Matono Takashi, Nagashima Maki, Mezaki Kazuhisa, Motohashi Ayano, Kutsuna Satoshi, Hayakawa Kayoko, Ohmagari Norio, Kaku Mitsuo
Disease Control and Prevention Center, Tokyo, Japan; Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
Disease Control and Prevention Center, Tokyo, Japan.
J Infect Chemother. 2018 Feb;24(2):153-155. doi: 10.1016/j.jiac.2017.10.014. Epub 2017 Nov 10.
Little is known about the prevalence of β-lactamase production in penicillin-susceptible Staphylococcus aureus isolates under high-susceptibility conditions. We analyzed S. aureus isolates with penicillin G minimum inhibitory concentration (MIC) ≤ 0.12 μg/ml that were recovered from in-/outpatients (n = 108) between 2016 and 2017 in Japan. β-Lactamase production was detected by nitrocefin-based and Clinical and Laboratory Standards Institute penicillin zone edge testing and blaZ PCR. All isolates were categorized as having penicillin G MIC ≤0.03 μg/ml using an automated system; MICs determined based on the microdilution method were 0.016 μg/ml (2%), 0.03 μg/ml (44%), and 0.06 μg/ml (54%). Notably, no isolates harbored the blaZ gene. The results from the nitrocefin-based and zone edge tests were consistent with those obtained by PCR. S. aureus isolates with penicillin G MIC ≤0.03 μg/ml exhibited a low frequency of β-lactamase production. Thus, screening for β-lactamase production may be unnecessary for isolates showing such high susceptibility.
在高敏感性条件下，对青霉素敏感的金黄色葡萄球菌分离株中β-内酰胺酶产生的流行情况知之甚少。我们分析了2016年至2017年期间在日本从门诊/住院患者中分离出的青霉素G最低抑菌浓度（MIC）≤0.12μg/ml的金黄色葡萄球菌分离株（n = 108）。通过基于头孢硝噻吩以及临床和实验室标准协会青霉素区域边缘试验和blaZ PCR检测β-内酰胺酶的产生。使用自动化系统将所有分离株分类为青霉素G MIC≤0.03μg/ml；基于微量稀释法测定的MIC分别为0.016μg/ml（2%）、0.03μg/ml（44%）和0.06μg/ml（54%）。值得注意的是，没有分离株携带blaZ基因。基于头孢硝噻吩和区域边缘试验的结果与PCR获得的结果一致。青霉素G MIC≤0.03μg/ml的金黄色葡萄球菌分离株β-内酰胺酶产生频率较低。因此，对于显示出如此高敏感性的分离株，可能无需筛查β-内酰胺酶的产生情况。
