The susceptibility of nosocomial pathogens to ceftazidime

The activities in vitro of ceftazidime and of cefuroxime have been compared against 201 strains of bacteria which had been isolated either from outbreaks of nosocomial infection or were typical of strains causing such outbreaks. Ceftazidime was found to be about 1000 times more active against Pseudomonas spp. and Proteus vulgaris, and between 10 and 100 times more active against Klebsiella pneumoniae, Enterobacter spp., Citrobacter freundii, Serratia marcescens, Proteus rettgeri, Proteus morganii, Providencia stuartii, Alcaligenes faecalis and Acinetobacter spp. On the other hand, cefuroxime was more active against Staphylococcus epidermidis. An increase in inoculum size to 106 had little effect on the activity of ceftazidime, except in the case of Pr. vulgaris strains, which grew, although only to a very limited extent, even in the presence of high concentrations of ceftazidime. Anaerobic and hypercapnic conditions did not adversely affect the activity of ceftazidime. Our in-vitro results thus indicate that ceftazidime had as broad a spectrum as gentamicin, and is more intrinsically active.