Is pandrug-resistance in A. baumannii a transient phenotype? Epidemiological clues from a 4-year cohort study at a tertiary referral hospital in Greece

Abstract

Pandrug-resistant A. baumannii (PDRAB) is increasingly being reported but remains rare. Several case studies show that A. baumannii can acquire resistance to last resort antibiotics during treatment by single-step chromosomal mutations. However, re-emergence of the ancestral susceptible strain after withdrawal of antibiotics has been described, possibly due to fitness cost associated with acquired resistance. Therefore, PDRAB may be a transient phenotype. Epidemiological data to show this process in larger cohorts are currently lacking. In this study of 91 hospitalized patients with PDRAB we showed the frequent (60%) isolation of non-PDRAB, often susceptible only to colistin, aminoglycosides and/or tigecycline, preceding and/or following PDRAB isolation. However, the isolation of PDRAB in two outpatients, 25 and 36 days after their discharge from the hospital, suggests the potential of some PDRAB strains to persist even in the absence of antimicrobial pressure.

Keywords:

• Acinetobacter baumannii
• resistance
• pandrug-resistant
• PDR
• epidemiology

Disclosure statement

We have no conflict of interest to declare.

Additional information

Notes on contributors

Stamatis Karakonstantis

Stamatis Karakonstantis, MD, PhD student. School of Medicine, University of Crete, Greece. Research interests: nosocomial infections, XDR/PDR Gram-negative bacteria, Acinetobacter baumannii.

Evangelos I. Kritsotakis

Evangelos I. Kritsotakis, PhD, FHEA, CStat. School of Medicine, University of Crete, Greece. Research interests: Statistical and epidemiological principles and methods to evaluate and improve the delivery of hospital care, especially in relation to observational research and epidemiological surveillance of healthcare-associated infections, antimicrobial drugs and multi-drug resistant pathogens.

Achilleas Gikas

Achilleas Gikas, Prof. Internal medicine and Infectious Diseases. University Hospital of Heraklion, Crete, Greece. Research interests: nosocomial infections, infection control.