Diagnostic Microbiology — Flashcards

Flashcard 51: The _____ is an agglutination test used to diagnose rickettsial infection

Answer: Weil-Felix test

Flashcard 52: Gram Negative Algorithm:Bacilli who are slow lactose fermenters include _____, Serratia

Answer: Citrobacter

Flashcard 53: _____zone phenomenon has excessive antigen in the test system, leading to weak or even absent precipitation.

Answer: Post

Flashcard 54: The Quantiferon Gold assay measures _____ levels released from T-cells exposed to Mycobacterium tuberculosis

Answer: IFN-gamma

Flashcard 55: Clostridium difficile is diagnosed via assay to detect _____ in stool or via PCR

Answer: toxins (A & B)

Flashcard 56: Gram Positive Algorithm:Staphylococcus Coagulase _____ is further broken into Novobiocin sensitivity (resistant or sensitive)

Answer: Negative

Flashcard 57: 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 58: _____ Agar will have lactose fermenting colonies (ie: E. coli) appear as a green metallic sheen

Answer: Eosin-Methylene Blue

Flashcard 59: Diagnosis of _____ occurs via microscopy of stool samples,with visualization of acid-fast oocysts.

Answer: Cryptosporidium

Flashcard 60: _____ Agar is a selective media for gram negative bacteria which contains bile salts to inhibit growth of gram positives

Answer: MacConkey's