title: Determination of trimethoprim-sulfamethoxazole resistance in Streptococcus pneumoniae by using the E test with Mueller-Hinton agar supplemented with sheep or horse blood may be unreliable. The Pneumococcal Study Group.
abstract: An international, multicenter study compared trimethoprim-sulfamethoxazole MICs for 743 Streptococcus pneumoniae isolates (107 to 244 isolates per country) by E test, using Mueller-Hinton agar supplemented with 5% defibrinated horse blood or 5% defibrinated sheep blood, with MICs determined by the National Committee for Clinical Laboratory Standards broth microdilution reference method. Agreement within 1 log2 dilution and minor error rates were 69.3 and 15.5%, respectively, on sheep blood-supplemented agar and 76.9 and 13.6%, respectively, with horse blood as the supplement. Significant interlaboratory variability was observed. E test may not be a reliable method for determining the resistance of pneumococci to trimethoprim-sulfamethoxazole.
authors.affiliation: National Centre for Streptococcus, Edmonton, Canada. ml@bugs.uah.ualberta.ca
authors.forename: M
authors.initials: M
authors.lastname: Lovgren
authors.forename: L
authors.initials: L
authors.lastname: Dell'Acqua
authors.forename: R
authors.initials: R
authors.lastname: Palacio
authors.forename: G
authors.initials: G
authors.lastname: Echániz-Aviles
authors.forename: A
authors.initials: A
authors.lastname: Soto-Noguerón
authors.forename: E
authors.initials: E
authors.lastname: Castañeda
authors.forename: C I
authors.initials: CI
authors.lastname: Agudelo
authors.forename: I
authors.initials: I
authors.lastname: Heitmann
authors.forename: M C
authors.initials: MC
authors.lastname: Brandileone
authors.forename: R C
authors.initials: RC
authors.lastname: Zanella
authors.forename: A
authors.initials: A
authors.lastname: Rossi
authors.forename: J
authors.initials: J
authors.lastname: Pace
authors.forename: J A
authors.initials: JA
authors.lastname: Talbot
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001769:Blood; D003470:Culture Media; D018432:Drug Resistance, Multiple / Q000235:genetics; D005069:Evaluation Studies as Topic; D006736:Horses; D006801:Humans; D008826:Microbial Sensitivity Tests; D012756:Sheep; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000302:isolation & purification; D013420:Sulfamethoxazole / Q000494:pharmacology; D014295:Trimethoprim / Q000494:pharmacology; D014296:Trimethoprim Resistance / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D014295:Trimethoprim; D013420:Sulfamethoxazole