Which bacterium is known for causing infections that lack a cell wall?

Mycoplasma is notable for causing infections without having a cell wall, which is a unique characteristic among bacteria. This organism belongs to a class of bacteria known as Mollicutes and is distinguished by its minimalistic structure. The absence of a cell wall gives Mycoplasma certain advantages, such as resistance to antibiotics that target cell wall synthesis, like penicillin. Additionally, this lack of a rigid cell wall allows Mycoplasma to adopt various shapes, contributing to its ability to evade the immune system and persist in host environments.

Treponema pallidum, Escherichia coli, and Staphylococcus aureus all contain a cell wall, which is critical for maintaining their shape and protecting them from environmental stresses. Escherichia coli and Staphylococcus aureus are classified as Gram-negative and Gram-positive bacteria, respectively, both characterized by their cell wall composition that impacts their reactions to staining and antibiotic sensitivity. Treponema pallidum, although a unique bacterium with a complex structure, still possesses a form of cell wall, even if it's not conventional. Therefore, Mycoplasma stands out as the sole example in this context of bacteria causing infections without a cell wall.