In vitro and in vivo Virulence Potential of the Emergent Species of the Acinetobacter baumannii (Ab) Group

Abstract

The increased use of molecular identification methods and mass spectrometry has revealed that Acinetobacter spp. of the A. baumannii (Ab) group other than A. baumannii are increasingly being recovered from human samples and may pose a health challenge if neglected. In this study 76 isolates of 5 species within the Ab group (A. baumannii n = 16, A. lactucae n = 12, A. nosocomialis n = 16, A. pittii n = 20, and A. seifertii n = 12), were compared in terms of antimicrobial susceptibility, carriage of intrinsic resistance genes, biofilm formation, and the ability to kill Caenorhabditis elegans in an infection assay. In agreement with previous studies, antimicrobial resistance was common among A. baumannii while all other species were generally more susceptible. Carriage of genes encoding different efflux pumps was frequent in all species and the presence of intrinsic class D β-lactamases was reported in A. baumannii, A. lactucae (heterotypic synonym of A. dijkshoorniae) and A. pittii but not in A. nosocomialis and A. seifertii. A. baumannii and A. nosocomialis presented weaker pathogenicity in our in vitro and in vivo models than A. seifertii, A. pittii and, especially, A. lactucae. Isolates from the former species showed decreased biofilm formation and required a longer time to kill C. elegans nematodes. These results suggest relevant differences in terms of antibiotic susceptibility patterns among the members of the Ab group as well as highlight a higher pathogenicity potential for the emerging species of the group in this particular model. Nevertheless, the impact of such potential in the human host still remains to be determined.

Emergence of ST63 Pandrug-Resistant Acinetobacter pittii Isolated From an AECOPD Patient in China

“…The terms multidrug resistance (MDR), extensive drug resistance (XDR) and pandrug resistance (PDR) were used worldwide to define the non-susceptibility level of isolates, which are resistant to at least one agent in three or more antimicrobial categories, to at least one agent in all but two or fewer categories and to all agents in all categories, respectively ( Magiorakos et al., 2012 ). MDR A. pittii including those resistant to antibiotics quinolones, carbapenems, etc., was reported across continents, yet PDR A. pittii was rarely reported ( Gu et al., 2015 ; Brasiliense et al., 2019 ; Chen et al., 2019a ; Cosgaya et al., 2019 ; Chopjitt et al., 2021 ). Here, we report the case of a patient with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) three years after double lung transplantation (DLT) and developed severe pneumonia associated with PDR A. pittii infection.…”

Surgical Site Infection Following Caesarean Section by Acinetobacter Species: A Report from a Hyperendemic Setting in the Brazilian Amazon Region

“…Additionally, other Acinetobacter species, such as A. nosocomialis and A. pittii , have been increasingly associated with hospital-acquired infections (HAIs) [ 9 ]. Despite the phenotypic similarities, differences between species of Acinetobacter have been described, mainly in relation to virulence factors and susceptibility profiles to antimicrobials [ 12 ].…”

Photoelimination Potential of Chitosan NanoparticlesIndocyanine Green Complex Against the Biological Activities of Acinetobacter baumannii Strains: A Preliminary In Vitro Study in Burn Wound Infections

“…ROS are highly reactive and can interact with important cellular molecules and consequently kill the bacteria or alter the antimicrobial susceptibility of bacterial cells. 7,8 According to power and the better penetration of an 810 nm diode laser in deep tissues and the consequence of better repair of damaged host cells, indocyanine green (ICG) as a PS is an appropriate choice for aPDT. 9 ICG is a non-toxic anionic cyanine type of photosensitizer with the disadvantage of instability, which is highly soluble in water with a high absorption of 810 nm.…”