Gülmez Dolunay, Hasçelik Gülşen
Hacettepe University Faculty of Medicine, Department of Medical Microbiology, Ankara, Turkey.
Mikrobiyol Bul. 2011 Jan;45(1):21-7.
Enterococcus spp. are important pathogens which are intrinsically resistant to most of the commonly used antimicrobial agents such as aminoglycosides and cephalosporins. Accurate determination of resistance is important to ensure appropriate antimicrobial therapy. This study was undertaken to compare the susceptibility results obtained by Phoenix system (Becton Dickinson, USA) with reference microdilution method. We included 1248 Enterococcus spp. (903 Enterococcus faecalis, 345 Enterococcus faecium) strains isolated from clinical samples between 2005-2007 in routine microbiology laboratory of Hacettepe University Hospital. The strains were identified and the antimicrobial susceptibilities were determined by the Phoenix system. Antimicrobial susceptibilities to ampicillin, teicoplanin, vancomycin, gentamicin and streptomycin were also studied by microdilution method according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Evaluation revealed excellent agreement for all of the antibiotics with category agreement rates of > 97%. Among 1248 strains, 76 revealed discordant results. Very major error rates were 1.5% for ampicillin, 1.3% for gentamicin, and 0.9% for streptomycin. Major error rates were 1.4% for streptomycin, 0.6% for ampicillin and vancomycin and 0.3% for gentamicin. Minor error rates were found as 0.2% for vancomycin, and 0.1% for teicoplanin. Resistance rates obtained by microdilution were as follows; high level streptomycin 44%, high level gentamicin 29.7%, ampicillin 25.6%, vancomycin 2.2% and teicoplanin 2.2%. Resistance rates were higher in E.faecium than E.faecalis and 96.4% of the vancomycin resistant enterococcus isolates were identified as E.faecium. In conclusion, based on the data obtained, Phoenix system is reliable for testing susceptibilities of Enterococcus spp. to these antimicrobials. Since isolation of vancomycin resistant enterococci has an important impact in terms of hospital infection control, vancomycin resistance reported by the Phoenix system should be confirmed with an alternative susceptibility testing method.
肠球菌属是重要的病原菌，对大多数常用抗菌药物如氨基糖苷类和头孢菌素类具有内在耐药性。准确测定耐药性对于确保适当的抗菌治疗至关重要。本研究旨在比较用菲尼克斯系统（美国BD公司）获得的药敏结果与参考微量稀释法的结果。我们纳入了2005年至2007年间在哈杰泰佩大学医院常规微生物实验室从临床样本中分离出的1248株肠球菌属（903株粪肠球菌，345株屎肠球菌）菌株。通过菲尼克斯系统对菌株进行鉴定并测定抗菌药敏性。还根据临床和实验室标准协会（CLSI）指南，用微量稀释法研究了对氨苄西林、替考拉宁、万古霉素、庆大霉素和链霉素的抗菌药敏性。评估显示所有抗生素的一致性都非常好，类别一致率>97%。在1248株菌株中，有76株结果不一致。氨苄西林的极重大错误率为1.5%，庆大霉素为1.3%，链霉素为0.9%。链霉素的重大错误率为1.4%，氨苄西林和万古霉素为0.6%，庆大霉素为0.3%。万古霉素的微小错误率为0.2%，替考拉宁为0.1%。通过微量稀释法获得的耐药率如下：高水平链霉素44%，高水平庆大霉素29.7%，氨苄西林25.6%，万古霉素2.2%，替考拉宁2.2%。屎肠球菌的耐药率高于粪肠球菌，96.4%的耐万古霉素肠球菌分离株被鉴定为屎肠球菌。总之，根据获得的数据，菲尼克斯系统对于检测肠球菌属对这些抗菌药物的药敏性是可靠的。由于耐万古霉素肠球菌的分离在医院感染控制方面具有重要影响，菲尼克斯系统报告的万古霉素耐药性应通过另一种药敏试验方法进行确认。
