title: [In vitro susceptibility of enterohemorrhagic Escherichia coli to 11 antimicrobials. Relationship between antibiotic resistance and toxigenic genotype].
abstract: Enterohemorrhagic E coli (EHEC) has been recognized as the main etiologic agent of hemorrhagic colitis and hemolytic uremic syndrome (HUS). The usefulness of antibiotic treatment in patients with EHEC infections is a matter of current debate. Knowledge on EHEC antimicrobial susceptibility patterns in different geographic areas is important for both treatment considerations and for strain characterization. We studied by diffusion disk agar technique the antibiotic susceptibility of 83 EHEC strains obtained from stools of patients with HUS or diarrhea. Eleven antimicrobials were tested (ampicillin, cotrimoxazole, tetracycline, chloramphenicol, furazolidone, gentamycin, amikacin, ciprofloxacin, erythromycin, vancomycin, and metronidazol). Resistant strains by disk diffusion were tested for MIC (mg/ml) by agar dilution. SLT-I and SLT-II were detected with specific biotinylated gene probes. All 83 strains were susceptible to furazolidone, ciprofloxacin, gentamycin and amikacin. Resistance was detected to tetracycline 4%, chloramphenicol 5%, cotrimoxazole 24% and ampicillin 25%. As expected for EHEC strains all were resistant to erythromycin, vancomycin, and metronidazol. Resistant strains were significantly more common in non toxigenic and SLT-I producing strains (p = 0.01). Resistant strains were similarly distributed among patients who had diarrhea only and those who developed HUS (p = 0.3). In Chile, resistant EHEC strains seem to be more common and of different genotypes than those reported in more developed countries. Regional differences of EHEC antibiotic susceptibility patterns indicate a need for continuous monitoring, specially if antibiotics prove to be useful in disease prevention.
authors.affiliation: Departamento de Microbiología, Universidad de Chile, Santiago.
authors.forename: V
authors.initials: V
authors.lastname: Prado
authors.forename: W
authors.initials: W
authors.lastname: Basualdo
authors.forename: C
authors.initials: C
authors.lastname: Arellano
authors.forename: J
authors.initials: J
authors.lastname: Martínez
authors.forename: M M
authors.initials: MM
authors.lastname: Levine
mesh_terms: D002675:Child, Preschool; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D005838:Genotype; D006463:Hemolytic-Uremic Syndrome / Q000382:microbiology / Q000517:prevention & control; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D007231:Infant, Newborn; D008826:Microbial Sensitivity Tests / Q000379:methods; D011247:Pregnancy
vernacular_title: Susceptibilidad in vitro de Escherichia coli enterohemorrágicas frente a 11 antimicrobianos. Relación entre resistancia antibiótica y genotipos toxigénicos.