Del' Alamo L, Cereda R F, Tosin I, Miranda E A, Sader H S
Special Clinical Microbiology Laboratory, Federal University of São Paulo, Brazil.
Diagn Microbiol Infect Dis. 1999 Jul;34(3):185-91. doi: 10.1016/s0732-8893(99)00034-6.
The antimicrobial susceptibility of 239 coagulase-negative staphylococci (CNS) isolates consecutively collected from blood culture in patients admitted in a 600-bed teaching hospital was evaluated. The isolates were identified to the species level by conventional methods and the MicroScan Positive Combo Panel type 6 system, and their susceptibility to vancomycin, teicoplanin, and oxacillin were tested by agar dilution, disk diffusion, and MicroScan-WalkAway system. The species distribution was as follows: Staphylococcus epidermidis 120 (50.2%), S. hominis 29 (12.1%), S. haemolyticus 24 (10.0%), S. cohnii 14 (5.9%), and isolates from other CNS species 52 (21.8%). The percentage of resistance to oxacillin was 74.5% by agar dilution. The highest percentages of oxacillin resistance were found among S. haemolyticus (95.8%) and S. epidermidis (80.8%). Teicoplanin resistance (MIC > or = 32 micrograms/mL) was detected in five S. haemolyticus isolates, whereas intermediate resistance (MIC = 16 micrograms/mL) was detected in nine strains. These isolates with reduced susceptibility to teicoplanin were resistant to oxacillin, but remained susceptible to vancomycin (MIC < or = 4 micrograms/mL). Two isolates, one S. haemolyticus and one S. epidermidis, showed a vancomycin MIC of 8 micrograms/mL, and both MicroScan and disk diffusion methods classified these isolates as susceptible. Our results showed that glycopeptide resistance is emerging among CNS isolates in our institution and the disk diffusion method may not detect isolates with decreased susceptibility to these antimicrobial agents.
对一家拥有600张床位的教学医院收治患者的血培养中连续收集的239株凝固酶阴性葡萄球菌（CNS）分离株的抗菌药物敏感性进行了评估。通过传统方法和MicroScan Positive Combo Panel 6型系统将分离株鉴定到种水平，并通过琼脂稀释法、纸片扩散法和MicroScan-WalkAway系统检测它们对万古霉素、替考拉宁和苯唑西林的敏感性。菌种分布如下：表皮葡萄球菌120株（50.2%），人葡萄球菌29株（12.1%），溶血葡萄球菌24株（10.0%），科氏葡萄球菌14株（5.9%），其他CNS菌种的分离株52株（21.8%）。通过琼脂稀释法测得对苯唑西林的耐药率为74.5%。在溶血葡萄球菌（95.8%）和表皮葡萄球菌（80.8%）中发现的苯唑西林耐药率最高。在5株溶血葡萄球菌分离株中检测到替考拉宁耐药（MIC≥32μg/mL），而在9株菌株中检测到中介耐药（MIC = 16μg/mL）。这些对替考拉宁敏感性降低的分离株对苯唑西林耐药，但对万古霉素仍敏感（MIC≤4μg/mL）。2株分离株，1株溶血葡萄球菌和1株表皮葡萄球菌，显示万古霉素MIC为8μg/mL，MicroScan法和纸片扩散法均将这些分离株分类为敏感。我们的结果表明，在我们机构的CNS分离株中出现了糖肽类耐药，并且纸片扩散法可能无法检测到对这些抗菌药物敏感性降低的分离株。
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