Antimicrobial susceptibility of Escherichia coli isolated from shrimp ( Litopenaeus vannamei) and pond environment in northeastern Brazil

Abstract

This study aimed to test the susceptibility ofEscherichia colistrains isolated from the water, bottom sediments and individualscultivated in shrimp farm ponds, to antibiotics belonging to different families, namely B-Lactams: Imipenem (IPM; 10μg), Ampi-cillin (AMP; 10μg), Cephalothin (CEP; 30μg), Cefoxitin (FOX; 30μg), Ceftriaxone (CRO; 30μg); Tetracycline: Tetracycline(TCY; 30μg); Aminoglycosides: Gentamicin (GEN; 10μg), Amikacin (AMK; 30μg); Chloramphenicol: Chloramphenicol (CHO;30μg); Fluoroquinolones: Ciprofloxacin (CIP; 5μg); Nitrofurans: Nitrofurantoin (NIT; 300μg); Sulfonamides: Trimethoprim-Sulfamethoxazole (SXT; 30μg); Quilononas: Nalidixic Acid (NAL; 30μg). In the laboratory, the method of dissemination (TestKirby-Bauer) was performed in order to fulfill the antibiogram tests. The results showed high indices of resistance to Imipenem,Cephalothin and Ampicillin. Chloramphenicol, Nitrofurantoin, Cefoxitin, Ceftiaxone and Ciprofloxacin have displayed the highestindex of sensitive strains. The antibiotic resistance index (ARI) and the multiple resistance index (MAR) varied within the ranges of0.068–0.077 and 0.15–0.39, respectively. More than 90.5% of strains ofEscherichia colishowed a variety of resistance profiles to thetested antibiotics. The high indices of resistance may be a consequence of indiscriminate use of antibiotics, but also the transfer ofresistance through mobile genetic elements found in shrimp farms