呼吸道感染儿童流感嗜血杆菌耐药性的研究

Study on the resistance of Haemophilus influenzae from children with respiratory tract infection

目的动态了解2000-2002年从呼吸道感染患儿鼻咽部分离出的流感嗜血杆菌(Hi)对8种常用抗菌药物的耐药性、产酶率以及b型Hi(Hib)感染的情况,以有效指导临床合理用药和预防。方法连续3年对呼吸道感染患儿的鼻咽分泌物进行Hi分离培养,用KirbryBauer(KB)法和Etest法每年测定100株Hi对8种抗菌药物的耐药率,以Nitrocefin纸片法测定β内酰胺酶的产生率;以玻片凝集法分离出b型株。结果Hi总分离率27.5%,Hib占21%;β内酰胺酶总产生率11.3%,其中Hib产酶率41.3%,明显高于非Hib产酶率3.0%(P<0.01)。Hi对阿莫西林克拉维酸、头孢曲松、头孢克洛和头孢呋辛均敏感,对氨苄西林、氯霉素耐药率处较低的水平,分别为9%～15%和6%～11%;对四环素、复方磺胺甲噁唑的耐药率分别为28%～66%和38%～68%。结论Hi对氨苄西林、氯霉素耐药率在增加,复方磺胺甲噁唑已不宜用于Hi引起的感染;Hib是儿童呼吸道感染重要血清型,产β内酰胺酶是Hi对氨苄西林耐药的重要机制。

Objective This study was designed to dynamically investigate the antibiotic resistance, prevalence of enzyme-producing strain of Haemophilus influenzae (Hi) and the infection caused by Hi type B (Hib) in clinical isolates from nasopharyngeal culture in Shanghai children during 2000-2002.Methods The nasopharyngeal secretions from children with respiratory tract infection were cultured to isolate Hi in 3 consecutive years. Susceptibility of Hi isolates (100 each year) to 8 antibacterial agents was determined by Kirby-Bauer (K-B) method and E test to calculate resistance rates. The enzyme-producing strain was tested by Nitrocefin disk. Type B Hi was identified by slide agglutination.Results The overall positive isolation rate of Hi was 27.5%. Hib accounted for 21%. The prevalence of β-lactamase was 11.3% in all Hi isolates, but ~41.3% in Hib strains, which was significantly higher than that in non-type B Hi (3.0%, P<0.01). The Hi isolates were susceptible to amoxicillin-clavulanic acid, ceftriaxone, cefaclor, and cefuroxime, but slightly resistant to ampicillin and chloramphenicol, the reistance rate of which was 6%-11% and 9%-15%. About 28%-66% of Hi isolates were resistant to tetracycline and 38%-68% resistant to trimethoprim-sulfamethoxazole.Conclusion The resistance rates of Hi to ampicillin and chloramphenical are inereasing. Trimethoprim-sulfamethoxazole is not appropriate for the treatment of infections caused by Hi. Hib is the important serotype causing respiratory tract infections in children. Beta-lactamase production is the important mechanism of Hi resistant to ampicillin.