Mirrett S, Monahan J S, Reller L B
Diagn Microbiol Infect Dis. 1987 Mar;6(3):217-21. doi: 10.1016/0732-8893(87)90015-0.
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.
为评估培养环境和培养基对从咽喉培养物中分离A组（GA）链球菌的影响，我们比较了接种于三种血琼脂平板（BAP）上的1098份咽喉拭子。其中两个平板含有甲氧苄啶 - 磺胺甲恶唑（SXT），一个平板不含抗生素。不含抗生素的培养基平板和一个含SXT的平板在35℃厌氧（AnO2）培养，而另一个含SXT的平板在35℃有氧（O2）环境下培养。厌氧血琼脂平板（BAP - AnO2）检测出201株GA中的85%，而含SXT的厌氧平板（SXT - AnO2）为96%，含SXT的有氧平板（SXT - O2）为92%。在BAP - AnO2上，仅29%的β溶血菌落被确认为GA，而在SXT - AnO2上为53%，在SXT - O2上为44%。然而，SXT似乎会延迟GA的识别；因为BAP - AnO2在第1天发现94%的阳性，而SXT - AnO2和SXT - O2分别为80%和62%。我们得出结论，BAP - SXT（厌氧或有氧）比BAP - AnO2更敏感、更具特异性，但在所研究的SXT选择性培养基上，需要培养第二天才能最佳地回收GA。
