129(accession no.X68422)to find molecular mechanisms of drug resistance.Results Fifty clinical strains were isolated from 370 specimens.Of 50 strains.4 strains were susceptible to macrulide,46 strains were macrolide resistant with the percentage of 92%.MICs of resistant strains to erythromycin.Azithromycin and josamycin were elevated.The sequence of 23SrRNA gene in 4 Susceptible strains and the reference strain FH was identical to Mycoplagma pneumoniae gene in GenBank.46 resistant strains arbored a point mutation respectively,among them,40 strains had all A to G transition at position 2063.1 strain had an A to C transition at position 2063,the other five strains showed an A to G transition at position 2064.Conclusions Macrolide resistance in Mycoplasma pneumoniae iS very serious health conceru.The point mutation in 23SrRNA.Xpecailly predominant position 2063 mutation contributed to the macrolide resistance in Mycoplagma pneumoniae.The MICs of resistant strains to erythromycin,azithromycin and iosamycin are much higher than Mycoplasma pneumoniae reference strain FH. Key words: Mycoplasma pneumoniae;  Macrolides;  Drug resistance,bacterial;  Microbial sensitivity test;  RNA,ribosomal,23S; Point mutation