Chlamydia

Chlamydia (Murray 3^rd Ed pp 362)

These belong to a family called Chlamydiaceae, and consist of four species. They are non-motile, gram-negative, obligate intracellular bacteria. They persist within the host cytoplasm. Unlike other bacteria, Chlamydia lack a peptidoglycan layer, but like other bacteria possess both DNA and RNA. They replicate by binary fission.

Developmental cycle (Murray 3^rd Ed pp 362)

Chlamydia exist in two morphologically distinct states: elementary body (EB), and reticulate body (RB). The elementary body attaches to susceptible cells (microvilli), then penetrate the cell actively. The phagolysosome remains intracellularly, and replication begins. They now reorganise into the RB, and these replicate by binary fission. The phagosome now contains many-replicated Chlamydia, and is now called an inclusion. Now the RBs reorganise back into EBs, and the cell ruptures giving off many EBs for further infection.

Systematics (Murray 3^rd Ed pp 362)

Chl. Psittaci, Chl. Trachomatis, Chl. Pneumoniae. (4^th species, Chl. Pecorum – rarely isolated).

Pathogenesis (Murray 3^rd Ed pp 363)

The bacteria gain access to intracellular space, replicate and upon lysing the cell get released into the tissues for further infection. The cell damage is called by HSP 60, which causes an inflammatory response (neutrophils, lymphocytes, plasma cells), initiated by the body and together both cause the sustained damage.

Category: Microbiology Notes