The terms "picket fence" and "Chinese letters" describe the common arrangement of cells for which organism?

The terms "picket fence" and "Chinese letters" refer specifically to the typical arrangement of cells seen in Corynebacterium species, particularly Corynebacterium diphtheriae. This organism exhibits a characteristic pattern when viewed under the microscope, often appearing as irregularly shaped rods that can align in a manner reminiscent of a picket fence or resemble Chinese characters due to their club-like shapes and angular arrangements.

This unique cellular arrangement is due to the way these bacteria divide; they exhibit a form of growth that leads to angular or V-shaped formations instead of separating completely after division, which leads to the distinctive patterns. These visual characteristics can help microbiologists identify Corynebacterium in clinical samples, differentiating it from other bacteria that do not present this arrangement.

In contrast, Bacillus cereus typically forms long chains of rod-shaped cells but does not exhibit the specific arrangements described by the terms "picket fence" or "Chinese letters." Staphylococcus aureus forms clusters resembling grapes, and Escherichia coli appears as single rods or in pairs, neither displaying the characteristic arrangements attributed to Corynebacterium.