Acinetobacter lwoffii: an Emerging Pathogen for Red Head Disease in Farmed Channel Catfish Ictalurus punctatus

Abstract

Red head disease has become a significant emerging cause of economic damage in the farming of channel catfish Ictalurus punctatus. Only scare information is available on this disease caused by Acinetobacter lwoffii in channel catfish. In this study, a virulent strain, temporarily named R21, was isolated from diseased channel catfish suffering from red head disease, and identified through phylogenetic analysis and phenotypic characteristics. A phylogenetic tree was constructed to examine isolate R21 and compare it to other known isolates. In addition, isolate R21 appears to be resistant to azithromycin, ciprofloxacin, erythromycin, norfloxacin, and oxacillin, but is still susceptible to aminoglycosides, amphenicols, sulfonamides and tetracycline drugs for veterinary uses in aquaculture as revealed when screened against a range of common antibiotics. This study confirms A. lwoffii as an emerging pathogen for red head disease in farmed channel catfish.