CAMLPR Evaluation and Interpretation Competency Practice Test

The key idea here is recognizing a staining artifact and how it can mislead organism identification. The smear shows kidney‑bean shaped diplococci, a classic clue for Neisseria meningitidis, which are Gram‑negative diplococci. The reported result, however, is Gram‑positive cocci in pairs, which doesn’t fit that morphology at all. When the smear description and the simple biochemical clues don’t line up with what the organism should look like, a technical error is likely.

Under-decolorization during Gram staining is a common source of this mismatch. If the decolorizer is not used long enough, Gram‑negative organisms can retain the crystal violet and appear Gram‑positive. That would make Neisseria (true Gram‑negative diplococci) look like Gram‑positive cocci in pairs on the slide, explaining the conflicting data.

Because the Gram stain result is inconsistent with the expected morphology of the suspected pathogen, the correct action is to reject the questionable Gram stain and re‑stain the specimen with proper technique, then reassess. If needed, follow up with culture and additional tests (oxidase, carbohydrate utilization, selective media for Neisseria) to confirm the organism.

In short: the data point to a staining error (likely under-decolorization) causing a false Gram‑positive appearance, so repeat the Gram stain rather than rely on the initial result.