Kligler iron agar (KIA) differs from triple-sugar iron agar (TSI) in which aspect?

Kligler iron agar (KIA) is specifically formulated without sucrose, unlike triple-sugar iron agar (TSI), which contains sucrose along with glucose and lactose. This difference in composition is significant because TSI is designed to differentiate between organisms that can ferment more than one type of sugar. KIA primarily focuses on glucose and lactose fermentation, which allows it to effectively identify certain Enterobacteriaceae that typically ferment these sugars.

The presence of sucrose in TSI can affect the interpretation of results since it serves as an additional fermentable sugar, potentially influencing acid production and gas formation. Therefore, selecting KIA or TSI depends on the specific microbiological tests being conducted and the types of fermentative activities that need to be distinguished.

The ability to detect H2S production is found in both media, so this aspect isn't unique to KIA. Furthermore, both KIA and TSI show color changes that indicate acid production, such as yellow color due to sugar fermentation, meaning the latter choices do not elucidate the primary difference between these two agar types. Hence, the distinction in the use of sucrose clearly sets KIA apart from TSI.