title: Comparison of three commercial MIC systems, E test, fastidious antimicrobial susceptibility panel, and FOX fastidious panel, for confirmation of penicillin and cephalosporin resistance in Streptococcus pneumoniae.
abstract: The performances of three commercial broth microdilution MIC assays adapted for use with fastidious organisms--the E test (ET), Fastidious Antimicrobial Susceptibility panel (FAS), and FOX Fastidious panel (FOX)--were compared with a MIC using Mueller-Hinton broth with 5% lysed horse blood (MHLHB) to confirm penicillin and cephalosporin resistance in clinical isolates of Streptococcus pneumoniae. Of the isolates screened for penicillin resistance, 5 (12.8%) were categorized as susceptible, 16 (41.0%) were categorized as intermediate, and 18 (46.2%) were categorized as resistant by MHLHB. Only the isolates exhibiting intermediate-to-resistant MICs were included in the comparison. Agreement within +/- 1 log2 dilution was found in 91, 21, and 76% of the ET, FAS, and FOX MICs, respectively, compared with the MHLHB MIC. No very major or major discrepancies occurred with the ET or FOX; however, two very major interpretive errors occurred with the FAS. Agreement between the ET and MHLHB for cefotaxime, ceftriaxone, and cefuroxime was 88, 85, and 100%, respectively. Less than 50% of cephalosporin MICs categorized as > 0.5 microgram/ml by MHLHB were detected by FAS or FOX. Of the methods compared, the ET was the most reliable alternative for susceptibility testing of pneumococci.
authors: Children's Medical Center of Dallas, Texas 75235.
authors: K K
authors: KK
authors: Krisher
authors: A
authors: A
authors: Linscott
mesh_terms: D002439:Cefotaxime / Q000494:pharmacology; D002444:Cefuroxime / Q000494:pharmacology; D018550:Cephalosporin Resistance; D006801:Humans; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance; D011008:Pneumococcal Infections / Q000382:microbiology; D013296:Streptococcus pneumoniae / Q000187:drug effects*
chemical_list: D002439:Cefotaxime; D002444:Cefuroxime