Development of resistance in Shigella flexneri isolates obtained in the past 20 years in eastern Romania

Our study is focused on the antimicrobial activity for a number of 626 Shigella flexneri strains collected from epidemic outbreaks and hospitalised patients during 1976-1995 period, in Eastern Romania. The metodology used for determining the in vitro activity of the antimicrobials was that described by NCCLS. The agents which are currently used in therapy (ampicillin, tetracycline, chloramphenicol) are less active than the newer drugs (third generation cephalosporins, aztreonam, imipenem, ciprofloxacin) for which sensitivity ranged between 93-100% The associated resistance between ampicillin, tetracycline, chloramphenicol was demonstrated. Isolates with MIC values for ampicillin > 8 micrograms/ml are still sensitive to the modern beta-lactams. For ampicillin/sulbactam association, sensitivity decreases from 100% in 1990-1993 to 43% in 1994-1995.