title: Characterization and antimicrobial susceptibility of motile aeromonads isolated from freshwater ornamental fish showing signs of septicaemia.
abstract: A total of 74 phenotypically identified presumptive motile Aeromonas isolates recovered from septicaemic freshwater ornamental fish in Sri Lanka were genetically characterized by sequencing of rpoD and gyrB genes. rpoD/gyrB phylogeny confirmed only 53 isolates as Aeromonas, among which A. veronii was the predominant species (79.2%), followed by A. hydrophila (7.5%), A. caviae (5.7%), A. jandaei (1.9%), A. dhakensis (3.8%) and A. entero pelogenes (1.9%). The aeromonads confirmed by sequencing were further subjected to 16S rDNA PCR-RFLP which substantiated sequencing results for 83% of isolates. Fingerprinting of A. enteropelogenes (n = 42) using ERIC-PCR revealed no dominant clones, and the majority were genetically distinct. All isolates were screened by PCR for 7 virulence determinant genes (aer, act, ast, alt, fla, ser, exu) and 2 integrase encoding genes (intI1, intI2). Each isolate contained ≥3 of the virulence genes tested for, with a heterogeneous distribution. Of the isolates, 77% harboured the intI1 gene, while none had intI2. In vitro antimicrobial susceptibility testing showed highest resistances towards tetracycline (58.5%) and erythromycin (54.7%). Our results indicate the diverse range of aeromonads that could potentially be associated with motile aeromonad septicaemia in ornamental fish. This is the first isolation of A. dhakensis from a septicaemic ornamental fish since its original description from the same host.
authors.affiliation: Laboratory of Aquatic Molecular Biology and Biotechnology, Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: S S S de S
authors.initials: SS
authors.lastname: Jagoda
authors.forename: T G
authors.initials: TG
authors.lastname: Wijewardana
authors.forename: A
authors.initials: A
authors.lastname: Arulkanthan
authors.forename: Y
authors.initials: Y
authors.lastname: Igarashi
authors.forename: E
authors.initials: E
authors.lastname: Tan
authors.forename: S
authors.initials: S
authors.lastname: Kinoshita
authors.forename: S
authors.initials: S
authors.lastname: Watabe
authors.forename: S
authors.initials: S
authors.lastname: Asakawa
mesh_terms: D000333:Aeromonas / Q000145:classification* / Q000187:drug effects*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005393:Fish Diseases / Q000382:microbiology; D005399:Fishes; D005618:Fresh Water; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D010802:Phylogeny; D058974:Phylogeography; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D018805:Sepsis / Q000382:microbiology / Q000662:veterinary*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S