ANTIMICROBIAL SUSCEPTIBILITIES AND BETA-LACTAMASE PRODUCTION OF SHIGELLA ISOLATES IN CRETE, GREECE, DURING THE PERIOD 1991-1995

The susceptibility to 11 antibiotics was determined for 52 strains of Shigella isolated from patients with diarrheal disease in Crete, Greec e, during the period 1991-1995. Forty-six percent of the isolates were resistant to ampicillin, 48% to tetracycline, 44.2% to chloramphenico l, and 28.8% to cotrimoxazole. Shigella flexneri was more resistant th an S. sonnei to ampicillin (82 vs 4.3%), to tetracycline (82 vs 8.7%) and to cotrimoxazole (42.8 vs 13%). Overall, 82% of all S. flexneri is olates were resistant to the three or four antimicrobial agents tested . The beta-lactamases produced by shigellae were identified by isoelec tric focusing and were found to be OXA-1, TEM-1, and a low-level beta- lactamase with a pI>8. The results from the present study, which is th e first carried out in Crete, emphasize the need for continuous survei llance of resistance and control of antibiotic usage.