Antibiotic-resistant enteric bacteria (Escherichia coli, Klebsiella-Aerobacter-Serratia, Salmonella, and Shigella) can transfer resistance to sensitive bacteria during bacterial conjugation (mating). The genetic element, responsible for both mating and resistance, is extrachromosomal deoxyribonucleic acid, known as an R factor. Genes responsible for resistance to ampicillin, tetracyclines, chloramphenicol, kanamycin, streptomycin, and sulfonamides may be linked on a single R factor.
Nosocomial infections with antibiotic-resistant E. coli and Klebsiella-Aerobacter-Serratia are common at our hospital. In the resistant bacteria causing these infections, 27% of the ampicillin, 72% of the tetracycline, 91% of the chloramphenicol, 72% of the streptomycin, and 81% of the kanamycin resistance were