Hasegawa Keiko, Yamamoto Kentarou, Chiba Naoko, Kobayashi Reiko, Nagai Kensuke, Jacobs Michael R, Appelbaum Peter C, Sunakawa Keisuke, Ubukata Kimiko
Kitasato Institute for Life Sciences & Graduate School of Infection Control Sciences, Kitasato University, Tokyo, 108-8641, Japan.
Microb Drug Resist. 2003 Spring;9(1):39-46. doi: 10.1089/107662903764736337.
Clinical isolates of Haemophilus influenzae from Japan (n = 296) and the United States (n = 100) were tested by the microdilution method for susceptibility in vitro to 10 beta-lactam antibiotics and molecular mechanisms of beta-lactam resistance. For all isolates, PCR was used to identify six elements, including beta-lactamase-producing ampicillin (AMP)-resistance (BLPAR) and beta-lactamase-nonproducing AMP-resistance (BLNAR) genes as follows: (1) TEM-1 type beta-lactamase gene, (2) ROB-1 type beta-lactamase gene, (3) part of normal ftsI gene encoding PBP3, which is involved in septal peptidoglycan synthesis, (4) a portion of the ftsI gene possessing some amino acid substitutions commonly detected in BLNAR strains, (5) p6 gene encoding P6 membrane proteins specific to H. influenzae, and (6) serotype b capsule gene. In Japanese and U.S. isolates, respective prevalences of each resistance class in Japan and the United States were 55.1% and 46% for beta-lactamase-nonproducing, AMP-susceptible (BLNAS); 3.0% and 26% for the TEM-1 type beta-lactamase gene; 0% and 10% for the ROB-1 type; 26.4% and 13% for low-BLNAR with a low degree of AMP resistance; and 13.2% and 0% for BLNAR strains. A few remaining isolates were beta-lactamase-producing strains with a mutation in the ftsI gene. MICs of all beta-lactam agents against low-BLNAR strains were 2-8 times higher than against BLNAS. MICs of cephalosporin antibiotics against BLNAR strains were 16-32 times higher than against BLNAS. The rank order of beta-lactam MIC90 values against BLNAR strains was piperacillin = ceftriaxone = cefditoren (0.25 microg/ml), meropenem (0.5), cefotaxime (1), AMP = cefpodoxime (8), cefdinir (16), amoxicillin (16), and cefaclor (64). Serotype b isolates were few in both countries (2.4% in Japan, 3% in the United States). Differences in proportions of respective AMP-resistant genes in H. influenzae isolates between the two countries might reflect differences in antibiotic agents ordinarily given to outpatients with community-acquired bacterial infections.
采用微量稀释法对来自日本（n = 296）和美国（n = 100）的流感嗜血杆菌临床分离株进行体外药敏试验，检测其对10种β-内酰胺类抗生素的敏感性及β-内酰胺耐药的分子机制。对于所有分离株，采用聚合酶链反应（PCR）鉴定6种元件，包括产β-内酰胺酶的氨苄西林（AMP）耐药（BLPAR）和不产β-内酰胺酶的AMP耐药（BLNAR）基因，具体如下：（1）TEM-1型β-内酰胺酶基因；（2）ROB-1型β-内酰胺酶基因；（3）编码参与隔膜肽聚糖合成的PBP3的正常ftsI基因的一部分；（4）ftsI基因的一部分，具有一些在BLNAR菌株中常见的氨基酸替代；（5）编码流感嗜血杆菌特异性P6膜蛋白的p6基因；（6）b型荚膜基因。在日本和美国的分离株中，日本和美国各耐药类别的相应流行率如下：不产β-内酰胺酶、对AMP敏感（BLNAS）的分别为55.1%和46%；TEM-1型β-内酰胺酶基因的分别为3.0%和26%；ROB-1型的分别为0%和10%；低AMP耐药的低BLNAR的分别为26.4%和13%；BLNAR菌株的分别为13.2%和0%。其余少数分离株为ftsI基因发生突变的产β-内酰胺酶菌株。所有β-内酰胺类药物对低BLNAR菌株的最低抑菌浓度（MIC）比对BLNAS菌株高2 - 8倍。头孢菌素类抗生素对BLNAR菌株的MIC比对BLNAS菌株高16 - 32倍。β-内酰胺类药物对BLNAR菌株的MIC90值排序为：哌拉西林 = 头孢曲松 = 头孢妥仑（0.25μg/ml）、美罗培南（0.5）、头孢噻肟（1）、AMP = 头孢泊肟（8）、头孢地尼（16）、阿莫西林（16）、头孢克洛（64）。两国的b型血清型分离株均较少（日本为2.4%，美国为3%）。两国流感嗜血杆菌分离株中各AMP耐药基因比例的差异可能反映了社区获得性细菌感染门诊患者通常使用的抗生素药物的差异。
