What distinguishing feature do human Mycoplasma species possess?

Human Mycoplasma species are characterized by the absence of bacterial peptidoglycan in their cell walls. This feature is significant as it differentiates them from most other bacteria, which typically possess a robust peptidoglycan layer that contributes to their structural integrity and shape. Mycoplasmas are unique among prokaryotes because they contain sterols in their membranes, which are usually found in eukaryotic cells, and since they lack peptidoglycan, they do not respond to antibiotics that target this component, such as penicillin.

The absence of peptidoglycan enables Mycoplasmas to have varied shapes and sizes, often leading to their classification as pleomorphic organisms. This characteristic is key in understanding their biology and the challenges they present in clinical settings, particularly concerning treatment since traditional antibacterial therapies may not be effective against infections caused by Mycoplasma species.

In contrast to the other options: while Mycoplasmas do have some degree of immune evasion, they are not entirely non-immunogenic. Furthermore, some species can indeed be cultivated in vitro, although this process can be challenging. Staining characteristics also apply differently; not all Mycoplasma species stain well with Giemsa