When a bacteria like a spirochete loses its cell wall, it becomes incapable of holding its spiral shape. It becomes a sphere surrounded by a thin semi-permeable membrane. This round sphere is like the evil counter pare to the classical spiral form. Why evil? Well, when the bacterium sheds its cell wall, it also sheds several proteins that are markers to the human immune system. In other words, the immune system has trouble finding and recognizing this new form of the bacteria. It's almost like a criminal using disguises to change identities after each crime. Only this disguise is also bullet proof because, without a cell wall, antibiotics like Rocephin are useless.

What is also intriguing is the fact that these cell wall deficient forms (also known as L-forms) can be seen from time to time as reverting back to the classical form. This means the Lyme spirochete appears to be capable of turning off the genes that create cell walls when it is convenient to do so, and the CWD form can then produce the classical spiral form when it needs to.* Does the bacteria do this to avoid antibiotic therapy? Probably not. It might be an evolved mechanism to dodge mammalian immune systems, but it is doubtful it has specifically evolved a defense mechanism against antibiotics. Survival against antibiotics just happens to be a consequence of this particular evolutionary morphologic development.