Department of Respiratory Medicine, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, China.
Department of Clinic Laboratory, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, China.
PLoS One. 2018 Jun 1;13(6):e0198061. doi: 10.1371/journal.pone.0198061. eCollection 2018.
Multidrug-resistant Acinetobacter baumannii (A. baumannii) has become one of the greatest threats worldwide to the therapeutic management of infections. Our previous research confirmed an in vitro synergistic effect of amlodipine and imipenem against A. baumannii, and this study is designed to understand its mechanism.
Sixty-four non-duplicate A. baumannii isolates were collected and tested for antimicrobial susceptibility by the disk diffusion method. PCR amplification and sequencing were used to identify the presence of the adeB, adeE, adeH, adeJ, abeM and abeS efflux pump genes. The minimal inhibitory concentrations of imipenem, imipenem+amlodipine and imipenem+carbonyl cyanide m-chlorophenyl-hydrazone against these isolates were also determined by the broth microdilution method before and after siRNA silencing of the expression of the adeABC efflux pump.
In this study, the combination of amlodipine with imipenem showed synergistic antimicrobial activity against sixty-four A. baumannii isolates when compared with the activity of imipenem alone (p<0.025). In the multidrug-resistant group, AML was more effective than carbonyl cyanide m-chlorophenyl-hydrazone (p<0.001). The efflux pump genes adeB, adeE, adeH, adeJ, abeM and abeS were detected in 100% (4/64), 75% (48/64), 0% (0/64), 100% (64/64), 96.9% (62/64) and 96.9% (62/64) of the sixty-four A. baumannii isolates, respectively. The expression of the adeABC efflux pump genes in the multidrug-resistant group (5.05±19.25) is clearly higher than in the non-multidrug-resistant group (0.17±0.20), (p = 0.01). A gene silencing test verified that the mRNA expression levels of adeABC were decreased at 12 h and increased at 24 h, while the reversal of imipenem resistance by amlodipine disappeared at 12 h and reappeared at 24 h.
The combination of amlodipine with imipenem exhibits an in vitro synergistic antimicrobial effect on multidrug-resistant A. baumannii, which may be due to the inhibition of the AdeABC efflux pump.
多药耐药鲍曼不动杆菌（A.baumannii）已成为全球治疗感染的最大威胁之一。我们之前的研究证实了氨氯地平和亚胺培南对鲍曼不动杆菌具有体外协同作用，本研究旨在了解其机制。
收集了 64 株非重复鲍曼不动杆菌分离株，并通过纸片扩散法检测其抗菌药物敏感性。采用 PCR 扩增和测序方法鉴定 adeB、adeE、adeH、adeJ、abeM 和 abeS 外排泵基因的存在。在用 siRNA 沉默 adeABC 外排泵的表达之前和之后，通过肉汤微量稀释法测定这些分离株对亚胺培南、亚胺培南+氨氯地平以及亚胺培南+羰基氰化物 m-氯代苯腙的最小抑菌浓度。
本研究中，与亚胺培南单独使用相比，氨氯地平联合亚胺培南对 64 株鲍曼不动杆菌分离株表现出协同抗菌活性（p<0.025）。在多药耐药组中，AML 比羰基氰化物 m-氯代苯腙更有效（p<0.001）。adeB、adeE、adeH、adeJ、abeM 和 abeS 外排泵基因在 100%（4/64）、75%（48/64）、0%（0/64）、100%（64/64）、96.9%（62/64）和 96.9%（62/64）的 64 株鲍曼不动杆菌分离株中均有检出。多药耐药组 adeABC 外排泵基因的表达（5.05±19.25）明显高于非多药耐药组（0.17±0.20）（p=0.01）。基因沉默试验证实，adeABC 的 mRNA 表达水平在 12 小时下降，在 24 小时上升，而氨氯地平逆转亚胺培南耐药的作用在 12 小时消失，在 24 小时重新出现。
氨氯地平和亚胺培南联合使用对多药耐药鲍曼不动杆菌具有体外协同抗菌作用，这可能是由于抑制了 AdeABC 外排泵。
