A total of 31 Aeromonas hydrophila isolates from cultured Nile tilapia (Oreochromas niloticus) were investigated for the effect of different frequencies of electromagnetic fields (EMFs). The isolates were investigated for their susceptibility to fourteen antimicrobial agent and (2.9 X 102CFU/ml) Aeromonas hydrophila viable count was introduced into the water of seven aquaria (each contains 25 fish), the aquaria then exposed to different strengths of electromagnetic fields and the bacterial content was evaluated in the water samples after 5,15.30 and 60 minutes. The total psychrotrophic count was also determined in the fish flesh after their storage in the ice for 0,24,72,120 and 168 hours. Most of the isolates were multidrug-resistant. The number of viable Aeromonas hydrophila was significantly decreased upon exposure to alternative low-frequency electromagnetic field (20 hz) when compared with the control and the other EMFs exposed aquaria. Psychrotrophic count of tilapia was significantly low in the electromagnetic treated Nile tilapia fish. The implementation of electromagnetic field as a new control impairing the growth of pathogenic Aeromonas hydrophila among Nile tilapia may be one of the potential measures and alternative approach to antimicrobials. However, further investigations should be implemented.
Aeromonas hydrophila, Nile tilapia, electromagnetic fields
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