TABLE 1.

Percentages of antimicrobial resistance among the heterotrophic bacteria recovered from water and fish samples in two eel farms and isolated on TSA, HE, and TCBS agar

SampleCounta% Resistant tob:
OTCNITOXASXT≥2 R
Total heterotrophic bacteria
    Farm 1
        Water
            Inlet1.5 × 1027.614.113.226.80
            Pond1.7 × 10744324133.360
            Outlet4.1 × 10741.353.449.58070
        Glass eel4.1 × 10617.628.615.275.750
        Eel intestine7.6 × 10718.83814.986.780
    Farm 2
        Water
            Inlet3.3 × 10319.423.420.830.40
            Pond4 × 10420.133.221.65025
            Outlet7.8 × 10519.334.82687.260
        Glass eel3.6 × 10525.539.611.870.345
        Eel intestine4.2 × 10718.227.222.575.470
Motile Aeromonas
    Farms 1 and 2
        Water
            Inlet725005020
            Pond92030107040
            Outlet1033.341.616.67558.3
        Glass eel944.333.311.141.666.6
        Eel intestine1258.35016.658.358.3
Salmonella
    Farm 1 (outlet water)333.31000100100
Vibrio furnissii
    Farms 1 and 2
        Glass eel54060206060
        Eel intestine933.377.522.233.377.5
Vibrio mimicus
    Farm 1 (water)
        Pond30100000
        Outlet30100066.666.6
  • a Counts of total heterotrophic bacteria are expressed as CFU ml−1, and counts of identified anaerobic facultative bacteria are expressed as number of strains isolated.

  • b Percentages of total heterotrophic bacteria are derived from differential plating on TSA medium with and without the respective drugs. Percentages of resistance of motile Aeromonas, Salmonella, V. furnissii, and V. mimicus were obtained after testing isolates by the agar diffusion method. ≥2 R, percentages of isolates resistant to two or more antibiotics.