Detection of pathogenic Aeromonas hydrophila from two rainbow trout ( Oncorhynchus mykiss ) farms in Peru.

Fish farms are one of the principal food industries located in peri-urban and rural communities that use available resources to ensure the quality of their products. However, trout can suffer from bacterial infections affecting the sector and being a key component of human health risk. We aimed to identify and characterize Enterobacteriaceae in 46 trout ( Oncorhynchus mykiss ) in two fish farms in Lima, Peru. Adult trouts older than seven weeks (> 200 grams weight) were included. Cultures were performed in duplicate (n=192 trials) with swabs from the squamous surface and visceral cavity. The isolates were identified with the Vitek® 2 Compact system, and the minimum inhibitory concentrations (MIC) were interpreted with the CLSI VET 03-A guide. At El Molino and El Angelito fish farms, 66 (68.8%) and 57 (59.4%) isolates were obtained. The most frequently isolated species were Escherichia coli (56.8%), Proteus sp. (4.2%) and Klebsiella pneumoniae (2.6%). E. coli was present in all sampling areas, and Aeromonas hydrophila was only present in one open viscera sample at El Angelito fish farm. A. hydrophila showed antibiotic resistance to Ampicillin/Sulbactam (≥32 MIC), Oxytetracycline (>8 MIC), Imipenem (8 MIC), Levofloxacin (>8 MIC), and Ceftazidime (≥64 MIC). Our results suggest the presence of multi-resistant A. hydrophila in O. mykiss . Further studies are needed to understand the developmental context of A. hydrophila, which is crucial to the food industry, aquaculture and public health.