Acinetobacter baumannii maintains its virulence after long-time starvation

Abstract

Acinetobacter baumannii is a cause of healthcare-associated infections. Although A. baumannii is an opportunistic pathogen, its infections are notoriously difficult to treat due to intrinsic and acquired antimicrobial resistance, often limiting effective therapeutic options. A. baumannii can survive for long periods in the hospital environment, particularly on inanimate surfaces. Such environments may act as a reservoir for cross-colonization and infection outbreaks and should be considered a substantial factor in infection control practices. Moreover, clothing of healthcare personnel and gadgets may play a role in the spread of nosocomial bacteria. A link between contamination of hospital surfaces and A. baumannii infections or between its persistence in the environment and its virulence has not yet been established. Bacteria under stress (i.e., long-term desiccation in hospital setting) could conserve factors that favor infection. To investigate whether desiccation and/or starvation may be involved in the ability of certain strains of A. baumannii to retain virulence factors, we have studied five well-characterized clinical isolates of A. baumannii for which survival times were determined under simulated hospital conditions. Despite a considerable reduction in the culturability over time (up to 88% depending on strain and the condition tested), some A. baumannii strains were able to maintain their ability to form biofilms after rehydration, addition of nutrients, and changing temperature. Also, after long-term desiccation, several clinical strains were able to grow in the presence of non-immune human serum as fine as their non-stressed homologs. Furthermore, we also show that the ability of bacterial strains to kill Galleria mellonella larvae does not change although A. baumannii cells were stressed by long-term starvation (up to 60 days). This means that A. baumannii can undergo a rapid adaptation to both the temperature shift and nutrients availability, conditions that can be easily found by bacteria in a new patient in the hospital setting.

Coping with low water activities and osmotic stress in Acinetobacter baumannii: significance, current status and perspectives

“…Nevertheless, sufficient examples demonstrate the ability of this pathogen to persist for months or even years in hospitals. Importantly, A. baumannii retains its capability for biofilm formation, survival in human serum as well as infection (of Galleria mellonella larvae) even after long‐term desiccation and starvation (Chapartegui‐González et al ., ). This impressively demonstrates that bacteria persisting for long periods of time in a hospital can constitute a reservoir for future outbreaks and thereby still pose a threat to human health.…”

“…This discussion is far beyond the scope of this review, but the reader should be aware of the terminological difficulties. So, while Gayoso and colleagues () assume the existence of persister cells under desiccative conditions, Ramos‐Vivas and coworkers (Bravo et al ., ; Chapartegui‐González et al ., ) suggest that entry in a VBNC state is not needed for survival of A. baumannii on dry surfaces without nutrients. It should be noted that the two latter studies observed quite high culturability for a long period of time (see Table ), leaving the question whether in most other studies bacteria simply die earlier or become unculturable due to transition in a VBNC state or leave a few persisting cells that remain undetected.…”

Acinetobacter baumannii biofilm biomass mediates tolerance to cold plasma

“…; Chapartegui‐González et al . ). Its ability to form biofilms on a range of surfaces in unfavourable conditions renders the biofilm phenotype an important virulence factor in A. baumannii infections.…”

<p>Discovery of a Novel Hypervirulent <em>Acinetobacter baumannii</em> Strain in a Case of Community-Acquired Pneumonia</p>

“…Furthermore, virulence is maintained despite desiccation and starvation. 5 In the case of this isolate, LS01, multiple virulence factors were identified including genes associated with biofilm formation, adherence, phospholipase, and iron uptake. Interestingly, many of these virulence genes have also been identified in MDR A. baumannii including ompA, bap, bfmS, csgA csuE, and pgaB 19 as well as the ATCC 17978-mff, AB5075-UW, and MDR-ZJ06 strains (data not shown).…”

“…Acinetobacter baumannii, a glucose-non-fermentative aerobic Gram-negative coccobacilli, causes up to 20% of intensive care unit (ICU) infections worldwide, including ventilator-associated and blood stream infections. 1,2 A. baumannii has a plastic genome, allowing for rapid mutations, acquisition of new genes, and increased virulence in response to environmental stress, 1,[3][4][5] posing a difficult challenge for treatment and infection control. With the global rise in antibiotic resistance, multi-drug resistant (MDR) A. baumannii is an increasing threat for both nosocomial and community-acquired infections.…”