Quantitative susceptibility testing with intra- and extramural Escherichia coli strains
Kwantitatief gevoeligheidsonderzoek met intra- en extramurale isolaten van Escherichia coli
de Neeling AJ, de Jong J, Overbeek BP, de Bruin RW, Dessens-Kroon M, van Klingeren B
RIVM Report 359001002
Three Dutch laboratories for medical microbiology collected a total number of 1432 strains of Escherichia coli. Of these 995 were obtained from routine samples taken in clinic and policlinic, 290 had been sent spontaneously by general practitioners for microbiological examination and 147 had been isolated from the urine of out-patients who had not been treated with antibiotics for at least six months. The highest resistance percentages were found for the older orally administered antibiotics in the strains that had been sent spontaneously by general practitioners. Resistance percentages were lowest, but still considerable, in the isolates obtained from patients who had not been treated with antibiotics: amoxycillin 20%, doxycycline 23%, sulfamethoxazole 32%, trimethoprim 10% and cotrimoxazole 10%. The level of resistance in clinic and policlinic was in between the levels in the two categories obtained from general practitioners. The resistance percentages for the other investigated antibiotics (Augmentin, cefazolin, cefaclor, cefamandole, cefuroxime, ceftazidime, imipenem, gentamicin, pipemidic acid, norfloxacin and nitrofurantoin) were lower than 7%. An explanation for the high level of resistance in the strains sent spontaneously by general practitioners is that they generally request susceptibility testing only if previous antibiotic therapy has failed.