PATHOGENIC ANALYSIS OF AEROMONAS-HYDROPHILA SEPTICEMIA

Aeromonas hydrophila has emerged as a potential pathogen in the immuno compromised host. Various aeromonal infections, including septicemia, have also been reported in apparently healthy individuals. For years, researchers have disagreed over the epidemiologic roles of aeromonads in gastroenteritis. Isolation rates of aeromonads by stool culture amo ng patients with gastroenteritis are not consistently high. Carriers o f this bacterium also exist. The septicemic course is, however, often fulminant and fatal, and may lack an obvious focus. Pathogenic mechani sms are complex and largely unresolved. The objective of this study is to report the necropsy findings from a uremic patient who presented w ith typical aeromonal septicemia of obscure origin asking if such inve stigation could give insight into some of the questions mentioned prev iously. Western blot immunostaining for aerolysin (beta-hemolysin of a eromonads) was used to evaluate whether or not such a virulence factor is involved in the process of septic dissemination. The autopsy showe d that the skin and liver contained microabscesses. The upper gastroin testinal mucosae and spleen contain patchy putrefactive lesions with a djacent focal hemorrhage. Perimortem blood cultures grew Aeromonas hyd rophila. A conventional Western blot analysis of the culture supernata nt failed to show aerolysin. A control Aeromonas sobia American Type C ulture Collection (ATCC) strain produces readily detectable aerolysin. It is concluded that this isolate may be aerolysin-deficient or one s ecreting low levels of aerolysin; these would require more sensitive m ethods of detection. The primary focus of infection might be the upper gastrointestinal tract. Other virulence factors including the bacteri al proteases and/or phospholipases might be responsible for the pathog enesis of septic dissemination.