Concentração inibitória mínima de oxitetraciclina para Aeromonas hydrophila isolada de pescado

Abstract

Aeromonas hydrophila is awide spread bacterium in water environments and it is associated with diseases in fishes and humans who acquire it through water and contaminated food. These bactéria can be a source of mobile genetic elements responsible for resistance to antibiotics. In Brazil, the use of oxytetracycline in pisciculture is common; however, the level of resistance of this pathogen to this particular antibiotic is not known. The aim of the present work is to determine the MIC (Minimal Inhibitory Concentration) of oxytetracycline for the A. hydrophila obtained from fishes meant for human consumptión, and to compare that profile with isolates of A. hydrophila originated from pond water and from outbreaks of hemorrhagic septicemia. Seventy samples of fresh and frozen fish from open markets and supermarkets from the Lavras city were collected. Arinse of the fish was carried out, and this was followed by serial dilution, spread-plating in dextrin-Ampicillin agar (ADA), and incubation at 30°C for 24 hours. No isolates were obtained from the frozen fish. From the fresh fish, there were 38 A. hydrophila isolates. These were submitted to the determiiiation for the oxytetracycline MIC together with 62 isolates of A. hydrophila originated from of hemorrhagic septicemia cases and pond water belonging to the bacterial culture collection of the UFLA Laboratório de Doenças de Animais Aquáticos (Laboratory of Diseases of Aquatic Animais of the Federal University of Lavras). The MIC results indicated that 14 of the 100 isolates have shown MIC higher than lOOug/ml (resistant) and the remaining lower than 12,5 ug/ml (sensitive). There was no difference in the distribution of MIC values amongst the isolates from fishes, clinicai cases and water. From the resistant isolates, 7 carne from fishes, 6 from the clinical case of hemorrhagic septicemia in fishes and only 1 from the pond water. It is concluded that the marketed fish can bea vehicle of A. hydrophila resistant to oxytetracycline in the human food chain.