在结合疫苗引入之前，保加利亚儿童急性中耳炎主要病因肺炎链球菌和无分型流感嗜血杆菌分离株的微生物学特征。
Microbiological characterization of Streptococcus pneumoniae and non-typeable Haemophilus influenzae isolates as primary causes of acute otitis media in Bulgarian children before the introduction of conjugate vaccines.
机构信息
Department of Medical Microbiology, Medical University of Sofia, Faculty of Medicine, Sofia, 1431, BULGARIA.
出版信息
Ann Clin Microbiol Antimicrob. 2013 Mar 25;12:6. doi: 10.1186/1476-0711-12-6.
BACKGROUND
Pneumococcal and Haemophilus influenzae type b (Hib) vaccines were introduced in our national immunisation program in April 2010. The aims of this retrospective, laboratory-based study were to determine the serotypes and antibiotic resistance of Streptococcus pneumoniae and H. influenzae isolates from middle ear fluid (MEF) collected before the introduction of immunization.
METHODS
S. pneumoniae (n = 128) and H. influenzae (n = 40) strains isolated from MEF of children with AOM between 1994 and 2011 were studied. MICs were determined by a microdilution assay. Serotyping of S. pneumoniae was done by Quellung method and PCR capsular typing was used for H. influenzae. Macrolide resistance genes were detected by PCR for erythromycin resistant S. pneumoniae (ERSP). DNA sequencing of ftsI gene was performed for ampicillin nonsusceptible H. influenzae.
RESULTS
The most common serotypes found among children with pneumococcal AOM were 19 F (20.3%), 6B (15.6%), and 19A (10.9%). The potential coverage rates by the PCV7, PCV10 and PCV13 of children aged < 5 years were 63.6%, 66.4% and 85.5%, respectively. Reduced susceptibility to oral penicillin was seen in 68.1%; resistance to erythromycin was 46.9%. We found erm(B) gene in 56.7% of the ERSP, mef(E) gene in 25%; 15% harbored both genes erm(B) + mef(E) and 3.3% had mutations of L4 ribosomal protein. Of the 40 H. influenzae isolates 97.5% were nontypeable. Nonsusceptibility to ampicillin occurred in 25%. Ampicillin resistance groups were: β-lactamase-positive ampicillin resistant (BLPAR) strains (10%), β-lactamase-negative ampicillin resistant (BLNAR) strains (12.5%) and β-lactamase-positive amoxicillin-clavulanate resistant (BLPACR) strains (2.5%). Among BLNAR and BLPACR most of the isolates (5/6) belonged to group II, defined by the Asn526Lys substitution.
CONCLUSIONS
The levels of antibiotic resistance among S. pneumoniae and H. influenzae causing severe AOM in children are high in our settings. The existence of multidrug-resistant S. pneumoniae serotype 19A is of particular concern. The rate of BLNAR and BLPACR strains among H. influenzae isolates was 15%.
背景
肺炎球菌和乙型流感嗜血杆菌（Hib）疫苗于 2010 年 4 月在我国免疫规划中引入。本回顾性、基于实验室的研究旨在确定免疫接种前从儿童中耳液（MEF）中分离的肺炎链球菌和流感嗜血杆菌分离株的血清型和抗生素耐药性。
方法
研究了 1994 年至 2011 年间因急性中耳炎从儿童 MEF 中分离的 128 株肺炎链球菌和 40 株流感嗜血杆菌菌株。采用微量稀释法测定 MIC。肺炎链球菌血清型通过 Quellung 法确定，流感嗜血杆菌通过 PCR 荚膜分型确定。通过 PCR 检测红霉素耐药肺炎链球菌（ERSP）中的大环内酯类耐药基因。对氨苄西林不敏感的流感嗜血杆菌进行 ftsI 基因的 DNA 测序。
结果
儿童肺炎球菌性 AOM 中最常见的血清型为 19F（20.3%）、6B（15.6%）和 19A（10.9%）。7 价、10 价和 13 价 PCV 对<5 岁儿童的潜在覆盖率分别为 63.6%、66.4%和 85.5%。口服青霉素的敏感性降低见于 68.1%；对红霉素的耐药率为 46.9%。我们发现 56.7%的 ERSP 携带 erm(B)基因，25%携带 mef(E)基因；15%同时携带 erm(B)基因和 mef(E)基因，3.3%的基因发生 L4 核糖体蛋白突变。40 株流感嗜血杆菌中有 97.5%为非分型。氨苄西林不敏感发生率为 25%。氨苄西林耐药组为：产β-内酰胺酶的氨苄西林耐药（BLPAR）菌株（10%）、产β-内酰胺酶的氨苄西林耐药（BLNAR）菌株（12.5%）和产β-内酰胺酶的阿莫西林克拉维酸耐药（BLPACR）菌株（2.5%）。在 BLNAR 和 BLPACR 中，大多数分离株（5/6）属于 Asn526Lys 取代定义的 II 组。
结论
在我们的环境中，引起儿童严重 AOM 的肺炎链球菌和流感嗜血杆菌的抗生素耐药水平很高。19A 血清型多药耐药肺炎球菌的存在尤其令人担忧。流感嗜血杆菌分离株中 BLNAR 和 BLPACR 菌株的发生率为 15%。
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