Nosocomial gram-negative bloodstream isolates: a comparison of in vitro antibiotic potency.

Nosocomial bloodstream infections add to the morbidity, mortality and length of hospitalization that is attributed to the underlying diseases alone. We have compared the in vitro potency of fifteen antibiotics against 136 isolates from clinically significant nosocomial gram-negative bacteraemias. Ciprofloxacin was the most potent antibiotic and had the broadest spectrum of activity (98% of isolates susceptible, MIC90 range: 0.06-0.5 micrograms ml-1). We subjected all isolates to beta-lactamase induction but antibiotic susceptibility was unaffected by this procedure.