苏州地区儿童感染流感嗜血杆菌β内酰胺酶基因检测

Detection of β-lactamase genes in Haemophilus influenzae strains isolated from infected children in Suzhou

目的 了解苏州地区儿童感染流感嗜血杆菌(Hi)对氨苄西林的耐药情况,并从分子生物学的角度研究其耐药机制。方法 对135株Hi临床分离株用K B法作药敏试验,头孢硝噻吩显色法进行β内酰胺酶测定,PCR法进行β内酰胺酶基因TEM、ROB测定。结果 本地区儿童感染Hi对氨苄西林的耐药率为17.8%,所有耐药株均产β内酰胺酶,未发现β内酰胺酶阴性耐氨苄西林Hi (BLNAR)菌株。β内酰胺酶基因TEM的检出率为27.4%(10.4%氨苄西林敏感株也检出TEM基因),ROB为0.7%(该ROB型株同时携带TEM 基因),发现1株非TEM非ROB 型产β内酰胺酶Hi。结论 本地区儿童感染Hi对氨苄西林的耐药情况不容乐观,其耐药机制主要是产生β内酰胺酶,且以TEM型为主,携带TEM基因的氨苄西林敏感株的出现,是否预示新一轮氨苄西林耐药株的产生,值得关注。

Objective This study was designed to investigate ampicillin resistance in H.influenzae strains isolated from infected children in Suzhou,and the mechanism of resistance.Methods The susceptibility of 135 of clinical isolates of H.influenzae were tested by Kirby-Bauer disc method.Chromogenic nitrocephin disc was used to detect beta-lactamase.TEM and ROB beta-lactamase genes were detected by PCR.Results The rate of ampicillin resistance was 17.8% in H.influenzae isolated from children in Suzhou.Beta-lactamase was produced by all ampicillin-resistant H.influenzae isolates.No beta-lactamase negative ampicillin-resistant H. influenzae (BLNAR) was identified.Beta-lactamase gene TEM was detected in 27.4% of H.influenzae isolates (TEM gene was also present in 10.4% of ampicillin-sensitive strains).ROB gene was detected in 0.7% of H.influenzae isolates (This ROB-type strain also carried TEM gene).One strain of non-TEM-type,and non-ROB-type beta-lactamse-producing H.influenzae was identified.Conclusions Ampicillin resistance in H.influenzae isolates from children in this region is challenging.The resistance mechanism of ampicillin resistant H.influenzae is production of beta-lactamase,mainly TEM-type enzyme.It should be noted that the emergence of ampicillin-sensitive strain carrying TEM gene,which may predicts the development of new ampicillin-resistant strains.