Resistenza ai principali antibiotici dei microrganismi isolati presso l’ospedale “Luigi Sacco” di Milano nel periodo 1997-2001

Antibiotic resistance of commonly isolated bacterial species at “L. Sacco” Hospital of Milan (Italy) is evaluated in the period 1997-2001. Staphylococcus aureus and Staphylococcus epidermidis are quite completely resistant to penicillin, while the agents with β-lactamase inhibitors are more active against Staphylococcus aureus than against Staphylococcus epidermidis. Also cephalotin and eritromycine are more active against Staphylococcus aureus than against Staphylococcus epidermidis. Cephalosporins are active against beta-haemolytic streptococci, while Streptococcus pyogenes shows a resistance of 25-30% against erytromicin. For Streptococcus pneumoniae there is a sporadic, not increasing, resistance to penicillin. Enterococcus faecalis shows an increasing resistance for the year 2001 against cotrimoxazole, but ampicillin and imipenem are always active against this species. Aztreonam is always active against Escherichia coli, while there is resistance to piperacillin (20-25%) and ampicillin (35-45%). Resistance to cephalotin is increasing in time, while cefotaxime is always active. For Haemophilus influenzae there is a certain resistance to ampicillin (10-20%). Pseudomonas aeruginosa is often resistant to widespectrum penicillins and to imipenem and ciprofloxacin (30%). With the only exclusion of a great increase of resistance of Enterococcus faecalis to cotrimoxazole in the year 2001, all the other patterns of resistance appear to be comparable in each of the five years considered. Substantially we do not observe an increase of antibiotic resistance.