[Antimicrobial susceptibility of shiga toxin producing E coli (STEC) strains isolated from human infections and food].
BACKGROUND
Shiga toxin-producing E coli (STEC) are zoonotic pathogens associated to sporadic episodes of bloody diarrhea, foodborne outbreaks, and Hemolytic Uremic Syndrome (HUS), with worldwide public health impact. Antibiotic use in STEC infections is controversial because of the potential to increase production and secretion of Shiga toxins.


OBJECTIVE
To study the in vitro antimicrobial susceptibility profile of STEC.


METHODS
The in vitro susceptibility profile against 10 antimicrobials of STEC strains isolated from 29 meat products, 20 patients with diarrhea and 9 HUS patients was studied. Minimal Inhibitory Concentrations (microg/ml) by agar dilution method for ampicillin, cloramphenicol, ciprofloxacin, amikacin, gentamycin, cotrimoxazol, ceftriaxone, tetracycline, fonsfomycin and azihromycin were measured according to NCCLS recommendations.


RESULTS
Strains from patients with diarrhea or HUS were all susceptible to the 10 antimicrobials and only 13.7% had intermediate resistance to cloramphenicol. Strains from meat products had a similar susceptibility profile, with only 3.5% resistance to tetracycline, 3.5% intermediate resistance to cloramphenicol and 7% to fosfomycin. All 58 strains were considered resistant to azithromycin (MIC >32 microg/ml).


CONCLUSIONS
Similarity of susceptibility profiles between STEC strains from human and food origin suggests a role of food chain in transmission to humans.
Reyes
Marcelo S
MS
Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago de Chile.
Durán
Claudia T
CT
Prado
Valeria J
VJ
D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D003967:Diarrhea / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology; D019453:Escherichia coli O157 / Q000187:drug effects / Q000378:metabolism; D006463:Hemolytic-Uremic Syndrome / Q000382:microbiology; D006801:Humans; D008461:Meat Products / Q000382:microbiology; D022603:Shiga Toxins / Q000096:biosynthesis*
D000900:Anti-Bacterial Agents; D022603:Shiga Toxins