A systematic review of implications, mechanisms, and stability of in vivo emergent resistance to colistin and tigecycline in Acinetobacter baumannii

Abstract

The potential of A. baumannii for acquired resistance to last resort antibiotics (colistin and tigecycline) during treatment has important clinical implications, especially when dealing with patients failing to improve despite treatment with an active antimicrobial. However, the relevant literature remains scattered. Therefore, a systematic search was conducted in PubMed and Scopus. Several studies reported emergence of resistance to colistin or tigecycline during treatment, in most cases (86%) resulting in persistent or recurrent infections, especially in cases of emergent resistance without fitness cost. Lipopolysaccharide modification in the case of colistin and overexpression of efflux pumps in the case of tigecycline were the main mechanisms of resistance. Emergent colistin resistance is often associated with fitness cost which may result in re-emergence of the fitter and more virulent colistin susceptible strain after cessation of antibiotic pressure. Prospective studies are needed to determine the frequency of emergent resistance during treatment and its impact on patient outcomes.

Keywords:

• Acinetobacter
• baumannii
• colistin
• tigecycline
• resistance
• in vivo

Disclsoure statement

I have no conflict of interest to declare.

Additional information

Notes on contributors

Stamatis Karakonstantis

Stamatis Karakonstantis is currently a resident of Internal Medicine in Venizeleio General Hospital of Heraklion and a PhD candidate in infectious diseases in the Medical School of the University of Crete. His current work focuses on extensively drug-resistant and pandrug-resistant Gram-negative bacteria, with a special interest on Acinetobacter baumannii.