Escherichia coli isolated from seafood: toxicity and plasmid profiles.
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 enterotoxins were 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.
Teophilo
Grace Nazareth Diogo
GN
Instituto de Ciências do Mar-Labomar, Universidade Federal do Ceará, Meireles, Fortaleza, Brazil.
dos Fernandes Vieira
Regine Helena Silva
RH
dos Prazeres Rodrigues
Dália
D
Menezes
Francisca Gleire R
FG
D000818:Animals; D001427:Bacterial Toxins / Q000032:analysis; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004768:Enterotoxins / Q000032:analysis; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D029968:Escherichia coli Proteins; D005396:Fish Products / Q000382:microbiology; D010957:Plasmids / Q000032:analysis*; D017747:Seafood / Q000382:microbiology*; D012758:Shellfish / Q000382:microbiology
D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C034151:heat stable toxin (E coli); C027538:heat-labile enterotoxin, E coli