Dynamics of resistance to cephalosporins.

Bacterial susceptibility to various cephalosporins of nine of the most frequently isolated organisms were analyzed for the five-year period 1980 to 1984. The disk diffusion susceptibility to cephalosporins of 1,640,031 strains of bacteria isolated from 242 hospitals in the United States were compared. No significant change has occurred in the susceptibility of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Haemophilus influenzae, or Streptococcus faecalis for this period; Enterobacter aerogenes showed a slight decrease in susceptibility to moxalactam, cephalothin, cefoxitin and cefamandole. Slight increases in susceptibility were observed with Pseudomonas aeruginosa to cefotaxime and moxalactam and for Bacteroides fragilis to cefoxitin and cefamandole. Staphylococcus aureus showed slight decreases in susceptibility to cefoperazone and ceftizoxime and slight increase to moxalactam.