PURPOSE OF REVIEW The aim of this study was to discuss the potential clinical significance of heteroresistance in nonfermenting Gram-negative bacilli (GNB). RECENT FINDINGS Recently, heteroresistance has been considered potentially responsible for clinical failure in Acinetobacter baumannii infections. This raised a scientific debate, still open, about the potential clinical significance of heteroresistance in nonfermenting GNB. SUMMARY We reviewed the literature of last 20 years and found a limited number of studies evaluating the relationship between heteroresistance and clinical outcome in nonfermenting GNB. Unlike Gram-positive bacteria, heteroresistance is reported in a significant proportion of nonfermenting GNB with some studies describing it in all tested strains and for several antibiotics (including tigecycline, carbapenems, levofloxacin, cefiderocol, colistin). One important issue is the need for validated detection method since the population analysis profile test, that is considered the gold standard, requires high costs and time. Studies evaluating the correlation between heteroresistance and clinical outcome are contrasting and have several limitations. Although in-vitro detection of heteroresistance in nonfermenting GNB has not been associated with in-vivo treatment failure, its presence may suggest to prefer combination regimens instead monotherapy when treating infections by nonfermenters. Further studies are needed to clarify the clinical significance of heteroresistance.

中文翻译：

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非发酵革兰氏阴性菌株中“异抗性”的临床意义是什么？

综述目的本研究的目的是讨论非发酵革兰氏阴性杆菌（GNB）异质抗性的潜在临床意义。最近的发现 最近，异质耐药性被认为可能是鲍曼不动杆菌感染临床失败的原因。这引发了一场关于非发酵 GNB 异质抗性的潜在临床意义的科学辩论，该辩论仍然悬而未决。总结 我们回顾了过去 20 年的文献，发现评估非发酵 GNB 异质抗性与临床结果之间关系的研究数量有限。与革兰氏阳性菌不同，据报道非发酵 GNB 中很大一部分存在异质抗性，一些研究描述了所有测试菌株和几种抗生素（包括替加环素、碳青霉烯类、左氧氟沙星、头孢地洛考、粘菌素）的异质抗性。一个重要的问题是需要经过验证的检测方法，因为被认为是黄金标准的群体分析概况测试需要高昂的成本和时间。评估异质抗性与临床结果之间相关性的研究是截然不同的，并且存在一些局限性。尽管体外检测到非发酵 GNB 的异质耐药性与体内治疗失败无关，但其存在可能表明在治疗非发酵菌感染时更倾向于联合治疗而不是单一疗法。需要进一步的研究来阐明异质抗性的临床意义。