| The prevalence of antibacterial agents resistance among clinical isolates of some common bacteria, namely, Streptococcus pneumoniae, Haemophilus influenzas and Moraxella catarrhalis from community-acquired pneumonia in Hangzhou, China was surveyed. Meanwhile, the macrolide resistant mechanism in Streptococcus pneumoniae was also investigated. The methods and results as well as conclusion are noted as follow.Methods: From October, 2002 to March2003, 68 isolates of S. pneumoniae, 64 isolates of H. influenzae and 28 isolates of M. catarrhalis from the patients with community-acquired pneumonia, were collected from six hospitals in Hangzhou. The antimicrobial susceptibilities of each bacteria! isolate to 6 or 11 antimicrobial agents were determined by the agar dilution method or E-test according to the National Committee for Clinical Laboratory Standards (NCCLS). Genomic DNA of S.pneumoniae was extracted using boiling lysis ,and then ermB and mefA genes were amplified by PCR and sequenced.Results: Among 68 isolates of S. pneumoniae, only one isolate (1.5%) was penicillin resistant, 42 isolates (61.8%), however, were intermediately resistant.The rate of resistance to cefaclor was 54.4%. 86.8% of these isolates performed resistance to both of erythromycin and azithromycin, 89.8% among which were highly resistant(MIC 64 g/ml). In contrast, more than 85% of isolates were susceptible to cefotaxime, ceftriaxone and levofloxacin, and 100% were still susceptible to amoxicillin/clavulanic, vancomycin. rifampicin and teicoplanin. 7.8% of 64 H. influenzae and 92.9% of 28 M. caiarrhalis produced pMactamase. Resistance in H influenza was 7.8% to ampicillin and 3.1% to azithromycin, AS to M catarrhalis isolates,35.7% were resistant only to ampicillin.Overall.the highest susceptible rates for these two common pathogens were noted with -lactam/p-lactamase inhibitor combination/the second, third-generation cephaloaporins and fluoroquinolones.Among 68 isolates of S.pneumaniae, 70.6% were ermB-carrier, and 25.0% were mefA-carrier. 93.8% of ermB-camer isolates and 100% /Tie/^-carrier isolates were erythromycin-resistant. The S. pneunoniae with both genes of ermB and mefA showed high resistance to erythromycin and azithromycin (MIC ^64 fig/ml). Neither ermB nor mefA gene was detected in 11 of 68 isolates.Cloning and sequencing were preformed for PCR products. DNA-sequencing results demonstrated that the sequences of ermB and mefA genes were almost identical to the sequences deposited in GenBank.Conclusion: In light of the fact that 61.8% of S. pneumonia performed intermediate penicillin-resistance although the penicillin resistant rate was low in Hangzhou, the increase tendency of the penicillin resistant rate should be concerned. The high resistance to cefaclor was obsverded. S. pneumonia has prevalently acted macrolide resistance, while still remained susceptible to the third-generation cephalosporins, amoxicillin/clavulanic acid, fluoroquinolones, rifampicin. vancomycin and teicoplanin. So it is necessary to monitor antimicrobial resistance of these bacteria so as to guide the suitable clinical choices of antimicrobial agents. p-lactamase-positive H.influenzae strains are few but P-lactamase-positive strains of M.catarrhalis are common in this area, p-lactam/p-lactamase inhibitor.combination,fluoroquinolones,azithromycin,second, third-generation cephalosporins still have excellent activity to these two pathogens.There were both ermB and mefA genes in 5. pneiunaniae in Hangzhou. Either express singly or together, they would result m macrolide resistance. In contrast, some isolates of S. pneumaniae without either of ermB and mefA genes also were resistant to macrolide. In general, the target modification by ermB-mythylase was regarded as the predominant mechanism of macrolide resistance in S. pneumaniae isolated in Hangzhou.
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