II. Pathophysiology
- Chlamydiaceae is a family of Gram Negative Cocci with 2 genera
- Chlamydia
- Chlamydia Trachomatis is the primary species in the Chlamydia genus
- Chlamydia Trachomatis is the most common Sexually Transmitted Infection (STI) worldwide
- Chlamydophila
- Chlamydophila species are uncommon to rare organisms in human disease
- Chlamydophila psittaci (bird borne Zoonosis)
- Chlamydophila pneumoniae or TWAR (uncommon Atypical Pneumonia)
- Chlamydia
- Chlamydiaceae are more akin to viruses than Bacteria
- Tiny Gram Negative Cocci
- Chlamydia Elementary Body is only 300 nm (nearly the diameter of a large virus)
- Like other Bacteria, they have both DNA and RNA (while viruses have one or the other)
- Chlamydiaceae lack a peptidoglycan layer (unlike other Gram Negatives)
- However, they do contain an inner and outer membrane (as with other Gram Negative Bacteria)
- Lack of peptidoglycan layer renders Chlamydiaceae immune to attack from Penicillins
- Obligate intracellular Parasites
- Similar to viruses (as well as a few other Bacteria families including Rickettsiae)
- Chlamydiaceae rely exclusively on host cell energy production (via ATP-ADP Translocator)
- Contrast with Rickettsiae, which can also generate its own energy
- Chlamydiaceae can only be cultured in live media
- Cell culture
- Chick embryo Yolk Sac
- Tiny Gram Negative Cocci
- Chlamydiaceae exist in 2 forms
- Elementary Body (EB)
- Tiny, round infectious particle (300 nm)
- Strong outer membrane of disulfide cross-linked bonds
- Inert, non-dividing particle able to persist extracellularly between hosts
- Elementary body (EB) attaches to columnar epithelial cells on mucous membranes (e.g. vagina)
- EB enters the columnar cells via endosomes (endocytosis)
- EB inhibits Phagosome-Lysosome fusion on Phagocytosis
- Once intracellular, EB transitions to Initial Body (as below)
- Initial Body (IB, Reticulate Body)
- Starts with Elementary Body (EB) entering host cells via Phagocytosis
- Within host cells, EB triples its size (to 1000 nm), increasing RNA synthesis
- EB particles then divide via binary fission within host cells, forming Initial Bodies (IBs)
- IBs are the active infectious agent within cells
- Synthesize RNA
- Harvest energy from host cells via ATP-ADP Translocator
- Reproduce via binary fission
- Once IBs accumulate within the host cell, they form EBs to infect other cells
- Some IBs transform back into EBs, to exit the host cell and infect other cells
- Elementary Body (EB)
III. Types: Genus Chlamydia
- Organism
- Eye Diseases
- Chlamydial Conjunctivitis (Inclusion Conjunctivitis, serotypes D to K)
- Trachoma (Conjunctival scarring with blindness, serotypes A to C)
- Genitourinary Disease
- Lymphogranuloma venereum (serotypes L1 to 3)
- Non-Lymphogranuloma venereum (serotypes L1 to 3)
- Chlamydial Urethritis
- Chlamydial Cervicitis
- Chlamydial Pelvic Inflammatory Disease (including Salpingitis)
- Respiratory
- Chlamydia Pneumonia in Newborns (serotypes A to C)
IV. Types: Genus Chlamydophila
-
Chlamydophila psittaci (previously Chlamydia psittaci)
- Human Psittacosis from bird borne Zoonosis
- Respiratory illness or typhoidal illness
- Chlamydophila pneumoniae (TWAR)
V. References
- Gladwin, Trattler and Mahan (2014) Clinical Microbiology, Medmaster, Fl, p. 110-1
- Cheong (2019) Microorganisms 7(5):146 +PMID: 31137741 [PubMed]