The long-term survival of Acinetobacter baumannii ATCC 19606T under nutrient-deprived conditions does not require the entry into the viable but non-culturable state

Abstract

Acinetobacter baumannii possesses a tremendous potential to thrive under hostile conditions. To learn more about its survival strategy and capacity to persist in the environment, we studied the effect of temperature, nutrient deprivation and dryness on the long-term survival of two A. baumannii strains (ATCC 19606(T) and a clinical isolate). Our results revealed that both strains show a great persistence under stress that appears to involve a bust-and-boom strategy. Bacterial survival was differentially affected by temperature and physical environment: Desiccation favored cell resistance to stress at 20 and 37 °C, while survival in aqueous environments was temperature dependent and led to changes in several cellular characteristics. In addition, we tested the ability of the A. baumannii ATCC 19606(T) strain to form biofilms by monitoring the expression of adhesion-/biofilm-related genes (ompA, bfmR and csuAB). The observed downregulation of these genes suggests that the potential difficulties to adhere to solid surfaces and form biofilms likely limit the capacity of starved cells to spread and colonize abiotic surfaces.

Spoilage of refrigerated Litopenaeus vannamei: eavesdropping on Acinetobacter acyl-homoserine lactones promotes the spoilage potential of Shewanella baltica

“…Both Sb and Ab were not found to produce antimicrobial compounds in the present study (data not shown), so space and nutrients should be the limiting factors for bacterial competition in the co-culture. Ab seem to be less prone to competitive inhibition, which might be explained by their well-known ability to survive under nutrient-limiting conditions (Bravo et al 2016).…”

“…Biofilm plays an important role in bacterial resistance to harsh environments, and has been well documented to be controlled by the AHL-dependent QS (Atkinson et al 2007). Ab can thrive under hostile conditions like desiccation, poor nutrition and high antibiotic exposure largely due to their good ability in biofilm formation (Bravo et al 2016). As shown in Fig.…”

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

“…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 maintains its virulence after long-time starvation

“…According to several authors, A . baumannii can survive desiccation, although this ability varies dramatically depending on the strains tested [ 18 , 21 , 29 , 30 ]. Our results show that the long-term survival of A .…”