Research Paper Volume 10, Issue 7 pp 1597—1608

Aging exacerbates mortality of Acinetobacter baumannii pneumonia and reduces the efficacies of antibiotics and vaccine

Hao Gu 1, , Dong Liu 1, , Xi Zeng 1, , Liu-Sheng Peng 1, , Yue Yuan 1, , Zhi-Fu Chen 1, , Quan-Ming Zou 1, , Yun Shi 1, ,

  • 1 National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Army Medical University, Chongqing 400038, PR China

received: May 8, 2018 ; accepted: July 5, 2018 ; published: July 18, 2018 ;
How to Cite

Copyright: Gu et al. This is an open‐access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Pneumonia caused by Acinetobacter baumannii has become a serious threat to the elderly. However, there are no experimental studies on the relevance between aging and A. baumannii infections. Here, we established an aged pneumonia mouse model by non-invasive intratracheal inoculation with A. baumannii. Higher mortality was observed in aged mice along with increased bacterial burdens and more severe lung injury. Increased inflammatory cell infiltration and enhanced pro-inflammatory cytokines at 24 hours post infection were detected in aged mice than those in young mice. Moreover, infected aged mice had lower myeloperoxidase levels in lungs and less reactive oxygen species-positive neutrophils in bronchoalveolar lavage fluid compared with infected young mice. Reduced efficacy of imipenem/cilastatin against A. baumannii was detected in aged mice. Vaccination of formalin-fixed A. baumannii provided 100% protection in young mice, whereas the efficacy of vaccine was completely diminished in aged mice. In conclusion, aging increased susceptibility to A. baumannii infection and impaired efficacies of antibiotics and vaccine. The aged mice model of A. baumannii pneumonia is a suitable model to study the effects of aging on A. baumannii infection and assess the efficacies of antibiotics and vaccines against A. baumannii for the elderly.


MDR: Multidrug-resistant; BALF: Bronchoalveolar lavage fluid; ROS: Reactive oxygen species; MPO: Myeloperoxidase; ffLAC-4: Formalin-fixed LAC-4; PBS: Phosphate buffer saline; TSA: Tryptone soy agar; CFU: Colony-forming unit; HBSS: Hank's balanced salt solution.