Shimada J, Hotomi M, Kuki K, Yamanaka N, Mitsuda T, Yokota S
Department of Otorhinolaryngology, Wakayama Medical College.
Nihon Jibiinkoka Gakkai Kaiho. 2000 May;103(5):552-9. doi: 10.3950/jibiinkoka.103.552.
We have recently been confronted with refractory upper respiratory infections with an increasing prevalence of penicillin (Pc)-resistant S. pneumoniae. There has been a broad consensus that acute otitis media (AOM) is caused by migration of pathogens from nasopharynx and proliferation in the middle ear space, and thus it is, very important to study the bacterial environment in the nasopharynx as the source of middle ear infections. Eighty pneumococcal isolates from the nasopharynx of children with acute otitis media were evaluated by polymerase chain reaction (PCR) for mutation of Pc-binding protein (PBP) genes. The results showed mutation of all three PBP genes, pbp 1a, pbp 2x, and pbp 2b, in 30% of the isolates, while 74% were found to possess various PBP gene mutations, mostly in one-year-old children. Of the 46 isolates whose minimum inhibitory concentration (MIC) of Pc was < or = 0.06 microgram/mL, 43% were found to possess a pbp 2x mutaion, which affects cefem resistance. We genotyped each pneumococcal isolate from the nasopharynx of children with recurrent AOM by pulsed-field gel electrophoresis (PFGE). In 9 of 11 pairs (82%) of consecutive AOM episodes, the nasopharyngeal isolate in the second episode was different. In addition, discrimination of each isolate based upon the mutation profile of its PBP genes in 8 pairs (72%) of consecutive AOM episodes showed that the isolates were different, and there was little difference between the results of PBP gene mutation and PFGE analysis. These findings suggest that most nasopharyngeal isolates from children with AOM possess PBP mutations and that children with increased numbers of drug-resistant bacteria in their nasopharynx during AOM has been colonized or recolonized by different strains during each episode. We therefore emphasize that clinicians should assess the antibiotic susceptibility of nasopharyngeal isolates from children during each episode. PBP gene mutation analysis of S. pneumoniae is useful not only in providing valuable information on the antibiotic susceptibility of each strain but for assessing changes in causative strains in the sequential episodes of pneumococcal infection.
我们最近面临着难治性上呼吸道感染，对青霉素（Pc）耐药的肺炎链球菌患病率不断上升。人们已普遍达成共识，急性中耳炎（AOM）是由病原体从鼻咽部迁移并在中耳腔增殖引起的，因此，研究作为中耳感染源的鼻咽部细菌环境非常重要。采用聚合酶链反应（PCR）对80株来自急性中耳炎患儿鼻咽部的肺炎链球菌分离株进行Pc结合蛋白（PBP）基因突变评估。结果显示，30%的分离株中pbp 1a、pbp 2x和pbp 2b这三个PBP基因均发生突变，而74%的分离株存在各种PBP基因突变，大多发生在一岁儿童中。在46株Pc最低抑菌浓度（MIC）≤0.06微克/毫升的分离株中，43%被发现存在pbp 2x突变，该突变影响头孢菌素耐药性。我们通过脉冲场凝胶电泳（PFGE）对复发性AOM患儿鼻咽部的每株肺炎链球菌分离株进行基因分型。在11对（82%）连续的AOM发作中，有9对在第二次发作时鼻咽部分离株不同。此外，在8对（72%）连续的AOM发作中，根据其PBP基因突变谱对每个分离株进行鉴别显示分离株不同，PBP基因突变结果与PFGE分析结果之间差异不大。这些发现表明，大多数来自AOM患儿的鼻咽部分离株存在PBP突变，且AOM期间鼻咽部耐药菌数量增加的患儿在每次发作期间已被不同菌株定植或重新定植。因此，我们强调临床医生在每次发作期间应评估患儿鼻咽部分离株的抗生素敏感性。肺炎链球菌的PBP基因突变分析不仅有助于提供关于每种菌株抗生素敏感性的有价值信息，还可用于评估肺炎链球菌感染连续发作中致病菌株的变化。
