title: Resistance to beta-lactam antibiotics in Aeromonas hydrophila isolated from rainbow trout (Oncorhynchus mykiss).
abstract: Bacterial infections caused by members of the genus Aeromonas, with a relatively high antibiotic resistance, are among the most common and troublesome diseases of fish raised in ponds with recirculation systems. In this study, carried out at an experimental aquaculture station in northern Portugal, 51 strains identified as belonging to the genus Aeromonas were isolated from 20 rainbow trout (Oncorhynchus mykiss) skin and kidney samples, as well as from raceway water samples. Macro- and microscopic examination of the fish tissues revealed lesions or cellular alterations in skin and kidney that seemed to correlate with the presence of those isolates. The sensitivity of all isolated strains to different groups of beta-lactam antibiotics (penicillins, cephalosporins, monobactams and carbapenems) was evaluated using the disc diffusion method. The highest rates of resistance were to amoxicillin, carbenicillin and ticarcillin. Unexpected resistance to imipenem, an antibiotic of clinical usage, was also detected, which suggests that resistance may have been transferred to the Aeromonas population from the environment.
authors.affiliation: Department of Veterinary Sciences, CECAV-University of Tras-os-Montes e Alto Douro, Vila Real, Portugal. saavedra@utad.pt
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Saavedra
authors.forename: Sandra
authors.initials: S
authors.lastname: Guedes-Novais
authors.forename: Anabela
authors.initials: A
authors.lastname: Alves
authors.forename: Paulo
authors.initials: P
authors.lastname: Rema
authors.forename: Marta
authors.initials: M
authors.lastname: Tacão
authors.forename: António
authors.initials: A
authors.lastname: Correia
authors.forename: Antonio
authors.initials: A
authors.lastname: Martínez-Murcia
mesh_terms: D016980:Aeromonas hydrophila / Q000187:drug effects* / Q000302:isolation & purification; D000818:Animals; D024881:Drug Resistance, Bacterial; D005393:Fish Diseases / Q000382:microbiology; D007769:Lactams / Q000494:pharmacology*; D017686:Oncorhynchus mykiss / Q000382:microbiology*; D012883:Skin Ulcer / Q000382:microbiology / Q000662:veterinary; D018440:beta-Lactam Resistance
chemical_list: D007769:Lactams