The innate resistome of “recalcitrant” Acinetobacter baumannii and the role of nanoparticles in combating these MDR pathogens

Acinetobacter baumannii, a nosocomial pathogen, and member of ESKAPE bacteria are currently a global threat. A. baumannii is equipped naturally laden with strong intrinsic resistance factors and is also capable of acquiring many resistance determinants against different antibiotic classes. Intrinsic resistome is defined as a mechanism of antibiotic resistance that is innately expressed/chromosomally encoded, irrespective of prior antibiotic exposure. Although these innate resistance factors are themselves poorly effective in conferring a high-level resistance, together with other resistance factors their force can be large enough to confer an organism multidrug resistant (MDR). In A. baumannii, which are predominantly of environmental origin (an opportunistic pathogen), weight on the impact of extreme resistance and evolution is often laid on their intrinsic antibiotic resistance phenotype. This review is focused on emphasizing the role of intrinsic resistome involved in the antibiotic resistance of A. baumannii, the understanding of which will be very helpful in combating this opportunistic pathogen. With a dead-end in the treatment of infections due to MDR A. baumannii, different avenues have to be explored for a better treatment option. This review will also discuss the application of nanoparticles as antimicrobials and as a conjugate for restoring the bioactivity of the available drugs against MDR pathogens.