Antibiotic-Resistant Vibrios in Farmed Shrimp

Antimicrobial susceptibility pattern was determined in 100 strains of Vibrio isolated from the Litopenaeus vannamei shrimp and identified phenotypically. A high antibiotic-resistance index (75%) was observed, with the following phenotypic profiles: monoresistance (n=42), cross-resistance to β-lactams (n=20) and multiple resistance (n=13). Plasmid resistance was characterized for penicillin (n=11), penicillin + ampicillin (n = 1), penicillin + aztreonam (n = 1), and ampicillin (n = 1). Resistance to antimicrobial drugs by the other strains (n=86) was possibly mediated by chromosomal genes. The findings of this study support the conclusion that the cultured shrimps can be vehicles of vibrios resistant to β-lactam and tetracycline.