title: Immunofluorescent test for simultaneous detection of Edwardsiella ictaluri and Flavobacterium columnare.
abstract: Enteric septicemia of catfish (ESC) and columnaris disease are 2 bacterial diseases significantly affecting the aquaculture industry, and thus rapid diagnosis of disease is imperative for making judicious management decisions. A rapid indirect fluorescent antibody (IFA) test with antibody conjugated fluorochromes having 2 different spectral properties (Alexa Fluor 488-emitting green fluorescence, and Alexa Fluor 594-emitting red fluorescence) was compared with bacteriological culture (accepted standard) for simultaneous detection of Edwardsiella ictaluri (EI) and Flavobacterium columnare (FC) in 3 groups of experimentally infected channel catfish (Ictalurus punctatus Rafinesque), and a fourth group that acquired an aquarium-infection with F. columnare. A total of 303 samples (derived from kidney, brain and nares) from 101 fish were concurrently examined by both tests. Fish in the 3 experimentally infected groups (I to III) were culture positive for the bacteria with which they were infected, and fish in Group IV, (the spontaneously infected fish) revealed F. columnare only. The IFA test compared favorably in sensitivity (EI= 80.7 %; FC = 87.2%) and specificity (EI = 83.9%; FC = 88.9%) with the standard bacteriological culture. The positive predictive value (EI = 96.2% Group I, 90.8% Group II, 93.7% Groups I and II combined; FC = 95.2% Group II, 95.3% Groups II, III and IV combined) was high, while the negative predictive value (EI = 66.7% Group I, 31.3% Group II, 59.5% Groups I and II combined; FC = 73.7% Group II, 72.7% Groups II, III and IV combined) was relatively low. The IFA test will serve as an efficient tool for rapid simultaneous detection of E. ictaluri and F. columnare in outbreaks of disease.
authors.affiliation: Aquatic Animal Health Research Unit, US Department of Agriculture, Agricultural Research Service, PO Box 952, Auburn, Alabama 36831, USA. vpanangala@ars.usda.gov
authors.forename: Victor S
authors.initials: VS
authors.lastname: Panangalal
authors.forename: Richard A
authors.initials: RA
authors.lastname: Shelby
authors.forename: Craig A
authors.initials: CA
authors.lastname: Shoemaker
authors.forename: Phillip H
authors.initials: PH
authors.lastname: Klesius
authors.forename: Amitava
authors.initials: A
authors.lastname: Mitra
authors.forename: Edward E
authors.initials: EE
authors.lastname: Morrison
mesh_terms: D000818:Animals; D001431:Bacteriological Techniques / Q000592:standards / Q000662:veterinary; D020610:Edwardsiella ictaluri / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000175:diagnosis*; D005393:Fish Diseases / Q000175:diagnosis* / Q000382:microbiology; D005398:Fisheries / Q000379:methods; D045826:Flavobacteriaceae Infections / Q000175:diagnosis*; D005417:Flavobacterium / Q000302:isolation & purification*; D019084:Fluorescent Antibody Technique, Indirect / Q000592:standards / Q000662:veterinary; D007059:Ictaluridae; D015151:Immunoblotting / Q000662:veterinary; D012680:Sensitivity and Specificity