Differences in antimicrobial susceptibilities of clinical isolates in Saudi Arabia and the United States.

In vitro antimicrobial susceptibilities of 3,530 clinical isolates at King Faisal Specialist Hospital and Research Center (KFSH), in Riyadh, Saudi Arabia, were compared with those of 11,041 bacterial isolates at two hospitals of comparable size in the United States. The gram-negative bacteria, especially Escherichia coli, Proteus-Morganella group, Enterobacter sp, Serratia marcescens, and Pseudomonas aeruginosa were generally more resistant to ampicillin, carbenicillin, cephalosporin, gentamicin, piperacillin, and trimethoprim-sulfamethoxazole at KFSH than in the United States. A larger number of isolates of Klebsiella pneumoniae were more resistant to cephalosporin, chloramphenical, gentamicin, piperacillin, and trimethoprim-sulfamethoxazole at one of the tertiary care hospitals in the United States. Hemophilus influenzae and gram-positive cocci exhibited similar susceptibilities toward commonly used antibiotics at all three institutions.