2002 - 2003年美国耐大环内酯类的化脓性链球菌

Macrolide-resistant Streptococcus pyogenes in the United States, 2002-2003.

作者信息

Richter Sandra S, Heilmann Kristopher P, Beekmann Susan E, Miller Norma J, Miller Ashley L, Rice Cassie L, Doern Christopher D, Reid Sean D, Doern Gary V

机构信息

Department of Pathology, University of Iowa Carver College of Medicine, Iowa City, IA 52242-1009, USA.

出版信息

Clin Infect Dis. 2005 Sep 1;41(5):599-608. doi: 10.1086/432473.

DOI:10.1086/432473

PMID:16080080

Abstract

BACKGROUND

Increased levels of macrolide-resistant Streptococcus pyogenes in focal regions of the United States have been reported. The purpose of this study was to determine the antimicrobial susceptibility of a large collection of S. pyogenes isolates from throughout the United States and to elucidate the mechanisms of resistance and genetic relatedness of macrolide-resistant isolates.

METHODS

During 2002-2003, a total of 1885 S. pyogenes clinical isolates were obtained from 45 US medical centers. Susceptibility to penicillin, cefdinir, erythromycin, azithromycin, clarithromycin, clindamycin, telithromycin, and levofloxacin was determined. Macrolide resistance phenotypes were determined by double-disk diffusion, and macrolide resistance genotypes were determined by polymerase chain reaction and sequencing. All macrolide-resistant isolates and all isolates recovered from sterile sites were further characterized by pulsed-field gel electrophoresis (PFGE) and emm typing.

RESULTS

The majority (85%) of isolates were pharyngeal. Resistance was detected to erythromycin (6.8% of isolates), azithromycin (6.9%), clarithromycin (6.6%), clindamycin (0.5%), telithromycin (0.2%), and levofloxacin (0.05%). The macrolide-resistance phenotype distribution was as follows: macrolide-lincosamide-streptogramin B (MLSB), 56% of isolates (inducible, 47%; constitutive, 9%); and M, 44%. The genotypes detected were as follows: ermA, 46% of isolates (95% with inducible MLSB phenotype); mefA, 43% (all with M phenotype); and ermB, 8.5% (45% with inducible MLSB and 45% with constitutive MLSB). Three isolates with constitutive MLSB phenotypes had 23S ribosomal RNA mutations. The 129 erythromycin-resistant isolates belonged to 28 emm types and 44 PFGE patterns, with 51% of the isolates in 4 major PFGE clones each associated with a predominant emm type (emm75, emm58, emm12, and emm114) and resistance genotype (mefA or ermA)).

CONCLUSIONS

The population of macrolide-resistant S. pyogenes isolates in the United States is small, but it includes several large clones with potential for expansion.

摘要

背景

据报道，美国部分地区抗大环内酯类化脓性链球菌的水平有所升高。本研究的目的是确定来自美国各地的大量化脓性链球菌分离株的抗菌药敏性，并阐明大环内酯类耐药菌株的耐药机制和遗传相关性。

方法

在2002 - 2003年期间，从美国45个医疗中心共获得了1885株化脓性链球菌临床分离株。测定了这些菌株对青霉素、头孢地尼、红霉素、阿奇霉素、克拉霉素、克林霉素、泰利霉素和左氧氟沙星的敏感性。通过双碟扩散法确定大环内酯类耐药表型，通过聚合酶链反应和测序确定大环内酯类耐药基因型。所有大环内酯类耐药菌株和从无菌部位分离出的所有菌株通过脉冲场凝胶电泳（PFGE）和emm分型进一步进行特征分析。

结果

大多数（85%）分离株来自咽部。检测到对红霉素（6.8%的分离株）、阿奇霉素（6.9%）、克拉霉素（6.6%）、克林霉素（0.5%）、泰利霉素（0.2%）和左氧氟沙星（0.05%）的耐药性。大环内酯类耐药表型分布如下：大环内酯 - 林可酰胺 - 链阳菌素B（MLSB），56%的分离株（诱导型，47%；组成型，9%）；M表型，44%。检测到的基因型如下：ermA，46%的分离株（95%具有诱导型MLSB表型）；mefA，43%（均具有M表型）；ermB，8.5%（45%具有诱导型MLSB，45%具有组成型MLSB）。三株具有组成型MLSB表型的菌株有23S核糖体RNA突变。129株红霉素耐药菌株属于28种emm型和44种PFGE模式，其中51%的菌株属于4个主要PFGE克隆，每个克隆都与一种主要的emm型（emm75、emm58、emm12和emm114）和耐药基因型（mefA或ermA）相关。