title: Surrogate disks for predicting cefotaxime and ceftriaxone susceptibilities of Streptococcus pneumoniae.
abstract: Cefotaxime- and ceftriaxone-resistant Streptococcus pneumoniae is now appearing in some medical centers, but 30-micrograms cefotaxime or 30-micrograms ceftriaxone disks are not reliable for detecting such strains. Studies were undertaken to select another cephalosporin disk that might be used as a screening test that could be used in conjunction with a 1-micrograms oxacillin disk. A 30-micrograms cefuroxime disk is proposed: strains with zones > or = 28 mm in diameter are predictably susceptible to cefotaxime and ceftriaxone, and those with smaller zones should be further studied to confirm resistance to either drug. A 30-micrograms ceftizoxime disk may also be used as a screening test with zones > or = 26 mm indicating susceptibility, but cefuroxime disks are preferred.
authors.affiliation: Clinical Microbiology Institute, Tualatin, Oregon 97062, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Barry
authors.forename: P C
authors.initials: PC
authors.lastname: Fuchs
mesh_terms: D002439:Cefotaxime / Q000494:pharmacology*; D002443:Ceftriaxone / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D006801:Humans; D011237:Predictive Value of Tests; D013296:Streptococcus pneumoniae / Q000187:drug effects*
chemical_list: D002511:Cephalosporins; D002443:Ceftriaxone; D002439:Cefotaxime