Acinetobacter baumannii: human infections, factors contributing to pathogenesis and animal models

Abstract

Acinetobacter baumannii has emerged as a medically important pathogen because of the increasing number of infections produced by this organism over the preceding three decades and the global spread of strains with resistance to multiple antibiotic classes. In spite of its clinical relevance, until recently, there have been few studies addressing the factors that contribute to the pathogenesis of this organism. The availability of complete genome sequences, molecular tools for manipulating the bacterial genome, and animal models of infection have begun to facilitate the identification of factors that play a role in A. baumannii persistence and infection. This review summarizes the characteristics of A. baumannii that contribute to its pathogenesis, with a focus on motility, adherence, biofilm formation, and iron acquisition. In addition, the virulence factors that have been identified to date, which include the outer membrane protein OmpA, phospholipases, membrane polysaccharide components, penicillin-binding proteins, and outer membrane vesicles, are discussed. Animal models systems that have been developed during the last 15 years for the study of A. baumannii infection are overviewed, and the recent use of these models to identify factors involved in virulence and pathogenesis is highlighted.

Acinetobacter baumannii: biology and drug resistance — role of carbapenemases

“…Recent analysis concerning genome sequencing, genetic manipulations and applications of animal models allow believing that current knowledge regarding additional factors will be broadened. Among virulence determinants responsible for the A. baumannii pathogenicity, there may be mentioned: lipopolysaccharide (LPS), capsular polysaccharides (CPS), A. baumannii outer membrane protein A (AbOmpA), outer membrane vesicles (OMV), phospholipase D (PLD), and biofilm [6,21].…”

“…These features are likely to be a major contributing factor to nosocomial spread of the A. baumannii [5]. It is thought that A. baumannii infections are mostly acquired after exposure to contaminated hospital equipment or by direct contact with healthcare personnel that have been previously exposed to the microorganism [6]. The other important features responsible for A. baumannii clinical relevance are: high natural resistance as well as an outstanding ability to up-regulate innate and acquire foreign mechanisms of antimicrobial resistance [5].…”

Prevalence Acinetobacter spp. in Kemerovo Region Healthcare Settings

“…способны ингибировать рост конкурирующих видов посред-ством секреции органических кислот, биосурфак-тантов, что в сочетании с мультирезистентностью к антимикробным препаратам определяет их вы-сокую способность к колонизации больничной среды и формированию госпитальных клонов [6]. Известно, что инфекции у людей, вызванные не-которыми представителями Acinetobacter spp., в основном приобретены после контакта с кон-таминированными медицинскими изделиями или в результате прямого контакта пациента с ме-дицинским персоналом [8]. Среди различных ви-дов Acinetobacter spp.…”

A Robust Pneumonia Model in Immunocompetent Rodents to Evaluate Antibacterial Efficacy against <i>S. pneumoniae</i>, <i>H. influenzae</i>, <i>K. pneumoniae</i>, <em>P. aeruginosa</em> or <em>A. baumannii</em>

“…Despite this severely immunocompromised state, the number of bacterial pathogens and strains which produce viable infections in rodents is limited. For example, it can be difficult to successfully establish Haemophilus influenzae or Acinetobacter baumannii in pneumonia models 9,10 , and even more virulent pathogens, such as Streptococcus pneumoniae, Pseudomonas aeruginosa and Klebsiella pneumoniae, can pose challenges [11][12][13] . In 1991, Smith described a lung infection model in immunocompetent weanling rats in which infection was established by instilling bacteria directly into the lungs via a simple nonsurgical intratracheal intubation method 14 .…”