ANTIMICROBIAL SUSCEPTIBILITY PATTERNS OF BACTERIAL ISOLATES AT THE AMERICAN-UNIVERSITY MEDICAL-CENTER IN LEBANON

In Lebanon, knowledge of the prevailing pattern of bacterial resistanc e to antimicrobial agents has been limited, particularly because of 15 years of civil strife. Thus, the current study was conducted to deter mine the antimicrobial susceptibility patterns of nonselected bacteria l isolates recovered from recent clinical specimens, using the standar dized disk agar diffusion technique. A total of 5216 isolates (1443 Gr am positive and 3773 Gram negative) were examined. Over 92% of Staphyl ococcus aureus and coagulase-negative staphylococci (CNS) were resista nt to penicillins. Methicillin resistance was more frequently noted am ong CNS (28%) compared with S. aureus (18%). For the pneumococci, 27% of the isolates were resistant to penicillin G. High but variable rate s of multidrug resistance were encountered among Acinetobacter spp., P seudomonas spp., Serratia spp., Citrobacter spp., and Enterobacter spp . Ampicillin resistance was detected in 65% of Escherichia coli and in 20% of Haemophilus influenzae isolates. Although one resistant Salmon ella typhi strain was observed, 17% of other Salmonella spp. and 60% o f Shigella spp, proved to be resistant to ampicillin, chloramphenicol, and cotrimoxazole. Among Vibrio cholerae isolates, high resistance to tetracycline (71%) and trimethoprim-sulfamethoxazole (94%) was observ ed. The overall antimicrobial resistance rates in Lebanon seem to fall between figures reported from the Arabian Gulf countries (higher) and those from medical centers in the United States (lower).