Acinetobacter : an emerging pathogen with a versatile secretome

Abstract

Acinetobacter baumannii is a notorious pathogen that has emerged as a healthcare nightmare in recent years because it causes serious infections that are associated with high morbidity and mortality rates. Due to its exceptional ability to acquire resistance to almost all available antibiotics, A. baumannii is currently ranked as the first pathogen on the World Health Organization’s priority list for the development of new antibiotics. The versatile range of effectors secreted by A. baumannii represents a large proportion of the virulence arsenal identified in this bacterium to date. Thus, these factors, together with the secretory machinery responsible for their extrusion into the extracellular milieu, are key targets for novel therapeutics that are greatly needed to combat this deadly pathogen. In this review, we provide a comprehensive, up-to-date overview of the organization and regulatory aspects of the Acinetobacter secretion systems, with a special emphasis on their versatile substrates that could be targeted to fight the deadly infections caused by this elusive pathogen.

Hybrid Antigens Expressing Surface Loops of ZnuD From Acinetobacter baumannii Is Capable of Inducing Protection Against Infection

“…Thus, the nature of the soluble form of the ZnuD (with a polyhistidine tag and Mbp fusion partner) is uncertain and could potentially be a partially misfolded aggregate that is kept soluble by the presence of the N-terminal Mbps. This could be partially explain why the all loops (2,5,7,11) hybrid antigen induced a more protective immune response than ZnuD (Figure 5), although we cannot exclude the increased focus on surface epitopes as an important factor.…”

“…In contrast, there was increased levels of the anti-inflammatory cytokine (IL-10) in all immunized infected mice except those immunized with the hybrid antigen displaying loop 5. The fact that the IL-10 levels in the mice immunized with loop 5 hybrid antigen and the all loop (2,5,7,11) hybrid antigen were the two most divergent, underscores the fact that these levels did not correlate with clearance of the bacteria.…”

“…Acinetobacter baumannii is an opportunistic coccobacillus pathogen (1), classified as one member of the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumonia, A. baumannii, Pseudomonas aeruginosa, Enterobacter spp.) group of pathogens by the Infectious Diseases Society of America (IDSA) (2). Acinetobacter infections such as septicemia, ventilator-associated pneumonia, bacteremia, urinary tract infections, wound sepsis, endocarditis, and meningitis have been observed in hospitalized patients.…”

Profiling the urinary microbiome in men with calcium-based kidney stones

“…The most differentially represented taxa at genus level were Acinetobacter in kidney stone patients, and Prevotella in healthy controls. As opportunistic pathogens, Acinetobacter are associated with urinary tract infection in individuals with underlying medical risk factors, such as diabetes mellitus and immunosuppression [22]. Interestingly, the abundance of Acinetobacter was showed to be higher in the faeces of nephrolithiasis patients and the urine of bladder cancer patients compared to controls, although its association with plasma trace elements or bladder cancer recurrence/progression had not been identified [23,24].…”

Insights into Acinetobacter baumannii: A Review of Microbiological, Virulence, and Resistance Traits in a Threatening Nosocomial Pathogen

“…Assembled T6SS system contracts to allow release of the effector protein, which typically targets other bacteria without self-intoxication [104]. In A. baumannii, T6SS may attack other bacteria, where it produces toxins like nucleases, peptidoglycan hydrolases, or cell-membrane active toxins [109]. Interestingly, clinical isolates with active T6SS are isolated at higher frequencies from immunocompromised patients, suggestive of competitive advantage against concomitant pathogens [110].…”