Escherichia coli isolated from seafood: toxicity and plasmid profiles

Authors

  • Grace Nazareth Diogo Teophilo Instituto de Ciências do Mar–Labomar, Universidade Federal do Ceará, Meireles, Fortaleza, Brazil
  • Regine Helena Silva dos Fernandes Vieira Instituto de Ciências do Mar–Labomar, Universidade Federal do Ceará, Meireles, Fortaleza, Brazil
  • Dália dos Prazeres Rodrigues Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
  • Francisca Gleire R. Menezes Instituto de Ciências do Mar–Labomar, Universidade Federal do Ceará, Meireles, Fortaleza, Brazil

Keywords:

Escherichia coli, enterotoxigenicity, seabob shrimp (Xiphopenaeus kroyeri), red snapper fish (Lutjanus purpureus), antimicrobial resistance

Abstract

Thirty-two Escherichia coli strains were isolated from red snapper (Lutjanus purpureus) and from seabob shrimp (Xiphopenaeus kroyeri). The strains were numbered S1–S16, and F1–F16, which corresponds to the isolation origin from shrimp (S) and fish (F). The isolates were biologically and antigenically characterized by agglutination tests with enteropathogenic E. coli (EPEC)-, enteroinvasive E. coli (EIEC)- and enterohemorrhagic E. coli (EHEC) O157-specific antisera. The ETEC enterotoxinswere characterized by GMI-ELISA for enterotoxin LT-1 (thermolabile) and by inoculation of supernatants prepared from newly born mice for enterotoxin Sta. A total of 14 strains produced exotoxins, of which seven were thermolabile (LT) and seven were thermostable (ST). Antimicrobial susceptibility profiles were determined by disc diffusion in agar using ampicillin, cephalothin, cefoxitin, ceftriaxone, imipenem, nalidixic acid, ciprofloxacin, chloramphenicol, gentamicin, nitrofurantoin, sulfamethoxazole–trimethoprim, and tetracycline. Four isolates showed lower susceptibility to some antibiotics, two strains were resistant to ampicillin, tetracycline, and sulfamethoxazole-trimethoprim, and two were resistant to tetracycline and nitrofurantoin. Plasmids were extracted in the four resistant isolates; two of them contained plasmids whose molecular weight varied from low to high. The characterization of LT- and ST-toxin-producing E. coli strains displaying multiresistance and containing plasmids suggests the need for tightening current control measures for the use of antimicrobials.

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Published

2010-03-10

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Section

Research Articles