In the past few years the increasing incidence of hospital infections with Acinetobacter baumannii, especially in immunocompromised patients, and its proneness to develop multidrug resistance have been raising considerable concern. This study examines the antimicrobial and antibiofilm activity of protegrin 1 (PG-1), an antimicrobial peptide from porcine leukocytes, against A. baumannii strains isolated from surgical wounds. PG-1 was tested both alone and combined with the antibiotics commonly used in clinical settings. Its antimicrobial activity was evaluated by determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), checkerboard assays, and time-kill experiments. Its effects on biofilm inhibition/eradication were tested with crystal violet staining. The strains were grown in subinhibitory or increasing PG-1 concentrations to test the development of resistance. Mammalian cell toxicity was tested by XTT assays. PG-1 MICs and MBCs ranged from 2 to 8 µg/ml. PG-1 was most active and demonstrated a synergistic interaction with colistin, a last resort antibiotic. Interestingly, antagonism was never observed. In time-kill experiments, incubation with 2 × MIC for 30 min suppressed all viable cells. PG-1 did not select resistant strains and showed a limited effect on cell viability, but it did exert a strong activity against multidrug-resistant A. baumannii. In contrast, in our experimental conditions it had no effect on biofilm inhibition/eradication. PG-1 thus seems to be a promising antimicrobial agent against multidrug-resistant Gram-negative infections.

中文翻译：

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Protegrin-1单独或与临床上有用的抗生素联合使用对从手术伤口分离的鲍曼不动杆菌菌株的体外活性。

在过去的几年中，鲍曼不动杆菌医院感染的发生率不断上升，尤其是在免疫功能低下的患者中，其易发展多药耐药性的问题引起了人们的广泛关注。这项研究检查了protegrin 1（PG-1）（一种来自猪白细胞的抗菌肽）对鲍曼不动杆菌的抗菌和生物膜活性。从外科伤口中分离出的菌株。PG-1既可以单独测试，也可以与临床环境中常用的抗生素结合使用。通过确定最小抑菌浓度（MIC）和最小杀菌浓度（MBC），棋盘试验和时间杀灭实验来评估其抗菌活性。用结晶紫染色测试了其对生物膜抑制/根除的作用。使菌株在亚抑制或增加的PG-1浓度下生长以测试耐药性的发展。通过XTT测定法测试了哺乳动物细胞毒性。PG-1 MIC和MBC的范围为2至8 µg / ml。PG-1活性最高，并显示出与最后一种抗生素大肠菌素的协同作用。有趣的是，从未观察到对抗。在时间杀灭实验中 用2×MIC孵育30分钟可抑制所有活细胞。PG-1没有选择抗药性菌株，并且对细胞生存力的作用有限，但是它确实具有很强的抗多药耐药性鲍曼不动杆菌。相反，在我们的实验条件下，它对生物膜的抑制/消除没有影响。因此，PG-1似乎是对抗多药耐药革兰氏阴性菌感染的有前途的抗菌剂。