Hello, Thnx to contact us. I understand your concern. If I am your treating doctor I advice you that Aeromonas hydrophilia is a rare pathogen isolated in the medical field. But it frequently isolated in immunocompromised individuals with gastroenteritis. It is very dangerous in such people. It is readily respond to antibiotics like doxycycline, chloramphenicol, ciprofloxacin, ofloxacin. You can choose one of the antibiotics under your doctors guidance. Secondary infection is when you having treatment of one infection and you got second one. I will be happy to answer more of your concerns, kindly know me, Wish you a very good health at health care magic. Dr. Arun Tank. Infectious Disease.