Lack of cell wall peptidoglycan versus penicillin sensitivity: new insights into the chlamydial anomaly.

Intracellular bacterial pathogens enter their hosts surrounded by a membrane-bound vacuole and use a panel of tricks to exploit or evade eukaryotic cell functions (9, 12). Chlamydia inhabits vesicles that do not fuse with lysosomes and remains within these parasitophorous vacuoles (termed inclusions) for the duration of its replication cycle. Although the biogenesis of these vacuoles is still poorly understood, it is becoming clear that the parasites which multiply within vacuoles modify those vesicles that arrest their maturation at discrete stages of the endocytic pathway, indicating more of a continuum along the endocyclic and lysosomal pathway than has been suspected in the past (18, 21, 30).