Objective To investigate antirnierobial resistance of comlnon pathogenic bacteria isolated from children's respiratory tract in Beijng friendship Hospital during the period between January 2004 and December 2006.Methods Forty-nine strains of Streptococcus pneumoniae,fifty-five strains of Staphylococcus aureus and fifteen strains of Group A β-hemolytic streptococcus were isolated from children with community-acquired respiratory tract infeetion in pediatric department of Beijng Friendship Hospital.Kirby-Bauer agar dilution method Was used to determine the susceptibility to antimicrobial agents.Results Ninety percent of Streptococcus pneumoniae strains were resistant to erythromycin.Penicillin-non-susceptible streptococcus pneumoniae accounted for 10%,while 90% of which were multi-drug resistant.For Staphylococcus aureu strains,the resistant rates of ampicillin,penicillin and oxacfllin were 86%,82%,and 9% respectively,and serere multi-drug resistance was found.Eighty percent of the group A β-hemolytic streptococcus strains were resistant to erythromycin,however all remained sensitive to penicillin and ampicillin.Conclusion The antimicrobials resistant pathogenic bacteria isolated from children with respiratory tract infection have become a severe prdblem.The resistant rates of macrolides are high for Streptococcus and Group A β-hemolytic streptococcus.MeticiUin resistant staphylococcus aureus(MRSA)strains were found in the study.Severe multi-drug resistance was found.Non β-lactam antibiotics should be avoided when respiratory tract bacterial infection occurred in children.

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.