Nosocomial infection caused by gentamicin-resistant, streptomycin-sensitive Klebsiella.

Resistance to gentamicin increased abruptly among nosocomial isolates of Klebsiella and Enterobacter at the New York Veterans Administration Hospital in 1973 and 1974. A prospective clinical survey revealed a greater incidence of true infection caused by Klebsiella than by Enterobacter. The initial site of implantation was usually the urinary tract. Multiple serotypes were involved, and one of these was found in rectal swabs of patients treated with antibiotics. Gentamicin resistance declined rapidly after the use of this antibiotic was restricted and increased several months after restrictions were removed. Gentamicin-resistant strains of Klebsiella were uniformly sensitive to amikacin; 75% were sensitive to polymyxin B and 70% to streptomycin. Antibiotic sensitivity among gram-negative pathogens might be preserved by a program in which the use of highly effective agents is periodically rotated.