Diagnostic Microbiology — Flashcards

Flashcard 61: Contents of MacConkey agar (Mnemonic: **PLANT**) **P**: _____ **L**: Lactose **A**: Agar **N**: Neutral red **T**: Sodium taurocholate

Answer: Peptone

Extra: MacConkey agar is both **selective** and **differential**. - **Selective**: Bile salts (sodium taurocholate) and crystal violet inhibit the growth of most Gram-positive bacteria. - **Differential**: Lactose and neutral red (pH indicator) distinguish between lactose fermenters (pink/red colonies) and non-lactose fermenters (pale/colorless colonies).

Flashcard 62: _____ reaction is an example of a neutralisation test.

Answer: Naglers

Flashcard 63: Modified Thayer-Martin (MTM) agar contains _____ and Colistin (polymyxin) to inhibit Gram-negative organisms.

Answer: Trimethoprim

Flashcard 64: _____ stain is used to stain the fungi Pneumocystis pneumonia and Coccidioides (coccidioidomycosis), as well as the bacteria Legionella and H. pylori

Answer: Silver (methenamine)

Flashcard 65: The Ziehl-Neelsen stain is used to stain the bacteria _____ and Nocardia, as well as the protozoa Cryptosporidium (its oocysts)

Answer: mycobacterium (ie: TB, leprosy)

Flashcard 66: _____ Agar has a similar function to that of MacConkey agar, as it also inhibits gram positive bacteria growth

Answer: Eosin-Methylene Blue

Flashcard 67: Diagnosis of Adenovirus is made via _____ or cell culture

Answer: serology

Flashcard 68: _____ Agar is used to identify Legionella

Answer: Buffered Charcoal Yeast Extract (BCYE)

Flashcard 69: _____ Agar contains NAD+ (factor V) and hematin (factor X) which are release when the RBCs are lysed

Answer: Chocolate

Flashcard 70: Gram Positive Algorithm:Streptococcus _____-hemolysis is further broken down via Bacitracin sensitivity (resistant/sensitive)

Answer: beta