Clin Lab. 2022 Jun 1;68(6). doi: 10.7754/Clin.Lab.2021.210936.
In our study, we evaluated the in vitro activities of plazomicin, amikacin, gentamicin, and tobramycin among fifty carbapenem resistant Klebsiella pneumoniae (CR-Kp) isolates. Aminoglycoside resistance genes in selected CR-Kp strains were also examined.
Minimum inhibitory concentration (MIC) of meropenem, plazomicin, tobramycin, gentamicin, and amikacin were determined by gradient test (G-test) method. In all strains carbapenemase activity was assessed by polymerase chain reaction (PCR). Aminoglycoside modifying enzyme (AME) genes in 14 CR-Kp strains that are resistant to at least one of tobramycin, gentamicin, and amikacin among fifty CR-Kp isolates, and 16S ribosomal methylase genes in 6 CR-Kp strains with plazomicin MIC ≥ 128 mg/L were investigated by PCR method.
The most frequently detected carbapenemase enzyme in the strains in our study was OXA-48 (88%). Aminoglycoside susceptibilities of all isolates were determined; plazomicin 84%, amikacin 66%, gentamicin 50%, tobramycin 18%. The most common AME gene positivities were found, 93% (n = 13) ant(3')-I, 78% (n = 11) aac(6')-Ib, 57% (n = 8) aac(3')-IV, 42% (n = 6) aac(3')-IIa, and 29% (n = 4) aph(3')-VI. Most of the isolates examined for the presence of AME carry at least two or more AME genes. The most common 16S ribosomal methylase gene was rmtH. In our study, MIC values of ≥ 256 µg/mL were found in 6 (12%) of 50 isolates against amikacin, tobramycin, and gentamicin, including plazomicin. At least two 16S ribosomal methylase gene positivity has been shown in these 6 strains.
In our study, increased in vitro efficacy of plazomicin was shown in CR-Kp isolates comparing to other aminoglycosides. Plazomicin is an effective treatment option against CR-Kp isolates and needs to be sup-ported by clinical studies.
在我们的研究中，我们评估了五十株耐碳青霉烯肺炎克雷伯菌（CR-Kp）分离株中黏菌素、阿米卡星、庆大霉素和妥布霉素的体外活性。还检查了选定的 CR-Kp 菌株中的氨基糖苷类耐药基因。
采用梯度试验（G 试验）法测定美罗培南、黏菌素、妥布霉素、庆大霉素和阿米卡星的最小抑菌浓度（MIC）。在所有菌株中均通过聚合酶链反应（PCR）评估碳青霉烯酶活性。对五十株 CR-Kp 分离株中至少有一株对妥布霉素、庆大霉素和阿米卡星耐药的 14 株 CR-Kp 菌株中的氨基糖苷类修饰酶（AME）基因，以及对黏菌素 MIC≥128mg/L 的 6 株 CR-Kp 菌株中的 16S 核糖体甲基酶基因进行了 PCR 法检测。
在本研究中，菌株中最常检测到的碳青霉烯酶是 OXA-48（88%）。所有分离株的氨基糖苷药敏性均确定；黏菌素 84%、阿米卡星 66%、庆大霉素 50%、妥布霉素 18%。发现最常见的 AME 基因阳性率为 93%（n=13）ant（3'）-I、78%（n=11）aac（6'）-Ib、57%（n=8）aac（3'）-IV、42%（n=6）aac（3'）-IIa 和 29%（n=4）aph（3'）-VI。检测 AME 存在的大多数分离株至少携带两种或更多种 AME 基因。最常见的 16S 核糖体甲基酶基因是 rmtH。在我们的研究中，对 50 株分离株中的 6 株（12%）对阿米卡星、妥布霉素和庆大霉素（包括黏菌素）的 MIC 值≥256µg/ml，这些菌株中至少有两种 16S 核糖体甲基酶基因阳性。
与其他氨基糖苷类药物相比，在 CR-Kp 分离株中，黏菌素的体外疗效有所提高。黏菌素是治疗 CR-Kp 分离株的有效治疗选择，需要临床研究支持。
