MCQ of the Day: 21 October 2026

Melioidosis is under-recognised but increasingly reported across India, especially in coastal states, during or after the monsoon. Exposure to soil and water is the main risk, along with diabetes, the strongest host risk factor. It is called the "great mimicker" because cavitary lung disease can resemble tuberculosis, and splenic or hepatic abscesses are a classic clue. In the laboratory, the safety-pin appearance, wrinkled colonies on Ashdown medium (crystal violet with gentamicin) and intrinsic resistance to aminoglycosides and polymyxins point to B. pseudomallei. Alert the laboratory, as it is a hazard group 3 organism.

• A. P. aeruginosa is also oxidase-positive, but it usually forms flat, spreading, pigmented colonies with a grape-like odour, does not show safety-pin staining and is normally susceptible to colistin.
• C. K. pneumoniae is oxidase-negative, non-motile and mucoid, and it does not grow on gentamicin-containing Ashdown medium.
• D. Y. pestis shows bipolar staining but is oxidase-negative, non-motile at 37 °C and does not fit this setting.