Comparative evaluation of medium and atmosphere of incubation for isolation of Streptococcus pyogenes.

Published

Journal Article

To evaluate the effects of medium and atmosphere of incubation for the isolation of group A (GA) streptococci from throat cultures, we compared 1098 throat swabs plated on each of three blood agar plates (BAP). Two plates contained trimethoprim-sulfamethoxazole (SXT) and one had no antibiotics. The antibiotic-free medium and one SXT plate were incubated anaerobically (AnO2) at 35 degrees C, whereas the other SXT plate was incubated in air (O2) at 35 degrees C. The BAP-AnO2 identified 85% of 201 GA compared with 96% for SXT-AnO2 and 92% for SXT-O2. GA were confirmed from only 29% of the beta-hemolytic colonies on BAP-AnO2 compared with 53% from SXT-AnO2 and 44% from SXT-O2. SXT, however, appeared to delay recognition of GA; since 94% of positives were found on day 1 with BAP-AnO2 versus 80% and 62% with SXT-AnO2 and SXT-O2, respectively. We conclude that BAP-SXT (AnO2 or O2) is more sensitive and more specific than BAP-AnO2, but that a second day of incubation is required for optimal recovery of GA on the SXT selective media studied.

Full Text

Duke Authors

Cited Authors

  • Mirrett, S; Monahan, JS; Reller, LB

Published Date

  • March 1, 1987

Published In

Volume / Issue

  • 6 / 3

Start / End Page

  • 217 - 221

PubMed ID

  • 3552389

Pubmed Central ID

  • 3552389

International Standard Serial Number (ISSN)

  • 0732-8893

Language

  • eng

Conference Location

  • United States