Which bacteria are arranged in curved lines resembling a string of beads and can cause infections?

The arrangement of bacteria in curved lines resembling a string of beads is characteristic of streptococci. These bacteria are gram-positive and are known for forming chains or pairs. They have the ability to cause various infections, including strep throat, scarlet fever, and skin infections. The bead-like arrangement is due to their method of division, where they divide in one plane but remain attached, forming chains.

While diplococci are arranged in pairs, they do not form the string-like structure described in the question. Bacilli are rod-shaped, and spirilla are spiral-shaped bacteria. These forms don't match the description of being arranged like beads. Thus, understanding the morphology and arrangement of streptococci helps identify their role in causing infections and differentiates them from other types of bacteria.