Ikonomidis Alexandros, Michail George, Vasdeki Afroditi, Labrou Maria, Karavasilis Vasilis, Stathopoulos Constantinos, Maniatis Antonios N, Pournaras Spyros
Department of Medical Microbiology, University Hospital of Larissa, Mezourlo, Larissa, Greece.
Antimicrob Agents Chemother. 2008 Nov;52(11):3905-8. doi: 10.1128/AAC.00653-08. Epub 2008 Aug 11.
Community-type Staphylococcus aureus strains that are positive for mecA and PBP2a but appear phenotypically susceptible to oxacillin are increasingly reported worldwide. Four S. aureus clinical isolates carrying the mecA gene with oxacillin MICs of <2 microg/ml were tested for oxacillin efficiency by population analyses and experimental thigh infections. These isolates harbored staphylococcal cassette chromosome mec type IV and belonged to two genotypes. Two of the four isolates were found by population analysis to be truly oxacillin susceptible. All four isolates exhibited significant reductions in the numbers of colonies grown after dicloxacillin treatment of experimental thigh infections, as also did a mecA-negative S. aureus control strain. These observations indicate that some of the phenotypically oxacillin susceptible mecA-positive Staphylococcus aureus isolates may be at least partially responsive to oxacillin.
全球范围内越来越多地报道了对mecA和PBP2a呈阳性但在表型上对苯唑西林敏感的社区型金黄色葡萄球菌菌株。对4株携带mecA基因且苯唑西林最低抑菌浓度（MIC）<2μg/ml的金黄色葡萄球菌临床分离株进行了群体分析和实验性大腿感染，以检测苯唑西林的有效性。这些分离株携带IV型葡萄球菌盒式染色体mec，属于两种基因型。通过群体分析发现，4株分离株中有2株对苯唑西林真正敏感。在用双氯西林治疗实验性大腿感染后，所有4株分离株以及mecA阴性的金黄色葡萄球菌对照菌株的菌落生长数量均显著减少。这些观察结果表明，一些表型上对苯唑西林敏感的mecA阳性金黄色葡萄球菌分离株可能至少对苯唑西林有部分反应。
