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目的研究流感嗜血杆菌(Hi)对β内酰胺类和氟喹诺酮类的敏感性和耐药机制。方法用琼脂二倍稀释法,检测Hi对β内酰胺类和氟喹诺酮类敏感性;Nitrocefin显色反应对所有菌株进行β内酰胺酶检测,PCR扩增检测Hi的β内酰胺酶基因(TEM-1和ROB-1)以及氟喹诺酮的耐药决定区(QRDR),并对特异条带测序并分析。结果对183株受试Hi,氨苄西林的敏感率为73.2%(134/183);对氨苄西林/舒巴坦、头孢噻肟和头孢吡肟均敏感率达100%。检出环丙沙星和莫西沙星不敏感Hi分别为2株(2/183)和3株(3/184),其中1株对环丙沙星和莫西沙星均不敏感。有34株(18.6%)TEM-1基因阳性;34株菌都携TEM-1型β内酰胺酶基因,未发现ROB-1基因;所有氟喹诺酮不敏感菌株的GyrA和ParC均发现一或多个氨基酸改变,且GyrA主要发生在84位和88位。结论除对氨苄西林外,Hi对头孢菌素和氟喹诺酮类保持较高敏感性。Hi对氨苄西林的耐药主要是产生β内酰胺酶,且主要为TEM-1型。QRDR的氨基酸改变是Hi对氟喹诺酮不敏感的主要机制。
Objective To study the sensitivity and resistance mechanism of Haemophilus influenzae to β-lactams and fluoroquinolones. Methods The sensitivity of Hi to β-lactams and fluoroquinolones was detected by two-fold agar dilution method. Nitrocefin color reaction was used to detect β-lactamases of all the strains. The PCR amplification was used to detect the Hi-β-lactamase gene (TEM- 1 and ROB-1) and fluoroquinolone resistance-determining regions (QRDR), and specific bands were sequenced and analyzed. Results The sensitivity of 183 strains to Hi and Ampicillin was 73.2% (134/183). The sensitivity to ampicillin / sulbactam, cefotaxime and cefepime was 100%. Two strains (2/183) and 3 strains (3/184) were found to be insensitive to ciprofloxacin and moxifloxacin, respectively. One of them was insensitive to ciprofloxacin and moxifloxacin. 34 (18.6%) were positive for TEM-1 gene. All 34 strains carried TEM-1 beta-lactamase gene and no ROB-1 gene was found. All of the fluoroquinolone-insensitive strains showed one or more of GyrA and ParC Amino acids change, and GyrA occurs mainly at positions 84 and 88. Conclusion Hi has a high sensitivity to cephalosporins and fluoroquinolones except for ampicillin. Hi resistance to ampicillin is mainly β-lactamase production, and mainly TEM-1 type. Amino acid changes in QRDR are the major mechanisms by which Hi is not susceptible to fluoroquinolones.