Co-culture of Aeromonas salmonicida and host cells in intraperitoneal implants is associated with enhanced bacterial survival

An experimental procedure that we named "in vivo co-culture technology" all owed us to study the interactions between Aeromonas salmonicida and host ce lls, inside semipermeable chambers implanted in the peritoneal cavity of At lantic salmon. Intraperitoneal implants containing bacteria and host cells, or bacteria and lysed cells, consistently yielded higher numbers of viable bacteria than implants containing bacteria only. Electron microscopy confi rmed that 30 min after chamber inoculation, numerous bacteria were already internalized by exudate cells, and that at 3 h, destruction of these cells was evident. Thus, the rapid invasion and (or) the A. salmonicida-mediated lysis of host cells may constitute a survival strategy in vivo. The co-cult ure of bacteria with exudate peritoneal cells may be applicable to the in v ivo study of other pathogens.