Molecular Mechanisms Involved in the Response to Desiccation Stress and Persistence in Acinetobacter baumannii

Abstract

Desiccation tolerance contributes to the maintenance of bacterial populations in hospital settings and may partly explain its propensity to cause outbreaks. Identification and relative quantitation of proteins involved in bacterial desiccation tolerance was made using label-free quantitation and iTRAQ labeling. Under desiccating conditions, the population of the Acinetobacter baumannii clinical strain AbH12O-A2 decreased in the first week, and thereafter, a stable population of 0.5% of the original population was maintained. Using label-free quantitation and iTRAQ labeling, 727 and 765 proteins, respectively, were detected; 584 of them by both methods. Proteins overexpressed under desiccation included membrane and periplasmic proteins. Proteins associated with antimicrobial resistance, efflux pumps, and quorum quenching were overexpressed in the samples subjected to desiccation stress. Electron microscopy revealed clear morphological differences between desiccated and control bacteria. We conclude that A. baumannii is able to survive long periods of desiccation through the presence of cells in a dormant state, via mechanisms affecting control of cell cycling, DNA coiling, transcriptional and translational regulation, protein stabilization, antimicrobial resistance, and toxin synthesis, and that a few surviving cells embedded in a biofilm matrix are able to resume growth and restore the original population in appropriate environmental conditions following a "bust-and-boom" strategy.

Novel Phage Lysin Capable of Killing the Multidrug-Resistant Gram-Negative Bacterium Acinetobacter baumannii in a Mouse Bacteremia Model

“…Outbreaks caused by MDR Acinetobacter have been reported from hospitals worldwide; more recently, they have become a serious problem in military medical facilities (4). One of the main reasons why A. baumannii is so persistent is its ability to tolerate desiccation and other stresses through its ability to form biofilms on solid surfaces, including medical implants and catheters (12). For these reasons, new and better ways of controlling A. baumannii are needed.…”

Global Dynamic Proteome Study of a Pellicle-forming Acinetobacter baumannii Strain

“…A. baumannii is known for its long-time survival in hospital settings because of its great ability to survive desiccation (6), oxidative stress (7), or treatment with disinfectants (8). This persistence is mostly linked to its capacity to form biofilms (9 -11).…”

Novel Engineered Peptides of a Phage Lysin as Effective Antimicrobials against Multidrug-Resistant Acinetobacter baumannii

“…The reasons for this high resistance include a high degree of genetic plasticity combined with an intrinsic resistance to certain antibiotics due to the presence of ␤-lactamases, the low permeability of the outer membrane, and highly efficient efflux pump systems (4). Furthermore, A. baumannii is prone to develop biofilms on solid surfaces, including medical devices (5). Thus, A. baumannii is not only problematic as an infectious agent but also increasingly difficult to be removed from hospital environments, a phenomenon similar to that observed with the Gram-positive nosocomial pathogen Staphylococcus aureus.…”