SUSCEPTIBILITY TO NEW BETA-LACTAMS OF ENTEROBACTERIAL EXTENDED-SPECTRUM BETA-LACTAMASE (ESBL) PRODUCERS AND PENICILLIN-RESISTANT STREPTOCOCCUS-PNEUMONIAE IN MEXICO

The activities of several beta-lactam antimicrobial agents, aminoglyco sides and ciprofloxacin, were determined against 62 clinical isolates of enterobacteria resistant to oxyimino cephalosporins (extended-spect rum beta-lactamase producers), collected during 1991 to 1993, and 16 p enicillin-resistant invasive isolates of Streptococcus pneumoniae coll ected during 1994-1996. The numbers and percentages of susceptible ent erobacterial strains to tested antibiotics were: imipenem 60 (97%), ci profloxacin 57 (92%), cefepime 56 (90%), cefpirome 34 (55%), aztreonam 13 (21%), cefotaxime 7 (11%), ceftazidime 0 (0%), amikacin 11 (18%) a nd gentamicin 16 (26%). Despite the fact that these strains had never been exposed previously to cefepime or cefpirome, the susceptibility w as 90% and 55%, respectively. No penicillin-resistant strains of S. pn eumoniae were susceptible to cefotaxime, imipenem or cefepime. Only on e strain was susceptible to ceftazidime and 4 (25%) were susceptible t o cefpirome. Erythromycin showed the greatest activity with 12 (75%) s usceptible strains.